US Patent 9500413 Thermosiphon systems with nested tubes

A thermosiphon system includes a condenser, an evaporator including a housing and a wick located in the housing, and a condensate line fluidically coupling the condenser to the evaporator. The condensate line includes an outer tube and an inner tube nested within the outer tube. A first passage defined by the inner tube is positioned to carry a liquid phase of a working fluid from the condenser to the evaporator, and a second passage defined by a volume between the inner tube and the outer tube is positioned to carry a vapor phase of the working fluid from the evaporator to the condenser.