Kyushu University Academic Staff Educational and Research Activities Database
List of Papers
Masamichi Kohno Last modified date:2023.06.26

Professor / Thermal eingineering / Department of Mechanical Engineering / Faculty of Engineering


Papers
1. Cheng Shao, Kensuke Matsuda, Shenghong Ju, Yoshifumi Ikoma, Masamichi Kohno, Junichiro Shiomi, Phonon transport in multiphase nanostructured silicon fabricated by high-pressure torsion, JOURNAL OF APPLIED PHYSICS, 10.1063/5.0037775, 129, 8, 2021.02, We present a combined experimental and numerical investigation of phonon transport in multiphase nanostructured silicon. The sample was synthesized by high-pressure torsion with a nominal pressure of 24GPa. Based on the x-ray diffraction measurement, we have identified the existence of three phases of silicon in the sample: Si-I, Si-III, and Si-XII, with volume fractions of 66%, 25%, and 9% and average grain sizes of 25, 14, and 11nm, respectively. The measured thermal conductivities of the sample in the temperature range of 150-330K are on the order of 5W/(mK) and exhibit weak temperature dependence. A multiscale modeling that incorporates first-principles lattice dynamics, the Monte Carlo ray-tracing method, and effective medium theory was used to understand the mechanism of phonon transport in multiphase nanostructured silicon as well as the weak temperature dependence. We found that the thermal conductivity of single-phase nanostructured silicon decreases with decreasing average grain size and is about an order of magnitude lower than the corresponding bulk counterpart when the average grain size isO (10The weak temperature-dependent thermal conductivity in the nanostructured silicon is attributed to the strong elastic phonon-boundary scattering at the grain boundary. The thermal conductivity predicted from the multiscale modeling matches reasonably well with the measurement. This work provides insights into phonon transport in multiphase nanostructured materials and suggests that the effective thermal conductivity of nanostructured silicon from high-pressure torsion can be further reduced by increasing the volume fractions of the Si-III and Si-XII phases..
2. Sarthak Nag, Yoko Tomo, Koji Takahashi, and Masamichi Kohno, Mechanistic Insights into Nanobubble Merging Studied Using In Situ Liquid-Phase Electron Microscopy, Langmuir, 10.1021/acs.langmuir.0c03208, 37, 874-881, 2021.01.
3. Kengo Tsukamoto, Yutaku Kita, Shinya Inoue, Takafumi Hamanosono, Sumitomo Hidaka, Satoshi Ueoka, Hiroyuki Fukuda, Masamichi Kohno, Yasuyuki Takata, On the onset of quench during spray cooling: The significance of oxide layers, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2020.115682, 179, 2020.10, The effect of thermally-insulating layer, particularly oxide layer as found in metallurgical applications, on the water spray-cooling process was discussed. Such layers have been found to increase the quenching temperature at which the sprayed liquid begins to contact the hot surface, greatly increasing the cooling rate. The conventional, thermal-resistance based model can predict the shift of the quenching point qualitatively, albeit significant deviations remain due to the lack of fundamental understanding of the onset of liquid-solid contact. In the present paper, we conducted two sets of experiments in an attempt to shed light on the quench mechanism and the effect of oxide layer. First, we compared temperature histories during spray cooling of a stainless-steel plate with various oxide layers. The quench temperatures varied depending both on the composition and the thickness of the oxide layer. Additionally, quench was observed at temperatures as high as 350 degrees C, exceeding the thermodynamic wetting limit. Then, we moved on to single droplet impingement experiments to investigate the change of droplet behavior with respect to the surface temperature in detail. High-speed imaging allowed us to identify the transition of droplet impact behavior i.e. deposition and bouncing, which also occurred at different wall temperatures depending on the composition of oxide layer. Subsequently, we calculated the contact surface temperature assuming the transient heat conduction for a contact between two semi-finite bodies. As a consequence, the onset of droplet behavior transition was always found at the contact surface temperature of ca. 250 degrees C regardless of the composition and thickness of the oxide layer. The difference between the contact surface temperature and the wall temperature increased as the thermal effusivity of the oxide layer decreased, which was a direct cause of the inconsistent "apparent" quenching temperature..
4. A. Widyaparaga, T. Hiromatsu, Deendarlianto, M. Kohno, Y. Takata, Acoustic field alteration in a 100 Hz dual acoustic driver straight tube travelling wave thermoacoustic heat pump for thermoacoustic heat transport control, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2019.119274, 151, 2020.04, A dual acoustic driver thermoacoustic heat pump was constructed to investigate the effect of acoustic field control on travelling wave thermoacoustic heat transport at a frequency of 100 Hz. The acoustic field was controlled by varying the phase difference and magnitude between the two drivers. Variation of phase difference demonstrated the change of both acoustic power flow direction and standing-travelling wave characteristics. Maximum temperature differences obtained between the ends of the regenerator were 23 °C and 19 °C when the acoustic power was flowing in the negative and positive directions, respectively. It has been shown that matching impedances on the cold and hot side of the regenerator influence the thermoacoustic heat pumping characteristics. Where monodirectional acoustic flow was observed on both sides of the regenerator, the impedance angles also coincided well. Variation of magnitude displayed a trend in which activation of an opposing acoustic driver at weaker power enhanced acoustic power flow and heat transport. A maximum temperature difference between the hot and cold sections of 23 °C is obtained when the input electric power of the opposing acoustic driver was 17% of the power of the initial acoustic driver where the impedances and impedance angles on both ends of the regenerator are matched but the acoustic field travelling wave characteristics are still sufficient for travelling wave device operation..
5. Qinyi Li, Koki Katakami, Tatsuya Ikuta, Masamichi Kohno, Xing Zhang, Koji Takahashi, Measurement of thermal contact resistance between individual carbon fibers using a laser-flash Raman mapping method, Carbon, 10.1016/j.carbon.2018.09.034, 141, 92-98, 2019.01, Thermal contact resistance (TCR) between individual carbon fibers (CFs) can dominate heat dissipation rates in CF-based composite materials. Here, we develop a totally non-contact “laser-flash Raman mapping” method to simultaneously measure the TCR at the CF-CF junction and their thermal conductivities. Laser power is used to heat the sample and the laser absorptivity is experimentally determined by a transient laser-flash Raman technique. The laser heating positions are changed along two connected CFs, and the change of temperature rise with varying positions is in-situ measured from the temperature dependent Raman band shifts. The high spatial resolution of the micro-Raman mapping allows direct observation of the abrupt jump of thermal resistance at the CF-CF junction, from which we extracted the TCR as well as the thermal conductivity. The laser absorptivity of the 11 μm-diameter CFs is measured to be 0.12 ± 0.03, the thermal conductivities of the individual CFs are around 200 W/mK, and the TCR of the CF-CF junction is (2.98 ± 0.92) × 105 K/W. This work provides indispensable knowledge for the design of CF-based composite for thermal management, and the novel non-contact measurement method can stimulate characterization and manipulation of contact/interface heat conduction between various micro- and nano-materials..
6. Bumsoo Chon, Yoshifumi Ikoma, Masamichi Kohno, Junichiro Shiomi, Martha R. McCartney, David J. Smith, Zenji Horita, Impact of metastable phases on electrical properties of Si with different doping concentrations after processing by high-pressure torsion, SCRIPTA MATERIALIA, 10.1016/j.scriptamat.2018.08.011, 157, 120-123, 2018.12, Si (100) wafers with various doping levels were subjected to high-pressure torsion (HPT). The resistivities for all doping levels increased by one or two orders of magnitude after initial compression, but then decreased after 10 revolutions of HPT processing to similar to 0.1 Omega cm for normally and heavily doped samples, and to similar to 0.02 Omega cm for the ultraheavily doped sample. After annealing at 873 K, the resistivities increased by four orders of magnitude compared to the original Si wafers. These results indicate that the formation of metastable phases plays an important role in the electrical resistivities of HPT-processed samples. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved..
7. Deendarlianto, Yasuyuki Takata, Arif Widyatama, Akmal Irfan Majid, Ardi Wiranata, Adhika Widyaparaga, Masamichi Kohno, Sumitomo Hidaka, Indarto, The interfacial dynamics of the micrometric droplet diameters during the impacting onto inclined hot surfaces, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2018.05.023, 126, 39-51, 2018.11, The interfacial dynamics of the micrometric size liquid droplets during impact onto inclined hot surfaces have been experimentally studied. The inclination angles were varied at 15° 30° and 45° from horizontal for surface temperatures were decreasing from 500 °C to 100 °C. The droplet diameters tested were 500 μm and 700 μm. The tested material was stainless steel-grade 304 (SUS 304) with varying surface roughness ranging from Ra 0.04 up to Ra 10. The interfacial dynamics during the impact onto inclined hot surfaces were investigated by using a high-speed video camera with the frame speed of 15,000 fps. The objectives of this study are to provide insight into the dynamic behaviors of contact angles and dependence of importance parameters at various surface temperatures. It was found that depending on the surface temperature the droplet evaporation and its bouncing process play an important role on the droplet detachment mechanisms from the inclined surface. Three transient regions of the interfacial evolution during the micrometric droplets impacting onto oblique hot surface were identified. Moreover, the contribution of the important physical parameters, such as, advancing and receding contact angles on the interfacial dynamics are presented..
8. Alexandros Askounis, Huacheng Zhang, Dejian Zhang, Yutaku Kita, Gyoko Nagayama, Masamichi Kohno, Yasuyuki Takata, K. Sefiane, UNVEILING THERMOCAPILLARY CONVECTION IN PURE WATER DROPS, Proceedings of the 16th International Heat Transfer Conference 16, 10.1615/IHTC16.bae.023953, 809-814, 2018.08.
9. Alexandros Askounis, Huacheng Zhang, Dejian Zhang, Yutaku Kita, Gyoko Nagayama, Jungho Kim, Masamichi Kohno, Yasuyuki Takata, Khellil Sefiane, Influence of localised heating on thermocapillary convection of pure water drops, Proceedings of the 16th International Heat Transfer Conference, IHTC16-23953, 2018.08.
10. Yutaku Kita, Yuya Okauchi, Daniel Orejon, Masamichi Kohno, Yasuyuki Takata, Khellil Sefiane, Quantifying vapor transfer into evaporating ethanol drops in humid atmosphere, Physical Chemistry Chemical Physics, 10.1039/C8CP02521E, 20, 29, 19430-19440, 2018.07.
11. Shen B, Suroto BJ, Hirabayashi S, Yamada M, Hidaka S, Kohno M, Takahashi K, Takata Y, Bubble activation from a hydrophobic spot at “negative“ surface superheats in subcooled boiling, Applied Thermal Engineering, 10.1016/j.applthermaleng.2014.10.054 , 88, 2018.06.
12. Bambang Joko Suroto, Masamichi Kohno, Yasuyuki Takata, Surface wettability and subcooling on nucleate pool boiling heat transfer, 1st International Conference and Exhibition on Powder Technology Indonesia, ICePTi 2017 1st International Conference and Exhibition on Powder Technology Indonesia, ICePTi 2017, 10.1063/1.5021240, 2018.02, The effect of varying surface wettabilities and subcooling on nucleate pool boiling heat transfer at intermediate heat flux has been examined and investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0, 5 and 10 K, respectively. The three types of heat transfer block were used that are bare surface/hydrophilic (polished copper), superhydrophilic/TiO2-coated on copper and hydrophobic/PTFE surface. The experimental results will be examined by the existing model. The results show that the heat transfer performance of surfaces with PTFE coating is better at low heat flux. While for an intermediate heat flux, superhydrophilic surface (TiO2) is superior compared to hydrophilic and hydrophobic surfaces. It is observed that the heat transfer performance is decreasing when the sub cooling degree is increased..
13. Hongbin He, Biao Shen, Liangyu Chen, Sumitomo Hidaka, Koji Takahashi, Masamichi Kohno, Yasuyuki Takata, Heat transfer enhancement of a loop thermosyphon with a hydrophobic spot-coated surface, Journal of Thermal Science and Technology, 10.1299/jtst.2018jtst0011, 13, 1, 2018.01, Heat transfer characteristic of a closed two-phase thermosyphon with enhanced boiling surface is studied and compared with that of a copper mirror surface. Two-phase cooling is widely used in application of thermal engineering and considerably more efficient than single-phase liquid cooling. The evaporator surfaces, coated with a pattern of hydrophobic circular spots (0.5 - 2 mm in diameter and 1.5 - 3 mm in pitch) on Cu substrates, achieve very high heat transfer coefficient and low incipience temperature overshoot with water as working fluid. Sub-atmospheric boiling on the hydrophobic spot-coated surface shows a much better heat transfer performance. Tests under heat loads 30 W to 260 W reveal the coated surfaces enhance nucleate boiling performance by increasing the bubbles nucleation-site density. The surface with hydrophobic spots with diameter 1 mm and pitch 1.5 mm achieves the maximal heat transfer enhancement with the minimum boiling thermal resistance as low as 0.03 K/W. A comparison of three evaporator surfaces with identical wettability patterns but with different surface topographies and coating thicknesses is carried out experimentally. The results show superior heat transfer rates and wear resistance on the surface coated with HNTs spots thanks to the large contact angle, great thickness, and durability of the coating layer..
14. Biao Shen, Masayuki Yamada, Tomosuke Mine, Sumitomo Hidaka, Junichiro Shiomi, Gustav Amberg, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata, Enhanced boiling heat transfer on surfaces patterned with mixed wettability, 16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference, 10.1615/ihtc16.bae.023482, 2018-August, 1379-1386, 2018, Amongst an extensive collection of surface characteristics that could affect boiling performance, surface wettability (as measured by the contact angle with water) proves to play a unique role in potentially manipulating bubble behavior to the advantage of higher heat transfer rates. In this study, we show experimentally that controlled bubble behavior be realized under the surface design incorporating these two characteristics (namely, by coating an array of hydrophobic spots on a hydrophilic substrate), which leads to a great enhancement in boiling heat transfer under various conditions. In reduced-pressure pool boiling, the strong pinning of the bubble contact line at the border between the hydrophilic and hydrophobic regions manages to prevent total deactivation of nucleation sites. As a result, the deleterious transition to intermittent boiling is effectively delayed, whereby no heat transfer deterioration occurs until a very low pressure of about 8 kPa is reached. Moreover, in subcooled boiling, bubble growth on a patterned surface is found to be facilitated by a pronounced presence of dissolved gas in defiance of exhaustive degassing efforts through continuous boiling, thanks to an unusually strong retention of gas contents by the hydrophobic surface. As experimental and numerical evidence show, only bubbles with sufficiently high concentrations of gas components (i.e., causing weakened condensation) are able to grow large enough on the hydrophobic surface such that periodic pinch-offs might take place, which is responsible for most of the initial heat transfer enhancement before large-scale bubble nucleation starts on the hydrophilic surface as well..
15. Sivasankaran Harish, Daniel Orejon, Yasuyuki Takata, Masamichi Kohno, Thermal conductivity enhancement of phase change nanocomposites in solid and liquid state with nano carbon inclusions, 16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference, 10.1615/ihtc16.tpm.023430, 2018-August, 8866-8872, 2018, Lauric acid based phase change nanocomposites with chemically functionalized graphene nanoplatelets (GnPs), multi-walled carbon nanotubes (MWCNTs) and single walled carbon nanohorns (SWCNHs) were prepared and its thermal conductivity was measured using transient hot wire method. We found that inclusion of graphene nanoplatelets increase the thermal conductivity of phase change nanocomposites by a factor of 2.3 at a loading of 1 vol %. We also show contrasting enhancements in thermal conductivity of such nanocomposites in the solid and liquid phase for the same loading of SWCNHs inclusions. Maximum thermal conductivity enhancement of SWCNHs inclusions in solid and liquid phase at 2 vol % is found to be ~37% and ~11% respectively. The thermal conductivity enhancement was significantly higher in the solid state than the liquid state of the material for all the nano composites. Thermal conductivity enhancement results were compared with the effective medium theory calculations considering the role of interfacial thermal resistance between the nanomaterial and the surrounding host matrix. The model calculations show that the interfacial thermal resistance significantly limits the thermal conductivity enhancement in the liquid state compared to the solid state. The model calculations also show that interfacial thermal resistance is an order of magnitude higher at the solid-liquid interface compared to that of solid-solid interface which leads to a contrasting thermal conductivity enhancement in liquid and solid state of the nanocomposites..
16. Alexandros Askounis, Huacheng Zhang, Dejian Zhang, Yutaku Kita, Gyoko Nagayama, Masamichi Kohno, Yasuyuki Takata, Khellil Sefiane, Unveiling thermocapillary convection in pure water drops, 16th International Heat Transfer Conference, IHTC 2018 International Heat Transfer Conference, 10.1615/ihtc16.bae.023953, 2018-August, 809-814, 2018, The existence of thermocapillary/Marangoni convection in pure water drops has been a hotly debated area over the last few years. In this paper, we report the induction of Marangoni convection in pure water drops by localized laser heating and visualized via high speed infrared and optical cameras. The optical camera recorded the evolution of drop shape over time and the infrared camera provided the spatiotemporal evolution of the temperature across the surface of the water drop. Localized heating induced a temperature gradient, which gave rise to a surface tension and eventually thermal and liquid flows within the drop. This flow manifested as twin vortices, which after experimental and theoretical arguments was attributed to Marangoni convection. We present, here, the influence of surface wettability which was found to play a major role in the convective patterns. Moreover, heating location and power on both the Marangoni convection patterns and the evaporation kinetics of the drops..
