Design and analysis of miniature free piston Stirling engine (FPSE) for on-board power production

Abstract

Free piston Stirling engine integrated with linear alternator has high efficiency, quiet operation, long durability and long life. It is flexible to use any kind of potential heat sources such as chemical energy power sources and solar power. Size, mass and less total heat exchanger area than other power converters makes the FPSE attractive to space power requirements, as soldier borne power sources and cogeneration applications. The step by step design of 100 W power generating FPSE with helium as working fluid is done in the Sage software. To get an output power of 100W, the parental and child components were suitably arranged in the modeling section and then numerically solved in the software (Sage) with various input parameters and the decision variables were optimized to get the desired objective function. The engine uses heater head of 750K at 20 bar mean charge pressure, frequency of 50 Hz and getting overall efficiency of 32%. The design consists of a displacer and a power piston supported on flexure bearings. Non – contacting clearance seals are used between internal volumes. A linear alternator is designed, which converts the piston motion into electricity. Analysis to find the behavior of alternator using FEA is also done.