The Magic of Heatpipes

A heatpipe works by transferring heat energy in the form of liquid vapour, within a sealed copper tube who contents are in a vacuum.

There is a small amount of water inside the tube (also known as working fluid) whose job it is to absorb the latent heat at the heat source. As the temperature rises it causes the working fluid to boil in the low pressure atmosphere, undergoing a phase change to water vapour. In our daily lives, water boils at 100C, but if you remember back to physics class as pressure is decreased, the temperature gradient required to vaporize water also drops. In any case, the small amount of water inside easily converts to water vapour as the temperature of the evaporator end of the heatpipe increases.

The vapour is subsequently drawn to the cooler end of the heatpipe and condenses - this part of the heatpipe is typically connected up the cooling fins. As the hot vapour cools back into a liquid, the heat energy that it previously stored is transferred into the surrounding environment, be it aluminum fin, or otherwise.

The condensed vapour, now called a working fluid once again, is drawn back to the hot evaporator end of the heatpipe by capillary action along an internal wick structure. As the working fluid again reaches the hot end of the heatpipe once more, the entire process repeats itself.

Heatpipes are a closed loop process which work within certain temperature ranges (for example 40C - 60C degrees). If the differential between the hot and cooler sides becomes too low (say for example, each end of the heatpipe is 40 degrees) the system can stall. That shouldn't be a problem here however. Next up, let's take a better look at the Taisol CMK702151A heatsink.