Heat Pipes

Abstract

Abstract The heat pipe is a device that utilizes the evaporation heat transfer in the evaporator and condensation heat transfer in the condenser in which the vapor flow from the evaporator to the condenser is caused by the vapor pressure difference and the liquid flow from the condenser to the evaporator is produced by the capillary force, gravitational force, electrostatic force, or other forces directly acting on it. A typical heat pipe consists of three sections: an evaporator or heat addition section, an adiabatic section, and a condenser or heat rejection section. For a heat pipe to function, the capillary pressure difference occurring in the heat pipe must always be greater than the summation of all the pressure losses occurring throughout the liquid and vapor flow paths. One of the simplest heat pipes is the thermosyphon. Cryogenic fluids are used in the cryogenic heat pipe.