Abstract: A thermal control system adapted for test in a 1G gravity environment and for operation as a microgravity environment includes a capillary pumped loop with a wicked evaporator which produces a coolant vapor head of about 1/2 PSI upon absorbing heat from a heat source. A heat pipe includes a cylindrical portion adapted for absorbing heat, and also includes a radiator panel which rejects absorbed heat. A heat exchanger coupled to receive coolant vapor from the wicked evaporator includes a manifold which directs the vapor to a plurality of parallel fluid channels helically wound about and thermally coupled with the heat absorbing portion of the heat pipe. A liquid manifold is coupled to the liquid side of the fluid channels for receiving cooled liquid, which is returned to the wicked evaporator.

Abstract: A heat exchanger includes a porous cylindrical sleeve with a bore into which liquid coolant is admitted. The liquid permeates the sleeve but cannot leave the outer surface. A pipe surrounds the sleeve. The pipe has a cylindrical outer surface and an inner surface defining protrusions and vapor channels about the protrusions. The inner ends of the protrusions bear against the outer surface of the sleeve. A plurality of helical channels are helically arranged about and in thermal contact with the outer surface of the pipe. The ends of the helical channels are coupled to plenums. Each plenum is coupled by a pipe and a fluid disconnect to one end of a thermal loop including a heat source. Heat-laden vapor passes through the helical channels and is cooled to liquid. The heat is withdrawn into the pipe and passes through the protuberances to vaporize the liquid near the surface of the porous sleeve. The resulting vapor is collected and coupled to a condenser.