间隙自然对流对单点接触热阻的影响研究

In this paper, the heat transfer characteristics of the heat flow pipe model under the natural convection of the gap medium are simulated, the spreading resistance is calculated by using the general calculation method and the interface thermal resistance network model, and the influence of size, physical properties parameters and boundary conditions on the thermal resistance of single-point contact is studied; the influence of three dimensionless factors, namely, radius ratio, height-diameter ratio, and gas-solid thermal conductivity ratio under convection, is further analyzed. The results show: When there is a gas medium in the gap, the change law of the thermal resistance of the single-point contact with the radius ratio under the action of natural convection is similar to the changing trend under vacuum conditions, but due to the conduction and convection of the gap medium, the single-point contact thermal resistance is less than the vacuum value of the same condition, and the smaller the radius ratio, the more obvious the influence of the medium heat leakage. When the radius ratio is 0.2, the dimensionless spreading resistance value under convection action is reduced by more than 15% compared with that in a vacuum environment. For general engineering conditions, when changing the heat flux density, heat source temperature and cooling temperature, the simulated dimensionless spreading resistance value changes by no more than 3%, which verifies the robustness of the model. Finally, the formula of dimensional spreading resistance affected by three dimensionless factors is obtained by nonlinear fitting, which has application value for practical engineering.