Initial characterization of a modular heat exchanger with an integral heat pipe

A conceptual design for a Stirling space engine for future NASA missions uses 40 modular heat exchangers, each with its own integral heat pipe to transport heat to the engine. An existing free-piston Stirling engine was modified to serve as a testbed for evaluating the heat-exchanger modules. The design and fabrication of the modules and the engine used for these tests are discussed. Evaluation of the individual heat pipes before installation in the engine is described. The initial test results with the modules in operation on the engine are presented. The results show that the heat exchangers operate successful on the engine. Measured characteristics of the heat pipes agree well with the analytical models. Temperature drops and the conditions at which the sonic limit is encountered also agree with the models. Future test plans are outlined