Heat pipes are Heat transfer devices. They are Hollow cylindrical pipes, filled with a small/little amount of working fluid that evaporates to produce heat. This heat then rejected from another end for its application on various industrial processes. For example, heat pipe is used in Air Conditioning and Refrigeration application.

A heat pipe is a closed evaporator-condenser cylindrical system sealed under vacuum with a small amount of working fluid. During non-operation, the working fluid contained inside the wick structure lines the inner diameter of the heat pipe. When heat is applied to the heat pipe, the liquid in the wick gets heated and forms a vapor. After that, the fluid vapor fills the entire pipe quickly spreads to the other end of the heat pipe.

At the destination end, known as the condenser, the heat given up by working fluid is rejected to an external heat sink. The fluid then returns via wick structure and passively pumps the fluid back to the heat source using capillary force. By utilizing this liquid and vapor phases, the heat pipe heat exchanger is extremely efficient. Because of its closed loop system, a heat pipe operates passively and continuously without any disturbance, creating a very reliable and efficient thermal management system.