A cryogenic pump produced by Barber-Nichols Inc. (BNI) is featured in NASA Tech Briefs because it uses composite materials to increase pump efficiency and reduce conductive heat leak. Several modifications were made to the design and operation of the extended-shaft cryogenic pump to increase the pumping efficiency. In general, cryogenic fluid pumping efficiency is limited by thermal losses (the thermal energy the pump adds to the fluid). The sources of the thermal losses are pump-inefficiency and leakage (conduction) of heat through the pump structure. Most cryogenic pumping systems are required to operate at maximum efficiency because the thermal energy added to the fluids by the pumps is removed by expensive downstream refrigeration equipment. It would be beneficial to reduce thermal losses to the point where the downstream refrigeration equipment is not necessary.