17. Nitesh Das, Masamichi Kohno, Yasuyuki Takata, Dhiraj V. Patil, Sivasankaran Harish, Enhanced melting behavior of carbon based phase change nanocomposites in horizontally oriented latent heat thermal energy storage system, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2017.07.084, 125, 880-890, 2017.10, Present study describes the numerical analysis of the melting process of phase change nanocomposites in a horizontally oriented shell-tube latent heat thermal energy storage system. Organic alkane n-eicosane is considered as the pristine phase change material. The influence of different carbon based allotropes in enhancing the thermal conductivity of n-eicosane is considered in this work. To enhance the thermal conductivity of organic alkane, highly conductive carbon nano inclusions of various dimensionalities such as spherical (nanodiamond), one dimensional (single-walled carbon nanotube) and two-dimensional (graphene nanoplatelets) structures were considered. Effective thermal conductivity of such nanocomposites are theoretically modeled based on effective medium formulation considering the influence of interfacial thermal boundary resistance between the nanostructure and the surrounding host matrix into account. Numerical results show that the interfacial thermal boundary resistance and dimensionality of the nano inclusion significantly affects the thermal conductivity enhancement of such nanocomposites. For a fixed nanomaterial loading of 1 vol%, spherical nanoparticle inclusions enhance the melting rate only by similar to 2%. The inclusion of 1 vol% loading of single-walled carbon nanotube and graphene nanoplatelets increases the melting rate by 27% and 40% respectively due to significant thermal conductivity enhancement of the nanocomposite compared to that of pure organic alkane. (C) 2017 Elsevier Ltd. All rights reserved..
18. Yamada M, Shen B, Imamura T, Hidaka S, Kohno M, Takahashi K, Takata Y, Enhancement of boiling heat transfer under sub-atmospheric pressures using biphilic surfaces, International Journal of Heat and Mass Transfer, 0.1016/j.ijheatmasstransfer.2017.08.078 , 115, 753-762, 2017.08.
19. Das N, Kohno M, Takata Y, Patil D, Harish S, Enhanced melting behavior of carbon based phase change nanocomposites in horizontally oriented latent heat thermal energy storage system, Applied Thermal Engineering, 10.1016/j.applthermaleng.2017.07.084 , 125, 880-890, 2017.07.
20. Naoya Sakoda, Jiang Shiheng, Masamichi Kohno, Shigeru Koyama, Yukihiro Higashi, Yasuyuki Takata, Gaseous PVT Property Measurements of cis-1,3,3,3-Tetrafluoropropene, Journal of Chemical and Engineering Data, 10.1021/acs.jced.7b00263, 62, 7, 2178-2182, 2017.07, PVT properties in the vapor phase of cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) were measured by a multiple expansion method in the temperature range from 353 to 413 K and at pressures up to 2.7 MPa. Thirty data along four isotherms are obtained in the temperatures between 353 and 413 K. The vapor pressures at the temperatures were also measured by adding a sample of R1234ze(Z) to a sample cell at the vapor-liquid equilibrium conditions. The uncertainties in temperature and pressure measurements are estimated to be within 6 mK and 0.3 kPa, respectively. The expanded uncertainty in density measurement is estimated within no greater than 0.12% (k = 2). The obtained PVT properties and vapor pressures are compared with the existing equation of state..
21. Askounis A, Kita Y, Kohno M, Takata Y, Koutsos V, Sefiane K, Influence of Local Heating on Marangoni Flows and Evaporation Kinetics of Pure Water Drops, Langmuir, 10.1021/acs.langmuir.7b00957, 33, 23, 5666-5674, 2017.05.
22. Das N, Takata Y, Kohno M, Harish S, Effect of carbon nano inclusion dimensionality on the melting of phase change nanocomposites in vertical shell-tube thermal energy storage unit, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2017.05.101, 113, 423-431, 2017.05.
23. He H, Furusato K, Yamada M, Shen B, Hidaka S, Kohno M, Takahashi K, Takata Y, Efficiency enhancement of a loop thermosyphon on a mixed-wettability evaporator surface, Applied Thermal Engineering, 10.1016/j.applthermaleng.2017.05.145 , 123, 1245-1254, 2017.05.
24. 河野 正道, 高田 保之, SIVASANKARAN HARISH, OREJON MANTECON DANIEL, Enhanced thermal conductivity of phase change nanocomposite in solid and liquid state with various carbon nano inclusions, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2016.10.109, 114, 1240-1246, 2017.03.
25. 河野 正道, 高田 保之, Yan, Shen, Dong, Cheng, Miao, Tingting, Wang, Wei, Ma, W, Zhang, Xing, Long delay time study of thermal transport and thermal stress in thin Pt film-glass substrate system by time-domain thermoreflectance measurements, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2016.08.110, 111, 1433-1440, 2017.01.
26. Biao Shen, Bambang Joko Suroto, Sana Hirabayashi, Masayuki Yamada, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata, Bubble activation from a hydrophobic spot at “negative“ surface superheats in subcooled boiling, Applied Thermal Engineering, 10.1016/j.applthermaleng.2014.10.054, 88, 2017.01, We present experimental results on the controlled bubble generation from a single PTFE (polytetrafluoroethylene) spot-with diameter varying from 2mm to 6mm-deposited on a flat polished copper surface that was submersed in subcooled pure water. The static contact angle of the PTFE coating was measured to be over 120°, which conveniently produced a clear contrast with the copper substrate in terms of wettability that ensured controlled bubble nucleation. By making use of a high-speed camera, statistical details about the bubble formation that include the departure frequency and diameter have been obtained at various surface temperatures. An interesting observation was made of repeated cycles of bubble nucleation and detachment at nominally negative surface superheats (i.e., the wall temperature being below the saturation temperature at the system pressure), which featured particularly long bubble growth time and seemingly no waiting time. The vertical temperature distribution inside the bubble, which was measured by a micro-thermocouple of about 250μm in diameter, suggests a relatively stable bubble composition of water vapor and dissolved air. A heat-pipe analogy was drawn to describe the internal heat transfer mechanism of bubble growth on a mixed wettability surface under subcooled conditions..
27. Nitesh Das, Yasuyuki Takata, Masamichi Kohno, Sivasankaran Harish, Effect of carbon nano inclusion dimensionality on the melting of phase change nanocomposites in vertical shell-tube thermal energy storage unit, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2017.05.101, 113, 423-431, 2017.01, In the present work, we numerically investigate the melting phenomena of carbon based nanocomposites in vertically oriented shell-tube latent heat thermal energy storage system. Organic alkane n-eicosane was considered as the phase change material and carbon allotropes as the nano fillers to enhance the thermal conductivity of n-alkane. The effect of different carbon allotropes like nanodiamond (spherical), single-walled carbon nanotubes (one-dimensional) and graphene nanoplatelets (two-dimensional) were considered. Thermal conductivity of nanocomposites was modeled using effective medium based formulation taking the interfacial thermal boundary resistance between nanomaterial and the surrounding host matrix into account. Numerical results show that spherical nano inclusions do not enhance the melting rate due to limited enhancement in the thermal conductivity of nanocomposites. However, the inclusion of one-dimensional and two-dimensional nanostructures shorten the melting time by ∼15% and ∼25% respectively at 1 vol% loading as a result of higher thermal conductivity enhancement..
28. Hongbin He, Kento Furusato, Masayuki Yamada, Biao Shen, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata, Efficiency enhancement of a loop thermosyphon on a mixed-wettability evaporator surface, Applied Thermal Engineering, 10.1016/j.applthermaleng.2017.05.145, 123, 1245-1254, 2017.01, This study presents an experimental investigation of the heat transfer performance of a two-phase loop thermosyphon with an enhanced mixed-wettability evaporator surface at sub-atmospheric pressures. For central-processing-unit (CPU) cooling applications, a lowering of the saturation temperature (pressure) is essential when water is used as the working fluid. Compared with copper mirror surfaces, up to over 100% enhancement of high heat transfer coefficient (HTC) was observed using surfaces with spotted wettability patterns, which consists of hydrophobic spots with contact angle ranged from 145° to 150°. The results revealed that the boiling behaviors changed drastically with the application of hydrophobic spots coating by artificially increasing the nucleation site density. Parametric tests with a variety of operating conditions, including different filling ratios, condenser temperatures, and heat loads revealed the minimum thermal resistance (i.e., the optimum thermosyphon performance) to be 0.03 K/W on the boiling side..
29. M. Yamada, B. Shen, T. Imamura, S. Hidaka, M. Kohno, K. Takahashi, Y. Takata, Enhancement of boiling heat transfer under sub-atmospheric pressures using biphilic surfaces, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2017.08.078, 115, 753-762, 2017, Surface wettability of a heating surface is one of the most important factors affecting boiling performance. While a biphilic surface (with juxtaposed hydrophilic and hydrophobic regions) is known as a promising technique to enhance water pool boiling at the atmospheric pressure, there is no research regarding its potential for sub-atmospheric applications. In the present study, we have investigated the characteristics of pool nucleate boiling on biphilic surfaces at sub-atmospheric pressures. Biphilic surfaces were made by applying Ni-TFEO (tetrafluoroethylene oligomer) electroplating (with a contact angle of about 140°) on a copper surface. The heat transfer performance of various biphilic surfaces (with different hydrophobic spot diameters and pitches) were measured in the pressure range from atmospheric to 6.9 kPa. At a pressure of 14.0 kPa, the wall superheat at the onset of nucleate boiling was reduced by 12 K on a biphilic surface compared with a mirror-finished copper surface. The experiment with three different biphilic patterns revealed that smaller pitch and diameter of the hydrophobic spots were favorable to heat transfer at 14.0 kPa. The enhancement of HTC over Kutateladze's correlation reached 270%. A sharp transition from continuous to intermittent boiling, resulting in large deterioration of HTC, was observed on a biphilic surface at a much lower pressure than that on a copper surface. Boiling performance was less affected by the pressure level above the transition pressure..
30. Takashi Nishiyama, Masamichi Kohno, Koji Takahashi, Tsuyoshi Yoshitake, Thermal Conductivity of Ultrananocrystalline Diamond/Hydrogenated Amorphous Carbon Composite Films Prepared by Coaxial Arc Plasma Deposition, ECS Transactions, 75, 25, 27-32, 2017.
31. Kita Y, Askounis A, Kohno M, Takata Y, Kim J, Sefiane K, Induction of Marangoni convection in pure water drops, Applied Physics Letters, 10.1063/1.4966542, 109, 17, 2016.10.
32. Bumsoo Chon, Yoshifumi Ikoma, Masamichi Kohno, Junichiro Shimoi, Zenji Horita, Investigation of electrical resistivities of nanograined Si produced by high-pressure torsion, Proceedings of the International Workshop on Giant Straining Process for Advanced Materials (GSAM2016), 53-54, 2016.10.
33. Nitesh Das, Yasuyuki Takata, Masamichi Kohno, Sivasankaran Harish, Melting of graphene based phase change nanocomposites in vertical latent heat thermal energy storage unit, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2016.06.166, 107, 101-113, 2016.08, The present study deals with the investigation of melting phenomena in single vertical shell-and-tube latent heat thermal energy storage unit. A two dimensional axi-symmetric computational fluid dynamics model based on the enthalpy-porosity method was developed to investigate the melting behaviour. Organic alkane n-eicosane and n-eicosane/graphene nanosheets with different volume fractions were considered as the phase change materials (PCMs). Water was considered as the heat transfer fluid (HTF) flowing inside the tube and the PCM is filled in the shell side of thermal energy storage unit. A variety of numerical simulations were performed for different heat transfer fluid inlet temperatures and varying loadings of graphene nanosheets. Numerical calculations show that higher inlet temperature of the heat transfer fluid decreases the melting time due to accelerated natural convection. We also show that the inclusion of graphene nanosheets significantly decreases the melting time due to the enhanced thermal conductivity of PCM. At 2 vol% graphene laoding, melting time reduces significantly by similar to 41% when the HTF temperature is 60 degrees C and similar to 37% when the HTF temperature is 70 degrees C. (C) 2016 Elsevier Ltd. All rights reserved..
34. Widyaparaga, A., Wakui, T, Kuntoro, H.Y, Deendarlianto, Masamichi Kohno, Yasuyuki Takata, Hidaka, S, Majid, A.I., Indarto, Thermoacoustic heat pumping direction alteration by variation of magnitude and phase difference of opposing acoustic waves, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2016.05.132, 101, 1217-1226, 2016.06.
35. 河野 正道, 高田 保之, Naoya Sakoda, Shigeru Koyama, Shiheng, J, Development of a burnett PVT apparatus for low-gwp refrigerants at high temperatures up to 473 K, Proceeding of the 8th Asian Conference on Refrigeration and Air Conditioning (ACRA2016), 2016.05.
36. Yuki Fukatani, Takaaki Wakui, Suhaila Hussain, Masamichi Kohno, Yasuyuki Takata, Khellil Sefiane, Jungho Kim, Effect of Hydrothermal Waves on Evaporation Distribution during Drop Evaporation, Heat Transfer Engineering, 10.1080/01457632.2015.1067103, 37, 7-8, 729-739, 2016.05, The objective of this study is to clarify physical mechanisms involved in the evaporation of small (a few microliters) sessile drops. We aim to understand the relation between local thermal information at the solid-liquid interface and overall evaporation. An infrared (IR) camera and a charge-coupled device (CCD) camera were used to determine the temperature and heat flux distribution at the solid-liquid interface and the profile of the evaporating drop, respectively. The temperature distribution at the solid-liquid interface was determined using a multilayer substrate consisting of a silicon wafer coated with a thin thermal insulator that is partially transparent to IR. The liquids used were water and FC-72. The evaporation rate of water drops was found to occur mostly at the contact line. However, the heat transfer distribution at the liquid-solid interface was relatively uniform, indicating the heat transferred from the wall must be transported within the drop to the contact line. The mechanisms by which this occurs have yet to be determined. In contrast, the evaporation rate of FC-72 drops where hydrothermal waves were present was found to be proportional to the liquid-vapor interface area rather than the circumference of the drop, indicating a more uniform distribution of evaporation..
37. A. Widyaparaga, T. Hiromatsu, T. Koshimizu, D. Deendarlianto, Masamichi Kohno, Yasuyuki Takata, Thermoacoustic heat pumping direction alteration by variation of magnitude and phase difference of opposing acoustic waves, Applied Thermal Engineering, 10.1016/j.applthermaleng.2016.02.032, 101, 330-336, 2016.05, Thermoacoustic refrigeration utilizes the temperature changes that occur due to pressure oscillations within a sound wave to transport heat from one point to another and achieve cooling. As such, it neither requires complicated machinery nor hazardous or environmentally harmful refrigerants. By altering the acoustic field, it is possible to also alter the direction of heat pumping allowing a single device to be capable of functioning as a heater or cooler without addition of complicated machinery. We have constructed a thermoacoustic heat pump employing dual opposing acoustic drivers or speakers connected by a resonator tube and a regenerator formed by layers of steel mesh positioned at the centre of the resonator to investigate the alteration of the acoustic field due to the interaction of opposing travelling waves. The acoustic field was manipulated by changing the phase difference and magnitude difference between the waves generated by the acoustic drivers. Experimental results show that the acoustic power flow on both sides of the regenerator was altered thus resulting in a change in heat pumping direction along the regenerator. In addition, it was also observed that the heat pumping was also influenced by the changes in the standing wave component (SWC) and the travelling wave component (TWC)..
38. Tingting Miao, Weigang Ma, Shen Yan, Xing Zhang, Masamichi Kohno, Yasuyuki Takata, Yoshifumi Ikoma, Thermal transport and thermal stress in a molybdenum film-glass substrate system, Journal of Vacuum Science and Technology B: Nanotechnology and Microelectronics, 10.1116/1.4941308, 34, 2, 2016.03, Three-dimensional integration with through-silicon vias is emerging as an approach for improving the performance of integrated circuits. Thermal transport and thermal stress in such designs currently limit their performance and reliability. In this study, the thermal dissipation and thermal stress in a 95.3-nm-thick molybdenum (Mo) film-glass substrate system were investigated using a picosecond laser pump-probe method with four different configurations. This allowed the thermal transport and the generation and propagation of coherent acoustic phonon waves in a Mo film-glass substrate system to be comprehensively studied for the first time. The universality of the superposition model previously proposed for a platinum film on a glass substrate was verified using the present Mo film-glass substrate system from the close agreement between experimental data and theoretical predictions. The thermal transport in the Mo film and the coherent acoustic phonon wave propagation in the Mo film and glass substrate, i.e., thermal diffusivity and longitudinal sound velocity, respectively, were also studied..
39. Widyaparaga, A., Hiromatsu, T, Koshimizu, T., Deendarlianto, Masamichi Kohno, Yasuyuki Takata, Thermoacoustic heat pumping direction alteration by variation of magnitude and phase difference of opposing acoustic waves
, Applied Thermal Engineering , 10.1016/j.applthermaleng.2016.02.032, 101, 330-336, 2016.02.
40. Masamichi Kohno, 高田 保之, Weigang Ma, Xing Zhang, Miao, T, Yoshifumi Ikoma, Thermal transport and thermal stress in a molybdenum film-glass substrate system, Journal of Vacuum Science and Technology B, 2016.01.
41. Masamichi Kohno, Harish Sivasankaran, Mitsuru Tabara, Yoshifumi Ikoma, Zenji Horita, Reduction in thermal conductivity of bulk silicon processed by high-pressure torsion, Proceedings of the International Workshop on Giant Straining Process for Advanced Materials (GSAM2015), 7-8, 2016.01.
