NASA Exploration Systems & Habitation (X-Hab)Academic Innovation Challenge 2020: Microgravity Gas/Liquid Separator for the CO2 Revitalization System Final Report

This report outlines the efforts of UNT X-Hab Team on a project titled, Microgravity Gas/Liquid Separator for the CO2 Revitalization System. The project is executed as a senior design project during academic year 2019-2020. The X-Hab 2020 Academic Innovation Challenge has selected eleven senior design teams from colleges across the US to demonstrate working prototypes for exploration systems and habitation. UNT has been tasked with the creation of a gas-liquid separator for an air revitalization system. Air revitalization technology has been used to support spaceflight by removing CO2 from enclosed systems in order to maintain breathable air. Solid sorbents such as zeolites or lithium hydroxide have been used in the past for these systems but are difficult to handle in microgravity environments and require a large amount of energy. This challenge aims to demonstrate vortex phase separator (VPS) technology for removing H2O from a CO2 stream. However, VPS technology also has the capability of using liquid sorbents for removing CO2 from an air stream. Further research could be done on liquid sorbents, such as liquid amine, in use with VPS systems. This would potentially be an alternative technology in replacing use of solid sorbents in CO2 removal systems. In 2019, NASA proposed a design that uses a gas/liquid contactor to allow for efficient contact between the two fluid phase. This was integrated into an overall CO2 removal system. The subsystems for gas-liquid separation and storage in NASA’s previous models for CO2 removal system could be replaced with a VPS. Innovative vortex separator technology is expected to allow for high throughput flow and highly efficient CO2 removal compared to other gas-liquid separation technologies. VPS relies on centripetal driven buoyancy forces to form a gas-liquid vortex within a fixed, right circular cylinder. The gas stream enters the separator through a tangential nozzle and breaks into very small bubbles (<<1 mm) resulting in a very large contact surface area for interaction with the liquid stream via energy and mass exchange. VPS technology can handle mismatches in inlet and outlet flow rates and system volume changes through the range of liquid thickness held in the separator (i.e., buffering and accumulating capability), and requires low pressure differences (<5-10 in H2O in most cases) for operation. The X-Hab 2020 team leverages these characteristics to investigate VPS technology as an alternative CO2 removal technology.