Increase thermophotovoltaic system efficiency using selective emitters
- Auburn Univ., AL (United States). Space Power Inst.
Thermophotovoltaics (TPV) is the term applied to the technique for energy conversion whereby the energy emitted by an incandescent source is converted to electrical energy by a photovoltaic cell. There are three approaches currently being investigated for practical devices. These are selective filtering, multi-bandgap conversion, and selective emission. The first two approaches rely on a blackbody-like radiator as the source for photovoltaic conversion. Only a fraction of this radiation is usable for photoconversion by the photocell and thus any excess energy used to generate radiation which is not photoconvertible, such as fuel in a combustion flame, is wasted. This is based on the principle that only a narrow band of radiation, which is centered near the bandgap of the photocell, is efficiently converted into usable electricity. The remaining radiation is wasted. Ideally, one would want a radiator which emits in a narrow band which is matched to the bandgap of the photocell which is being used. This is the principle behind selective emission. Selective emission can be obtained by thermally exciting certain rare earth oxides which emit in a single narrow band in the infrared. These rare earth oxides exhibit peak emittances of about 0.8 in the narrow band and emittances approaching 0 elsewhere. The infrared region of the spectrum is where the bandgaps of common photocells occur including silicon and indium gallium arsenide. This paper will show both theoretically and experimentally that selective emission can reduce the energy requirements of the thermal source in a TPV system and hence increase the overall system efficiency.
- OSTI ID:
- 163398
- Report Number(s):
- CONF-950729--
- Country of Publication:
- United States
- Language:
- English
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