Characterization of Potassium Superoxide and a Novel Packed Bed Configuration for Closed Environment Air Revitalization

摘要

Potassium superoxide (KO2) has been used in environmental control and life support systems (ECLSS) ranging from early Soviet spacecraft to self-contained self-rescuer devices for mine safety. By reacting with moisture carried in an air flow, KO2 releases oxygen and absorbs carbon dioxide. Because KO2 performs multiple functions required in closed environments (humidity removal, oxygen provision, carbon dioxide removal), and its reactions are triggered by a metabolic waste product (respired moisture), KO2 can be used as a basis for a simple, passive, and compact air revitalization system. The performance of KO2, lithium hydroxide, and silica gel with respect to carbon dioxide adsorption, oxygen release, and humidity control is reviewed. The operation of these granular chemicals was characterized in sequentially layered, plug-flow, packed beds with both steady state and transient (feedback controlled) inlet conditions for durations of up to 10 days. Because the output of these chemical beds in a symmetric layering configuration either exceeded or fell short of metabolic requirements at different times, an alternative packing configuration was desired. As a result of this research, a proposed system concept of an asymmetrically packed granular bed was developed to provide constant output environmental control utilizing KO2, lithium hydroxide, and silica gel. Such a system can be initially designed to meet an expected metabolic loading profile for a given duration. In this way, a reliable and volumetrically efficient air revitalization system can be provided for applications including mine rescue shelters, military vehicles, and human space transportation vehicles for durations of up to 10 days.