Roelf J. Meijer

Design and testing of a heat pipe gas combustion system for the STM4-120 Stirling engine

Evaporators of a novel geometry, designed to have a more compact size yet the same output as larger, conventional heat pipes, have been fabricated and tested. A technique was developed to calculate capillary pressure required inside the heat pipe. Several quarter- and full-scale evaporators were designed and successfully tested. The burner, film-cooled combustion chamber, and preheater were designed and tested separately. A complete heat pipe gas combustion system (HPGC) was tested, showing an efficiency of 89% was measured at 20 kW/sub th/. A film-cooled combustion chamber was tested with flame temperatures of 2200 degrees C and wall temperatures below 1000 degrees C using preheated air for film cooling. Also, a full-scale HPGC was tested at an excess of 95 kW/sub th/, showing efficiency in the range of 85 to 90% under steady-state conditions. Results of transient and startup tests, carried out to evaluate the performance of the heat pipe, all also reported.<<ETX>>

STM4-120 Stirling Engine Test Development

Stirling Thermal Motors, Inc. (STM) of Ann Arbor, Michigan, has been developing and testing a general purpose, 40 kW Stirling engine designated the STM4-120. This engine configuration features a heat pipe heater head designed to receive heat from the condensing metal vapor (sodium, Na) of a heat pipe using any one of a variety of heat sources. Several quarter-scale models of this evaporator design have been fabricated and successfully demonstrated. This paper describes the test hardware, the performance and related problems of the engine and heat pipe systems. Plans for future development and testing are outlined and include a heat pipe solar receiver supported by the DOE Solar Thermal Program.