Convection heat transfer model and verification for the vacuum chamber during charge and discharge processes

The change of temperature is obvious in the vacuum chamber during charge and discharge processes. The thermodynamic model needs to consider the convection heat transfer between air and wall in the vacuum chamber. It is the most important to get the expression of the convection heat transfer coefficient on studying the convection heat transfer model. In previous researches of the pressure chamber, the expression of the convection heat transfer coefficient was complicated and related to the Reynolds number which had no accordant calculation method. To solve these problems, an alternative approach is proposed, relating the heat transfer coefficient to the rate of change of pressure. Based on the thermodynamic model of the chamber and combined with temperature curve obtained by the stop method experiment, the convection heat transfer coefficient during charge and discharge processes in the vacuum chamber is calculated. Then, the simplified expression of the convection heat transfer coefficient by the least square method is identified. Compared with the simulated and measured pressure response curves of 0.2 L and 0.8 L vacuum chambers, the convection heat transfer model with the simplified expressions during charge and discharge processes in the vacuum chambers is proved to be effective.