A heat pipe heat exchanger is a simple device which is used to move heat from one location to another, using an evaporation-condensation cycle. Heat pipes are referred to as the “superconductors” of heat due to their fast transfer capability with marginal heat loss. The whole process only utilizes three major components which are the container, the working fluid inside the pipe and the thermosyphon effect, also called the capillary structure. However before studying the specific details of exactly how the heat pipe works, it is best to understand the history of heat pipe technology to get a solid “feel” of its system and exactly how it varies from some other similar devices.
The history of the heat pipe can be traced back to Angier March Perkins who in 1839 got a patent on the hermetic boiler tube. He toyed with the concept of a working fluid, but in only one phase and at a high pressure. His descendant, Jacob Perkins, additionally took a patent on the Perkins Tube (1936) in which a long, twisted tube filled with water was passed over an evaporator then a condenser. In this case the water inside operated in 2 phases. These very early designs also relied on gravity so the water might travel back to the evaporator, but nonetheless they were an adequate jump-start for present heat pipe technology.
The idea of the modern heat pipe was first put forth by R. S. Gaugler of General Motors Inc. in 1944. He patented a light-weight, heat transfer instrument which was allegedly applied to a refrigeration system. He added the concept of using a wick to make the inner fluid return back to the evaporator, instead of gravity. But throughout that period there was no great requirement for such a thing, so the development made no impact for about two decades. It resurfaced only during 1962 when G. M. Grover and his co-workers from the Los Alamos Scientific Laboratory created prototypes on the design and coined the name “heat pipe”.
By this time the idea of such a thing was established as useful in different fields, so heat pipe technology became prominent. Industries and laboratories began utilizing heat pipes for numerous things. Though at first water was made use of as the working fluid, other substances (i.e. mercury, ethanol, and nitrogen) were ultimately utilized to replace it, depending on the operating vapor temperature range. During 1969, NASA, space agencies and some other aircraft companies expressed interest in using heat pipes to regulate spacecraft temperature.
