Principle 1.

Heat pipe is with the aid of the working medium of airtight in the process of evaporation heat, condensation heat to transfer heat.

Type 2.

Heat pipe in order to maintain its normal work, in order to achieve the purpose of heat transfer, condensation of liquid would automatically return the evaporation region. According to the use of force by way of condensation water reflux, classified as shown in table 6-8 - l.

If according to the use of heat pipe temperature, it can be divided into:

(1) the cryogenic heat pipe

These are designed to run on a 200 k o temperature range of the heat pipe. The temperature of operation in the area of heat pipe, the media can be used in the form of a single element of pure chemicals (helium, neon, member, chlorine and oxygen) and compounds (ethane, freon). The cryogenic heat pipe heat transfer by the relatively small, because of the latent heat of evaporation is small, the viscosity and surface tension. In heating zone can achieve low heat flux is also a limiting factor, a version is less than its value

L 0 'w. m 2.

(2) low temperature heat pipe

These are run in 200 a 550 k temperature range of heat pipe. Work in this temperature region of the working medium with freon, ammonia, alcohol, acetone and water and some organic compounds. In this type of heat pipe, the most/" extensive use of working medium is water, it has good thermal physical properties. The low temperature heat pipe than cryogenic heat pipe can reach larger axial heat transmission.

(3) in the warm pipe

This type of heat pipe run in 500 a 750 k temperature range. This type of heat pipe working medium for sulphur, mercury, alkali metals (e.g., pound, riveting, etc.), also can be certain compounds, such as thermal conductivity, heat transfer agent in warm tube of the axial heat transfer than cryogenic heat pipe and heat pipe has a further increase in low temperature.

(4) high temperature heat pipe

The heat pipe run on more than 750 k temperature region. Potassium, sodium, hammer, aluminum, silver, steel and other high melting point metal can be used as working medium, the medium, especially the buried, can reach 1.5 x 10. W "m" of the axial heat transfer.