Capillary Fluidic CO2 Scrubbing Aboard Spacecraft: the CVS Demonstration on ISS: Part I Overview

Falling liquid film amine sorbent reactors have been successfully employed to scrub CO2 aboard submarines for decades. However, applying such proven methods aboard orbiting and coast spacecraft is significantly challenged by the nearly weightless environment, where liquid sprays and films do not fall, and vapor bubbles and gases do not rise. The Capillary sorbent Visible System (CVS) is a technology demonstration experiment performed aboard the ISS April 18 – 21, 2023. The system establishes stable steady thin liquid film flows in Contactor (absorber) and Degasser (desorber/stripper) replacing the passive role of gravity with the combined passive roles of surface tension, wetting, and system geometry. A viscous TOX-0 fructose ersatz liquid sorbent is employed such that the 'transparent' experiments can be performed and filmed by the crew in the open cabin of the ISS. Completed objectives include demonstrations of stable passive 'massively' parallel planar thin film capillary flows across atmospheric pressure Contactor and sealed heated Degasser. The impacts of varying flow rate, flow direction, heat input, viscosity, condensate collection and return, fluid distribution, interfacial stability, and others are reported. Over 49 diagnostics are recorded for digitization and subsequent thermal-fluids model validation by a single HD video downlink during the nearly 22 hours of operations. This paper (Part I) provides an overview of the flight hardware including description of the components, diagnostics, crew procedures, flight operations, and summary of accomplishments. A second paper (Part II) provides further details of the diagnostics, tests performed, data reduction, data archive, analysis, and technology impacts.