Heat pipe is a kind of heat transfer element with high thermal conductivity, which transfers heat through the evaporation and condensation of working fluid in the fully enclosed vacuum tube shell, with extremely high thermal conductivity, good isothermal properties, heat transfer area on both sides of cold and hot can be changed arbitrarily, heat transfer over long distances, temperature control and a series of advantages. The heat pipe heat exchanger composed of heat pipes has the advantages of high heat transfer efficiency, compact structure, small fluid resistance, and is conducive to controlling dew point corrosion. At present, it has been widely used in metallurgy, chemical industry, oil refining, boiler, ceramics, transportation, textile, machinery and other industries, as an energy-saving equipment for waste heat recovery and heat energy utilization in the process of processing, and has achieved significant economic benefits.
A typical gravity heat pipe is shown in the figure, first pumped into a vacuum in a closed tube, filled with an appropriate amount of working fluid in this state, heated at the lower end of the heat pipe, the working fluid absorbs heat and vaporizes into steam, and under a small pressure difference, rises to the upper end of the heat pipe, and releases heat to the outside world, condensing into liquid. Under the action of gravity, the condensate returns to the heating section along the inner wall of the heat pipe, and is heated and vaporized again, and so on, continuously transferring heat from one end to the other. Since it is a phase change heat transfer, the thermal resistance in the heat pipe is very small.
Compared with silver, copper, aluminum and other metals, the heat pipe per unit weight can transfer several orders of magnitude more, so it can obtain a larger heat transfer rate with a small temperature difference, and the structure is simple, with the characteristics of single heat conduction, especially due to the special structure of the heat pipe, so that the heat exchange between the cold and hot fluids is carried out outside the tube, which can easily strengthen the heat transfer. In addition, because the inside of the heat pipe is generally pumped into a vacuum, the working fluid is very easy to boil and evaporate, and the heat pipe starts very quickly.
Heat pipe this kind of heat transfer element, can be used alone, can also be used in combination, according to the conditions of the user site, with the corresponding circulation structure combined into various forms of heat exchanger, heat pipe heat exchanger has high heat transfer efficiency, small resistance loss, compact structure, reliable work and less maintenance costs and other advantages, it has been widely used in space technology, electronics, metallurgy, power, petroleum, chemical and other industries.
