Pressure Controlled Heat Pipes

William Anderson, John Hartenstine, Calin Tarau, David Sarraf, Kara Walker
2011 41st International Conference on Environmental Systems   unpublished
In a Variable Conductance Heat Pipe (VCHP), a Non-Condensable Gas (NCG) is added to the heat pipe to allow the conductance to vary. A Pressure Controlled Heat Pipe (PCHP) is a VCHP variant, where the heat pipe operation is controlled by varying either the gas quantity or the volume of the gas reservoir. This paper will discuss two applications for PCHPs: 1. Precise Temperature Control, and (2) Switching thermal power between multiple sinks. A prototype aluminum/ammonia PCHP was built and tested
more » ... as built and tested to demonstrate the capability of controlling the evaporator section of an aluminum/ammonia pressure controlled heat pipe to milli-Kelvin levels over an extended period of time. The external (simulated radiator or heat sink) temperature was varied and the heat input into the evaporator section was varied during those tests. Temperature set point changes were also demonstrated. PCHPs can also be used to switch power between multiple high temperature reactors. In a second program, a heat pipe solar receiver was designed to accept, isothermalize and transfer the solar thermal energy to reactors for oxygen production from lunar regolith. The receiver has two PCHPs and two CCHPs to supply heat to two reactors. During operation, one reactor is producing hydrogen at low solar power, while the other reactor is warming up a fresh batch of regolith. The PCHPs switch power between the two reactors as required.
doi:10.2514/6.2011-5232 fatcat:paksbx2hyjha5dzk6gpi4ztgjm