42. S. Takeichi, Takashi Nishiyama, M. Tabara, S. Kawawaki, M. Kohno, K. Takahashi, T. Yoshitake, Thermal conductivity of ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition, Symposium on Carbon Nanostructures: From Fundamental Studies to Applications and Devices - PRiME 2016/230th ECS Meeting Carbon Nanostructures From Fundamental Studies to Applications and Devices, 10.1149/07525.0027ecst, 27-32, 2016.01, The thermal conductivity of ultrananocrystalline diamond/hydrogenated amorphous carbon composite films prepared by coaxial arc plasma deposition (CAPD) was measured by a timedomain thermoreflactance method. The specific heat and density of the films were measured to be 0.891 J/gK and 1.70 g/cm3, respectively, as parameters for the estimation of the thermal conductivity. Based on them, the thermal conductivity was estimated to be 2.32 W/m-K. This value is smaller than that of general UNCD/a-C:H films prepared by chemical vapor deposition (CVD). It might be because the CAPD films possesses a huge number of grain boundaries owing to extremely small grains of approximately 2.3 nm as compared with those of CVD films and its structure enhances phonon scattering..
43. Masamichi Kohno, Yuki Fukatani, 高田 保之, Wakui, T, Hussain, S, Kim, J., Sefiane, K, Effect of Hydrothermal Waves on Evaporation Distribution During Drop Evaporation, Heat Transfer Engineering, 2015.11.
44. N. Sakoda, T. Hisatsugu, K. Furusato, K. Shinzato, M. Kohno, Y. Takata, Viscosity measurements of hydrogen at high temperatures up to 573 K by a curved vibrating wire method, Journal of Chemical Thermodynamics, 10.1016/j.jct.2015.04.028, 89, 22-26, 2015.10, The viscosities of hydrogen were measured at temperatures of (296 to 573) K and at pressures up to 0.7 MPa by the vibrating wire method. In this study, a tungsten wire 50 μm in diameter and 24 mm in length is bent into semicircular form. The direction of the vibrating motion is fixed using the curved wire, and a more compact sample vessel can be used than in a traditional straight vibrating wire method requiring weight for the tension in the wire. Alternating voltages with different frequencies were supplied to the curved wire, which was set between samarium cobalt magnets. The generated induced voltages depending on the supplied frequencies were measured by a lock-in amplifier, and the resonant curve was obtained. The resonant frequency and half-width of the resonant curve were determined by curve fitting. The wire's effective diameter and internal friction coefficient, which represents the damping from the wire material and the magnetic force, are very important parameters for evaluating the viscosities, and they were precisely calibrated by measuring helium and nitrogen as reference fluids. Finally, the viscosities of hydrogen were obtained with an uncertainty of 1.4% (k = 2)..
45. Masamichi Kohno, Sivasankaran Harish, 高田 保之, Thermal conductivity enhancement of lauric acid phase change nanocomposite with graphene nanoplatelets, Applied Thermal Engineering, 80, 205-211, 2015.04.
46. Sivasankaran Harish, Daniel Orejon, Yasuyuki Takata, Masamichi Kohno, Thermal conductivity enhancement of lauric acid phase change nanocomposite with graphene nanoplatelets, Applied Thermal Engineering, 10.1016/j.applthermaleng.2015.01.056, 80, 205-211, 2015.04, In this work, we prepared lauric acid based phase change nanocomposites with chemically functionalized graphene nanoplatelets and measured its thermal conductivity using transient hot wire method. We show that inclusion of graphene nanoplatelets increases the thermal conductivity of phase change material by 230% at a loading of 1 vol%. Comparing the experimental results with the model calculations based on the effective medium theory suggests that graphene based nanocomposites outperforms those with carbon nanotubes or metal nanoparticles reported in the literature. High thermal conductivity, high aspect ratio and low thermal interface resistance at the graphene - host matrix interface makes it the most suitable nano filler candidate to enhance the thermal conductivity of low conductive materials. Differential scanning calorimetry study of the nanocomposites show that the phase change enthalpy and the melting temperature remains similar to that of pristine material, which makes graphene a promising candidate for thermal energy storage applications..
47. Weigang Ma, Tingting Miao, Xing Zhang, Masamichi Kohno, Yasuyuki Takata, Comprehensive study of thermal transport and coherent acoustic-phonon wave propagation in thin metal film - Substrate by applying picosecond laser pump - Probe method, Journal of Physical Chemistry C, 10.1021/jp512735k, 119, 9, 5152-5159, 2015.03, Three-dimensional integration with through silicon vias offers a promising solution for future technology nodes. However, the heat accumulation and thermal strain may seriously affect performance, leakage, and reliability of circuits. The cross-plane thermal transport, generation, and propagation of coherent acoustic-phonon wave in thin Pt film-glass substrate have been comprehensively studied by applying the picosecond laser pump-probe method with different configurations. Significantly different time-dependent reflectance signals have been obtained in different configurations and an effect superposition model is proposed to account for cross plane thermal transport inducing ipsi- and contralateral temperature change in thin Pt film, propagation of coherent acoustic-phonon wave in thin Pt film and in glass substrate. The corresponding theoretical predictions match well with the experimental data in the whole delay time range..
48. Masamichi Kohno, 高田 保之, Weigang Ma, Xing Zhang, Comprehensive Study of Thermal Transport and Coherent Acoustic-Phonon Wave Propagation in Thin Metal Film-Substrate by Applying Picosecond Laser Pump-Probe Method, The Journal of Physical Chemistry C, 2015.02.
49. Masamichi Kohno, Sivasankaran Harish, 高田 保之, Thermal conductivity enhancement of lauric acid phase change nanocomposite in solid and liquid state with single-walled carbon nanohorn inclusions, Thermochimica Acta, 600, 1-6, 2015.01.
50. Harish Sivasankaran, Daniel Mantecon Orejon, Yasuyuki Takata, Masamichi Kohno, Thermal conductivity enhancement of lauric acid phase change nanocomposite in solid and liquid state with single-walled carbon nanohorn inclusions, Thermochimica Acta, 10.1016/j.tca.2014.12.004, 600, 1-6, 2015.01, We prepared lauric acid based phase change nanocomposite embedded with chemically functionalized single-walled carbon nanohorns and measured its thermal properties. We report contrasting enhancements in thermal conductivity of such nanocomposites in the solid and liquid phase for the same loading of nanohorn inclusions. Maximum thermal conductivity enhancement in solid and liquid phase at 2 vol% is found to be ∼37 and ∼11%, respectively. The nanocomposites' thermal conductivity enhancement is compared with calculations of effective medium theory considering the role of interfacial thermal transport. Model calculations show that Kapitza resistance is an order of magnitude lower at the solid-solid interface compared to the solid-liquid interface. Differential scanning calorimetry study of the nanocomposites shows that the phase change temperature and enthalpy marginally increases to that of pristine material. Such a nanocomposite with enhanced thermal transport and phase change enthalpy makes it a promising candidate for thermal energy storage applications..
51. Development of Gas Viscosity Measurement System with Vibrating Wire Method.
52. Masamichi Kohno, Takuma Hiromatsu, 高田 保之, SHELL AND TUBE HEAT EXCHANGER FOR THERMOACOUSTIC DEVICES EFFECTS ON REGENERATOR TEMPERATURE DISTRIBUTION AND ACOUSTIC FIELD, Proceeding of ISTP25 International Symposium on Transport Phenomena, 2014.11.
53. Masamichi Kohno, Takaaki Wakui, 高田 保之, HEAT TRANSFER OF SPRAY DROPLETS IMPINGING ONTO HOT INCLINED SUFACE, Proceeding of ISTP25 International Symposium on Transport Phenomena, 2014.11.
54. Masamichi Kohno, S. Hussain, 高田 保之, 2D Simulation of FC72 Sessile Droplet Evaporation in the constant Contact Line Region, International Review of Mechanical Eingineering, 8, 1, 52-61, 2014.08.
55. Masamichi Kohno, Hiroyuki Moroizumi, 高田 保之, Water Molecule Adsorption on Vertically Aligned Single-Walled Carbon Nanotubes, Proceedings of 12th International Conference on Nanochannels, Microchannels, and Minichannels (ICNMM2014), 2014.08.
56. Masamichi Kohno, Yuki Fukatani, 高田 保之, The Effect of Humidity in Ambient Gas on HTWs in Volatile Drops, Proceeding of International Heat Transfer Conference 15 (IHTC-15), 2014.08.
57. Masamichi Kohno, Naoya Sakoda, 高田 保之, Vacuum generation by hydrogen permeation to atmosphere through austenitic and nickel-basealloy vessel walls at temperatures from 573 K to 773 K, International Journal of Hydrogen Energy, 39, 21, 11316-11320, 2014.07.
58. Masamichi Kohno, Huaiyu Shao, 高田 保之, Hydrogen storage and thermal conductivity properties of Mg-based materials with different structures, International Journal of Hydrogen Energy, 39, 18, 9893-9898, 2014.06.
59. Masamichi Kohno, Tingting Miao, 高田 保之, Study on the Cross Plane Thermal Transport of Polycrystalline Molybdenum Nanofilms by Applying Picosecond Laser Transient Thermoreflectance Method, Journal of Nanomaterials, Article ID 578758, 2014.06.
60. Masamichi Kohno, Sivasankaran Harish, 高田 保之, Thermal conductivity reduction of crystalline silicon by high-pressure torsion, Nanoscale Research Letters, 9, 326, 2014.06.
61. Masamichi Kohno, Masayuki Yamada, 高田 保之, Effect of Dissolved Air on Subcooled Pool Boiling from a Mixed Wettability Surface, Proceedings of The 101 EUROTHERM Seminar “TRANSPORT PHENOMENA IN MULTIPHASE SYSTEMS”, 2014.06.
62. Huaiyu Shao, Weigang Ma, Masamichi Kohno, Yasuyuki Takata, Gongbiao Xin, Shigenori Fujikawa, Sayoko Fujino, Sean Bishop, Xingguo Li, Hydrogen storage and thermal conductivity properties of Mg-based materials with different structures, International Journal of Hydrogen Energy, 10.1016/j.ijhydene.2014.02.063, 39, 18, 9893-9898, 2014.06, Mg-based hydrogen storage materials can be very promising candidates for stationary energy storage application due to the high energy density and low cost of Mg. Hydrogen storage kinetics and thermal conductivity are two important factors for the material development for this kind of application. Here we studied several types of Mg-based materials with different structure-micrometer scale Mg powders, Mg nanoparticles, single crystal Mg, nanocrystalline Mg 50Co50 BCC alloy and Mg thin film samples. It seems the Mg materials with good kinetics usually are the ones with nanostructure and tend to show poor thermal conductivity due to electron/phonon scattering resulting from more interfaces and boundaries in nanomaterials. Based on this work, good crystallinity Mg phase incorporated in carbon nano framework could be one promising option for energy storage..
63. Sivasankaran Harish, Mitsuru Tabara, Yoshifumi Ikoma, Zenji Horita, Yasuyuki Takata, David G. Cahill, Masamichi Kohno, Thermal conductivity reduction of crystalline silicon by high-pressure torsion, NANOSCALE RESEARCH LETTERS, 10.1186/1556-276X-9-326, 9, 2014.06, We report a dramatic and irreversible reduction in the lattice thermal conductivity of bulk crystalline silicon when subjected to intense plastic strain under a pressure of 24 GPa using high-pressure torsion (HPT). Thermal conductivity of the HPT-processed samples were measured using picosecond time domain thermoreflectance. Thermal conductivity measurements show that the HPT-processed samples have a lattice thermal conductivity reduction by a factor of approximately 20 (from intrinsic single crystalline value of 142 Wm(-1) K-1 to approximately 7.6 Wm(-1) K-1). Thermal conductivity reduction in HPT-processed silicon is attributed to the formation of nanograin boundaries and metastable Si-III/XII phases which act as phonon scattering sites, and because of a large density of lattice defects introduced by HPT processing. Annealing the samples at 873 K increases the thermal conductivity due to the reduction in the density of secondary phases and lattice defects..
64. Masamichi Kohno, Masayuki Yamada, 高田 保之, Observation of periodic bubble nucleation on a hydrophobic spot at negative surface superheats under subcooled conditions, Proceedings of The Heat Transfer Symposium 2014, 2014.05.
65. Masamichi Kohno, Yasuyuki Takata, Takafumi Seto, Phase Transition and Restructuring of Carbon Nanoparticles induced by Aerosol Laser Irradiation, Carbon, 70, 224-232, 2014.04.
66. Masamichi Kohno, Deendarlianto, 高田 保之, Effect of static contact angle on the droplet dynamics during the evaporation of a water droplet on the hot walls, International Journal of Heat and Mass Transfer, 71, 691-705, 2014.04.
67. Deendarlianto, Yasuyuki Takata, Sumitomo Hidaka, Indarto, Adhika Widyaparaga, Samsul Kamal, Purnomo, Masamichi Kohno, Effect of static contact angle on the droplet dynamics during the evaporation of a water droplet on the hot walls, International Journal of Heat and Mass Transfer, 10.1016/j.ijheatmasstransfer.2013.12.066, 71, 691-705, 2014.04, The effect of surface wettability on the collision dynamics and heat transfer phenomena of a single water droplet impacting upon a heated solid surface has been studied experimentally. To modify the surface wettability, two modules of stainless steel coated by TiO2 were employed. The first module was induced by ultraviolet irradiation to produce the hydrophilic surface, while the second one was not. The diameter and the depth of coating surface were 30 mm and 200 nm, respectively. The droplet size was varied from 1.90 to 2.90 mm and substrate temperature raised up to 340 C. The interaction of an impact water droplet with a heated solid surface was investigated using a high-speed video camera. As a result, it was found that; (1) in the lower surface temperature region the evaporation time decreases as the static contact angle decreases, (2) the wetting limit temperature decreases with the increase of static contact angle, (3) the ultraviolet irradiation on the TiO2 surface does not change the qualitative behavior of the evolution of wetting diameters, and (4) the maximum wetting diameter increases with the decrease of static contact angle below the wetting limit temperatures..
68. Takafumi Seto, Ayumi Inoue, Hidenori Higashi, Yoshio Otani, Masamichi Kohno, Makoto Hirasawa, Phase transition and restructuring of carbon nanoparticles induced by aerosol laser irradiation, Carbon, 10.1016/j.carbon.2013.12.111, 70, 224-232, 2014.04, We recently reported that laser irradiation of aerosol amorphous carbon nanoparticles induces formation of onion-like carbon structures. In this study, the further analyses of laser induced phase transitions and restructuring of aerosol carbon nanoparticles were carried out using the combination of off-line and in-flight measurement techniques. Laser-synthesized carbon agglomerates composed of 7-nm amorphous primary nanoparticles were used as starting materials. Irradiation of multiple laser shots to the gas-suspended carbon agglomerates resulted in the formation of variety of unique structures, such as diamond-like, defective graphite, concentric shell structures, and their agglomerates. Evolutions of the carbon nanostructures were found to be responsible for the in-flight mass-to-mobility spectra..
69. S. Hussain, Y. Fukatani, Masamichi Kohno, K. Sefiane, Yasuyuki Takata, 2D simulation of FC72 sessile droplet evaporation in the constant contact line region, International Review of Mechanical Engineering, 8, 1, 52-61, 2014.01, A 2-dimensional simulation of FC72 sessile droplet evaporation on a substrate layer consisting of silicon and Kapton tape has been carried out to study the heat and fluid flow inside the droplet as well as its surroundings. The momentum and volume fraction (VOF) equations were solved simultaneously with the heat and diffusion equations to obtain the flow profiles. The simulated conditions were based on actual experiments. This paper presents the findings for the simulated experimental condition for the same substrate and surrounding temperature under a constant contact line condition. The initial conditions for the substrate, surroundings and droplet was set to, as best as possible, the same condition as the experiment. Quantitative as well as qualitative comparisons were made between the experimental and simulated results. The simulation also predicted the temperature and concentration fields inside and outside the evaporating droplet. The predicted temperature and heat transfer profiles were compared to experimental results and were found to be qualitatively agreeable..
70. Shinya Fukuda, Masamichi Kohno, Keisuke Tagashira, Nobuya Ishihara, Sumitomo Hidaka, Yasuyuki Takata, Behavior of small droplet impinging on a hot surface, Heat Transfer Engineering, 10.1080/01457632.2013.812496, 35, 2, 204-211, 2014.01, The effects of droplet diameter, surface roughness, and impinging velocity on the behavior of a droplet impinging on a hot surface were studied. The surface samples used in the experiment were cylinder blocks of stainless steel having four different degrees of roughness: Ra 0.04, Ra 0.2, Ra 3, and Ra 10. The diameter and impinging velocity were controlled independently using a microjet dispenser, and their values were in the ranges of 300-700 μm and 1.0-4.0 m/s, respectively. The contact time was found to increase with an increase in the surface roughness and was of the order of the self-oscillation of the water droplet. The maximum spread of the droplet decreased with increasing impinging velocity. A cooling curve was obtained for surface temperatures ranging from 500°C to 100°C, and the cooling time was found to decrease with an increase in the surface roughness of stainless steel. Moreover, the cooling effectiveness of each droplet increased with an increase in the surface roughness, a decrease in the droplet diameter, and an increase in the impinging velocity..
