1. |
Uthpala Perera, Kyaw Thu, Takahiko Miyazaki, Naoya Sakoda, Yukihiro Higashi, Saturaiton Pressure Measurements of the New Refrigerant HFO1132(E), *Proceedings of the 2nd IIR Conference on HFOs and Low GWP Blends*, Paper ID 1023, 2021.06. |

2. |
Naoya Sakoda, Yukihiro Higashi, Thermodynamic Properties Measurement of HFO1132(E), *Proceedings of the 2nd IIR Conference on HFOs and Low GWP Blends,*, Paper ID 1024 , 2021.06. |

3. |
Naoya Sakoda, Yukihiro Higashi, Thermodynamic Properties Measurement of Binary HFC32 + CF3I Refrigerant Mixtures, *Proceedings of the 6th IIR Thermophysical Properties and Transfer Processes of Refrigerants Conference*, Paper ID 1966, 2021.09. |

4. |
Uthpala A Perera, Naoya Sakoda, Takahiko Miyazaki, Kyaw Thu, Yukihiro Higashi, Measurements of Saturation Pressures for the Novel Refrigerant R1132(E), *International Journal of Refrigeration*, 135, 148-153, 2022.03. |

5. |
Siyuan Cheng, Fengyi Li, Fei Shang, Weigang Ma, Hui Jin, Naoya Sakoda, Xing Zhang, Liejin Guo, A Review of Experimental Researches on the Thermophysical Properties of Hydrogen-Containing Mixtures at High Temperatures and High Pressures, *Journal of Chemical and Engineering Data*, 66, 3361-3385, 2021.09. |

6. |
Taichi Kuroki, Kazunori Nagasawa, Michael Peters, Daniel Leighton, Jennifer Kurtz, Naoya Sakoda, Masanori Monde, Yasuyuki Takata, Thermodynamic Modeling of Hydrogen Fueling Process from High-Pressure Storage Tank to Vehicle Tank, *International Journal of Hydrogen Energy*, 46, 22004-22017, 2021.06. |

7. |
Naoya Sakoda, Yukihiro Higashi, Ryo Akasaka, Measurements of PvT properties, vapor pressures, saturated densities, and critical parameters for trans-1,1,1,4,4,4-hexafluoro-2-butene (R1336mzz(E)), *Journal of Chemical and Engineering Data*, https://doi.org/10.1021/acs.jced.0c00848, 66, 734-739, 2021.02. |

8. |
T. Yamada, H. Miyamoto, N. Sakoda, Y. Higashi, Vapor–Liquid Equilibrium Property Measurements for R32/R1234yf Binary Mixtures in Low R32 Concentration, *International Journal of Thermophysics*, https://doi.org/10.1007/s10765-020-02752-2, 41, 167, 2020.12. |

9. |
Siyuan Cheng, Weigang Ma, Naoya Sakoda, Xing Zhang, Thermodynamic Calculations of the Critical Points of the H2–CO2–CH4–CO–H2O System, *International Journal of Thermophysics*, https://doi.org/10.1007/s10765-020-02725-5, 41, 141, 2020.10. |

10. |
Naoya Sakoda, Yukihiro Higashi, Ryo Akasaka, Measurements of Vapor Pressures for trans-1-Chloro-3,3,3-trifluoropropene (R1233zd(E)) and cis-1,1,1,4,4,4-Hexafluoro-2-butene (R1336mzz(Z)), *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.0c00239, 2020.09, Vapor pressures for new low-GWP refrigerants of R1233zd(E) (trans-1-chloro-3,3,3-trifluoropropene) and R1336mzz(Z) (cis-1,1,1,4,4,4-hexafluoro-2-butene) were measured by the isochoric method. Twelve vapor-pressure measurements of R1233zd(E) were obtained at temperatures between 300 and 410 K, whereas 17 vapor-pressure measurements of R1336mzz(Z) were obtained at temperatures between 290 and 410 K. Temperature was measured with a 25 ω standard platinum resistance thermometer with an aid of ITS-90, and pressure was measured with a digital quartz pressure transducer. The experimental uncertainties in temperature and pressure are estimated to be within 5 mK and 1 kPa, respectively. The experimental data were compared with the previous experimental data and equations of state. New vapor-pressure correlations of R1233zd(E) and R1336mzz(Z) have been formulated on the basis of the data obtained.. |

11. |
H. Miyamoto, T. Saito, N. Sakoda, U. Perera, T. Ishii, K. Thu, Y. Higashi, Measurement of the Vapor-liquid Equilibrium Properties of the Binary low GWP Refrigerant R32/R1123, *International Journal of Refrigeration*, 119, 340-348, 2020.11. |

