Preliminary Tests with Variable Conductance Radiator for CO2 Deposition in Deep Space Transit



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51st International Conference on Environmental Systems


NASA's challenging deep space exploration missions demand innovative, reliable, and cost-effective technologies to achieve the required life support systems. An alternative technology under consideration, to replace current solid sorbent-based CO2 removal technology, is CO2 deposition that leverages the different phase change temperatures of air constituents to selectively remove CO2. NASA has recently demonstrated use of Stirling cryogenic coolers to create cold surfaces and deposit CO2 out of flowing air stream. Such cryocoolers are very reliable but require significant energy input to operate. As Mars missions provide a capability to view deep space at environmental temperature of ~4K, thermal radiators are emerging as an opportunity to complement or replace cryogenic coolers. This study investigates an innovative Variable Conductance Radiator (VCR) that could provide modulated and efficient heat rejection technology for CO2 deposition systems. The VCR operates in CO2 capture and CO2 recovery modes in alternating manner. During capture mode, a liquid is circulated through the radiator, transporting heat from the CO2 deposition surface to the heat rejection surface, and creating a low temperature gradient/thermal resistance across the radiator. In recovery mode, the circulating liquid is evacuated and replaced with a stagnant, non-condensable gas, enabling high temperature gradient/thermal resistance across the radiator. During recovery mode, a heater sublimates the deposited CO2 layer and prepares the surface for the next capture period. The prototype VCR system consists of two radiator panels separated by an enclosed space. It features electric heaters to represent heat input during CO2 deposition and dry ice/acetone bath to represent heat rejection to deep space. The prototype is used to evaluate the VCR performance at various operating conditions and obtain results for comparison with simulations. Initial data showed variable conductance, low and high temperature gradient/ thermal resistance across the radiator in CO2 capture and recovery modes, respectively.


Balmore Giron-Olivares, University of North Texas, US
Huseyin Bostanci, University of North Texas, US
Cable Kurwitz, Texas A&M University, US
Grace Belancik, NASA Ames Research Center, US
Darrell Jan, NASA Ames Research Center, US
ICES302: Physio-chemical Life Support- Air Revitalization Systems -Technology and Process Development
The 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.


Air Revitalization, CO2 Removal, CO2 Deposition, Thermal Radiator