71. Hiroyuki Moroizumi, Shohei Chiashi, Yasuyuki Takata, Masamichi Kohno, Water molecule adsorption on vertically aligned single-walled carbon nanotubes, ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting, 10.1115/ICNMM2014-21468, 2014.01, A single walled carbon nanotube, which adsorbed water molecule in its nano channel, was observed using Raman spectroscopy, and two samples' spectrums were compared under the same conditions. The SWNT samples that were vertically aligned on the silicon substrate were used. One of the samples was not covered by polymer whereas the other sample was covered by polymer. In our experiment, a nano channel was made using a nanosecond pulse laser (Nd:YAG laser). In order to adjust the focus, the sample was set on the automatic stage and controlled on the PC using a USB camera to watch closely. By moving the stage for over 30 seconds, the sample was processed to make the nano channel. The cell with the laser-processed sample in it was set on the Raman spectroscopy's platform. Then, the cell was connected to the vacuum chamber and erlenmeyer flask by the valve. Both of the valves were opened first and left for a while to make the cell vacuum. Second, the vacuum chamber's valve was closed and left for a while to let water molecule spread in the cell. Finally, the SWNT successfully adsorbed water molecule in its nano channel. Ar-ion laser was used in the Raman spectroscopy and the laser wavelength is 488nm. With the Raman spectroscopy, Radial Breathing Mode (RBM), D-band, and G-band were mainly observed. The RBM, D-band, and G-band originated from radial vibration frequency, defective structure, and graphite structure respectively. According to the sample types, the RBM spectrums were compared in our experiment..
72. Tingting Miao, Weigang Ma, Xing Zhang, Keisuke Kubo, Masamichi Kohno, Yasuyuki Takata, Tatsuya Ikuta, Koji Takahashi, Study on the cross plane thermal transport of polycrystalline molybdenum nanofilms by applying picosecond laser transient thermoreflectance method, Journal of Nanomaterials, 10.1155/2014/578758, 2014, 2014, Thin metal films are widely used as interconnecting wires and coatings in electronic devices and optical components. Reliable thermophysical properties of the films are required from the viewpoint of thermal management. The cross plane thermal transport of four polycrystalline molybdenum nanofilms with different thickness deposited on glass substrates has been studied by applying the picosecond laser transient thermoreflectance technique. The measurement is performed by applying both front pump-front probe and rear pump-front probe configurations with high quality signal. The determined cross plane thermal diffusivity of the Mo films greatly decreases compared to the corresponding bulk value and tends to increase as films become thicker, exhibiting significant size effect. The main mechanism responsible for the thermal diffusivity decrease of the present polycrystalline Mo nanofilms is the grain boundary scattering on the free electrons. Comparing the cross plane thermal diffusivity and inplane electrical conductivity indicates the anisotropy of the transport properties of the Mo films..
73. Hiroyuki Moroizumi, Shohei Chiashi, Yasuyuki Takata, Masamichi Kohno, Water molecule adsorption on vertically aligned single-walled carbon nanotubes, ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting ASME 2014 12th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2014, Collocated with the ASME 2014 4th Joint US-European Fluids Engineering Division Summer Meeting, 10.1115/ICNMM2014-21468, 2014, A single walled carbon nanotube, which adsorbed water molecule in its nano channel, was observed using Raman spectroscopy, and two samples' spectrums were compared under the same conditions. The SWNT samples that were vertically aligned on the silicon substrate were used. One of the samples was not covered by polymer whereas the other sample was covered by polymer. In our experiment, a nano channel was made using a nanosecond pulse laser (Nd:YAG laser). In order to adjust the focus, the sample was set on the automatic stage and controlled on the PC using a USB camera to watch closely. By moving the stage for over 30 seconds, the sample was processed to make the nano channel. The cell with the laser-processed sample in it was set on the Raman spectroscopy's platform. Then, the cell was connected to the vacuum chamber and erlenmeyer flask by the valve. Both of the valves were opened first and left for a while to make the cell vacuum. Second, the vacuum chamber's valve was closed and left for a while to let water molecule spread in the cell. Finally, the SWNT successfully adsorbed water molecule in its nano channel. Ar-ion laser was used in the Raman spectroscopy and the laser wavelength is 488nm. With the Raman spectroscopy, Radial Breathing Mode (RBM), D-band, and G-band were mainly observed. The RBM, D-band, and G-band originated from radial vibration frequency, defective structure, and graphite structure respectively. According to the sample types, the RBM spectrums were compared in our experiment..
74. Bambang Joko Suroto, Masahiro Tashiro, Sana Hirabayashi, Sumitomo Hidaka, Masamichi Kohno, Koji Takahashi, Yasuyuki Takata, A photographic study on the effects of hydrophobic-spot size and subcooling on local film boiling, ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013 ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013, 10.1115/ICNMM2013-73069, 2013.12, The effects of hydrophobic circle spot size and subcooling on local film boiling phenomenon from the copper surface with single PTFE (Polytetrafluoroethylene) hydrophobic circle spot at low heat flux has been investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0 and 10K. The heat transfer surfaces are used polished copper block with single PTFE hydrophobic circle spot of diameters 2, 4 and 6 mm, respectively. A high-speed camera was used to capture bubble dynamics and disclosed the sequence of the process leading to local film boiling. The result shows that local films boiling occurs on the PTFE circle spot at low heat flux and was triggered by the merging of neighboring bubbles. The study also showed that transition time required for change from nucleate boiling regime to local film boiling regime depends on the diameter of the hydrophobic circle spot and the subcooling. A stable local film boiling occurs at the smallest diameter of hydrophobic spot. Subcooling cause the local film boiling occur at negative superheat and oscillation of bubble dome..
75. Temujin Uehara, Kosuke Yoshimura, Elin Yusibani, Kan'ei Shinzato, Masamichi Kohno, Yasuyuki Takata, Hydrogen viscosity measurements with capillary tube under high pressure, ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013 ASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013, 10.1115/ICNMM2013-73139, 2013.12, Viscosity of hydrogen has been measured at high pressures and high temperatures by using capillary tube method. The measurement apparatus was designed specifically for high pressure gas up to 100MPa. The capillary used quartz glass tube 0.1mm in inner diameter and 400mm in length. The measurement range is 0.1MPa to 100MPa, and room temperature up to 723K. We have to generate laminar flow inside the capillary tube that is the range of Reynolds number from 250 to 900. Since we measured nitrogen gas viscosity at the same range and many nitrogen viscosity data have already been measured in these ranges, nitrogen data was used in this study to confirm the accuracy of our apparatus before measurements of hydrogen. The measurement results of hydrogen are evaluated compared with our existing correlation(Yusibani Correlation)[1]. The results of hydrogen viscosity agree well with the existing correlation within 2% except for the measurements at 723K. The relative uncertainty of the present measurement system is estimated to be as much as 2%..
76. Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Thermodynamic behavior of hydrogen binary systems with critical curve divergence and retrograde condensation, Journal of Thermal Science and Technology, 10.1299/jtst.8.603, 8, 3, 603-612, 2013.12, In binary systems of hydrogen and hydrocarbons, the fluid-phase thermodynamic behavior is unique in having the divergence of the critical curves to a high pressure region. The thermodynamic properties of the binary systems including hydrogen with methane, ethane, propane, and carbon dioxide were calculated from a Peng-Robinson equation of state (PR EOS). The mixing parameter of the present EOS has a functional form of temperature generalized by the critical temperatures of the hydrocarbons and carbon dioxide. Based on the corresponding states principle, the coefficients of the parameter were determined with a non-linear least squares fitting to the experimental critical points of the mixtures. The developed PR EOS shows good agreement with the experimental data of not only the critical points but also the phase equilibria. In the hydrogen binary systems, retrograde condensation is expected. The volumetric and enthalpy changes in this process were simulated for a hydrogen + carbon dioxide mixture of 0.55 mole fraction using the PR EOS at 270 K..
77. Masamichi Kohno, Yasuyuki Takata, Naoya Sakoda, Thermodynamic Behavior of Hydrogen Binary Systems with Critical Curve Divergence and Retrograde Condensation, Journal of Thermal Science and Technology, 8, 3, 603-612, 2013.11.
78. Masamichi Kohno, Yasuyuki Takata, El-Sayed R. Negeed, Effect of the surface roughness and oxidation layer on the dynamic behavior of micrometric single water droplets impacting onto heated surfaces, International Journal of Thermal Sciences, 70, 65-82, 2013.08.
79. El Sayed R. Negeed, S. Hidaka, Masamichi Kohno, Yasuyuki Takata, Effect of the surface roughness and oxidation layer on the dynamic behavior of micrometric single water droplets impacting onto heated surfaces, International Journal of Thermal Sciences, 10.1016/j.ijthermalsci.2013.03.004, 70, 65-82, 2013.08, The present research study investigates the effects of surface roughness amplitude and surface oxide layer thickness on the dynamic behavior of micrometric single water droplets during collision with surfaces at high temperature. Stainless steel-grade 304 (SUS 304) surfaces of different amplitudes of surface roughness; Ra = 0.04, 2, 4, 6, 8 and 10 μm, have been considered. Each heat transfer surface was heated up to different temperatures; 1108, 1158 and 1198 K, to control the oxide layer thickness over the hot surface. An individual water droplet is ejected from a needle of the micro jet dispenser where the droplet's size and its velocity were controlled independently. The behavior of droplet during the collision with hot surface was observed with a high-speed camera. By analyzing the experimental results, the effects of the surface roughness amplitude, oxide layer thickness, droplet Weber number, and surface superheat on the hot solid-liquid contact time, and on the maximum droplet spread diameter were investigated. Empirical correlations have been deduced describing the relationship between the hydrodynamic characteristics of an individual droplet impinging on a heated surface and concealing the affecting parameters in such process. Also, the comparison between the current results and the results due to other investigators shows the effects of oxide layer thickness and surface roughness amplitude on the impact behavior of water droplet onto the heated surfaces..
80. Bambang Joko Suroto, Masahiro Tashiro, Sana Hirabayashi, Sumitomo Hidaka, Masamichi Kohno, Yasuyuki Takata, Effects of hydrophobic-spot periphery and subcooling on nucleate pool boiling from a mixed-wettability surface, Journal of Thermal Science and Technology, 10.1299/jtst.8.294, 8, 1, 294-308, 2013.08, The effect of subcooling and length of hydrophobic-spot periphery on nucleate pool boiling heat transfer from TiO2-coated surface with and without PTFE (polyetatafluoroethylene) hydrophobic circle spots at intermediate heat flux has been examined. The experiments are performed with liquid subcooling ranging from 0-20 K and heat transfer block used were TiO2-coated copper block with a PTFE hydrophobic circle spot with various diameters with total area of PTFE being constant. Bubble nucleation and behavior were observed by using high-speed camera. The results showed that the heat transfer performance of surfaces with PTFE hydrophobic circle spot is better than superhydrophilic surface in overall condition. Furthermore, the heat transfer performance decreases under subcooled condition for all surfaces. Increase in peripheral length of hydrophobic-spot enhances the heat transfer performance..
81. Hong Duc Doan, Yoshihiko Akamine, Naoki Iwatani, Masamichi Kohno, Kazuyoshi Fushinobu, Generation of bessel beam by using thermal lens, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.79.1354, 79, 803, 1354-1362, 2013.08, Bessel beam has been gaining strong attention from various applications. In this study, a new concept for generating zero-order Bessel beams was studied theoretically and experimentally. The principle of the generation of a Bessel-like beam is discussed based on Fourier optics. A preliminary model is proposed that accounts for heat conduction and diffraction effect. Analytical modeling results indicated that Bessel beam can be generated by using a thermal lens and a convergent lens. A simple and flexible method to convert a Gaussian laser beam into a Bessel-like beam with a long and narrow focal line by using a thermal lens effect is demonstrated experimentally. Experimental and calculated results show a good agreement for generation and characteristics of Bessel-like beam. Experimental results also show that the focal depth of the Bessel beam can be controlled by adjusting some parameters in the thermal lens system. The paper concludes with suggestions for further research and potential applications for the work..
82. Masamichi Kohno, Yasuyuki Takata, Bambang Joko SUROTO, Effects of Hydrophobic-Spot Periphery and Subcooling on Nucleate Pool Boiling from a Mixed-Wettability Surface, Journal of Thermal Science and Technology, 8, 1, 294-308, 2013.07.
83. Masamichi Kohno, Yasuyuki Takata, Shinya FUKUDA, Behavior of Small Droplet Impinging on a Hot Surface, Heat transfer engineering, 35, 2, 204-211, 2013.07.
84. E. Yusibani, P. L. Woodfield, K. Shinzato, Yasuyuki Takata, Masamichi Kohno, A compact curved vibrating wire technique for measurement of hydrogen gas viscosity, Experimental Thermal and Fluid Science, 10.1016/j.expthermflusci.2012.11.008, 47, 1-5, 2013.05, Studies with the view to application of a curved vibrating wire method to measure hydrogen gas viscosity have been done. A fine tungsten wire with a nominal diameter of 50. μm is bent into a semi-circular shape and arranged symmetrically in a magnetic field. The frequency domain response for forced oscillation of the wire is used for calculating the viscosity. Argon, nitrogen, helium and hydrogen viscosities have been measured at room temperature up to 0.7. MPa. The deviations with respect to existing equations suggest that with more refinements it may be possible to take gas viscosity measurements with a precision of less than 1%..
85. E. Yusibani, P.L. Woodfield, K. Shinzato, Yasuyuki Takata, Masamichi Kohno, A compact curved vibrating wire technique for measurement of hydrogen gas viscosity, Experimental Thermal and Fluid Science, 51, 1-2, 551-559, 2013.01.
86. El Sayed R. Negeed, S. Hidaka, Masamichi Kohno, Yasuyuki Takata, High speed camera investigation of the impingement of single water droplets on oxidized high temperature surfaces, International Journal of Thermal Sciences, 10.1016/j.ijthermalsci.2012.07.014, 63, 1-14, 2013.01, This study investigates the influence of oxide layer over the hot surfaces on the behavior of single droplets impacting the high temperature surfaces using high speed camera. In the present work, an experimental apparatus was installed where direct contact between mono-dispersed water droplet and solid hot surface in the presence of different values of oxide layer (4.5, 6.7, 9.4 and 12.6 μm) over the hot surface was experimentally investigated. The droplets size and its velocity were controlled independently. The results presented the effects of surface oxide layer, droplet velocity, droplet size and surface superheating on the hot solid-liquid contact wettability time and on the maximum droplet spread diameter on the hot surface. Empirical correlations are presented describing the hydrodynamic characteristics of an individual droplet impinging on a heated surface and concealing the affecting parameters for surface oxidation phenomena in such process. Also, the comparison between the obtained results at oxidation phenomena and the results due to others at non oxidation phenomena shows the effect of surface oxidation phenomena on the behavior of single droplet impacting the high temperature surface. These experimental observations provide the validation data required for multi-phase modeling of these phenomena by computational fluid dynamics (CFD) (e.g. Volume of Fluid (VOF) modeling) methods..
87. B. A. Cola, H. Daiguji, C. Dames, N. Fang, K. Fushinobu, S. Inoue, G. Kikugawa, M. Kohno, S. Kumar, D. Y. Li, J. R. Lukes, J. A. Malen, A. J.H. McGaughey, O. Nakabeppu, K. Pipe, P. Reddy, S. Shen, L. Shi, M. Shibahara, Y. Taguchi, K. Takahashi, T. Yamamoto, T. Zolotoukhina, Report on the seventh U.S.-Japan Joint seminar on nanoscale transport phenomena-science and engineering, Nanoscale and Microscale Thermophysical Engineering, 10.1080/15567265.2012.745913, 17, 1, 25-49, 2013.01, The seventh U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Shima, Japan, from December 11 to 14, 2011. The goals of this joint seminar were to provide a critical assessment of the state of the art and future directions in the field of nanoscale transport phenomena and energy conversion processes, to foster U.S.-Japan collaborations, and to provide international exposure to a new generation of scientists in this field. Issues discussed in the joint seminar were organized in 10 topical sessions, including (1) nanoscale thermophysical measurements; (2) optical characterization; (3) thermal and molecular transport; (4) phonon transport modeling; (5) energy storage and conversion; (6) nanoscale fluidics and phase change phenomena; (7) biological and organic systems; (8) interfacial thermal transport; (9) novel thermoelectric and thermal management materials; and (10) nanocarbon materials and devices. In addition to these topical sessions, the joint seminar featured an opening plenary session and a closing plenary session as well as an expert panel, where leading experts provided critical assessment of the past progress and addressed future directions in the field. In addition, an evening poster session provided opportunities for graduate and postdoc students to present their latest research results. About 35 researchers from Japan and 31 researchers from the United States participated in the meeting. The meeting was organized by S. Maruyama, K. Fushinobu, L. Shi, and J. Lukes together with about 20 other participants who served as session chairs. Summaries of different sessions of the seminar were prepared by the session and conference chairs and are collected into this report..
88. Shinri Nonaka, Tastuhiro Mori, Yasuyuki Takata, Masamichi Kohno, The effect of the laser beam wavelength and pulse width on micro grooving
Comparison of nanosecond and femtosecond laser, ASME 2012 10th Int. Conf. on Nanochannels, Microchannels, and Minichannels, ICNMM 2012 Collocated with the ASME 2012 Heat Transfer Summer Conf. and the ASME 2012 Fluids Engineering Division Sum, ICNMM 2012 ASME 2012 10th Int. Conf. on Nanochannels, Microchannels, and Minichannels Collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Sum, ICNMM 2012, 10.1115/ICNMM2012-73135, 275-280, 2012.12, Processing technique of micro grooves and channels is very important to study the phenomenon of fluids in micro scale. Micro grooves and microchannels play an important role in various devices, such as μ-TAS (Micro-Total Analysis Systems) and micro reactors. Laser processing is currently widely used for drilling and grooving of various materials including metals, polymers, glasses and composite materials, since laser machining can avoid the problems that conventional machining methods have. For example wear of a working tool, lowering of processing accuracy, and wear debris becoming contaminants are some of the problems of the conventional method. Additionally, compared to other non-contact machining processes such as electron beam machining (EBM) and focused ion beam (FIB), machining a vacuum is not required. Therefore, applicability is wider and setup costs can be more economical..