12. |
Ryo Akasaka, Yukihiro Higashi, Naoya Sakoda, Sho Fukuda, Eric W. Lemmon, Thermodynamic Properties of Trifluoroethene (R1123): (p, ρ, T) Behavior and Fundamental Equation of State, *International Journal of Refrigeration*, 119, 457-467, 2020.11. |

13. |
Siyuan Cheng, Fei Shang, Weigang Ma, Hui Jin, Naoya Sakoda, Xing Zhang, Liejin Guo, Viscosity Measurements of the H_{2}-CO_{2}, H_{2}-CO_{2}-CH_{4}, and H_{2}-H_{2}O Mixtures and the H_{2}-CO_{2}-CH_{4}-CO-H_{2}O System at 280-924 K and 0.7-33.1 MPa with a Capillary Apparatus, *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.0c00176, 65, 8, 3834-3847, 2020.06, The viscosity of hydrogen mixtures in the supercritical region of water is significant for the optimization of the gasification process of organic substances in supercritical water. In this work, a capillary apparatus was developed for measuring the viscosity of fluids and their mixtures at 279-980 K and up to 34 MPa. The viscosities of pure water, nitrogen, and hydrogen at 279-980 K and 0.5-31.0 MPa were measured, and the results were compared with the reference equations. Then, the viscosities of the H2-CO2 and H2-CO2-CH4 mixtures at 280-677 K and 0.7-33.1 MPa and of the H2-H2O mixtures and the H2-CO2-CH4-CO-H2O system at 720-924 K and 19.9-31.1 MPa were measured. The expanded relative uncertainty (k = 2) for the dynamic viscosity was estimated as 0.05. The viscosity data of the hydrogen mixtures were compared with those predicted using the equation of Wilke considering the nonideal gas effect. The absolute relative deviations between the calculated and experimental dynamic viscosities are less than 4.87%.. |

14. |
A Review on Thermophysical Property Researches for Low-GWP Olefin Refrigerants. |

15. |
Y. Kawano, T. Kuroki, N. Sakoda, M. Monde, Y. Takata, Thermal analysis of high-pressure hydrogen during the discharging process, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2019.08.167, 44, 49, 27039-27045, 2019.10, The transient temperature and pressure of hydrogen are measured during the hydrogen discharging process through an orifice in a high-pressure vessel. The initial pressures of hydrogen in the vessel are set to approximately 30, 60, and 100 MPa. The mass flow rate and heat flux between hydrogen and the inner wall of the vessel are theoretically estimated using fundamental equations and experimental results with accurate thermophysical properties of hydrogen. The generation of temperature distribution and flow due to heat transfer in the vessel during discharge is verified by numerical analysis. Further, the relationship between reference gas temperature and heat flux in the vessel during the release of high-pressure hydrogen is studied. The average heat flux in the vessel is calculated using experimental and numerical analysis. The appropriate reference temperature is obtained using the comparison of the average heat flux in the vessel. In addition, the dominant heat transfer mode during hydrogen discharge is investigated. Numerical analysis shows that natural convection is formed inside the vessel due to a decrease in temperature. The Nusselt numbers in this process are presented as a function of Rayleigh numbers which are obtained by the experimental results and mass and energy conservations. The relationship between the Nusselt and Rayleigh numbers agrees with the heat transfer correlations of natural convections.. |

16. |
Naoya Sakoda, Jiang Shiheng, Masaya Nakazaki, Yasuyuki Takata, Yukihiro Higashi, Thermodynamic properties of binary mixtures of Trifluoroethene (HFO1123) + 2,3,3,3-Tetrafluoroprop-1-ene (HFO1234yf), *The 25th IIR International Congress of Refrigeration*, DOI: 10.18462/iir.icr.2019.1608, 2019.08. |

17. |
Siyuan Cheng, Fei Shang, Weigang Ma, Hui Jin, Naoya Sakoda, Xing Zhang, Liejin Guo, Density measurements of the H_{2}-CO_{2}-CH_{4}-CO-H_{2}O System by the Isochoric Method at 722-930 K and 15.4-30.3 MPa, *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.9b00399, 64, 9, 4013-4023, 2019.09, The density of the H_{2}-CO_{2}-CH_{4}-CO-H_{2}O system in the supercritical region of water is significant for analyzing the gasification process of organic substances in the supercritical water. We report density measurements of the quinary system by the isochoric method at 722-930 K and 15.4-30.3 MPa. The upper limit of the expanded uncertainty at 95% confidence for temperature is 0.2 K. The upper limits of the expanded relative uncertainties at 95% confidence for pressure and density are 0.0006 and 0.0125, respectively. The density data were compared with those predicted using the GERG-2008 equation of state. The absolute relative deviations between the calculated and experimental densities are not more than 1.79%. Furthermore, the excess volume of the quinary system decreases monotonically with the increase of temperature in the isochoric process at 722-930 K. The thermal expansion coefficients of the quinary system were also determined.. |

