Search Results

NASA JSC has contracted with Hamilton Standard Space Systems International (HSSSI) to develop a combined CO2/H2O removal system for an advanced space suit. This system will operate with a novel solid amine sorbent that has demonstrated a large increase in capacity over previous solid amine sorbents. The concept will use two beds of the sorbent operating on a pressure swing removal process. This paper discusses the design, fabrication and testing of this prototype system. The overall system design consists of two sorbent beds, a spool valve for directing vacuum and process air, and a controller to monitor the overall process and switch the spool valve at the appropriate time. We will include a discussion of the quick-cast process used in the fabrication of major system components. Finally, we will present the results of testing the full-scale prototype at HSSSI, and its ability to remove CO2/H2O and be regenerated continuously.

Supported amines have been shown to absorb CO2 cyclically under temperature swing absorption (TSA) conditions, and show a substantial decrease in desorption energy compared to zeolite materials. Supported amines may therefore be a viable alternative for cyclic capture of CO2 on long-term space missions where minimal energy expenditure is a critical consideration. The research described in this paper presents efforts to improve the TSA-supported amine system with a focus on relationships between important parameters affecting cyclic CO2 capacities, as well as reaction effects of CO2 with the modified amine tetraethylenepentamine.

In this study, a parametric examination of the main factors affecting cyclic CO2 absorption into supported amine sorbents has been conducted. A bench-scale test apparatus and Taguchi statistical design of experiments were used to assess the importance of cycle time, inlet CO2 concentration, residence time, humidity, absorption temperature, desorption temperature and desorption pressure on cyclic CO2 capacity. Two amine sorbents were considered: TEPAN and modified E-100. Amine decomposition, amine oxidation, and the effects of amine chemical composition were also examined. For typical ranges of system variables found on-board the space shuttle orbiter, results indicated that desorption pressure over the range of 25–85 torr, desorption temperature over the range of 50–60°C, absorption temperature over the range of 20–30°C, and CO2 concentration over the range of 6–9 mmHg were the most important variables affecting cyclic CO2 removal capacity.