1 Introduction
Traditional cooling methods are mainly air cooling, forced air cooling and water cooling.
(1) Air cooling
Also known as natural cooling, generally is the heating core of electronic components and the profile radiator contact, through the natural convection of air will heat out. It has the advantages of simple structure, convenient installation and low cost. The disadvantage is low cooling power.
(2) Air cooling
This is the most common way of heat dissipation at present. Generally, the heating core of power electronic components is contacted with the radiator to conduct heat, and then the fan is rotated to strengthen the air flow, and the heat on the heat sink is transferred to the surrounding environment by forced convection.
Advantages: simple structure, low price, safe and reliable, mature technology.
Disadvantages: the cooling effect is limited, can not reach a satisfactory level, and has noise, fan service life is also limited.
(3) Water cooling
The principle is to use the water pump to drive the water through the heat source for heat absorption and transfer.
Advantages: water cooling has high heat dissipation efficiency, and its heat conductivity is more than 20 times that of the traditional air cooling method. It can solve the heat dissipation problem of hundreds to several kilowatts, which is incomparable with the air cooling effect. Because even the turbine fan with the highest heat dissipation efficiency is cooled by air, its temperature is about 10 ℃ higher than that by water cooling; compared with air cooling, water cooling cooling cooling will not produce vibration and high noise due to no fan.
Disadvantages: it needs good ventilation environment, large volume, inconvenient installation and maintenance, easy leakage, low safety and relatively high price.
(4) Heat pipe heat dissipation
Heat pipe is a new type of heat transfer element with extremely high thermal conductivity. It transfers heat through evaporation and condensation of liquid in the closed vacuum tube. It has good refrigeration effect by using fluid principle such as capillary action. It has the characteristics of high thermal conductivity, good isotherm, arbitrary change of heat transfer area on both sides of cold and hot side, long-distance heat transfer and temperature control. The substrate of heat pipe radiator is closely contacted with the core of high-power power electronic devices such as thyristor, IGBT and IGCT, and the heat of the tube core can be directly exported.
Through the analysis of the above heat dissipation methods, it is not difficult to see that heat pipe has the following advantages compared with other traditional cooling methods:
Heat pipe heat dissipation technology has the advantages of good heat dissipation effect, relatively small thermal resistance, long service life and fast heat transfer. The thermal conductivity of heat pipe is more than 100 times that of common metal;
The heat transfer direction is reversible, and any end can be evaporation end and condensation end;
Excellent thermal response. The steam vaporized in the heat pipe can be transported at the speed close to the sound speed, thus effectively improving the heat conduction effect;
It has simple and compact structure, light weight, small volume and convenient maintenance;
No power consumption, no noise, meeting the industrial "green" requirements;
It can be used in the environment without gravity field.
To sum up: heat pipe heat transfer uses the principle of heat conduction and the rapid heat transfer property of the cooling medium, and transfers the heat of the heating object to the outside of the heat source rapidly through the heat pipe. Using heat pipe technology, even if the radiator adopts low speed, low air volume motor, or even does not need fan, completely adopts self cooling mode, it can also obtain satisfactory heat dissipation effect, which can solve the noise problem of air cooling heat dissipation and heat dissipation problem of high-power power power module. With the continuous improvement of heat pipe processing technology, its reliability, safety and durability will be improved And the cost and price will be further reduced. The heat pipe radiator will have the advantage that the traditional radiator can not compare with. Its appearance has opened up a new field for the heat dissipation industry.