89. Adhika Widyaparaga, Masashi Kuwamoto, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Theoretical and experimental study of a flexible wiretype Joule-Thomson microrefrigerator for use in cryosurgery, Journal of Heat Transfer, 10.1115/1.4004937, 134, 2, 2012.01, We have developed a model capable of predicting the performance characteristics of a wiretype Joule-Thomson microcooler intended for use within a cryosurgical probe. Our objective was to be able to predict cold tip temperature, temperature distribution, and cooling power using only inlet gas properties as input variables. To achieve this, the model incorporated gas equations of state to account for changing gas properties due to heat transfer within the heat exchanger and expansion within the capillary. In consideration of inefficiencies, heat in-leak from free convection and radiation was also considered and the use of a 2D axisymmetric finite difference code allowed simulation of axial conduction. To validate simulation results, we have constructed and conducted experiments with two types of microcoolers differing in inner tube material, poly-ether-ether-ketone (PEEK) and stainless steel. The parameters of the experiment were used in the calculations. CO 2 was used as the coolant gas for inlet pressures from 0.5 MPa to 2.0 MPa. Heat load trials of up to 550 mW along with unloaded trials were conducted. The temperature measurements show that the model was successfully able to predict the cold tip temperature to a good degree of accuracy and well represent the temperature distribution. For the all PEEK microcooler in a vacuum using 2.0 MPa inlet pressure, the calculations predicted a temperature drop of 57 K and mass flow rate of 19.5 mg/s compared to measured values of 63 K and 19.4 mg/s, therefore, showing that conventional macroscale correlations can hold well for turbulent microscale flow and heat transfer as long as the validity of the assumptions is verified..
90. Adhika Widyaparaga, Masashi Kuwamoto, Eiji Noda, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Analytical optimization of heat exchanger dimensions of a joule-thomson microcooler, ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011 ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 10.1115/ICNMM2011-58205, 203-207, 2011.12, In designing a Joule-Thomson microcooler, aiming for a compact size yet maintaining good performance, it is important to find the optimum dimensions of its heat exchanger. We have developed a model capable of predicting the performance characteristics of a wiretype Joule-Thomson microcooler utilizing analytical methods and incorporating changing gas properties via gas equations of state. The model combined the heat exchanger and the JT expander, thus requiring only the inlet gas properties as input. The model results were compared to experimental measurements using C2H4 and N2O as coolant gases. Predicted mass flow rate and temperature drop were in good agreement with the measured values. The long capillary length present in the tested microcooler was revealed to maintain performance of the microcooler for longer heat exchanger lengths due to it functioning as a secondary heat exchanger. Using the calculation results it was possible to correctly estimate the optimum heat exchanger length for C2H 4 and for N2O..
91. Masahiro Tomoda, Teppei Kawahara, Yohei Tasaki, Yasuyuki Takata, Makoto Hirasawa, Takafumi Seto, Masamichi Kohno, Carbon nanotube synthesis from metal nanoparticles sizeclassified by a differential mobility analyzer, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 2011.12, In this study, carbon nanotubes (CNTs) were synthesized from size-classified catalyst metal nanoparticles to observe the effect of the nanoparticles' diameter on the diameter of the CNTs. The nanoparticles were generated by laser vaporization and classified by a differential mobility analyzer, which sorts them by diameter according to differences in electrical mobility. After classification, the nanoparticles were collected on a Si substrate. CNTs were synthesized from these catalyst metal nanoparticles by using chemical vapor deposition. This experiment synthesized mainly multi-walled carbon nanotubes (MWNTs), with a small amount of single-walled carbon nanotubes (SWNTs). The reason is thought to be that the particles' diameters were appropriate for MWNT synthesis..
92. Shuhei Inoue, Takashi Tomie, Yukihiko Matsumura, Masamichi Kohno, Possible growth region of single-walled carbon nanotube in CVD synthesis on the CHO components diagram, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 2011.12, Considering the massive-scale synthesis of single-walled carbon nanotube (SWCNT), chemical vapor deposition has become a standard process for synthesizing CNTs. In most of these processes, oxygen and hydrogen atoms were included originally or added later; and they are expected to have important roles such that they helped in the removal of amorphous carbon and prevented SWCNTs from containing metal particles. However, whole perspectives for suitable carbon source or ideal balance among carbon, hydrogen, and oxygen have not been reported. We examined a variety of raw materials in our newly developed round-trip-type vacuum furnace in order to determine whether they could be used to synthesize a carbon nanotube. We used Raman spectroscopy for evaluation, and plotted the component ratios of effective and ineffective materials on a C-H-O ternary diagram. Consequently, it is clear that the growth region should satisfy the equation O
93. Koichi Kimura, Shogo Moroe, Peter Woodfield, Jun Fukai, Kan'ei Shinzato, Masamichi Kohno, Motoo Fujii, Yasuyuki Takata, Thermal conductivity measurement of hydrogen at high pressure and high temperature, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 2011.12, The thermal conductivities and thermal diffusivities of hydrogen were measured with a transient short hot wire method for temperature range up to 300 °C and pressure range up to100MPa. The measured thermal conductivities showed good reproducibility and agreed with the existing values within a deviation of ±2%..
94. Adhika Widyaparaga, Takao Koshimizu, Eiji Noda, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, The frequency dependent regenerator cold section and hot section positional reversal in a coaxial type thermoacoustic Stirling heat pump, CRYOGENICS, 10.1016/j.cryogenics.2011.09.001, 51, 10, 591-597, 2011.10, We have constructed and tested two travelling wave thermoacoustic heat pumps using a coaxial configuration with the regenerator positioned in the annulus. We discovered a frequency dependent positional reversal of the cold section and hot section of the regenerator within the test frequency range. By decomposing the measured pressure wave within the annulus, we obtained the positive (w(+)) and negative (w(-)) propagating travelling waves. It has been revealed the change of frequency is accompanied by a change in magnitudes of w(+) and w(-) which is in part influenced by the presence of travelling wave attenuation through the regenerator. The resulting change of dominant travelling wave on a given end of the regenerator will then change the direction of thermoacoustic heat pumping at that end. This will alter the regenerator temperature distribution and may reverse the cold and hot sections of the regenerator. As the reversal does not require additional moving parts, merely a change in frequency, this feature in coaxial travelling wave devices has tremendous potential for applications which require both heating and cooling operation. (C) 2011 Elsevier Ltd. All rights reserved..
95. S. Moroe, P. L. Woodfield, K. Kimura, M. Kohno, J. Fukai, M. Fujii, K. Shinzato, Y. Takata, Measurements of hydrogen thermal conductivity at high pressure and high temperature, International Journal of Thermophysics, 10.1007/s10765-011-1052-5, 32, 9, 1887-1917, 2011.09, The thermal conductivity for normal hydrogen gas was measured in the range of temperatures from 323 K to 773 K at pressures up to 99 MPa using the transient short hot-wire method. The single-wire platinum probes had wire lengths of 10 mm to 15 mm with a nominal diameter of 10 μm. The volume-averaged transient temperature rise of the wire was calculated using a two-dimensional numerical solution to the unsteady heat conduction equation. A non-linear least-squares fitting procedure was employed to obtain the values of the thermal conductivity required for agreement between themeasured temperature rise and the calculation. The experimental uncertainty in the thermal-conductivity measurements was estimated to be 2.2 % (k = 2). An existing thermal-conductivity equation of state was modified to include the expanded range of conditions covered in the present study. The new correlation is applicable from 78 K to 773 K with pressures to 100 MPa and is in agreement with the majority of the present thermal-conductivity measurements within ±2 %..
96. Elin Yusibani, Yosuke Nagahama, Masamichi Kohno, Yasuyuki Takata, Peter L. Woodfield, Kanei Shinzato, Motoo Fujii, A capillary tube viscometer designed for measurements of hydrogen gas viscosity at high pressure and high temperature, International Journal of Thermophysics, 10.1007/s10765-011-0999-6, 32, 6, 1111-1124, 2011.06, A capillary tube viscometer was developed to measure the dynamic viscosity of gases for high pressure and high temperature. The apparatus is simple and designed for safe-handling operation. The gas was supplied to the capillary tube from a high-pressure reservoir tank through a pressure regulator unit to maintain a steady state flow. The measurements of a pressure drop across the capillary tube with high accuracy under extreme conditions are the main challenge for this method. A differential pressure sensor for high pressures up to 100MPa is not available commercially. Therefore, a pair of accurate absolute pressure transducers was used as a differential pressure sensor. Then the pressure drop was calculated by subtracting the outlet pressure from the inlet one with a resolution of 100 Pa at 100 MPa. The accuracy of the present measurement system is confirmed by measuring the viscosity of nitrogen as a reference gas. The apparatus provided viscosities of nitrogen from ambient temperature to 500K and hydrogen from ambient temperature to 400 K and for pressures up to 100MPa with a maximum deviation of 2.2% compared with a correlation developed by the present authors and with REFPROP (NIST)..
97. S. Moroe, P. L. Woodfield, J. Fukai, K. Shinzato, M. Kohno, M. Fujii, Y. Takata, Thermal conductivity measurement of gases by the transient short-hot-wire method, Experimental Heat Transfer, 10.1080/08916152.2010.503310, 24, 2, 168-178, 2011.04, Measurements of the thermal conductivity of helium and hydrogen are performed using the transient short-hot-wire method. The short hot wire is made of platinum and has a diameter of about 10 μm and a length of about 15 mm. It is attached by spot welding to platinum terminals with a diameter of 1.5 mm. The probe is inserted into the sample vessel that has a volume of 35 cm 3 and an inner diameter of 30 mm. The thermal conductivity is evaluated by comparing a numerical solution of the heat conduction in and around the short wire with the experimentally obtained temperature rise of the wire. The measured thermal conductivities show good reproducibility. Also, the measured thermal conductivities agree with the reference equations within a deviation of ± 1%..
98. Masahiro Tomoda, Teppei Kawahara, Yohei Tasaki, Yasuyuki Takata, Makoto Hirasawa, Takafumi Seto, Masamichi Kohno, Carbon Nanotube Synthesis from Metal nanoparticles Size-Classified by a Differential Mobility Analyzer, Proceedings of the ASME/JSME 2011 8th Thermal Engineering Joint Conference (AJTEC2011), AJTEC2011-44414, 2011.03.
99. Koich Kimura, Shogo Moroe, Peter Woodfield, Jun Fukai, Kan’ei Shinzato, Masamichi Kohno, Motoo Fujii, Yasuyuki Takata, Thermal Conductivity Measurement of Hydrogen at High Pressure and High Temperature, Proceedings of the ASME/JSME 2011 8th Thermal Engineering Joint Conference (AJTEC2011), AJTEC2011-44415, 2011.03.
100. Moroe S, Woodfield PL, Fukai J, Shinzato K, Kohno M, Fujii M, Takata Y, HERMAL CONDUCTIVITY MEASUREMENT OF GASES BY THE TRANSIENT SHORT-HOT-WIRE METHOD, EXPERIMENTAL HEAT TRANSFER, 24, 2, 168-178, 2011.02.
101. El Sayed R. Negeed, S. Hidaka, Masamichi Kohno, Yasuyuki Takata, Experimental and analytical investigation of liquid sheet breakup characteristics, International Journal of Heat and Fluid Flow, 10.1016/j.ijheatfluidflow.2010.08.005, 32, 1, 95-106, 2011.02, The main objective of this research is to study analytically and experimentally the liquid sheet breakup of a flat fan jet nozzle resulting from pressure-swirling. In this study the effects of nozzle shape and spray pressure on the liquid sheet characteristics were investigated for four nozzles with different exit widths (1.0, 1.5, 2.0 and 2.5. mm). The length of liquid sheet breakup, liquid sheet velocity and the size of formed droplets were measured by a digital high speed camera. The breakup characteristics of plane liquid sheets in atmosphere are analytically investigated by means of linear and nonlinear hydrodynamic instability analyses. The liquid sheet breakup process was studied for initial sinuous and also varicose modes of disturbance. The results presented the effect of the nozzle width and the spray pressure on the breakup length and also on the size of the formed droplets. Comparing the experimental results with the theoretical ones for all the four types of nozzles, gives a good agreement with difference ranges from 4% to 12%. Also, the comparison between the obtained results and the results due to others shows a good agreement with difference ranged from 5% to 16%. Empirical correlations have been deduced describing the relation between the liquid sheet breakup characteristics and affecting parameters; liquid sheet Reynolds number, Weber number and the nozzle width..
102. El-Sayed R. Negeed, S. Hidaka, M. Kohno, Y. Takata, Experimental and analytical investigation of liquid sheet breakup characteristics, International Journal of Heat and Fluid Flow, 32, 95-106, 2011.01.
103. Masamichi Kohno, Teppei Kawahara, Masahiro Tomoda, Yasuyuki Takata, Shuhei Inoue, Shinzo Suzuki and Shigeo Maruyama, Synthesis of single-walled carbon nanotubes using laser-vaporized metal nanoparticle catalyst, Journal of Mechanical Science and Technology, 25, 1, 1253-1260, 2011.01.
104. Masamichi Kohno, Teppei Kawahara, Masahiro Tomoda, Yasuyuki Takata, Shuhei Inoue, Shinzo Suzuki, Shigeo Maruyama, Synthesis of single-walled carbon nanotubes using laser-vaporized metal nanoparticle catalyst, Journal of Mechanical Science and Technology, 10.1007/s12206-010-1110-0, 25, 1, 11-15, 2011.01, SWNTs were synthesized by laser-vaporized CCVD (catalytic chemical vapor deposition). The diameter distributions and the abundance of SWNTs synthesized at different temperatures and using different catalysts were investigated by Raman spectroscopy. Further, this technique was compared with other synthesis techniques (laser-oven and conventional-alcohol CCVD), and C60 was synthesized simultaneously as a byproduct only using the laser-oven technique. With increasing synthesis temperature, the diameter distribution shifted towards larger diameters, and the G/D ratio became larger as the synthesis temperature increased to 1000°C. Ni, Co, and Fe played a catalytic role, though Fe was less effective under our experimental conditions. The diameter distribution of SWNTs synthesized with the Fe catalyst was shifted to smaller values compared to those synthesized with Ni or Co catalysts..
105. Masahiro Tomoda, Teppei Kawahara, Yohei Tasaki, Yasuyuki Takata, Makoto Hirasawa, Takafumi Seto, Masamichi Kohno, Carbon nanotube synthesis from metal nanoparticles sizeclassified by a differential mobility analyzer, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 10.1115/ajtec2011-44414, 2011, In this study, carbon nanotubes (CNTs) were synthesized from size-classified catalyst metal nanoparticles to observe the effect of the nanoparticles' diameter on the diameter of the CNTs. The nanoparticles were generated by laser vaporization and classified by a differential mobility analyzer, which sorts them by diameter according to differences in electrical mobility. After classification, the nanoparticles were collected on a Si substrate. CNTs were synthesized from these catalyst metal nanoparticles by using chemical vapor deposition. This experiment synthesized mainly multi-walled carbon nanotubes (MWNTs), with a small amount of single-walled carbon nanotubes (SWNTs). The reason is thought to be that the particles' diameters were appropriate for MWNT synthesis..
106. Shuhei Inoue, Takashi Tomie, Yukihiko Matsumura, Masamichi Kohno, Possible growth region of single-walled carbon nanotube in CVD synthesis on the CHO components diagram, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 10.1115/ajtec2011-44193, 2011, Considering the massive-scale synthesis of single-walled carbon nanotube (SWCNT), chemical vapor deposition has become a standard process for synthesizing CNTs. In most of these processes, oxygen and hydrogen atoms were included originally or added later; and they are expected to have important roles such that they helped in the removal of amorphous carbon and prevented SWCNTs from containing metal particles. However, whole perspectives for suitable carbon source or ideal balance among carbon, hydrogen, and oxygen have not been reported. We examined a variety of raw materials in our newly developed round-trip-type vacuum furnace in order to determine whether they could be used to synthesize a carbon nanotube. We used Raman spectroscopy for evaluation, and plotted the component ratios of effective and ineffective materials on a C-H-O ternary diagram. Consequently, it is clear that the growth region should satisfy the equation O
107. Koichi Kimura, Shogo Moroe, Peter Woodfield, Jun Fukai, Kan'ei Shinzato, Masamichi Kohno, Motoo Fujii, Yasuyuki Takata, Thermal conductivity measurement of hydrogen at high pressure and high temperature, ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011 ASME/JSME 2011 8th Thermal Engineering Joint Conference, AJTEC 2011, 10.1115/ajtec2011-44415, 2011, The thermal conductivities and thermal diffusivities of hydrogen were measured with a transient short hot wire method for temperature range up to 300 °C and pressure range up to100MPa. The measured thermal conductivities showed good reproducibility and agreed with the existing values within a deviation of ±2%..
108. El-Sayed R. Negeed, N. Ishihara, K. Tagashira, S. Hidaka, M. Kohno, Y. Takata, Experimental study on the effect of surface conditions on evaporation of sprayed liquid droplet, International Journal of Thermal Sciences, 49, 12, 2250-2271, 2010.12.
