3. Two-phase thermosiphons

Two-phase thermosyphons are heat pipes in which the driving force for liquid return is not capillary action, but gravity. This is only possible when the condenser is above the evaporator.

When a thermosiphon includes a capillary structure, such as a groove, its only role is to improve local performance (exchange coefficient, homogenization of the condensate film, stabilization of the liquid-vapor interface, etc.). In fact, smooth-walled thermosiphons are widely used in the industrial sector to keep costs to a minimum.

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