Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1021/acs.jced.0c00848

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1007/s10765-020-02752-2

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1007/s10765-020-02725-5

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1021/acs.jced.0c00239

Language：English   Publishing type：Research paper (international conference proceedings)  

DOI： DOI: 10.18462/iir.icr.2019.1608

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

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%.

DOI： 10.1021/acs.jced.0c00176

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2019.08.167

Language：English   Publishing type：Research paper (scientific journal)  

PvT properties, vapor pressures, and saturated densities for a new low-GWP refrigerant; R1224yd(Z) (cis-1-chloro-2,3,3,3-tetrafluoropropene; CF₃CF=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.

DOI： 10.1021/acs.jced.9b00374

Language：English   Publishing type：Research paper (scientific journal)  

The density of the H₂-CO₂-CH₄-CO-H₂O 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.

DOI： 10.1021/acs.jced.9b00399

Language：English   Publishing type：Research paper (scientific journal)  

The PVT properties of the (H₂ + CO₂) mixtures and the (H₂ + CO₂ + CH₄) 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 H₂ + 0.3995 CO₂), (0.6992 H₂ + 0.3008 CO₂), and (0.6026 H₂ + 0.1948 CO₂ + 0.2026 CH₄) 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.

DOI： 10.1021/acs.jced.8b01206

Language：English   Publishing type：Research paper (other academic)  

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.

DOI： 10.18462/iir.icr.2019.1608

Language：English   Publishing type：Research paper (scientific journal)  

Measurements of PvT properties, saturated densities, and critical parameters were carried out for a low-GWP refrigerant: 3,3,3-trifluoropropene (HFO1243zf, CF₃CH=CH₂). 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.

DOI： 10.1021/acs.jced.8b00452

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2018.01.111

Language：English   Publishing type：Research paper (scientific journal)  

Saturation pressures for new low global warming potential refrigerants trifluoroethene (R1123, CF₂= CHF) and 3,3,3-trifluoropropene (R1243zf, CF₃CH=CH₂) 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.

DOI： 10.1021/acs.jced.7b00818

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2017.12.072

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.4271/2018-01-1304

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2017.11.033

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1021/acs.jced.7b00263

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2016.06.114

Language：English   Publishing type：Research paper (scientific journal)  

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).

DOI： 10.1016/j.jct.2015.04.028

Language：Japanese   Publishing type：Research paper (scientific journal)  

Development of Gas Viscosity Measurement System with Vibrating Wire Method

DOI： 10.2963/jjtp.28.15

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.ijhydene.2014.05.031

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1299/jtst.8.603

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

DOI： 10.2963/jjtp.26.86

Language：English   Publishing type：Research paper (scientific journal)  

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 %).

DOI： 10.1007/s10765-012-1168-2

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1115/1.4004937

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1007/s10765-011-1120-x

Language：English   Publishing type：Research paper (other academic)  

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.

DOI： 10.1115/ICNMM2011-58205

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1016/j.cryogenics.2011.09.001

Language：English   Publishing type：Research paper (other academic)  

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.

DOI： 10.1115/FEDSM-ICNMM2010-30127

Language：English   Publishing type：Research paper (scientific journal)  

This study examines the performance of a wire-type Joule Thomson microcooler utilizing a flexible concentric counterflow heat exchanger. Three gases: C₂H₄, CO₂ and N₂ were used separately for trials conducted at inlet pressures ranging from 0.5 MPa to 5 MPa with C₂H₄ having the best performance. During unloaded tests at an inlet pressure of 2.0 MPa, C₂H₄ obtained a minimum temperature of 225 K while CO₂ obtained a minimum temperature of 232 K. Using CO₂ 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.

DOI： 10.1016/j.applthermaleng.2010.07.007

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1007/s10765-009-0699-7

Language：Japanese   Publishing type：Research paper (scientific journal)  

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

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1299/jsmeicope.2009.2._2-265_

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1524/zpch.2005.219.9.1299

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1007/s10765-005-8090-9

Language：English   Publishing type：Research paper (scientific journal)  

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.

DOI： 10.1023/B:IJOT.0000034234.06341.8a

Event date： 2023.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Paris   Country：France  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Repository Public URL： https://hdl.handle.net/2324/7177192

Event date： 2022.10

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Venue：和歌山   Country：Japan  

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Event date： 2022.6

Language：Japanese   Presentation type：Oral presentation (general)  

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Country：Japan  

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Country：Japan  

Event date： 2021.3

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Country：Japan  

Event date： 2021.3

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Event date： 2020.10

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Country：Japan  

Event date： 2020.9

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Country：Japan  

Event date： 2020.9

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Country：Japan  

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Language：Japanese   Presentation type：Oral presentation (general)  

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Event date： 2017.11

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Event date： 2017.9 - 2018.9

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Event date： 2017.9 - 2018.9

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Event date： 2016.9

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Event date： 2016.9

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Event date： 2016.9

Language：English   Presentation type：Oral presentation (general)  

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Event date： 2016.9

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Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

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Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Presentation type：Oral presentation (general)  

Event date： 2022.6

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2014.11

Language：English   Presentation type：Oral presentation (general)  

Venue：東京工業大学   Country：Japan  

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Type：Competition, symposium, etc. 

Type：Peer review 

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Type：Peer review 

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Type：Competition, symposium, etc. 

Type：Peer review 

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Proceedings of domestic conference Number of peer-reviewed papers：0

Type：Competition, symposium, etc. 

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