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Life issues relating to a sodium-heat-pipe heat transport system are discussed. The heat-pipe system provides heat, at a temperature of 1050 K, to a 50-kWe Stirling engine/linear alternator power converter called the Stirling space power converter (SSPC). The converter is being developed under a National Aeronautics and Space Administration program. Because corrosion of heat-pipe materials in contact with sodium can affect the life of the heat pipe, a literature review of sodium corrosion processes was performed. It was found that impurity reactions, primarily oxygen, and dissolution of alloy elements were the two corrosion processes likely to be operative in the heat pipe. Approaches that are being taken to minimize these corrosion processes are discussed.

Following the successful testing of the 25 kWe Space Power Demonstrator (SPD) engine in 1985, a Stirling Space Engine (SSE) technology advancement program was initiated. The program's objective was to advance free-piston Stirling engine/alternator technology sufficiently so that a Stirling engine system may become a viable candidate for space power applications. Evolution of the SSE technology is planned to occur at three different engine heater temperature levels: 650, 1050, and 1300 K. These temperatures define three phases of technology development with the first phase involving the 650 K SPD engine. Technology development of the 650 K engine and preliminary design of the 1050 K engine will be discussed in this paper.

The NASA Lewis Research Center (LeRC) as Project Manager of the Department of Energy's Automotive Heat Engine Program, is developing advanced gas turbine and Sterling engines for automobiles. To accomplish the program goals of improved fuel economy, reduced emissions, and broad alternative fuel capability major development programs have been undertaken for both engines. These programs are described along with the predicted characteristics of the engines under development and the key technology problems that must be resolved to achieve these objectives. NASA LeRC is also responsible for the development of the power con-version systems for the Parabolic Dish Solar Thermal Power Systems being developed for the Department of Energy by the NASA Jet Propulsion Laboratory. The requirements of this solar thermal application are reviewed and compared with the predicted characteristics of the automobile engines under development.