Regenerable Cross Flow HEPA Filter with Integral Biohazard Treatment Stage

HEPA level (or better) particulate filters are an indispensable requirement for maintaining a healthy, breathable atmosphere inside life support envelopes on extraterrestrial platforms. For missions of indefinite duration into deep space it is not feasible or economical to rely on a finite inventory of disposable HEPA filters. Therefore it is necessary to develop permanent HEPA filters that can be regenerated in situ. Permanent HEPA filters have been qualified and installed for venting of nuclear power generation plants and for acoustic insulation to abate noise in military aircraft. The present technology can support the design of permanent HEPA cross flow filters with a remarkable media stacking density of 50 to 100 square meters of media surface area/cubic meter of housing volume. This optimum media stacking density can be realized by the deployment of seamless metallic membranes of up to 2.5 square meters of surface area in rectangular channel housings. Models based on fluid dynamics and cake formation kinetics are of significant value in filter design. Theoretical analysis of the transient behavior of cross flow filters will be presented. The challenge of adapting these filters to meet deep-space mission-specific objectives such as minimum volume footprint, minimum launch mass and provision for biohazard treatment of all materials discharged to space will be discussed with emphasis on the limitations of existing technologies. The design described in this presentation will operate with minimum energy consumption with the option of returning the heat energy used for biohazard treatment back to the LSE (life support envelope). Next steps leading to the full realization of a regenerable cross flow HEPA filter for application in a closed cabin environment in deep space will be discussed.