Design and Testing of a Shell-Flow Hollow-Fiber Venting Gas Trap

Abstract

A Venting Gas Trap (VGT) was designed, built, and tested at NASA Johnson Space Center to eliminate dissolved and free gas from the circulating coolant loop of the Orion Environmental Control Life Support System. The VGT was downselected from two different designs. The VGT has robust operation, and easily met all the Orion requirements, especially size and weight. The VGT has a novel design with the gas trap made of a five-layer spiral wrap of porous hydrophobic hollow fibers that form a cylindrically shaped curtain terminated by a dome-shaped distal plug. Circulating coolant flows into the center of the cylindrical curtain and flows between the hollow fibers, around the distal plug, and exits the VGT outlet. Free gas is forced by the coolant flow to the distal plug and brought into contact with hollow fibers. The proximal ends of the hollow fibers terminate in a venting chamber that allows for rapid venting of the free gas inclusion, but passively limits the external venting from the venting chamber through two small holes in the event of a long-duration decompression of the cabin. The VGT performance specifications were verified in a wide range of flow rates, bubble sizes, and inclusion volumes. Long-duration and integrated Orion human tests of the VGT are also planned for the coming year. Nomenclature

Determining the effect of non-condensable gas on a two-phase ammonia heat transfer loop of the satellite

“…Gas traps were included in the projects of Grumman, RSC Energia, and the European Columbus station. Gas traps are also used in single-phase heat transfer loops in the American segment of the International Space Station (ISS) [8].…”

“…In the Sundstrand and Boeing project, the separation and removal of NCG was provided for in the multifunctional unit -Rotating Fluid Management Device (RFMD). However, works [2,3,8] lack justification for the need for gas traps, their design and volume, and installation location in the loop.…”

“…From the above literature [2][3][4][5][6][7][8][9][10][11][12][13][14] it is clear that NCG can have a significant impact on the parameters in 2PMPL. The information available is limited and sometimes contradictory.…”