Evaluation of advanced component concepts for an integrated environmental control/life support, resistojet control system

Flow restricting devices were studied for their suitability as liquid water propellant flow limiters for the biowaste resistojet. Flow limiting during the start-up transient is required to prevent thrustor instabilities and icing which could result in heater failure in the electrical resistance heated thrustor (resistojet). The study was directed toward simple devices which would function passively (i.e., without power except from the propellant flow itself), and would offer high reliability and simplicity. In addition to the flow limiting devices, a thermal pumping system was studied to determine whether CO2, desorbed from molecular sieves could be pumped thermally in a space station application. The thermal pump is considered a possible replacement for mechanical pumps. It involves a cyclic, constant volume cryopumping system which employs space radiators to achieve the cryotemperatures. The frozen CO2 would be vaporized periodically, using a waste heat loop, to attain sufficient pressure to transfer a large portion of the trapped CO2 to storage tanks.