Experimental study of the convection heat transfer model of porous media for isothermal chamber during discharging

The temperature drop during isothermal chamber discharging is obtained by the “stop method” generally. One of the most important things is to keep sealing during the whole process according to the test principle. As a result, the temperature changing is very difficult to be determined and the whole process is time-consuming. This study aims to find out a new method to forecast the temperature drop based on the convective heat transfer model for isothermal chamber during discharging. First, four kinds of isothermal chambers were discharged by four solenoid valves with known flow rate characteristics respectively, and the pressure curves and temperature curves during discharging were obtained by experiments. Second, based on the thermodynamic model and combined with pressure curves and temperature curves, the convection heat transfer empirical formulae were achieved according to the similarity principle, which reflect the influence of not only the discharging speed and the copper wire filling density but also the air compression ratio to heat transfer. Third, four different isothermal chambers were discharged by the two different solenoid valves, and pressure and temperature data were obtained by experiments. In addition, the temperature drop could be obtained by analyzing the pressure data combined with the thermodynamic model including the convective heat transfer empirical formulae. Compared the analyzed temperature drop with that obtained by using the “stop method”, it can be found that the difference is within the acceptable range, which shows that the convection heat transfer empirical formulae were reasonable for predicting the temperature drop for isothermal chambers during discharging.