Search Results

Research into increased capacity solid amine sorbents has found a candidate (SA9T) that will provide enough increase in cyclic carbon dioxide removal capacity to produce a fully redundant Regenerative Carbon Dioxide Removal System (RCRS). This system will eliminate the need for large quantities of backup LiOH, thus gaining critical storage space on board the shuttle orbiter. This new sorbent has shown an ability to package two fully redundant (four) sorbent beds together with their respective valves, fans and plumbing to create two operationally independent systems. The increase in CO2 removal capacity of the new sorbent will allow these two systems to fit within the envelope presently used by the RCRS. This paper reports on the sub-scale amine testing performed in support of the development effort. In addition, this paper will provide a preliminary design schematic of a fully redundant RCRS.

Carbon dioxide removal on the Shuttle is performed either by flowing cabin ventilation air through single use LiOH beds or by using the Regenerable CO2 Removal System (RCRS) (Ref 1,2,3). The RCRS was designed for single string mechanical operation with redundancy only on electrical components. It therefore can become disabled by a number of possible single point failures such as fan failure, actuator failure or a large internal leak through the beds. Because of these possible failures, LiOH must be flown on all RCRS missions to provide contingency CO2 removal. These LiOH canisters occupy valuable stowage space onboard the shuttle orbiter. The development of a new sorbent material called HS-X with significantly more CO2 removal capacity per unit volume has made much smaller sorbent bed sizes possible. With significantly smaller beds each of the single point failures can be addressed and a fully redundant RCRS can be built to fit within the existing RCRS envelope.

The NASA objective of expanding the human experience into the far reaches of space will require the development of regenerable life support systems. On-board carbon dioxide (CO2) removal units play a key role in such systems ensuring high quality cabin air for crew members. Similar but more compact units are needed for extravehicular activities (space suit). The use of monolithic (e.g., honeycomb-shaped) rather than granular sorbents has the potential to result in a CO2-removal system that possesses substantial weight, size, and power-requirement advantages over current systems (improved CO2 adsorption and lower pressure drop). The subject of this study was the use and manufacture of lightweight, porous carbon monoliths with controlled pore characteristics that will serve as support for the sorbent material (e.g., liquid amines). The objective was to demonstrate the technical feasibility of the above approach.

A number of amine-based carbon dioxide (CO2) removal systems have been developed for atmosphere revitalization in closed loop life support systems. Most recently, Hamilton Sundstrand has developed an amine-based sorbent, designated SA9T, possessing approximately 2-fold greater capacity compared to previous formulations. This new formulation has demonstrated applicability for controlling CO2 levels within vehicles and habitats as well as during extravehicular activity (EVA). Our current data demonstrates an amine-based system volume which is competitive with existing technologies which use metal oxides (Metox) and lithium hydroxide sorbents. Further enhancements in system performance can be realized by incorporating humidity and trace contaminant control functions within an amine-based atmosphere revitalization system. A 3-year effort to develop prototype hardware capable of removing CO2, H2O, and trace contaminants from a cabin atmosphere has been initiated.

Pyrolysis processing is one of several options for solid waste resource recovery in space. It has the advantage of being relatively simple and adaptable to a wide variety of feedstocks and it can produce several usable products from typical waste streams. The overall objective of this study was to produce a prototype mixed solid waste pyrolyzer for spacecraft applications. A two-stage reactor system was developed which can process a maximum of about 0.5 kg of waste per cycle. The reactor includes a pyrolysis chamber where the waste is heated to temperatures above 600 °C for primary pyrolysis. The volatile products (liquids, gases) are transported by a N2 purge gas to a second chamber which contains a catalyst bed for cracking the tars at temperatures of about 1000-1100 °C. The tars are cracked into carbon and additional gases. Most of the deposited carbon is subsequently gasified by oxygenated volatiles (CO2, H2O) from the first stage.

This project investigates methods to capture an astronaut's exhaled carbon dioxide (CO2) before it becomes diluted with the high volumetric oxygen flow present within a space suit. Typical expired breath contains CO2 partial pressures (pCO2) in the range of 20-35 mm Hg (.0226-.046 atm). This research investigates methods to capture the concentrated CO2 gas stream prior to its dilution with the low pCO2 ventilation flow. Specifically this research is looking at potential designs for a collection cup for use inside the space suit helmet. The collection cup concept is not the same as a breathing mask typical of that worn by firefighters and pilots. It is well known that most members of the astronaut corps view a mask as a serious deficiency in any space suit helmet design. Instead, the collection cup is a non-contact device that will be designed using a detailed Computational Fluid Dynamic (CFD) analysis of the ventilation flow environment within the helmet.