Feasibility Demonstration of a Multi-Cylinder Stirling Convertor with a Duplex Linear Alternator

Stirling Technology Company (STC) proposes to integrate an existing Multi-Cylinder Free-Piston Stirling Engine (MPFPSE) with innovative compact linear alternators. Future manned and unmanned scientific and exploration missions will require substantially more electric power from nuclear, solar, and other heat sources than existing launch-capable systems can effectively provide. A scalable, cost-effective, safe, reliable, low mass, robust, high-efficiency, heat-to-electric power convertor is proposed. Innovative aspects include: 1) increased power density through the use of a double-acting MCFPSE, 2) increased system efficiency by improving phase angle and reducing alternator losses, and 3) an innovative duplex linear alternator design with the potential to improve efficiency and reduce mass. This advanced dynamic power system for heat-to-electric power conversion is based on a free-piston implementation of the well-known Siemens four-cylinder heat exchanger interconnection arrangement combined with highly reliable, flexure-supported linear alternators. These proven technologies provide high power density, while retaining the simplicity and long-life inherent with flexure-supported hardware, as evidenced by an on-going 79,000-hour (9-year) maintenance-free, degradation-free endurance test at STC. Power convertors based on this innovative arrangement are scalable up to tens of kilowatts, while modular combinations of coaxially-aligned, opposed power convertors will produce very low net vibration forces.