18. |
Naoya Sakoda, Yukihiro Higashi, Measurements of PvT Properties, vapor pressures, saturated densities, and critical parameters for cis-1-chloro-2,3,3,3-tetrafluoropropene (R1224yd(Z)), *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.9b00374, 64, 9, 3983-3987, 2019.09, PvT properties, vapor pressures, and saturated densities for a new low-GWP refrigerant; R1224yd(Z) (cis-1-chloro-2,3,3,3-tetrafluoropropene; CF_{3}CF=CHCl), were measured. Forty-six PvT property data were obtained along four lower density isochores in the superheated region; 22, 48, 55, and 103 kg·m^{-3}, and three higher density isochores in the compressed liquid region; 970, 1107, and 1197 kg·m^{-3} at pressures up to 6.4 MPa. Fifteen vapor pressure data were obtained in the temperature range from 310 to 410 K and at pressures up to 2393 kPa, and a vapor pressure correlation was formulated based on these vapor pressure measurements. Saturated vapor and liquid densities were directly measured by the visual observation of the vapor-liquid meniscus disappearance in the critical region, and also graphically determined by the intersections of the vapor pressure curve and the isochores of the PvT properties. In addition, the critical temperature T_{c} = 428.69 ± 0.02 K, the critical density ρ_{c} = 535 ± 5 kg·m^{-3}, and the critical pressure P_{c} = 3331 ± 3 kPa for R1224yd(Z) were determined.. |

19. |
Siyuan Cheng, Fei Shang, Weigang Ma, Hui Jin, Naoya Sakoda, Xing Zhang, Liejin Guo, Density Data of Two (H_{2} + CO_{2}) Mixtures and a (H_{2} + CO_{2} + CH_{4}) Mixture by a Modified Burnett Method at Temperature 673 K and Pressures up to 25 MPa, *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.8b01206, 64, 4, 1693-1704, 2019.04, The PVT properties of the (H_{2} + CO_{2}) mixtures and the (H_{2} + CO_{2} + CH_{4}) mixtures in the supercritical region of water are significant for making full use of the gas mixtures in the coal and supercritical water gasification. We report PVT measurements of the (0.6005 H_{2} + 0.3995 CO_{2}), (0.6992 H_{2} + 0.3008 CO_{2}), and (0.6026 H_{2} + 0.1948 CO_{2} + 0.2026 CH_{4}) mixtures (all in mole fractions) at temperature 673 K and pressures of (0.5 to 25) MPa, measured by a modified Burnett method. The upper bounds of the expanded uncertainties at 95% confidence are 0.2 K for temperature, 0.015·p for pressure, and 0.008·ρ for density. The density data were compared with those predicted using the GERG-2008 equation of state. The deviations between the calculated and experimental data are not more than 0.021·ρ. Furthermore, the densities were found in accordance with the weighted average of the components' existing equations of state using their mole fractions within 0.0076·ρ for all of the mixtures in this work. The second and third virial coefficients were determined at temperature 673 K for hydrogen and all of the mixtures investigated.. |

20. |
Naoya Sakoda, Jiang Shiheng, Masaya Nakazaki, Yasuyuki Takata, Yukihiro Higashi, Thermodynamic properties of binary mixtures of Trifluoroethene (HFO1123) + 2,3,3,3-Tetrafluoroprop-1-ene (HFO1234yf), *25th IIR International Congress of Refrigeration, ICR 2019
ICR 2019 - 25th IIR International Congress of Refrigeration*, 10.18462/iir.icr.2019.1608, 1782-1787, 2019.01, PvTx properties of a binary mixture of 50 mass% HFO1123 (trifluoroethene) + 50 mass% HFO1234yf (2,3,3,3-tetrafluoroprop-1-ene) were measured in the temperature range from 294 to 410 K, in the density range between 83 kg.m^{-3} and 905 kg.m^{-3}, and at pressures up to 8.1 MPa by an isochoric method, and the obtained data are compared with an equation of state (EOS) compiled in REFPROP 10.0. In addition, the critical parameters and saturated densities of the mixture were measured. Vapor-liquid equilibrium of HFO1123 + HFO1234yf was also measured at temperatures from 273 to 313 K by a recirculation method, and the binary interaction parameter of a cubic EOS was determined.. |

