Effects of Air Bubble Contamination in Recirculating Water Loop

Long life in space of the Columbus recirculating water transport loop indicates probability that air bubble contamination will inadvertently be added to the loop during service revision, or repair procedures. This paper describes the results of tests run to simulate the effects of bubble contamination on the operation in zero gravity of a recirculating water loop.

All major components of the loop were installed with their water inlet and outlet connections at the top to prevent bubbles from being separated and stored in the components. In this way the bubbles were encouraged to recirculate in the loop in the manner expected in space with zero g operation. Maximum air injection without adverse pump operation was determined.

A brief trade-off of prospective bubble trap concepts is presented, and a preliminary investigation of a hydrophobic membrane bubble separator for this application is discussed.