Heat-Driven Pulse Pump (GSC13739)

Most single-and two-phase thermal control systems for spacecraft use a mechanical pump to produce the pressure head needed to overcome the loop pressure drop and circulate the working fluid. However, these mechanical pumps have moving parts that can wear out or break. They also require elaborate electronic control circuits that generate heat and can fail. For long missions, pump reliability is an important issue. Goddard researchers devised the heat-driven pulse pump as an alternative to applications using mechanical pumps with low flow rates. The basic concept of this invention is to use the working fluid itself to create the pumping pressure head. The pump consists of a grooved cylinder, two check valves (one each on the inlet and outlet), a wick, and strip heaters. For a specified time, power is applied to the pump, vaporizing the liquid and creating a pressure head that exceeds the pressure drop in the system. This pressure head pushes the liquid in the cylinder through the wick and past the outlet check valve. As the liquid in the cylinder is displaced, the liquid in the grooves is wicked toward the heater and sustains vaporization until the heater is turned off. An added benefit is that it may be possible to use waste heat as an alternative to the strip heaters. Three pumps installed in parallel provide continuous operation. As the next pump in the series is heated, the displaced liquid is pushed/pumped through the loop past the evaporator, picking up heat, then through the condenser and back into the other previously emptied pump. After startup, power is applied to one of the pumps for a preset time interval. Just prior to the end of that interval, heat is applied to the next pump in the series so that it can begin heating up. This is repeated for each of the pumps. For a short period of time, power is simultaneously applied to two of the pumps. This overlap provides more consistent flow: one pump is emptying, one filling, and one heating up. Researchers co

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