Heat pipe air preheater

I’m not very familiar with it, but heat cannot be transferred in a vacuum

Please check out the working principle of heat pipes. From a thermodynamic perspective, why do heat pipes possess such excellent thermal conductivity? The absorption and release of heat by objects are relative; whenever there is a temperature difference, heat will inevitably transfer from the higher-temperature area to the lower-temperature area. Among the three modes of heat transfer: radiation, convection, and conduction, heat conduction is the fastest in the principle of heat pipe cooling. A heat pipe utilizes evaporation cooling to create a large temperature difference between its two ends, thereby enabling rapid heat transfer. A typical heat pipe consists of a tube shell, a wick, and end caps. The inside of a heat pipe is under negative pressure, and it is filled with an appropriate liquid that has a low boiling point and is prone to vaporization. The tube wall has a wicking core, which is made of capillary porous material. One end of the heat pipe is the evaporation end, while the other end is the condensation end. When one end of the heat pipe is heated, the liquid in the capillary tube evaporates rapidly; the vapor then flows to the other end under a slight pressure difference, releasing heat in the process and recondensing into a liquid. This liquid then flows back to the evaporation end through the porous material due to capillary action, and this cycle repeats continuously, allowing heat to be transferred from one end of the heat pipe to the other. This cycle occurs rapidly, allowing heat to be transferred continuously.