109. Takashi Tomie, Shuhei Inoue, Masamichi Kohno, Yukihiko Matsumura, Prospective growth region for chemical vapor deposition synthesis of carbon nanotube on C2H6O ternary diagram, Diamond & Related Materials, 19, 1401-1404, 2010.12.
110. El Sayed R. Negeed, N. Ishihara, K. Tagashira, S. Hidaka, M. Kohno, Y. Takata, Experimental study on the effect of surface conditions on evaporation of sprayed liquid droplet, International Journal of Thermal Sciences, 10.1016/j.ijthermalsci.2010.08.008, 49, 12, 2250-2271, 2010.12, The present study investigates experimentally the effects of thermal properties of the hot surface and droplet characteristics on the droplet evaporation. Cylindrical blocks made of Stainless Steel, Aluminum and Brass with different degrees of surface roughness were used. The droplet diameter and velocity were controlled independently. The behavior of droplet during the collision with hot surface was observed with a high-speed camera. The results presented the effect of the thermal properties of the hot surface, droplet Weber number, droplet velocity, droplet size, hot surface conditions; surface superheat and degree of surface roughness on the solid-liquid contact time and the maximum spread of droplet over the surface. Empirical correlations have been deduced describing the relationship between the hydrodynamic characteristics of an individual droplet impinging on a heated surface and concealing the affecting parameters in such process. Also, the comparison between the current results and the results due to others investigators shows good agreement in which the difference between them ranged from 5% to 25%..
111. Adhika Widyaparaga, Masashi Kuwamoto, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Theoretical study of a flexible wiretype Joule Thomson micro-refrigerator for use in cryosurgery, ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2010 Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels Collocated with 3rd Joint US-European Fluids Engineering Summer Meeting, ICNMM2010, 10.1115/FEDSM-ICNMM2010-30127, 591-598, 2010.12, We have developed a model capable of predicting the performance characteristics of a wiretype Joule-Thomson microcooler intended for use within a cryosurgical probe. Our objective was to be able to predict evaporator temperature, temperature distribution and cooling power using only inlet gas properties as input variables. To achieve this, the model incorporated changing gas properties due to heat transfer within the heat exchanger and isenthalpic expansion within the capillary. In consideration of inefficiencies, heat in-leak from free convection and radiation was also considered and the use of a 2D axisymmetric finite difference code allowed simulation of axial conduction. Two types of microcoolers differing in inner tube material, poly-ether-ether-ketone (PEEK) and stainless steel, were tested and simulated. CO2 was used as the coolant gas in the calculations and experimental trials for inlet pressures from 0.5 MPa to 2.0 MPa. Heat load trials of up to 550 mW along with unloaded trials were conducted. Comparisons to experiments show that the model was successfully able to obtain a good degree of accuracy. For the all PEEK microcooler in a vacuum using 2.0 MPa inlet pressure, the calculations predicted a temperature drop of 57 K and mass flow rate of 19.5 mg/s compared to measured values of 63 K and 19.4 mg/s therefore showing that conventional macroscale correlations can hold well for turbulent microscale flow and heat transfer as long as the validity of the assumptions is verified..
112. Masashi Kuwamoto, Adhika Widyaparaga, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Effect of Working Gas and Heat Exchanger Dimensions on Joule Thomson Microcooler Performance, Proceedings of the International Symposium on Innovative Materials for Processes in Energy Systems (IMPRES2010), 203-207, 2010.11.
113. Shinya Fukuda, Keisuke Tagashira, Nobuya Ishihara, Sumitomo Hidaka, Masamichi Kohno, Yasuyuki Takata, Study on Heat Transfer of Small Droplet Impinging onto a Hot Surface, Proceedings of the International Symposium on Innovative Materials for Processes in Energy Systems (IMPRES2010), 197-202, 2010.11.
114. Tatsuhiro Mori, Takuhito Otofuji, Hiromi Kubota, Yasuyuki Takata, Masamichi Kohno, The Effects of a Beam Wavelength on Laser Micro Processing of Ceramics, Proceedings of the 21st International Symposium on Transport Phenomena, Paper-228, 2010.11.
115. Takashi Tomie, Shuhei Inoue, Masamichi Kohno, Yukihiko Matsumura, Prospective growth region for chemical vapor deposition synthesis of carbon nanotube on C-H-O ternary diagram, Diamond and Related Materials, 10.1016/j.diamond.2010.08.005, 19, 11, 1401-1404, 2010.11, Chemical vapor deposition has become a standard process for synthesizing carbon nanotubes. Since the successful use of chemical vapor deposition for the first time, much effort has been expended into exploring various carbon sources that can be used to synthesize carbon nanotubes, such as methane, ethane, and ethanol. However, whole perspectives for suitable carbon sources have not been clear. In this study, we performed experiments in order to determine that the appropriate C-H-O components ratio in raw materials can be used to synthesize carbon nanotubes. We also examined a variety of raw materials in our newly developed round-trip-type vacuum furnace in order to determine whether they could be used to synthesize a carbon nanotube. We used Raman spectroscopy to identify the developed carbon nanotube, and we plotted the component ratios of effective and ineffective materials on a C-H-O ternary diagram; in this diagram, the growth region became highly apparent. It should be noted that for the growth of the carbon nanotube, this region should satisfy the equation O
116. Adhika Widyaparaga, Masashi Kuwamoto, Atsushi Tanabe, Naoya Sakoda, Hiromi Kubota, Masamichi Kohno, Yasuyuki Takata, Study on a wire-type Joule Thomson microcooler with a concentric heat exchanger, APPLIED THERMAL ENGINEERING, 10.1016/j.applthermaleng.2010.07.007, 30, 16, 2563-2573, 2010.11, This study examines the performance of a wire-type Joule Thomson microcooler utilizing a flexible concentric counterflow heat exchanger. Three gases: C(2)H(4), CO(2) and N(2) were used separately for trials conducted at inlet pressures ranging from 0.5 MPa to 5 MPa with C(2)H(4) having the best performance. During unloaded tests at an inlet pressure of 2.0 MPa, C(2)H(4) obtained a minimum temperature of 225 K while CO(2) obtained a minimum temperature of 232 K. Using CO(2) the microcooler was able to maintain a temperature of 273 K at 100 mW heat input and 2 MPa inlet pressure. An inlet pressure of 3 MPa allowed a 550 mW heat input at 273 K. Theoretical performance calculations were conducted and compared to experimental results revealing considerable reduction of microcooler performance due to the presence of heat in-leak. Results have displayed that the JT coefficient of the coolant gas is a more dominant factor than heat transfer properties in determining the performance of the coolant. Due to the microscale of the device, relevant scaling effects were evaluated, particularly entrance effects, surface roughness and axial conduction. (C) 2010 Elsevier Ltd. All rights reserved..
117. Shogo Moroe, Koichi Kimura, Jun Fukai, Masamichi Kohno, Yasuyuki Takata, Peter L Woodfield, Kan’ei Shinzato, Motoo Fujii, Dependence of Hydrogen Thermal Conductivity on Ortho-Para Composition Ratio, Proceedings of the 9th Asian Thermophysical Properties Conference, ATPC9-109077, 2010.10.
118. Elin Yusibani, Kanei Shinzato, Motoo Fujii, Yosuke Nagahama, Masamichi Kohno, Yasuyuki Takata, Peter L. Woodfield, Hydrogen Viscosity at 293 to 400K up to 100 MPa with Capillary Tube Method, Proceedings of the 9th Asian Thermophysical Properties Conference, ATPC9-109172, 2010.10.
119. Naoya Sakoda, Kenta Shindo, Koichi Motomura, Supriatno, Kan’ei Shinzato, Masamichi Kohno, Yasuyuki Takata, Motoo Fujii, Measurement of PVT Property of Hydrogen at High Pressures Up to 100 MPa and Development of a Virial Equation of State, Proceedings of the 9th Asian Thermophysical Properties Conference, ATPC9-109156, 2010.10.
120. Jiraporn Klanwan, Takafumi Seto, Takuma Furukawa, Yoshio Otani, Tawatchai Charinpanitkul, Masamichi Kohno, Makoto Hirasawa, Generation and size classification of single-walled carbon nanotube aerosol using atmospheric pressure pulsed laser ablation (AP-PLA), Journal of Nanoparticle Research, 10.1007/s11051-010-9847-z, 12, 8, 2747-2755, 2010.10, Gas suspended single-walled carbon nanotubes (SWCNTs) with single tube diameter smaller than 2 nm and length of longer than 500 nm were generated by simple and continuous system using laser ablation technique under atmospheric conditions. Graphite target containing 0.5 wt%-nickel and 0.5 wt%-cobalt was ablated by Nd:YAG laser in an electrical furnace under atmospheric pressure of nitrogen flow that allowed one step and continuous synthesis of the SWCNTs. Size distribution of the gas suspended SWCNTs aerosol was measured using size-classification by a differential mobility analyzer (DMA) coupled with a condensation particle counter (CPC) used as a detector. Characteristics of SWCNT aerosol generated under the different temperature were also investigated using scanning and transmission electron microscopes and Raman scattering. Mono-mobility SWCNT aerosol with mobility diameter of 100 and 200 nm was successfully prepared after the size separation using a DMA..
121. Adhika Widyaparaga, Masashi Kuwamoto, Naoya Sakoda, Masamichi Kohno, Yasuyuki Takata, Theoretical Study of a Flexible Wiretype Joule Thomson Micro-Refrigerator for Use in Cryosurgery, Proceedings of the 8th International Conference on Nanochannels, Microchannels and Minichannels, FEDSM-ICNMM2010-30127, 2010.08.
122. Jiraporn Klanwan; Takafumi Seto; Takuma Furukawa; Yoshio Otani; Tawatchai Charinpanitkul; Masamichi Kohno; Makoto Hirasawa., Generation and size classification of single-walled carbon nanotube aerosol using atmospheric pressure pulsed laser ablation (AP-PLA), Journal of Nanoparticle Research, 12, 8, 2747-2755, 2010.05.
123. Elin Yusibani, Peter L. Woodfield, 新里寛英, 河野正道, 高田保之, 藤井丕夫, 高温高圧水素の粘性係数推算式の提案, 熱物性誌, 24, 1, 22-27, 2010.03.
124. N. Sakoda, K. Shindo, K. Shinzato, M. Kohno, Y. Takata, and M. Fujii, Review of the Thermodynamic Properties of Hydrogen Based on Existing Equations of State, International Journal of Thermophysics, 31, 2, 276-296, 2010.02.
125. N. Sakoda, K. Shindo, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, Review of the thermodynamic properties of hydrogen based on existing equations of state, International Journal of Thermophysics, 10.1007/s10765-009-0699-7, 31, 2, 276-296, 2010.02, Currently available equations of state (EOSs) for hydrogen are reviewed, and the data for the critical point, normal boiling point, and triple point are summarized. Through comparisons of PVT, saturated properties, heat capacity, and speed of sound among the latest EOSs for hydrogen, their features are discussed. The proper use of the EOSs, including a consideration of the nuclear isomers (ortho-and parahydrogen), is of great importance, especially for saturated properties, heat capacity, and speed of sound because these properties are different between the nuclear isomers. The present review concludes with recommendations for use of the EOSs for hydrogen..
126. Development of a PVT Property Measurement Apparatus by the Burnett Method for High Pressure Hydrogen.
127. Masamichi Kohno, Koichi Kimura, Shogo Moroe, Yasuyuki Takata, Peter L. Woodfield, Motoo Fujii, Measurement of effective thermal conductivity of CNT-nanofluids by transient short-wire method, ASME 2009 Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT2009 Proceedings of the ASME Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT2009, 10.1115/MNHMT2009-18068, 407-412, 2010, Thermal conductivity and thermal diffusivity of CNT-nanofluids and Al 2O3-nanofulids were measured by the transient short-hot-wire method. The uncertainty of their measurements is estimated to be within 1% for the thermal conductivity and 5% for the thermal diffusivity. Three different shapes of Al2O3 particles were prepared for Al2O3-water nanofluids. For the thermal conductivity of Al2O3-water nanofluids, there are differences in the enhancement of thermal conductivity for differences in particle shapes. Hardly any enhancement of thermal conductivity was observed for SWCNT-water nanofluids because the volume fraction of SWCNT was extremely low. However, we consider by increasing the volume fraction of SWCNTs, it will be possible to enhance the thermal conductivity..
128. M. Kohno, A. Tanabe, Y. Kuwamoto, H. Kubota, Y. Takata, Flexible Joule-Thomson micro-refrigerator, 7th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2009 Proceedings of the 7th International Conference on Nanochannels, Microchannels, and Minichannels 2009, ICNMM2009, 10.1115/ICNMM2009-82215, 835-840, 2009.12, In this study, a prototype flexible Joule-Thomson micro-refrigerator was fabricated and its cooling power was examined. The micro-refrigerator uses N2, C2H4 or CO2 as a working gas and it consists mainly of a heat exchanger and an evaporator. The outside diameter of the heat exchanger outer tube is 0.9 mm and that of the inner tube is 0.4 mm. The length of the heat exchanger is 450mm. The inner diameter of the evaporator capillary is 0.1 mm. A cooling power of 100 mW at an evaporator temperature of 277 K was attained for inlet and outlet gas (CO2) pressures of 5.0 MPa and 0.1 MPa, respectively. To understand the cooling performance, a numerical analysis of the heat exchanger has been done and the effects of mass flow rate and dimensions of the heat exchanger on temperature profiles and effectiveness were examined..
129. P. L. Woodfield, S. Moroe, J. Fukai, M. Fujii, K. Shinzato, M. Kohno, Y. Takata, Techniques for accurate resistance measurement in the transient short-hot-wire method applied to high thermal-diffusivity gas, International Journal of Thermophysics, 10.1007/s10765-009-0668-1, 30, 6, 1748-1772, 2009.12, The accuracy of high-speed transient resistance measurements is an important issue particularly for measuring the thermal conductivity of high thermal-diffusivity (low-density) gases. This is because the hot-wire temperature rise against the logarithm of time is non-linear and can approach a steady state within the typical measurement time of 1 s. Two types of voltmeters are compared for use in the transient short-hot-wire method. Details of suitable procedures for taking accurate transient resistance measurements with either a two-channel high-speed analog/digital converter or a pair of integrating digital multimeters are presented..
130. P. L. Woodfield, S. Moroe, J. Fukai, M. Fujii, K. Shinzato, M. Kohno and Y. Takata, Techniques for Accurate Resistance Measurement in the Transient Short-Hot-Wire Method Applied to High Thermal-Diffusivity Gas, International Journal of Thermophysics, 30, 6, 1748-1772, 2009.11.
131. E. Yusibani, P. L. Woodfield, M. Kohno, K. Shinzato, Y. Takata, M. Fujii, End effects in the three-omega method to measure gas thermal conductivity, International Journal of Thermophysics, 10.1007/s10765-009-0572-8, 30, 3, 833-850, 2009.06, A two-dimensional analytical solution is derived for the three-omega method for measurement of thermal conductivity of materials with a fine wire. The analytical solution includes the wire heat capacity and the effect of heat losses from the ends of the wire. To derive the solution, finite Fourier transforms are applied in the direction parallel to the wire axis. The solution is compared with a one-dimensional solution and experimental data. It is found that heat losses from the wire ends have a significant effect on the 3ω components at low frequency and tend to be less important at high frequency. Moreover, it is shown that two-dimensional effects will be severe for nano-scale wires, even if the wire length-to-diameter ratio is very large..
132. Yasuyuki Takata, Sumitomo Hidaka, Masamichi Kohno, Wettability improvement by plasma irradiation and its applications to phase-change phenomena, Heat Transfer Engineering, 10.1080/01457630802594820, 30, 7, 549-555, 2009.06, Plasma irradiation is one of the techniques to improve surface wettability. This technique can be used to enhance heat transfer of liquid-vapor phase change. For instance, evaporation of a water droplet can be enhanced by plasma irradiation. The relation between plasma irradiation time and contact angle was examined first for three metals and then the lifetime of a water drop on a hot surface was measured changing the surface wettability by plasma irradiation. The lifetime of the water drop decreased and the wetting limit temperature increased with the increasing irradiation time of plasma. Hydrophilicity by plasma irradiation is not a permanent effect but it will be useful for enhancement of cooling of hot metal..
133. TAKATA, HIDAKA AND KOHNO, WETTABILITY IMPROVEMENT BY PLASMA IRRADIATIONAND ITS APPLICATIONS TO PHASE CHANGE PHENOMENA, Heat Transfer Engineering, 2009.01.
134. Elin Yusibani, Peter Lloyd Woodfield, Shogo Moroe, Kanei Shinzato, Masamichi Kohno, Yasuyuki Takata, Motto Fujii, A procedure for application of the three-omega method to measurement of gas thermal conductivity, Journal of Thermal Science and Technology, 10.1299/jtst.4.146, 4, 1, 146-158, 2009, A non-linear least-squares curve-fitting procedure is proposed to analyze three-omega voltage data from a fine wire in a gas sample using the three-omega method. The method uses both three-omega components of the voltage arising from a sinusoidal heating current to determine the thermal conductivity of the surrounding medium. The proposed procedure is tested against simulated data and some experimental data for air at atmospheric pressure. Treating the technique as an absolute method and assuming a known sample heat capacity, the thermal conductivity of air has been measured at room temperature to within 11% of a reference value. Practical application of the method may require a calibrated effective wire length and wire diameter. An average wire temperature rise of around 10 K to ensure the three-omega components is enough for accurate measurement..
