Views:2 Author:Site Editor Publish Time: 2020-06-24 Origin:Site
In 1942, American engineers proposed the principle of heat pipes. In the early 1960s, research and trial production began. It was first used in spacecraft and nuclear reactors. In the 1970s, heat pipe heat exchangers were eventually used as heat energy recovery devices in new wind systems. In the HVAC industry, it demonstrates its superiority. The heat pipe is a heat transfer element that realizes heat transfer by the phase change of its internal liquid. It has the following characteristics: (1) Each heat pipe is permanently sealed, there is no additional energy loss during heat transfer, no running parts, and operation reliability high. ⑵The structure of the heat pipe heat exchanger determines that it is a typical countercurrent heat exchange, and the heat pipe is almost isothermal operation, so the heat pipe heat exchanger has a high efficiency. (3) Due to the heat exchange of cold and hot gas, the heat receiving area is easily expanded on the outer surface of the heat pipe. ⑷The cold and hot gases are separated by a partition, there is no leakage, so there is no cross contamination problem. ⑸ Due to the wide fluid flow channel, the resistance loss is small. ⑹Each heat pipe is completely independent and easy to maintain. ⑺ From the perspective of environmental adaptability, waste heat recovery efficiency, pressure loss, prevention of clogging, cleaning, life and other comprehensive indicators, heat pipe heat exchangers have an advantage.
The heat pipe is composed of a tube shell, a liquid absorbing core and an end cap. The tube is filled with a proper working fluid in a vacuum, and then the two ends are sealed. The heat pipe is both an evaporator and a condenser. One end of the heat flow absorbs heat is the evaporation section. The working medium absorbs the heat and then evaporates and vaporizes. It flows to the other end, the condensation section, releases heat and liquefies, and flows back to the evaporation section by capillary force to complete the cycle automatically.
The heat pipe heat exchanger is assembled by a single heat pipe, and the evaporation section and the condensation section are separated by a partition in the middle. The heat pipe heat exchanger completes the heat transfer by the phase change of the working medium in the heat pipe. Each heat pipe is an unpowered refrigeration cycle system. The heat transfer rate is thousands to tens of thousands of times of the same metal. The temperature difference of 0.1 ℃ is the thermal response. It was originally used on artificial satellites to solve the sun and shade. Uneven heating is one of the necessary equipment on the artificial satellite. Now, it is more and more widely used in the field of air conditioning and waste heat recovery. An expert from Waseda University in Japan said: "Japan pays special attention to energy conservation and environmental protection, and heat pipe technology has found a way for energy conservation and environmental protection due to its efficient heat transfer. new road". The heat pipe heat exchanger is introduced and selected in the HVAC design manual.