During the fast-filling of a high-pressure hydrogen tank, the temperature of hydrogen would rise significantly and may lead to failure of the tank. In addition, the temperature rise also reduces hydrogen density in the tank, which causes mass decrement into the tank. Therefore, it is of practical significance to study the temperature rise and the amount of charging of hydrogen for hydrogen safety. In this paper, the change of hydrogen temperature in the tank according to the pressure rise during the process of charging the high-pressure tank in the process of a 82-MPa hydrogen filling system, the final temperature, the amount of filling of hydrogen gas, and the change of pressure of hydrogen through the pressure reducing valve, and the performance of heat exchanger for cooling high-temperature hydrogen were analyzed by theoretical and numerical methods. When high-pressure filling began in the initial vacuum state, the condition was called the “First cycle”. When the high-pressure charging process began in the remaining condition, the process was called the “Second cycle”. As a result of the theoretical analysis, the final temperatures of hydrogen gas were calculated to be 436.09 K for the first cycle of the high-pressure tank, and 403.55 for the second cycle analysis. The internal temperature of the buffer tank increased by 345.69 K and 32.54 K in the first cycle and second cycles after high-pressure filling. In addition, the final masses were calculated to be 11.58 kg and 12.26 kg for the first cycle and second cycle of the high-pressure tank, respectively. The works of the paper can provide suggestions for the temperature rise of 82 MPa compressed hydrogen storage system and offer necessary theory and numerical methods for guiding safe operation and construction of a hydrogen filling system.

The hydrogen compression cycle system recycles hydrogen compressed by a compressor at high pressure and stores it in a high-pressure container. Thermal stress is generated due to increase in the pressure and temperature of hydrogen in the hydrogen storage tank during the fast filing process. For the sake of safety, it is of great practical significance to predict and control the temperature change in the tank. The hydrogen charging process in the storage tank of the hydrogen charging station was studied by experimentation and simulation. In this paper, a Computational Fluid Dynamics (CFD) model for non-adiabatic real filling of a 50 MPa hydrogen cylinder was presented. In addition, a shear stress transport (k-ω) model and real gas model were used in order to account for thermo-fluid dynamics during the filling of hydrogen storage tanks (50 MPa, 343 L). Compared to the simulation results with the experimental data carried out under the same conditions, the temperatures calculated from the simulated non-adiabatic condition results were lower (by 5.3%) than those from the theoretical adiabatic condition calculation. The theoretical calculation was based on the experimentally measured pressure value. The calculated simulation mass was 8.23% higher than the theoretical result. The results of this study will be very useful in future hydrogen energy research and hydrogen charging station developments.

The technique of solar dish and Stirling engine combination is the most challenging and promising one. For the efficient conversion of the externally concentrated heat to the usable power, we studied the influences of the wall temperature, inclination angle, and open area ratio of the receiver on the Stirling engine power and efficiency. The theoretical analysis of the heat exchange element of the solar Stirling engine was performed, and the simulation model of the cavity absorber was built and analyzed. The temperature cloud and heat loss trends of the receiver under different wall temperatures, inclination angles, and opening ratios were illustrated. When the wall temperature of the absorber changes from 700 to 1000 K, the efficiency of the engine has increased by 8.8% from 21.34% to 30.11%. The higher the temperature, the higher the efficiency. As the inclination angle of the absorber increases from 0° to 60°, the efficiency of the engine is increased by 7.7% from 21.1% to 28.8%. With the increases of the aperture ratio, the engine output and efficiency reduced. The engine efficiency at the aperture ratio of 0.5 is 4% larger than that at the aperture ratio of 1.

During the fast filing process, thermal stress is generated due to the increase in the pressure and temperature of hydrogen in the hydrogen storage tank. For its safety purpose, it is necessary to predict and control the temperature change in the tank. The aim of this study is quantitative analysis of the final temperature and the mass of the hydrogen in the tank through experimental and theoretical methods. In this paper; Theoretical model for adiabatic and non-adiabatic real filling processes of high pressure hydrogen cylinder has been proposed. The cycle of filling process from the initial vacuum state is called the “First cycle.” After the first cycle is completed, there is a certain residual pressure in the tank. Then the second filling process called “Second cycle” begins. The final temperature in fast filling of hydrogen storage cylinders depends on targeted pressure, initial pressure and temperature, and mass filling rate. The final temperature of hydrogen in the tank was calculated from the real gas equation of state, mass and energy conservation equations. As a result of the analysis, based on the first cycle analysis of high pressure tank, the final temperatures were calculated to be 442.11 K for the adiabatic filling process, and 422.37 K for the non-adiabatic process. Based on the second cycle analysis of high pressure tank, the final temperature were obtained as 397.12 K and 380.8 K for the adiabatic and non-adiabatic processes, respectively. The temperatures calculated from the theoretical non-adiabatic condition were lower than those from the adiabatic condition by 5%. The results of this study can provide a reference basis in terms of how to control the temperature in the actual hydrogen storage tank during the fast filling process and how to improve safety.