Hardware development and initial subassembly test of a gas-fired Stirling/Rankine residential heat pump

A gas-fired Stirling/Rankine heat pump is being developed at Sunpower, Inc. The free-piston Stirling engine/magnetic coupling/refrigerant compressor (FPSE/MC/C) assembly used as the power module for this type of heat pump is currently in the assembly and test phase. To achieve high efficiency, low cost, and a more durable system, modifications have been made to a previously introduced design. The modifications include changes in material selection, a different displacer drive, and the use of low-cost and more efficient cooler design. A commercially available R-22 compressor is used in the prototype. Low cost iron-neodymium permanent magnets are used to provide an efficient magnetic coupling design. To match the engine power to the load, a double-acting variable has spring is arranged in parallel with the engine and compressor. After the gas spring was designed and fabricated, it was tested with the compressor. Before system integration and test, the engine/alternator and the compressor/heat pump have been set up and are to be tested separately. 5 refs., 9 figs., 2 tabs.