135. Naoya Sakoda, Kenta Shindo, Kan'ei Shinzato, Masamichi Kohno, Yasuyuki Takata, Motoo Fujii, C216 PVT MEASUREMENTS OF HIGH PRESSURE GAS BY THE BURNETT METHOD(Hydrogen and Reforming-2), The Proceedings of the International Conference on Power Engineering (ICOPE), 10.1299/jsmeicope.2009.2._2-265_, 2009, 0, _2-265_-_2-270_, 2009, A PVT measurement apparatus by the Burnett method for the temperature range from room temperature to 250 ℃ and at pressures up to 100 MPa has been developed with a remote operation system. PVT measurements of hydrogen, helium and nitrogen have been accomplished up to 97 MPa. The density uncertainty of the present measurements at 80 ℃ is estimated to be 0.2 % from the deviations for nitrogen. An existing equation of state (EOS) for hydrogen agrees well with the present measurements within ±0.22 % at 80 ℃. The systematic deviations between the EOS and the present measurements at 120 ℃ and 160 ℃ are shown with the maximum deviation of 0.52 % at 120 ℃ and 97 MPa..
136. Masamichi Kohno, Takashi Nishizono, Yasunori Onaka, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata, Micro oscillation heat pipe fabricated on silicon wafer, 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008 Proceedings of the 6th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM2008, 10.1115/ICNMM2008-62082, 1343-1346, 2008.12, Heat transport characteristics of micro oscillation heat pipe have been investigated. A single winding flow path consists of 28 turns microchannels fabricated on a silicon wafer the size of which was 31mmx27mm. We used heat pipe with non-uniformed cross section. Equivalent diameters of channels were 0.19 and 0.10mm. Test fluid was R141b and liquid fractions were 0, 75, 85%. It was found that steady pulsating flow occurred by increasing the number of turns and the frequency of vibration has an effect on heat transfer performance..
137. Masamichi Kohno, Takashi Nishizono, Yasunori Onaka, Sumitomo Hidaka, Koji Takahashi, Yasuyuki Takata , Micro Oscillation Heat Pipe Fabricated on Silicon Wafer
, Sixth International ASME Conference on Nanochannels, Microchannels and Minichannels, 2008.07.
138. Y. Takata, S. Hidaka, A. Okabe, M. Kohno, Y. Shigesato and G. Hayase, Wettability Effect in Condensation on Fin Surface, 19th International Symposium on Transport Phenomena, 2008.07.
139. Deendarlianto, Y. Takata, S. Hidaka, M. Kohno, The Effect of Contact Angle on the Evaporation of Water Droplet on a Heated Solid Surface, Fifth International Conference on Transport Phenomena in Multiphase Systems, 2008.05.
140. Y. Takata, K. Sugahara, T. Tachikawa, S. Moroe, H. Kubota, M. Kohno, K. Takahashi, T. Koshimizu, Micro-refrigerator fabricated on silicon wafer, 5th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2007 Proceedings of the 5th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2007, 10.1115/ICNMM2007-30108, 749-754, 2007.12, A prototype Joule-Thomson micro-cooler was fabricated on silicon wafer by making use of photofabrication. The microcooler uses ethylene as a refrigerant and it consists mainly of heat exchanger and evaporator. The cooling power of 20mW at evaporator temperature of 272K was attained at the inlet and outlet gas pressures of 2.5MPa and 0.1MPa, respectively. To understand the low cooling performance, numerical analysis of heat exchanger has been done and the effects of mass flow rate and thermal conductivity of solid on temperature profiles and effectiveness were examined. It was found that the flow rate of present experiment is too large and the decrease in flow rate gives better temperature effectiveness of heat exchanger. It was also found that the low thermal conductivity of solid improves the performance of heat exchanger..
141. Peter L. Woodfield, Shogo Moroe, Jun Fukai, Motoo Fujii, Masamichi Kohno, Yasuyuki Takata, Ka N.Ei Shinzato, Numerical simulation for design of probe to measure hydrogen thermal conductivity at high pressure by the transient short-wire method, Memoirs of the Faculty of Engineering, Kyushu University, 67, 4, 209-220, 2007.12, Hydrogen energy is expected to be a next generation clean energy. However there are still many issues that must be overcome before commercializing hydrogen energy. Clarifying the mechanism for the effects of hydrogen on all types of materials and understanding the characteristics of hydrogen at high temperature and high pressure are indispensable. This study focuses on the development of the measurement technique for the thermal conductivity of hydrogen in the high pressure and the high temperature region. Numerical simulations are performed to investigate the effect of wire diameter, length and vessel size in a short-wire thermal conductivity probe designed for the study of hydrogen gas in the range of pressures from 0.1 to 100 MPa and temperatures from 25 to 500°C. The two-dimensional unsteady heat conduction equation is discretized using the finite volume method to calculate the thermal field. The influence of the natural convection was examined using an empirical equation from the literature. The size of the vessel, the wire diameter, and the wire length respectively were changed within the range of R=2.5-50mm, d=5-50μm, and H=20-160mm..
142. Naoya Sakoda, Elin Yusibani, Peter Lloyd Woodfield, Kan'ei Shinzato, Masamichi Kohno, Yasuyuki Takata, Motoo Fujii, Review of Thermophysical Properties of Hydrogen and the Related Work of HYDROGENIUS, Proceedings of the 8th Asian Thermophysical Properties Conference, Paper No.178, 2007.08.
143. Soma Yamamoto, Keita Tani, Yasumori Onaka, Yasuyuki Takata, Shinzo Suzuki, Yasushi Shibuta, Shigeo Maruyama, Masamichi Kohno, Synthesis of Single Walled Carbon Nanotubes by Laser Vaporized Catalytic Chemical Vapor Deposition Technique, Proceedings of HT2007: 2007 ASME-JSME Thermal Engineering Summer Heat Transfer Conference, HT2007-32776, 2007.07.
144. Y. Takata, H. Kubota, M. Kohno and K. Takahashi, T. Koshimizu, Micro-Refrigerator Fabricated on Silicon Wafer, Proceedings of ASME ICNMM2007: 5th International Conference on Nanochannels, Microchannels and Minichannels, Paper No. ICNMM2007-30108, 2007.06.
145. Y. Takata, S. Hidaka and M. Kohno, Wettability Improvement by Plasma Irradiation and its Applications to Phase Change Phenomena, Proceedings of the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Paper No. K1, 2007.06.
146. S. Chiashi, M. Kohno, Y. Takata and S. Maruyama, Localized synthesis of single-walled carbon nanotubes on silicon substrates by a laser heating catalytic CVD, Journal of Physics Conference Series Journal, 59, 155-158, vol.59, pp.155-158, 2007.05.
147. Shohei Chiashi, Masamichi Kohno, Yasuyuki Takata, Shigeo Maruyama, Localized synthesis of single-walled carbon nanotubes on silicon substrates by a laser heating catalytic CVD, Journal of Physics: Conference Series, 10.1088/1742-6596/59/1/033, 59, 1, 155-158, 2007.04, Synthesis of high-purity single-walled carbon nanotubes (SWNTs) is demonstrated by a laser heating catalytic CVD method. This method makes it possible to produce SWNTs without the use of an electric furnace or hot filament. SWNTs were synthesized from alcohol using Fe/Co catalyst particles supported on zeolite and Mo/Co particles deposited directly on a substrate. Synthesis of high purity SWNTs was confirmed by in situ Raman scattering analysis and AFM and FE-SEM observations..
148. Soma Yamamoto, Yasumori Onaka, Shinzo Suzuki, Shigeo Maruyama, Keita Tani, Yasuyuki Takata, Yasushi Shibuta, Masamichi Kohno, Synthesis of single walled carbon nanotubes by laser vaporized catalytic chemical vapor deposition technique, 2007 ASME/JSME Thermal Engineering Summer Heat Transfer Conference, HT 2007 2007 Proceedings of the ASME/JSME Thermal Engineering Summer Heat Transfer Conference - HT 2007, 10.1115/HT2007-32776, 387-393, 2007, SWNTs were synthesized by laser vaporized CCVD (Catalytic Chemical Vapor Deposition). The diameter distribution and the purity of SWNTs synthesized at different temperatures, laser intensities and catalysts were investigated by Raman spectroscopy. Both of them tended to shift towards a larger area as reacting temperature or laser intensity was increased. Ni, Co and Fe played a catalytic role, though Ag and Cu were less effective at our experimental conditions. In addition, the conventional laser oven technique and laser vaporized CCVD technique were also compared. The diameter distribution of SWNTs which were synthesized by the conventional laser oven technique was narrower than that of SWNTs synthesized by the laser vaporized CCVD technique..
149. S. Kawauchi.M. Kohno, Y. Takata and Y. Matsuoka, Microdrilling in Thin Metal Foils with a Nanosecond Pulsed Bessel Laser Beam, Proceedings of the 17th International Symposium on Transport Phenomena, 2006.09.
150. M.Kohno, S.Kawauchi, Y.Takata, Y.Matsuoka, Microdrilling of Metals with a Nano-Second Pulsed Bessel Laser Beam, Procedings of the International Heat Transfer Conference IHTC-13, 2006.08.
151. Y. Takata, S. Hidaka, M. Kohno, Enhanced Nucleate Boiling by Superhydrophobic Coating with Checkered and Spotted Patterns, ECI International Conference on Boiling Heat Transfer Spoleto, 7月12日, pp.7-12, 2006.05.
152. Yasuyuki TAKATA, Sumitomo HIDAKA and Masamichi. KOHNO, Boiling from a Super-Water-Repellent Surface, Proceedings of the Fifth International Conference on Enhanced, Compact and Ultra-Compact Heat Exchangers: Science, Engineering and Technology, 2005.09.
153. Yasuyuki TAKATA, Sumitomo HIDAKA and Masamichi KOHNO, Pool Boiling from a Super-Water-Repellent Surface, Proceedings of the 3rd Korea-Japan Joint Seminar on Heat Transfer: Challenging Researches in Thermal Engineering, 65-69, pp.65-69, 2005.09.
154. Yasuyuki TAKATA, Sumitomo HIDAKA and Masamichi KOHNO, Boiling Heat Transfer from a Super-Water-Repellent Surface, Proceedings of the 6th World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics, 2005.04.
155. Masamichi Kohno, Shuhei Inoue, Shigeo Maruyama, Chemisorption of silicon cluster ions (Sin+, n=10-30) with ethylene (C2H4) by using FT-ICR mass spectrometer, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.71.1148, 71, 704, 1148-1154, 2005.04, Mass-selected silicon cluster ions were levitated in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer and monitored during chemisorption reaction with ethylene (C2H4). Through measurements of "time-dependency" of this reaction process, large change of the reactivity depending on the number of absorbed ethylene was observed, in addition to the strong dependency to silicon cluster size. From Si15+ to Si18+ shows a special stability of SixEy+ when x + y = 19, such as Si15E4+. The large decrease in the reactivity of Sin+ was observed due to the contamination of hydrogen atom to Sin+. Rate constants for the adsorption of the first C2H4 molecules on Sin+ were estimated. The reaction kinetics data suggest that structural isomers are present for all clusters except Si14+ in the size range investigated..
156. Yohji ACHIBA, Masamichi KOHNO, Michiaki OHARA, Shinzo SUZUKI, Haruo SHIROMARU, Electron Detachment Spectroscopic Study on Carbon and Silicon Cluster Anion, Journal of Electron Spectroscopy and Related Phenomena, 10.1016/j.elspec.2004.09.016, 142, 3, 231-240, vol.142, pp.231-240, 2005.02.
157. M.Kohno, T.Orii, M.Hirasawa, T.Seto, Y.Murakami, S.Chiashi, Y.Miyauchi, S.Maruyama, Synthesis of single-walled carbon nanotube (SWNTs) from size-selected catalytic metal particles, Applied Physics A, 79, 787-790, vol.79, pp.787-790,, 2004.09.
158. Masamichi Kohno, Yoshihiko Matsuoka, Microfabrication and drilling using diffraction-free pulsed laser beam generated with axicon lens, JSME International Journal, Series B: Fluids and Thermal Engineering, 10.1299/jsmeb.47.497, 47, 3, 497-500, 2004.08, Laser microfabrication using a diffraction-free beam (Bessel beam) was performed. Microfabrication with a deep focal depth is possible because a diffraction-free beam has a main lobe with a small diameter, which does not depend on propagation length. The diffraction-free beam was generated using an axicon lens, and the generation was confirmed using an optical microscopy image of a laser-fabricated spot on a silicon wafer. Nevertheless using a nanosecond pulsed Nd:YAG laser, microfabrication with a spot diameter
159. Masamichi KOHNO, Yoshihiko MATSUOKA, Microfabrication and Drilling Using Diffraction-Free Pulsed Laser Beam Generated with Axicon Lens, JSME International Journal, Series B, Vol.47, No.3, pp.497-500, 2004.01.
160. Masamichi Kohno, T. Orii, M. Hirasawa, T. Seto, Y. Murakami, S. Chiashi, Y. Miyauchi, S. Maruyama, Growth of single-walled carbon nanotubes from size-selected catalytic metal particles, Applied Physics A: Materials Science and Processing, 10.1007/s00339-004-2756-1, 79, 4-6, 787-790, 2004.01, Single-walled carbon nanotubes (SWNTs) were synthesized using size-controlled catalyst nanoparticles created by the pulsed laser ablation method. Specifically, the alloy particles (Co/Mo or Co/Pt) were prepared by ablation of the target alloy materials in an inert gas atmosphere. Size selection was performed using a differential mobility analyzer (DMA). The obtained nanoparticles were deposited on a quartz substrate from which SWNTs were grown by the alcohol catalytic CVD (ACCVD) technique that was developed by the authors' group. AFM and Raman scattering analysis revealed that SWNTs were successfully synthesized. It seems the Co/Mo alloy catalyst was more effective for the synthesis of SWNTs than the Co/Pt catalyst, though this is a preliminary result to be further investigated..
161. Seisuke Kano, Masamichi Kohno, Kaname Sakiyama, Shinya Sasaki, Hirofumi Shimura, Fullerenes synthesis from carbon powder using CW-CO2 laser, Proceedings of SPIE - The International Society for Optical Engineering, 10.1117/12.478570, 4977, 615-622, 2003.12, A semi-continuous process for the synthesis of fullerenes is described. This novel process incorporated a carbon powder feed system in combination with a continuous-wave CO2 laser irradiation source. The carbon powder contained no fullerenes but did contain graphite crystals and amorphous carbons of selected particle sizes (5, 10, or 20 μm), and selected irregular or spherical particle shapes. The method was successfully used to deposit C60 and C70 powders and films continuously. Laser irradiation of the carbon powder produced an observable laser plume. The experimental results and mechanism for the process are discussed..
162. Seisuke Kano, Masamichi Kohno, Kaname Sakiyama, Shinya Sasaki, Nobuhiro Aya, Hirofumi Shimura, Irradiation of CW-CO2 laser on a powder target. Formation of fullerene film from graphite powder, Chemical Physics Letters, 10.1016/S0009-2614(03)01326-5, 378, 5-6, 474-480, 2003.09, A process was investigated to irradiate a continuous-wave CO2 laser (4.5 kW) on graphite powder with a mean diameter of 5 μm in a flow of Ar or He gas at 30 or 200 Torr. The film produced on a Ni substrate in the Ar flow at 200 Torr showed the Raman bands of C60 and C70, and the C60/C70 ratio was estimated to be 5/1 by MALDI-TOF mass spectrometry. The film formation process is discussed on the basis of an analysis of laser-irradiated powder, which included 0.01 wt% of C60, by UV-Vis absorption, and by observations of the plumes and SEM images..
163. Shuhei Inoue, Masamichi Kohno, Shigeo Maruyama, Chemical reaction of silicon clusters with nitric oxide by using FT-ICR mass spectrometer, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.69.1879, 69, 684, 1879-1885, 2003.08, Chemical reaction of small silicon cluster ions (Sin+:13, 15 ≤i ni ≤i 29) with nitric oxide was studied by using the FT-ICR (Fourier Transform Ion Cyclotron Resonance) mass spectrometer. Silicon clusters were generated by a pulsed laser-vaporization supersonic-expansion cluster beam source directly connected to the FT-ICR mass spectrometer. Fully thermalized and mass-selected clusters were reacted with NO in the ICR cell. The primary reaction was the exchange of a silicon atom with a nitrogen atom as Sin+ + NO → Sin-1N+ + SiO. Then, smaller clusters than Si23N+ (with exceptions for Si16N+ and Si20N+) fragmented to much smaller clusters. It was explained that in general smaller clusters could not survive with the exothermal reaction heat. On the other hand, the magic number clusters of Si16N+ and Si20N+ probably represented the geometrical special stability..
164. Masamichi Kohno, Shuhei Inoue, Shigeo Maruyama, Mass spectroscopy and reaction studies of laser-vaporized clusters from metal-doped carbon materials, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.69.1886, 69, 684, 1886-1892, 2003.08, Metal-carbon binary clusters are believed to be important precursor clusters both for single-walled carbon nanotubes (SWNTs) and endohedral metallofullerene. Metal-carbon binary clusters (MCn M = La, Ni or Co) and carbon clusters (Cn) were generated with a pulsed laser-vaporization supersonic-expansion cluster beam source directly connected to the FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometer, and chemical reaction of MCn- and Cn- with nitric oxide was studied. Depending on the metal element, the generation efficiency and the reactivity of metal-carbon binary clusters were completely different. LaCn- (n=even, n≥36) was much less reactive to NO than pure carbon clusters, while MCn- (M = Ni or Co) was much more reactive than pure carbon clusters. It was speculated that LaCn- (n=even, n≥36) had a fullerene-like cage structure with a metal atom inside, and that MCn- (M = Ni or Co) had an imperfect cage structure where a metal atom preferentially attached to the imperfect site..