21. |
Yukihiro Higashi, Naoya Sakoda, Measurements of PvT Properties, Saturated Densities, and Critical Parameters for 3,3,3-Trifluoropropene (HFO1243zf), *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.8b00452, 63, 10, 3818-3822, 2018.10, Measurements of PvT properties, saturated densities, and critical parameters were carried out for a low-GWP refrigerant: 3,3,3-trifluoropropene (HFO1243zf, CF_{3}CH=CH_{2}). Seventy-five PvT property data points along seven isochores around the critical point were obtained in the temperature range from 328 to 430 K, in the density range between 50 and 899 kg m^{-3}, and at pressures up to 6.9 MPa by the isochoric method. Fourteen saturated densities were obtained by the observation of meniscus disappearance in the critical region. On the basis of these measurements, the critical parameters of T_{c} = 376.93 ± 0.01 K and ρ_{c} = 414 ± 3 kg m^{-3} were determined. The present results are compared to an available equation of state.. |

22. |
T. Kuroki, N. Sakoda, K. Shinzato, M. Monde, Y. Takata, Dynamic simulation for optimal hydrogen refueling method to Fuel Cell Vehicle tanks, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2018.01.111, 43, 11, 5714-5721, 2018.03, A dynamic simulation approach to investigate an optimal hydrogen refueling method is proposed. The proposed approach simulates a transient temperature, pressure and mass flow rate of hydrogen flowing inside filling equipment in an actual station during the refueling process to an Fuel Cell Vehicle (FCV) tank. The simulation model is the same as in an actual hydrogen refueling station (HRS), and consists of a Break-Away, a hose, a nozzle, pipes and an FCV tank. Therefore, we can set actual configurations and thermal properties to the simulation model, and then simulate the temperature, pressure and mass flow rate of hydrogen passing through each position based on the supply conditions (temperature and pressure) at the Break-Away. In this study, the simulated temperature, pressure and mass flow rate are compared with the corresponding experimental data. Therefore, we show that the dynamic simulation approach can accurately obtain those values at each position during the refueling process and is an effective step in proposing the optimal refueling method.. |

23. |
Yukihiro Higashi, Naoya Sakoda, Md Amirul Islam, Yasuyuki Takata, Shigeru Koyama, Ryo Akasaka, Measurements of Saturation Pressures for Trifluoroethene (R1123) and 3,3,3-Trifluoropropene (R1243zf), *Journal of Chemical and Engineering Data*, 10.1021/acs.jced.7b00818, 63, 2, 417-421, 2018.02, Saturation pressures for new low global warming potential refrigerants trifluoroethene (R1123, CF_{2}= CHF) and 3,3,3-trifluoropropene (R1243zf, CF_{3}CH=CH_{2}) were measured by the isochoric method for temperatures between 278 and 377 K. Temperature was measured with a 25 standard platinum resistance thermometer on ITS-90. Pressure was measured with a digital quartz pressure transducer. The experimental uncertainties in temperature and pressure are estimated to be 5 mK and 1 kPa (k = 2), respectively. New saturation-pressure correlations for the refrigerants have been formulated based on the present saturation-pressure data. The critical pressures of R1123 and R1243zf were also determined.. |

24. |
T. Kuroki, N. Sakoda, K. Shinzato, M. Monde, Y. Takata, Temperature rise of hydrogen storage cylinders by thermal radiation from fire at hydrogen-gasoline hybrid refueling stations, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2017.12.072, 43, 5, 2531-2539, 2018.02, This study focuses on two types of hydrogen-gasoline hybrid refueling stations, and a risk assessment study on thermal radiation is carried out with a fire at each hybrid station. One of the hybrid stations has bare hydrogen storage cylinders, and the other has container walls around the cylinders. We calculate radiative flux to the cylinders from the fire occurring at the gasoline refueling machines in each hybrid station. Additionally, we calculate the temperature rise of the cylinders based on the obtained radiative flux. To evaluate a dangerous case for hybrid stations, we calculate the radiative flux and temperature rise using a large scale and high temperature fire. Based on our analysis, we find that the container walls can greatly insulate the radiative flux. Therefore, we show that we are able to keep the temperature of the cylinders below the hazardous temperature of 358 K by installing container walls around them.. |

