Novel Modular Double-Acting Free-Piston Stirling Convertor

We will build and test a stirling-cycle convertor for generating electrical power from the heat output of a radioisotope heat source (GPHS), addressing evolving NASA requirements for highly reliable, robust, and easily adaptable configurations for space-power applications. Our double-acting stirling cycle configuration combines a linear alternator with a moving piston/regenerator assembly into a self-contained module. A number of such modules can be connected together into several possible convertor layouts to scale power, achieve system redundancy and cancel vibration forces. This modular approach provides the system designer with unique packaging options not available with conventional stirling convertors. Our primary Phase II focus will be to build and test this core module within a simple three-module convertor configuration. The part count per module is low and the design is amenable to mass production manufacturing methods. An intrinsic feature within the thermodynamic circuit prevents catastrophic piston over-stroke in the event the electrical load is interrupted. A potentially transformational passive reciprocating hydrodynamic gas bearing suspends the moving piston within its cylinder, eliminating wear and providing a highly effective piston seal. An optional hydrodynamic spin bearing system is available as a backup.