High Performance, Microfabricated Converters for Space Science Missions

This proposal addresses the need for the efficient conversion of thermal energy from a radioisotope heat source to electrical energy for space science missions. We propose to develop a miniature Turbo-Brayton Power Unit (TBPU) using a closed-loop Brayton cycle to provide approximately 55 We at a sink temperature of 300 K. This TBPU promises to achieve a net thermal efficiency of 22% and have a mass of only 3.0 kg. The technical approach that enables high efficiency relies on unique micro-fabrication techniques that have been developed at Creare. These techniques have been used in long-life, vibration-free turbo-Brayton cryocoolers that have been successfully space flight qualified and tested. Here we plan to apply the basic technology to high temperature power generation. During Phase I, we proved the feasibility of the concept by demonstrating the operation of a prototypical turbomachine rotor in gas bearings at speeds in excess of the design speed. During Phase II, we will develop a prototype TBPU and test it at prototypical power levels and temperatures. The project team that will collaborate on this effort has extensive experience in the development of space-flight hardware incorporating high-speed turbomachines, high-performance recuperators, and precision gas film bearings.