Radioisotope Thermophotovoltaic Generator Design and Performance Estimates for Terrestrial Applications

This work provides the design methods and performance estimates of the radioisotope thermophotovoltaic system (RTPV) for terrestrial applications. The modeling is based on an experimentally tested prototype using two-dimensional high temperature photonic crystal to realize spectral control. The design efforts focus on the optimization of the system efficiency and contain the heat source number, the size of the energy conversion elements, the insulation configuration, and the heat sink design. An equivalent circuit model was developed for the thermal and electrical performances. Based on a specific output requirement, an optimized heat source number and energy conversion area can be computed for a certain cell type and insulation design. The selection and characterization of the low bandgap thermophotovoltaic (TPV) cells applicable to the generator are compared and discussed. The generator’s heat sink design uses extended fins and the performance is estimated based on the external operating conditions. Finally, the work provides a design example of a terrestrial RTPV generator with an output level of ∼40 W electrical power (W_e) using InGaAsSb cell, reaching an efficiency of 8.26%.