Theoretical Performance of a Radioisotope Thermophotovoltaic (RTPV) Power System

An RTPV power system with a nominal output of 38W is being developed by NASA. As part of that program, a theoretical model of a planar thermophotovoltaic (TPV) system has been developed. Performance results from that model will be presented. The model uses experimentally determined optical and electrical properties of the major components (emitter, filter and photovoltaic array) of the system. One of the objectives of the model is to compare a system that uses a single optical cavity to one that has two optical cavities. Spectral emittance must be decreased as emitter and array size increase in order to maintain the high emitter temperature required for system efficiency. Several low vapor pressure metals as emitter materials will be modeled. Another objective is to determine the parasitic heat loss that occurs in the system. Discussion of these two objectives will be a major part of the presentation.