Development of a Miniature, Reliable Ammonia Pump for Spaceborne Two-Phase Pumped Loops

NASA’s future remote sensing science missions require advanced thermal management technologies to maintain multiple instruments at very stable temperatures and utilize waste heat to keep other critical subsystems to stay above minimum operational temperatures. Two-phase pumped loops are an ideal solution for these applications. A critical need for these pumped loops is an ammonia pump that reliably circulates very slightly subcooled liquid ammonia in the loop. To meet this need, Creare is developing a reliable, pump that has innovative features to prevent cavitation in the pumping chamber and in the hydrodynamic fluid bearings, enhancing the overall pumped loop reliability. This paper first discusses design challenges for ammonia circulation pumps for two-phase pumped loop applications. It then discusses the key performance features of Creare’s ammonia-compatible pump and presents the hydrodynamic performance test data of a brassboard pump and its measured Net Positive Suction Head before cavitation occurs. Finally, the paper discusses the preliminary assessment of the pump reliability and exported vibrations.