摘要:

This paper presents a parametric study of thermophotovoltaic (TPV) system efficiency and output power density based upon a simple model of the TPV system. The efficiencies presented here are based on thermodynamic limits. Some issues relating to the choice of TPV materials are considered. It is shown that the optimum TPV cell band gap depends not only on the emitter spectrum, but on the type and effectiveness of the spectral selection. Trade‐offs between efficiency and output power are also illustrated. In addition, issues associated with creating a more detailed TPV system model are discussed. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49695

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

At the NASA Lewis Research Center we have developed a systems model for a general thermophotovoltaic (TPV) system. The components included in the model are a solar concentrator, a receiver, a thermal storage module, an emitter, a protective window, a filter, and a photovoltaic (PV) array. The system model requires the wavelength dependence of the optical properties of the components, together with the PV cell spectral response and the cell current‐voltage characteristics. With these inputs, the system efficiency, the emitter or filter efficiencies, the PV cell efficiency, the emitter operating temperature, and the cell output power density are calculated.In this paper we compare the performance of a variety selective emitter and filter TPV systems. The overall system model is based on the solar TPV system being developed jointly by McDonnell‐Douglas and NASA. In the current study, the concentrator, receiver, and storage parameters are fixed; only the characteristics of the emitter/filter and the PV cell are varied.We present computed results for the emitter/filter efficiency, the PV cell efficiency, and the cell output power, at a number of emitter operating temperatures, as functions of the PV cell bandgap energy. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49684

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Data is presented on a recently developed new type of optical filter that appears to be ideally suited to the thermophotovoltaic energy conversion application. (AIP) ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49716

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

In papers presented at last year’s conference, the authors described an integrated Radioisotope Thermophotovoltaic (RTPV) power system design study they had conducted for the U.S. Department of Energy, and examined the system’s applicability to an illustrative space mission to Pluto. The power system employed previously flown and safety‐qualified radioisotope heat source modules, radiating their heat to gallium antimonide photovoltaic cells covered with spectrally selective infrared filters. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49710

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The National Aeronautics and Space Administration’s recently inaugurated New Millennium program, with its emphasis on miniaturized spacecraft, has generated interest in a low‐power (10‐ to 30‐watt), low‐mass, high‐efficiency RTPV power system. This led to a Department of Energy (DOE)‐sponsored design study by OSC (formerly Fairchild) personnel, who had previously conducted very encouraging studies of 75‐watt RTPV systems based on two 250‐watt General Purpose Heat Source (GPHS) modules. Since these modules were too large for the small RTPVs described in this paper, OSC generated derivative designs for 125‐watt and 62.5‐watt heat source modules. To minimize the need for new development and safety verification studies, these contained identical fuel pellets, clads, impact shell, and thermal insulation as the previously developed and safety‐qualified 250‐watt units. OSC also generated a novel heat source support scheme to reduce the heat losses through the structural supports, and a new and much simpler radiator structure, employing no honeycombs or heat pipes. OSC’s previous RTPV study had been based on the use of GaSb PV cells and spectrally selective Infra‐Red (IR) filters that had been partially developed and characterized by Boeing (now EDTEK) personnel. The present study was based on greatly improved selective filters developed and performance‐mapped by EDTEK under an OSC‐initiated subcontract. The paper describes illustrative small‐RTPV designs and analyzes their mass, size, power output, system efficiency, and specific power, and illustrates their integration with a miniaturized New Millennium spacecraft. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49711

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

This paper describes the conceptual design of a TPV system that uses a durable powder metal selective emitter surface and spectrally matched InGaAs PV cells. The materials and components have been selected to maximize output power density and system efficiency at an operating temperature of 1100 °C. The proposed generator offers several notable features including a high system efficiency, an inherent resistance to thermal shock and vibration, and an ability to use a variety of fuels interchangeably. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49712

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

This paper presents the results of an investigation to demonstrate thermophotovoltaic energy conversion using InGaAs photovoltaic cells, yttrium‐aluminum‐garnet‐ (YAG‐) based selective emitters, and bandpass/reflector filters, with the heat source operating at 1100 °C. InGaAs cells were grown on InP by organometallic vapor phase epitaxy with bandgaps of 0.60 and 0.75 eV and coupled to Ho‐, Er‐, and Er‐Tm‐doped YAG selective emitters. Infrared reflector and/or shortpass filters were also used to increase the ratio of in‐band to out‐of‐band radiation from the selective emitters. Efficiencies as high as 13.2% were recorded for filtered converters. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49680

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A natural gas fired thermophotovoltaic generator using infrared‐sensitive GaSb cells and a silicon carbide emitter is described. The emitter is designed to operate at 1400 °C. Twelve GaSb receivers surround the emitter. Each receiver contains a string of series connected cells. Special infrared filters are bonded to each cell. These filters transmit short wavelength useful IR to the cells while reflecting longer wavelength IR back to the emitter. Combustion air is supplied to the burner through a counterflow heat exchanger where the air is preheated by the exhaust from the burner. The unit is air cooled and designed to produce approximately 100 Watts of electric power. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49681

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have discovered that the flame from a single candle when surrounded by a bracelet‐sized ring of GaSb cells can provide enough power to operate a transistor radio. Spectral measurements of the flame show that a large fraction of the flame energy is in the infrared in a blackbody‐like emission band centered at 1.3 microns. GaSb cells capture infrared energy out to 1.7 microns, providing enough energy to power the radio. Traditional silicon solar cells only capture energy out to 1.1 microns and produce less than 30% of the power of GaSb cells, which is not enough to operate the radio. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49682

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A laboratory model of a TPV generator in the kilowatt range was developed and tested. It was based on methane/oxygen combustion and a spectrally matched selective emitter/collector pair (ytterbia emitter‐silicon PV cell). The system demonstrated a power output of 2.4 kilowatts at an overall efficiency of 4.5% without recuperation of heat from the exhaust gases. Key aspects of the effort include: 1) process development and fabrication of mechanically strong selective emitter ceramic textile materials; 2) design of a stirred reactor emitter/burner capable of handling up to 175,000 Btu/hr fuel flows; 3) support to the developer of the production silicon concentrator cells capable of withstanding TPV environments; 4) assessing the apparent temperature exponent of selective emitters; and 5) determining that the remaining generator efficiency improvements are readily defined combustion engineering problems that do not necessitate breakthrough technology. The fiber matrix selective emitter ceramic textile (felt) was fabricated by a relic process with the final heat‐treatment controlling the grain growth in the porous ceramic fiber matrix. This textile formed a cylindrical cavity for a stirred reactor. The ideal stirred reactor is characterized by constant temperature combustion resulting in a uniform reactor temperature. This results in a uniform radiant emission from the emitter. As a result of significant developments in the porous emitter matrix technology, a TPV generator burner/emitter was developed that produced kilowatts of radiant energy. ©1996 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.49683

出版商:AIP    

年代:1996

数据来源: AIP