The Effect of Trace-Contaminant Sorbent Monolith Geometry on Sorbent Performance

Date

2022-07-10

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Publisher

51st International Conference on Environmental Systems

Abstract

The current trace-contaminant (TC) control technology in the Exploration Portable Life Support System (xPLSS) involves a packed bed of acid impregnated granular charcoal, which is difficult to regenerate and is considered a consumable. The preferred implementation of TC control is pressure-swing adsorption (PSA) using a regenerable sorbent, where TCs are adsorbed in adsorption steps followed by regeneration by exposure to space vacuum (desorption steps). The adsorption-desorption steps are repeated cyclically in parallel beds, which ensures continuous TC removal. The use of sorbent monoliths is advantageous due to the low pressure drop and low fan-power requirement. TC-sorption capacity is an important sorbent property, which, in conjunction with the gas residence time within the sorbent, strongly affects sorbent performance. Sorbent-monolith geometry plays an important role through the complex mass-transfer and sorption/desorption kinetic phenomena that occur within the sorbent structure. In this paper, results are presented on the development of vacuum-regenerable TC sorbents for use in the xPLSS, with the effects of sorbent-monolith geometry studied in sorption-desorption experiments. The sorbents were derived from 3D-printed polymer honeycomb monoliths that were carbonized and oxidized to develop porosity, and also to enhance the TC-sorption capacity by the creation of carbon-oxygen surface complexes. Results are presented on the following aspects of sorbent-monolith geometry: (1) monolith size (volume); and (2) channel cross-sectional shape and size. The use of predominantly microporous carbon monoliths is associated with the following benefits: high sorption capacity; low pressure drop; rapid vacuum desorption; high mechanical strength and resistance to attrition; good thermal management (high thermal conductivity and low thermal effects associated with physisorption/desorption); good resistance to dusty environments; low toxicity and flammability.

Description

Marek A. W jtowicz, Advanced Fuel Research, Inc., US
Joseph E. Cosgrove, Advanced Fuel Research, Inc., US
Michael A. Serio, Advanced Fuel Research, Inc., US
Andrew E. Carlson, Advanced Fuel Research, Inc., US
Cinda Chullen, NASA, US
ICES402: Extravehicular Activity: PLSS Systems
The 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.

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Keywords

Extravehicular Activities (EVAs), Portable Life Support System (PLSS), Trace Contaminant Control System (TCCS), trace contaminants (TCs), ammonia, adsorption, vacuum regeneration, pressure-swing adsorption, carbonization, activation, monoliths

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