25. |
Taichi Kuroki, Kiyoshi Handa, Masanori Monde, Shigehiro Yamaguchi, Kane'I Shinzato, Yasuyuki Takata, Naoya Sakoda, Dynamic Simulation Software for Prediction of Hydrogen Temperature and Pressure during Fueling Process, *2018 SAE World Congress Experience, WCX 2018
SAE Technical Papers*, 10.4271/2018-01-1304, 2018-April, 2018.01, In this study, in order to relax the pre-cooling regulations at hydrogen fueling stations, we develop a software algorithm to simulate an actual hydrogen fueling process to Fuel Cell Vehicle (FCV) tanks. The simulation model in the software consists of the same filling equipment found at an actual hydrogen fueling station. Additionally, the same supply conditions (pre-cooling temperature, pressure and mass flow rate) as at a hydrogen fueling station were set to the simulation model. Based on the supply conditions, the software simulates the temperature and pressure of hydrogen in each part of filling equipment. In order to verify the accuracy of the software, we compare the temperature and pressure simulated at each stage of the filling process with experimental data. We show that by using the software it is possible to accurately calculate the hydrogen temperature and pressure at each point during the fueling process. Subsequently, we carry out a sensitive analysis of the filling equipment with large heat capacity, the initial temperature in the FCV tank and the pre-cooling temperature, and then propose an effective step to relax the regulation regarding the pre-cooling temperature. KeywordsFilling equipment, Hydrogen fueling station, Hydrogen temperature, Hydrogen pressure, Pre-cooling temperature.. |

26. |
T. Kuroki, Naoya Sakoda, K. Shinzato, M. Monde, Yasuyuki Takata, Prediction of transient temperature of hydrogen flowing from pre-cooler of refueling station to inlet of vehicle tank, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2017.11.033, 43, 3, 1846-1854, 2018.01, A thermodynamic analytical approach is proposed to obtain the transient temperature rise of hydrogen when pre-cooled hydrogen is heated through filling equipment at a refueling station. In this approach, the filling equipment is assumed to be a simple and straight pipeline, and the heat balance based on the thermodynamics for hydrogen flowing in the pipeline is analyzed. The internal surface temperature of the pipeline wall is required to calculate the heat flux into hydrogen. Therefore, we propose a solution to obtain the temperature distribution in the pipeline wall when hydrogen with lower temperature than the pipeline flows unsteadily. Based on the proposed solution, we calculate the heat flux and acquire the hydrogen temperature. The hydrogen temperatures predicted by this approach are compared with experimental data for the temperature rise of hydrogen heated through actual filling equipment, and a good agreement is shown. Thus, we show that this approach is useful for simulating the temperature rise of hydrogen flowing in the filling equipment.. |

27. |
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.. |

28. |
Naoya Sakoda, Jiang Shiheng, Masamichi Kohno, Yasuyuki Takata, Yukihiro Higashi, Vapor-Liquid Equilibrium Measurements of HFO Refrigerant Mixtures , *5th IIR International Conference on Thermophysical Properties and Transfer Processes of Refrigerants (TPTPR2017)*, PAPER ID 108, 2017.04. |

29. |
Naoya Sakoda, Kiyoaki Onoue, T. Kuroki, K. Shinzato, Masamichi Kohno, M. Monde, Yasuyuki Takata, Transient temperature and pressure behavior of high-pressure 100 MPa hydrogen during discharge through orifices, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2016.06.114, 41, 38, 17169-17174, 2016.10, High-pressure hydrogen at a maximum of 100 MPa in a 1-L-volume vessel is discharged through 0.1-mm- and 0.2-mm-diameter orifices that imitate cracks, and the transient temperature and pressure behavior of the hydrogen in the vessel is presented. The hydrogen at the initial pressure of 100 MPa during its discharge through the ϕ 0.2-mm orifice reaches half of the initial pressure after 16 s, while it takes approximately nine times longer for the ϕ 0.1-mm orifice to reach half of the initial pressure. We theoretically calculate the transient temperature and pressure according to the fundamental equations based on the mass and energy conservations using an accurate equation of state for hydrogen. The actual flow rate through an orifice is generally smaller than the theoretically calculated flow rate because of the contraction flow. Therefore, in this study, we adopt the effective diameters of the orifices instead of the actual diameters, and from comparisons with the experimental pressure, we estimate them to be 0.6 and 0.9 of the actual diameters for the ϕ 0.1-mm and ϕ 0.2-mm orifices, respectively. We use a functional form with a time constant for the heat transfer coefficient to represent the transient temperature behavior, and we describe the time dependence of the heat transfer coefficient. The results show that the calculated temperature and pressure are in good agreement with the experimental values obtained.. |

30. |
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).. |

31. |
K. Kuroki, N. Sakoda, K. Shinzato, M. Kohno, M. Monde, Y. Takata, Risk Assessment Study about Fire Outbreaks of Hydrogen Refueling Station with Gas Station, *Proceedings of The 27th International Symposium on Transport Phenomena (ISTP27)*, Paper No. 197, 2016.09. |

