When the valve is normally closed, the internal temperature will gradually decrease due to the heat dissipation valve. For empty-valve, temperature drops to ambient temperature; For non-empty-gate, the temperature decreases to the saturation temperature corresponding to the pressure behind the valve. If the saturation temperature corresponding to the pressure behind the valve is lower than the ambient temperature, the temperature decreases to the ambient temperature.

When a valve leaks, there is a working fluid flow in the pipe that is warmer than the ambient temperature. Will through the tube wall tube and the thermal insulation layer to the outer cooling, by the high temperature heat pipe working medium to the outside air pass, mainly including the convective heat transfer of working medium and the pipe wall inside Φ 1, pipe wall and tube wall heat conduction Φ 2, Φ of thermal conductivity of thermal insulation layer 3, radiant heat insulation layer surface and the environment of the convection Φ 4 process. Due to heat dissipation, working medium and wall temperature drop along the long direction of the pipe gradually decreased, and there was also temperature difference along the long direction of the pipe wall. There was also heat conduction along the long direction of the pipe wall, but the heat conduction was relatively small, which could be ignored in the analysis and calculation.

Where: — convection heat transfer between working medium in the tube and inner wall of the tube.