Design, Analysis, and Optimization of a Radioisotope Thermophotovoltaic (RTPV) Generator, and its Applicability to an Illustrative Space Mission

Abstract

Sectioned at Mid-Plane *Fine-Weave Pierced Fabric, a 90%-dense 3D carbon-carbon composite *Carbon-Bonded Carbon Fibers, a 10%-dense high-temperature insulator *62.5-watt 238 Pu02 pellet • RTPV heat source consists of two GPHS modules, identical to those used on Galileo, Ulysses, and upcoming Cassini missions. • This is a 60% reduction from the five modules used in the RTG design for PFF. • GPHS modules have undergone very extensive safety analyses, tests, and reviews.' These need not be repeated as long as the PFF launch vehicle is no more severe than the Shuttle or Titan-4. *

Design and performance analysis of a 500-W heat source for radioisotope thermophotovoltaic converters

“…The RTG uses a thermocouple array to convert this decay heat through the Seebeck effect . The General Purpose Heat Source (GPHS) using Plutonium‐238 ( 238 PuO 2 ) is a modular component of an RTG and was used for NASA spacecraft such as Voyager, New Horizon, and Curiosity Rover. The GPHS‐RTG generates electric power by converting the α decay heat of 238 Pu into electrical energy using a thermoelectric array; however, the system has a low conversion efficiency of 6 to 7% .…”

“…The General Purpose Heat Source (GPHS) using Plutonium‐238 ( 238 PuO 2 ) is a modular component of an RTG and was used for NASA spacecraft such as Voyager, New Horizon, and Curiosity Rover. The GPHS‐RTG generates electric power by converting the α decay heat of 238 Pu into electrical energy using a thermoelectric array; however, the system has a low conversion efficiency of 6 to 7% . A high fuel inventory with a low conversion efficiency is required to meet a required amount of electricity output, without which there will be inefficiency in spacecraft launch.…”

“…A high fuel inventory with a low conversion efficiency is required to meet a required amount of electricity output, without which there will be inefficiency in spacecraft launch. On the other hand, a radioisotope thermophotovoltaic (RTPV) system typically has a much higher energy conversion efficiency of ~20% because the system absorbs the decay heat of radioisotopes and re‐radiates photons with tailored wavelengths toward a photovoltaic (PV) cell . Previous comparative studies showed that the RTPV with tungsten emitters has a potential to achieve ~60% reduction of fuel mass compared with RTGs due to the enhanced specific power density …”

“…By tailoring the radiative properties of emitters/filters and increasing the quality of low bandgap PV cells, RTPVs have a potential to further surpass the conventional RTG conversion efficiency. Previous studies have investigated the detailed performance of RTPVs mostly using a numerical approach without much consideration of the radiation shielding issues. Such studies have reported ~15% to 25% conversion efficiency by varying the emitter temperature, emitter design, and PV cells.…”

“…In most previous studies, 238 PuO 2 was considered as the fuel material to use the α‐decay heat of 238 Pu due to its high specific power density (480 W/kg), long half‐life (87.8 years), and high melting point (~2353 K). Also, the chemical and material stability of PuO 2 has been well verified in the nuclear engineering field.…”