Simulations and analyses of experimental data from leaks from high-pressure hydrogen storage systems will require knowledge of the stagnation state time histories and stream properties exiting the orifices.An analytical ideal-gas model based on the ideal gas state equation and a computer program making use of the NIST standard reference database(REFPROP)were developed to model the entire process of leaks from high-pressurized hydrogen gas containers.The results obtained by the two methods agree with each other well.As the gas behavior departs from the ideal gas properties at high pressures,the actual stagnation pressure and temperature decay more rapidly than with the ideal-gas assumption.
The temperature overshooting phenomenon in one-dimensional nanoscale heat conduction in thin films is studied for various boundary conditions.The results show that when ballistic heat transport strongly affects the heat transport process,temperature overshooting is more likely to occur.A sudden increase of temperature on only one surface of a thin film cannot trigger temperature overshooting,while symmetric boundary temperature perturbations lead to the largest temperature overshooting.Twodimensional heat conduction is also studied in a nanoscale area.The analytic results show that Fourier’s law may severely underestimate the temperatures in nanofilms as well as in nanoareas when temperature overshooting occurs.
