The working principle of heat pipe
From the perspective of thermodynamics, why does a heat pipe have such a good thermal conductivity?
The heat absorption and heat release of objects are relative. Whenever there is a temperature difference, the phenomenon of heat transfer from high temperature to low temperature will inevitably occur. From the perspective of the three ways of heat transfer (radiation, convection, conduction), convection conduction is the fastest. The heat pipe uses the phase change process in which the medium evaporates at the hot end and condenses at the cold end (that is, the latent heat of vaporization and condensation of the liquid), so that heat is quickly transferred. Generally, a heat pipe is composed of a tube shell, a wick and an end cover. The inside of the heat pipe is pumped into a negative pressure state and filled with an appropriate liquid, which has a low boiling point and is easy to volatilize. The tube wall has a wick, which is made of capillary porous material.
One end of the heat pipe is the evaporating end, and the other end is the condensing end. When one end of the heat pipe is heated, the liquid in the capillary tube quickly vaporizes, and the vapor flows to the other end under the power of thermal diffusion, and condenses at the cold end to release heat. The liquid flows along the porous material back to the evaporating end by capillary action, and the cycle continues until the temperature at both ends of the heat pipe is equal (the steam thermal diffusion stops at this time). This kind of circulation is rapid, and heat can be continuously conducted away.
