The air conditioning heat pipe, the idea was proposed in 1942, similar in many respects, the water heater. Do not use a large number of applications heatpipes strictly defined below, but the use of heaters (Fig. a), sometimes called gravity using heat pipes.

A device for efficient heat transfer between two locations containing through evaporation and condensation of the liquid it contains. Air conditioning heat pipes have many applications in areas where reliable performance and low cost is a primary example importancefor electronics and heat exchangers. See also the heat exchanger.

A small quantity of liquid is placed in a tube from which the air is then evacuated, and the tube is sealed. The lower end of the tube is heated, causing liquid to vaporize and the vapor to move to the cooler end of the tube, where it condenses.

 The condensate is returned to the evaporator section by gravity. Since the latent heat of evaporation is generally high, considerable quantities of heat can be transported with a very small temperature difference between the two ends. Thus the structure has a high effective thermal conductance.

The thermosiphon, also known as the Perkins tube, has been used for many years. A wide variety of working fluids have been employed, ranging from helium to liquid metals.