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The sodium-sulfur battery is emerging as a prime high-temperature energy storage technology for space flight applications. Useable specific energy of two to three times that of Ni-H2 batteries is the key advantage of Na-S. This represents a significant launch cost savings, and increased payload mass capability. A Na-S cell demonstration is planned for a 1995 NASA Space Shuttle flight which focuses on the micro-gravity effects on individual cells. This paper will describe the experiment plan in detail.

Performance tests of a small, high-speed, uniflow steam engine (expander) are described and theoretical and experimental results compared. The engine delivered a maximum of 10.7 hp at 2100 rpm with superheated steam at 230 psi. A minimum steam consumption rate of 23.2 lb/hp-hr was measured at 40% cutoff with 590 F superheated steam. The mechanical efficiency of the engine was determined as 92% and overall engine efficiencies of over 70% were measured. Problems in the engine design uncovered in the tests involving the valve arrangement for short cutoffs are discussed.