Development Status of a Low-Power CO2 Removal and Compression System for Closed-Loop Air Revitalization

Abstract

The ‘low-power CO2 removal (LPCOR) system’ is an advanced air revitalization system that is under development at NASA Ames Research Center. The LPCOR utilizes the fundamental design features of the ‘four bed molecular sieve’ (4BMS) CO2 removal technology of the International Space Station (ISS). It will reduce the cabin air CO2 concentration by 60% with a 50% power savings compared to the current ISS standard. In addition, it will recover pure, compressed CO2 for oxygen recovery. LPCOR improves the power efficiency by replacing the desiccant beds of the 4BMS with a membrane dryer and a state-of the art structured adsorbent device that require 25% of the thermal energy required by the 4BMS desiccant beds. The CO2 removal and recovery functions are performed in a two-stage adsorption compressor. CO2 is removed from the cabin air and partially compressed in the first stage. The second stage performs further compression and delivers the compressed CO2 to a reduction unit such as a Sabatier reactor for oxygen recovery. This paper describes the development status of the LPCOR system, including the breadboard experiments to determine the performance parameters of the full-scale LPCOR components for an optimized process, characterization tests and long-term performance testing of individual components. Also discussed in this paper are the flow distribution challenges encountered in a low pressure-drop system such as the residual water adsorber, configured as an engineered structured sorbent, and the efforts to mitigate the flow-related issues.