32. |
Development of Gas Viscosity Measurement System with Vibrating Wire Method. |

33. |
N. Sakoda, R. Kumagai, R. Ishida, K. Shinzato, M. Kohno, Y. Takata, Vacuum generation by hydrogen permeation to atmosphere through austenitic and nickel-base-alloy vessel walls at temperatures from 573 K to 773 K, *International Journal of Hydrogen Energy*, 10.1016/j.ijhydene.2014.05.031, 39, 21, 11316-11320, 2014.07, The permeation of hydrogen through metals is of great concern in hydrogen containment systems. In this study, hydrogen contained in seamless coiled tube vessels made of SUS 316L and Inconel 625 permeated the vessel walls at temperatures from 573 K to 773 K, and the decreasing interior pressure of the vessels was monitored for an extended period to characterize the behavior of the pressure change. It was found that the pressure became lower than the surrounding atmospheric pressure, and the vessels reached a vacuum. Hydrogen permeabilities through SUS 316L and Inconel 625 were determined from the pressure drop measurements. In order to ensure the reliability of the measurements, the permeabilities were also determined with a gas chromatograph that measured the concentration of hydrogen completely permeating the vessel wall. The permeabilities obtained with the two methods were in good agreement with each other. The pressure drop behavior was compared to, and found to be consistent with, theoretical calculations performed using the obtained permeabilities based on Fick's law of diffusion.. |

34. |
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.. |

35. |
Development of an Apparatus for Measuring PVT Properties by the Isochoric Method for High-Temperature and High-Pressure Hydrogen. |

36. |
N. Sakoda, K. Shindo, K. Motomura, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, Burnett PVT measurements of hydrogen and the development of a virial equation of state at pressures up to 100 MPa, *International Journal of Thermophysics*, 10.1007/s10765-012-1168-2, 33, 3, 381-395, 2012.03, PVT properties weremeasured for hydrogen by the Burnettmethod in the temperature range from 353K to 473K and at pressures up to 100MPa. In the present Burnett method, the pressure measurement was simplified by using an absolute pressure transducer instead of a differential pressure transducer, which is traditionally used. The experimental procedures become easier, but the absolute pressure transducer is set outside the constant temperature bath because of the difficulty of its use in the bath, and the data acquisition procedure is revised by taking into account the effects of the dead space in the absolute pressure transducer. The measurement uncertainties in temperature, pressure, and density are 20mK, 28kPa, and 0.07% to 0.24% (k = 2), respectively. Based on the present data and other experimental data at low temperatures, a virial equation of state (EOS) from 220K to 473K and up to 100MPa was developed for hydrogen with uncertainties in density of 0.15%(k = 2) at P ≤ 15MPa, 0.20 % at 15 MPa < P ≤ 40 MPa, and 0.24 % at P > 40 MPa, and this EOS shows physically reasonable behavior of the second and third virial coefficients. Isochoric heat capacities were also calculated from the virial EOS and were compared with the latest EOS of hydrogen. The calculated isochoric heat capacities agree well with the latest EOS within 0.5% above 300K and up to 100MPa, while at lower temperatures, as the pressure increases, the deviations become larger (up to 1.5 %).. |

37. |
Naoya Sakoda, K. Shindo, K. Motomura, K. Shinzato, Masamichi Kohno, Yasuyuki Takata, M. Fujii, Burnett method with absolute pressure transducer and measurements for PVT properties of nitrogen and hydrogen up to 473 K and 100MPa, *International Journal of Thermophysics*, 10.1007/s10765-011-1120-x, 33, 1, 6-21, 2012.01, Ameasurement method for PVT properties of high-temperature and highpressure gases was developed by simplifying the Burnett method and revising the data acquisition procedure. Instead of a differential pressure transducer, which is traditionally used, an absolute pressure transducer is used in the present method, and the measurement of pressure becomes easier. However, the absolute pressure transducer is placed outside the constant temperature bath because of the difficulty of its use in high-temperature surroundings, and some parts with different temperatures from the sample vessels exist as dead space. The present method takes into account the effect of the dead space in the data acquisition procedure. Nitrogen was measured in the temperature range from 353K to 473K and at pressures up to 100MPa to determine the apparatus constants, and then, hydrogenwasmeasured at 473Kand up to 100MPa. The determined densities are in agreement within uncertainties of 0.07% to 0.24% (k = 2), both with the latest equation of state and existing measured data.. |

38. |
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.. |

39. |
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 C_{2}H_{4} and N_{2}O 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 C_{2}H _{4} and for N_{2}O.. |