165. Shigeo Maruyama, Yuhei Miyauchi, Shohei Chiashi, Masamichi Kohno, Low-temperature generation of high-purity single-walled carbon nanotubes by alcohol CCVD technique, Nippon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.69.918, 69, 680, 918-924, 2003.04, By using alcohol such as ethanol and methanol as the carbon source, a new simple catalytic chemical vapor deposition technique to generate high-purity single-walled carbon nanotubes at low temperature is demonstrated. Vapor phase alcohol was supplied over Fe/Co catalyst supported with Zeolite in an electric furnace. The blackened sample was analyzed by resonant Raman spectroscopy, transmission electron microscopy and scanning electron microscopy. Because of the etching effect of decomposed OH radical attacking carbon atoms with a dangling bond, impurities such as amorphous carbon, multi-walled carbon nanotubes, metal particles and carbon nanoparticles are completely suppressed even at relatively low reaction temperature such as 700-800°C..
166. S. Kano, M.Kohno, K. Sakiyama, S. Sasaki, N. Aya and H. Shimura, Synthesis of fullerenes and fullerene thin films from a graphite powder using a continuous-wave CO2 laser, Chem. Phys. Lett., 378, 474-480, vol.378, p.474-480, 2003.01.
167. Masamichi Kohno, Shuhei Inoue, Ft-icr study of precursor clusters of single-walled carbon nanotubes (swnts), Microscale Thermophysical Engineering, 10.1080/10893950390150458, 7, 1, 33-39, 2003.01, Metal-carbon binary clusters generated by the laser vaporization of Ni/Co and Ni/Y doped graphite samples used for the macroscopic laser-oven production of SWNTs were studied. Positive and negative clusters generated by the laser-vaporization supersonic-expansion cluster beam source were directly injected into the FT-ICR (Fourier Transform Ion Cyclotron Resonance) mass spectrometer. Depending on the metal species, the generation efficiency of metal-carbon binary clusters was drastically different. The chemical reaction of these clusters with NO gas was used as the probe of the geometrical structure of clusters. The reactivity to NO of these binary clusters was completely different. In case of YCn (n = even, n ≥ 36), chemical reaction of YCn with NO was not observed while pure carbon clusters were reacted. On the other hand, for MCn (M = Ni or Co), the reactivity was much higher than pure carbon clusters. It was speculated that a few Ni or Co atoms attached outside of imperfect carbon cage for Ni/Co doped case and that Y atom was included in the carbon cage for Ni/Y doped case..
168. Masamichi Kohno, Shuhei Inoue, Ryosuke Kojima, Shohei Chiashi, Shigeo Maruyama, FT-ICR studies of laser vaporized clusters from Ni/Co- and Ni/Y-loaded graphite samples, Proceedings of the Tsukuba Symposium on Carbon Nanotube in Com (CNT10) Physica B: Condensed Matter, 10.1016/S0921-4526(02)00996-1, 323, 1-4, 272-274, 2002.10, Metal-carbon binary clusters generated by the laser vaporization of Ni/Co- and Ni/Y-loaded graphite samples used for the macroscopic production of SWNTs were studied. Positive and negative clusters generated by the laser-vaporization supersonic-expansion cluster beam source were directly injected into the FT-ICR mass spectrometer. The chemical reaction of these clusters with NO was used as the probe of the geometrical structure of clusters. It was speculated that a few Ni or Co atoms attached outside of imperfect carbon cage for Ni/Co loaded case, and that Y atom was included in the carbon cage for Ni/Y loaded case..
169. Shigeo Maruyama, Ryosuke Kojima, Yuhei Miyauchi, Shohei Chiashi, Masamichi Kohno, Low-temperature synthesis of high-purity single-walled carbon nanotubes from alcohol, Chemical Physics Letters, 10.1016/S0009-2614(02)00838-2, 360, 3-4, 229-234, 2002.07, By using alcohol as the carbon source, a new simple catalytic chemical vapor deposition technique to synthesize high-purity single-walled carbon nanotubes at low temperature is demonstrated. Because of the etching effect of decomposed OH radical attacking carbon atoms with a dangling bond, impurities such as amorphous carbon, multi-walled carbon nanotubes, metal particles and carbon nanoparticles are completely suppressed even at relatively low reaction temperature such as 700-800 °C. By using methanol, generation of SWNTs even at 550 °C is demonstrated. The high-purity synthesis at low temperature promises large scale production at low cost and the direct growth of SWNTs on conventional semiconductor devices already patterned with aluminum..
170. M.Kohno, S.Inoue, R.Kojima, S.Chiashi and S.Maruyama, FT-ICR Studies of Laser Vaporized Clusters from Ni/Co and Ni/Y Loaded Graphite Samples, Physica B, 323, 1月4日, 272-274, Vol.323, No.1-4, p.272-274, 2002.01.
171. M. Kohno, S. Inoue, A. Yabe and S. Maruyama, FT-ICR Studies of Precursor Clusters of Single Wall Carbon Nanotubes, Micro. Thermophys. Eng., 7, 1, 33-39, Eng., vol.7, no.1, p.33-39, 2002.01.
172. S Maruyama, R. Kojima, Y. Miyauchi, S. Chiashi and M. Kohno, Low-temperature synthesis of high-purity single-walled carbon nanotubes from alcohol, Chem. Phys. Lett., 360, 229-234, vol.360, p. 229-234, 2002.01.
173. Masamichi Kohno, Shinzo Suzuki, Haruo Shiromaru, Kaoru Kobayashi, Shigeru Nagase, Yohji Achiba, Hardy Kietzmann, Barbara Kessler, Gerd Gantefoer, Wolfgang Eberhardt, Photoelectron spectroscopy study of MCn- (M = Sc, Y, and La, 5≤n≤20), Journal of Electron Spectroscopy and Related Phenomena, 10.1016/S0368-2048(00)00210-3, 112, 1-3, 163-173, 2000.11, Photoelectron spectra of metal-attached carbon cluster anions MCn- (M = Sc, Y, and La, 5≤n≤20) generated in a laser-vaporization ion source were measured using a magnetic bottle time-of-flight photoelectron spectrometer with 6.4 eV photon energy. The vertical detachment energy (vDE) of each species was estimated from the spectra and compared with the vDE of the linear and monocyclic ring forms of Cn. It was found that PES features of MCn- (5≤n≤20, n = odd) could be understood under the assumption that the π electronic structure of MCn- is similar to those of the linear carbon chains. However, the PES features of MCn- (12≤n≤20, n = even) indicate the presence of a π electronic structure similar to the isomers having ring form. Further possible electronic and molecular structures are presented and discussed for MCn- of odd n and even n, respectively..
174. M.Kohno, S. Suzuki, H. Shiromaru, K. Kobayashi, S. Nagase and Y. Achiba, Photoelectron Spectroscopy Study of MCn- ( M = Sc, Y and La, 5n20 ), Journal of Electron Spectroscopy and Related Phenomena, 112, 163-173, vol.112 p.163-173, 2000.01.
175. M. Kohno, S. Suzuki, T. Kodama, D. Kasuya, H. Shiromaru, Y. Achiba, Ultraviolet photoelectron spectroscopy of C-60 produced by three different generation methods, European Physical Journal D, 10.1007/s100530050456, 9, 1-4, 359-362, 1999.12, The photoelectron spectra of C-60 produced with three different generation methods were recorded with 6.4eV photon energy using a magnetic-bottle-type time-of-flight photoelectron spectrometer. From these spectra, it was suggested that the laser vaporization of a graphite rod mainly produces C-60 of ring-like structure. On the other hand, C-60 produced by the fragmentation process of the fullerene C70 through C2 or C2n elimination give different photoelectron features from those of C-60 having an icosahedral (Ih) symmetry or a ring-like structure..
176. Shigeo Maruyama, Tetsuya Yoshida, Masamichi Kohno, FT-ICR studies of laser desorbed carbon clusters, Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B, 10.1299/kikaib.65.3791, 65, 639, 3791-3798, 1999.11, For experimental treatments of atomic clusters, a FT-ICR (Fourier Transform Ion Cyclotron Resonance) spectrometer with a direct injection supersonic cluster beam source was implemented. Newly designed ICR cell in 6 Tesla superconducting magnet was proved to give a high mass-resolution for positive and negative cluster ions. With this mass-spectrometer, pure carbon and metal-carbon binary clusters generated by the laser-vaporization supersonic-expansion cluster-beam source were studied. A special cluster beam source condition was found where only C60+ was observed for pure carbon clusters. Furthermore, positive lanthanum-carbon, yttrium-carbon and scandium-carbon binary clusters showed only MC2n+ signal in the range of 36≤2n≤76 with strong magic numbers at MC 44+, MC50+ and MC60 +. Characteristics of these small clusters were compared with results of molecular dynamics simulations..
177. Masamichi Kohno, Shinzo Suzuki, Haruo Shiromaru, Yohji Achiba, Characterization of the lowest triplet states of linear form C2n+1 by anion photoelectron spectroscopy, Journal of Chemical Physics, 10.1063/1.478269, 110, 8, 3781-3784, 1999.02, Photoelectron spectroscopy was applied to characterize electronically excited states of carbon clusters consisting of odd number atoms, C-
2n-1 (n = 2-7). By optimizing the cluster generation condition so that the fraction of C-
n anions with a linear form increases, the energy difference between the ground and the first excited states of the carbon linear chains up to C-
15 was systematically examined. As a result, it was found that the photoelectron second bands are attributed to the first excited triplet states of neutral carbon linear chains. The monotonous decrease of the excitation energy found for C7-15 clearly indicates that these linear chains possess a common electronic property for the lowest triplet states. Furthermore, by analyzing the decrease of the excitation energy in the triplet manifold, it was found that the gap tends to converge to almost zero by increasing a length of carbon chain..
178. M.Kohno, S.Suzuki, H.Shiromaru and Y.Achiba, Characterization of the lowest triplet states of linear form C2n+1 by anion photoelectron spectroscopy, J.Chem.Phys., 110, 3781-3784, 1999.01.
179. S. Maruyama, Y. Yamaguchi, M. Kohno and T. Yoshida, Formation Process of Empty and Metal-Containing Fullerene. -Molecular Dynamics and FT-ICR Studies, Fullerene Science and Technology, 7, 4, 621-639, vol. 7, no. 4, 621-639, 1999.01.
180. S. Maruyama, M. Kohno and S. Inoue, FT-ICR Study of Chemical Reaction of Silicon clusters, Therm. Sci. Engng., 7, 6, 69-74, vol. 7, no.6, p.69-74, 1999.01.
181. M.Kohno, S. Suzuki, T. Kodama, D.Kasuya, H.Shiromaru, Y.Achiba, Ultraviolet Photoelectron Spectroscopy of C60- produced by three different generation methods, Europe. J. Phys. D, D9, 359-362, D9, p.359-362, 1999.01.
182. Shigeo Maruyama, Yasutaka Yamaguchi, Masamichi Kohno, Tetsuya Yoshida, Formation process of empty and metal-containing fullerenes - molecular dynamics and FT-ICR studies, Fullerene Science and Technology, 10.1080/10641229909351366, 7, 4, 621-636, 1999.01, The formation mechanism of empty and metal-containing fullerene was studied through MD (molecular dynamics) simulations and FT-ICR (Fourier transform ion cyclotron resonance) mass spectroscopy of laser vaporized carbon cluster. Multi-body classical potential functions for metal-carbon and metal-metal interactions were constructed based on DFT (density functional theory) calculations of various forms of small clusters MCn and Mn (M = La, Sc, Ni). Using the modified Brenner potential for carbon-carbon interaction, the clustering process starting from 500 isolated carbon atoms and 5 metal atoms in gas phase was simulated under the controlled temperature condition at 3000K. The difference of clustering process of LaCn, ScCn and NiCn were compared with empty fullerene formation simulation. FT-ICR mass spectrometer directly connected to the laser vaporization cluster beam source was implemented in order to experimentally study the clustering process. The increase of cluster nozzle pressure roughly corresponded to the later stage of the molecular dynamics simulation. The FT-ICR mass spectra of metal-carbon composite clusters were compared for various sample materials used for arc-discharge generation of metal-containing fullerene and SWNT (single-wall carbon nanotube); La, Y, Sc, Gd, Ce, Ca, and Ni-Y. Positive La-C, Y-C, Sc-C, Gd-C, Ce-C binary clusters commonly showed strong MC2n+ signal in the range of 36 44+, MC50+ and MC60+. It was speculated that the even-numbered clusters corresponded to the annealed random caged clusters observed in the MD simulation..
183. M.Kohno, S.Suzuki, H.Shiromaru, T.Moriwaki and Y.Achiba, Ultraviolet photoelectron spectroscopy on the linear conformer of negatively charged carbon clusters Cn- (10≦n≦16), Chem.Phys.Lett., 282, 330-334, vol.282, p.330-334, 1998.01.
184. M. Kohno, S. Suzuki, H. Shiromaru, T. Moriwaki, Y. Achiba, Ultraviolet photoelectron spectroscopy on the linear conformer of negatively charged carbon clusters Cn- (10≤n≤16), Chemical Physics Letters, 10.1016/S0009-2614(97)01273-6, 282, 3-4, 330-334, 1998.01, A photoelectron spectroscopy technique was successfully applied to the detection and characterization of a linear conformer of negatively-charged carbon clusters from C10- to C16-. By controlling the laser fluence for vaporization it was found that the fraction of a linear conformer was enriched. The presence of the linear form up to C16- was confirmed by the photoelectron spectroscopic evidences. On the basis of the present observations, it was also found that the observed vertical electron affinity up to C16 shows a distinct even-odd alternation, converging into the asymptotic value of ca. 5.0 eV..
185. T.Wakabayashi, M.Kohno, H.Shiromaru, Y.Achiba, T.Momose, T.Shida, K.Naemura and Y.Tobe J.Chem.Phys., Photoelectron spectroscopy of Cn- produced from laser ablated dehydroannulene derivatives having carbon ring size of n=12,16,18,20,and 24, J. Chem. Phys., 107, 4783-4787, vol.107, p.4783-4787, 1997.11.
186. K. Kaizu, M. Kohno, S. Suzuki, H. Shiromaru and Y. Achiba, Neutral carbon cluster distribution upon laser vaporization, J. Chem. Phys, 106, 9954-9956, vol.106, p.9954-9956, 1997.10.
187. S.Suzuki, M.Kohno, H.Shiromaru, Y.Achiba, H.Kietzmann, B.Kessler, G.Gantefr and W.Eberhardt, Time-of-flight mass and photoelectron spectroscopy study of LaCn-, Z. Phys. D, 40, 407-409, vol.40, p.407-409, 1997.10.
188. Tomonari Wakabayashi, Masamichi Kohno, Yohji Achiba, Haruo Shiromaru, Takamasa Momose, Tadamasa Shida, Koichiro Naemura, Yoshito Tobe, Photoelectron spectroscopy of C-n produced from laser ablated dehydroannulene derivatives having carbon ring size of n=12, 16, 18, 20, and 24, Journal of Chemical Physics, 10.1063/1.474841, 107, 13, 4783-4787, 1997.10, n-Dehydroannulenes with the ring size of n= 12, 16, 18, 20, and 24 and with three to five indanyl substituents are laser ablated by 355 nm photons. The indanyl unit is lost stepwise up to the complete deletion to leave the bare annulenyl skeleton. The monoanions of these products are mass analyzed first, and then subjected to a second laser pulse of 266 nm to obtain photoelectron spectra for C-n with n=12, 16, 18, 20, and 24. The spectra are compared with those obtained by using graphite as a target of the laser ablation. The comparison of the two spectra provides useful information on the structure of neutral carbon clusters..
189. K. Kaizu, M. Kohno, S. Suzuki, H. Shiromaru, T. Moriwaki, Y. Achiba, Neutral carbon cluster distribution upon laser vaporization, Journal of Chemical Physics, 10.1063/1.473883, 106, 23, 9954-9956, 1997.06, The mass distribution of neutral carbon clusters generated by a laser vaporization of graphite in He was safely determined by a single photon (10.5 eV) ionization technique. The resulting mass distribution was surprisingly different from those reported in previous articles. It was found that the carbon clusters generated under a moderate laser fluence condition (0.1-1 J/cm2) consists of mostly even-numbered monocyclic rings with the cluster sizes of n = 10-18. The formation mechanism of such neutral carbon clusters upon laser irradiation is discussed..
190. S. Suzuki, M. Kohno, H. Shiromaru, Y. Achiba, H. Kietzmann, B. Kessler, G. Ganteför, W. Eberhardt, Time-of-flight mass and photoelectron spectroscopy study of LaCn-, Zeitschrift fur Physik D-Atoms Molecules and Clusters, 10.1007/s004600050238, 40, 1, 407-409, 1997.01, Mass spectra of LaCn- were taken by using a laser-vaporization source (LVS) and pulsed arc cluster ion source (PACIS) applied to La-carbon composite rods (1:130 atomic ratio). The mass spectrum using the LVS with annealing procedure has shown several magic numbers for LaCn- (n = 44, 50, 60, and 70), whereas only small LaCn- (up to n = 14) have been observed in the mass spectrum using the PACIS. Photoelectron spectra of some of these have been measured using a magnetic-bottle type time-of-flight electron spectrometer. These results indicate the exsistence of a few conformational isomers for small La-containing carbon cluster negative ions LaCn- (n = 5-8)..