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Completed TRL 7 (started at 4, targeting 7)
This work addresses the development and demonstration of a Variable Heat Rejection Radiator (VHRR) using a vortex phase separator. As the name implies, a variable heat rejection radiator alters its effective heat transfer coefficient based on the environment to meet the needs of the given mission phase. Our plan is to essentially drain specific sections of the radiator of the working fluid replacing it with a non-condensable gas. Building on previous work in reduced gravity two-phase flow and phase separation, we plan to 1) identify a baseline thermal system design with a variable heat rejection radiator, 2) demonstrate operation of the system in various earth-g conditions, 3) demonstrate microgravity operation of the proposed system.
Problem Statement
NASA and others have supported several programs to develop and evaluate technologies to provide variable heat rejection. The proposal team plans to utilize a vortex phase separator developed at Texas A&M University and licensed to Advanced Cooling Technologies. This device has undergone extensive reduced gravity aircraft testing and has been part of two space flight experiments that have yet to fly. The device has a number of attractive features such as 1) it has no moving parts and 2) relies only on the injected fluid momentum to provide complete separation. This device has been shown to operate from all liquid to all gas inlet flow as well as being able to serve as an accumulator and heat exchanger. The accumulation function is instrumental in our approach in that we plan to exchange gas in the separator with liquid in the radiator to affect the heat rejection variability.
Variable heat-rejecting radiators utilizing a vortex phase separator are a technology that will benefit future NASA missions and other government agencies such as the Department of Defense. NEO pre-cursor robotic and Crew-to-LEO missions require variable heat rejection radiators due to the variable thermal loads and changes in the thermal rejection environment.
Future Customers
Many spaceflight missions will benefit from variable heat rejection systems specifically missions outside LEO and systems with challenging duty cycles. The ability to change the heat rejection capability for the radiator provides mission flexibility important for operationally responsive space (Air Force) and enhances interplanetary or near-earth object missions (NASA).
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