40. |
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.. |

41. |
Thermodynamic Analysis of Pressure Change in an In-vehicle Hydrogen Container at the Crack Outbreak. |

42. |
N. Sakoda, K. Motomura, Supriatno, Y. Fukatani, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, Development of Apparatuses for PVT Properties of Hydrogen and Measurements at High Temperatures and High Pressures, *Book of Abstracts, 19th European Conference on Thermophysical Properties*, 298, 2011.08. |

43. |
A. Widyaparaga, M. Kuwamoto, E. Noda, N. Sakoda, M. Kohno, Y. Takata, Analytical Optimization of Heat Exchanger Dimensions of a Joule-Thomson Microcooler, *9th International Conference on Nanochannels, Microchannels and Minichannels*, 2011.06. |

44. |
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. CO_{2} 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.. |

45. |
M. Kuwamoto, A. Widyaparaga, N. Sakoda, M. Kohno, Y. Takata, Effect of Working Gas and Heat Exchanger Dimensions on Joule Thomson Microcooler Performance, *International Symposium on Innovative Materials for Processes in Energy Systems 2010, For Fuel Cells, Heat Pumps and Sorption Systems*, 203-207, 2010.11. |

46. |
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.. |

47. |
Y. Takata, N. Sakoda, K. Shinzato, M. Fujii, Measurement of Hydrogen Thermophysical Properties at Ultra High Pressures, *Proceedings of the 9th Asian Termophysical Properteis Conference*, paper number 109309, 2010.10. |

48. |
N. Sakoda, K. Shindo, K. Motomura, Supriatno, K. Shinzato, M. Kohno, Y. Takata, M. 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 Termophysical Properteis Conference*, paper number 109156, 2010.10. |

49. |
A. Widyaparaga, M. Kuwamoto, N. Sakoda, M. Kohno, Y. Takata, Theoretical Study of a Flexible Wiretype Joule Thomson Micro-refrigerator for Use in Cryosurgery, *8th International Conference on Nanochannels, Microchannels and Minichannels*, 2010.08. |

50. |
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.. |

51. |
Development of a PVT Property Measurement Apparatus by the Burnett Method for High Pressure Hydrogen. |

52. |
N. Sakoda, K. Shindo, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, PVT Measurements of High Pressure Gas by the Burnett Method, *Proceedings of the International Conference on Power Engineering 2009(ICOPE-09)*, Vol. 2, 265-270, 2009.11. |

53. |
Naoya Sakoda, Kenta Shindo, Kan'ei Shinzato, Masamichi Kohno, Yasuyuki Takata, Motoo Fujii, 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_, 2009.11, 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.. |

54. |
Y. Takata, P. L. Woodfield, N. Sakoda, K. Shinzato, M. Fujii, Measurement of Hydrogen Thermophysical Properties at High Pressure, *The Eleventh UK National Heat Transfer Conference (UKHTC2009)*, 2009.06. |

55. |
N. Sakoda, K. Shindo, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, PVT Measurements of Hydrogen at High Pressures, *Abstracts of the 17th Symposium on Thermophysical Properties*, 370, 2009.06. |

56. |
N. Sakoda, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, Development of PVT Measurement Apparatus and Preliminary Measurements for Hydrogen, *Book of Abstracts of 18th European Conference on Thermophysical Properties*, 197, 2008.08. |

57. |
Y. Takata, N. Sakoda, K. Shinzato, K. Fujii, M. Fujii, Research Project of Hydrogen Thermophysical Properties at Ultra High Pressure, *Proceedings of Sixth International Conference on Enhanced, Compact and Ultra-Compact Heat Exchangers: Science, Engineering and Technology*, 2007.09. |

58. |
N. Sakoda, E. Yusibani, P. L. Woodfield, K. Shinzato, M. Kohno, Y. Takata, M. Fujii, Review of Thermophysical Properties of Hydrogen and the Related Work of HYDROGENIUS, *Proceedings of the 8th Asian Thermophysical Properties Conference*, 141, 2007.08. |

59. |
N. Sakoda, A. Wachi, N. Masuda, M. Uematsu, PVT Measurements of Ammonia and Its Aqueous Mixtures in the Temperature Range from 350 K to 600 K at Pressures up to 200 MPa, *Abstracts of THERMO INTERNATIONAL 2006 (The 19th IUPAC International Conference on Chemical Thermodynamics)*, 523-524, 2006.07. |

60. |
Naoya Sakoda, Masahiko Uematsu, Thermodynamic properties of the binary mixture of methane and hydrogen sulfide, *Zeitschrift fur Physikalische Chemie*, 10.1524/zpch.2005.219.9.1299, 219, 9, 1299-1319, 2005.10, From the interest of the thermodynamic properties for natural gas system, we have developed the thermodynamic property model for the binary mixture of methane and hydrogen sulfide system by the Helmholtz free energy function. Our model represents divergence of the critical curve and vapor-liquid-liquid equilibrium of this system as well as thermodynamic properties with high accuracy. The behavior of critical curve and phase equilibrium is discussed in detail with comparison of that for the mixture of methane and ethane system. Thermodynamic properties of methane and hydrogen sulfide system have been calculated using our model and their behavior as a function of composition is also reported.. |

61. |
D. Kume, N. Sakoda, M. Uematsu, An Equation of State for Thermodynamic Properties of Methanol, *Book of Abstracts, The 17th European Conference on Thermophysical Properties*, 292, 2005.09. |

62. |
N. Sakoda, M. Uematsu, Thermodynamic Properties of the Binary Mixture of Methane and Hydrogen Sulfide, *Zeitschrift für Physikalische Chemie*, Vol. 219, 1299-1319, 2005.09. |

63. |
N. Sakoda, M. Uematsu, A thermodynamic property model for the binary mixture of methane and hydrogen sulfide, *International Journal of Thermophysics*, 10.1007/s10765-005-8090-9, 26, 5, 1303-1325, 2005.09, A thermodynamic property model with new mixing rules using the Helmholtz free energy is presented for the binary mixture of methane and hydrogen sulfide based on experimental P _{ρ} T _{x} data, vapor-liquid equilibrium data, and critical-point properties. The binary mixture of methane and hydrogen sulfide shows vapor-liquid-liquid equilibria and a divergence of the critical curve. The model represents the existing experimental data accurately and describes the complicated behavior of the phase equilibria and the critical curve. The uncertainty in density calculations is estimated to be 2%. The uncertainty in vapor-liquid equilibrium calculations is 0.02 mole fraction in the liquid phase and 0.03 mole fraction in the vapor phase. The model also represents the critical points with an uncertainty of 2% in temperature and 3% in pressure. Graphical and statistical comparisons between experimental data and the available thermodynamic models are discussed.. |

64. |
N. Sakoda, M. Uematsu, Thermophysical Properties of the Binary Mixture of Methane and Hydrogen Sulfide, *Abstracts of Thermodynamics*, 50, 2005.04. |

65. |
N. Sakoda, M. Uematsu, A Thermodynamic Property Model for the Binary Mixture of Methane and Hydrogen Sulfide, *Abstract book, The 18th IUPAC International Conference on Chemical Thermodynamics*, 140, 2004.08. |

66. |
N. Sakoda, M. Uematsu, A thermodynamic property model for fluid phase hydrogen sulfide, *International Journal of Thermophysics*, 10.1023/B:IJOT.0000034234.06341.8a, 25, 3, 709-737, 2004.05, A Helmholtz free energy equation of state for the fluid phase of hydrogen sulfide has been developed as a function of reduced temperature and density with 23 terms on the basis of selected measurements of pressure-density-temperature (P, ρ, T), isobaric heat-capacity, and saturation properties. Based on a comparison with available experimental data, it is recognized that the model represents most of the reliable experimental data accurately in the range of validity covering temperatures from the triple point temperature (187.67 K) to 760 K at pressures up to 170 MPa. The uncertainty in density calculation of the present equation of state is 0.7% in the liquid phase, and that in pressure calculation is 0.3% in the vapor phase. The uncertainty in saturated vapor pressure calculation is 0.2%, and that in isobaric heat-capacity calculation is 1% in the liquid phase. The behavior of the isobaric heat-capacity, isochoric heat-capacity, speed-of-sound, and Joule-Thomson coefficients calculated by the present model shows physically reasonable behavior and those of the calculated ideal curves also illustrate the capability of extending the range of validity. Graphical and statistical comparisons between experimental data and the available thermodynamic models are also discussed.. |

67. |
N. Sakoda, M. Uematsu, Thermodynamic Property Model for Binary Mixtures of Methane and Hydrogen Sulfide, *Abstracts of the 15th Symposium on Thermophysical Properties*, 20, 2003.06. |

68. |
K. Tanaka, N. Sakoda, M. Uematsu, Development of a Calorimeter for Measurements of Isobaric Heat Capacity for Fluids and Fluid Mixtures in a Wide Range of Temperatures and Pressures, *Book of Abstracts, 9th International Conference on Properties and Phase Equilibria for Product and Process Design*, 126, 2001.05. |