A thermophotovoltaic electric generating system provides high thermal to electric conversion efficiency by use of matched radiation emitter and radiation collector. The radiation emitter comprises ceramic materials which emit thermally stimulated quantum radiation in at least two characteristic wavelength bands when heated above a threshold temperature. By employing a low emissivity ceramic doped with rare earth metal oxide, more than 50% of the radiation emitted from the surface can be concentrated in two or more characteristic wavelength bands. A multilayer photovoltaic device selectively absorbs the radiation at the characteristic wavelength bands for high electric conversion efficiency. An overlying layer of the photovoltaic collector selectively absorbs at least one of such characteristic wavelength bands and is transparent to another wavelength band which is absorbed by an underlying photovoltaic layer. Preferably the emitter is a porous fiber matrix surface combustion burner comprising primarily aluminum oxide, from 8 to 20% yttrium oxide, and a minor amount of rare earth metal oxide. A ceramic tube burner may be used in an embodiment with preheated air, the outside of the tube having such a thermally stimulated quantum emitter.
A thermophotovoltaic device includes at least one thermal radiator tube, a cooling tube concentrically disposed within each thermal radiator tube and an array of thermophotovoltaic cells disposed on the exterior surface of the cooling tube. A shell having a first end and a second end surrounds the thermal radiator tube. Inner and outer tubesheets, each having an aperture corresponding to each cooling tube, are located at each end of the shell. The thermal radiator tube extends within the shell between the inner tubesheets. The cooling tube extends within the shell through the corresponding apertures of the two inner tubesheets to the corresponding apertures of the two outer tubesheets. A plurality of the thermal radiator tubes can be arranged in a staggered or an in-line configuration within the shell.
An apparatus is provided for generating electrical energy. The apparatus consists of a housing; particularly, a housing having a spherical surface; a natural gas light for generating radiation capable of being converted to electrical energy; and a plurality of photovoltaic cells for converting the radiation by the natural gas light to electrical energy.
A combustion device for producing predetermined radiation spectral output and heat for a variety of applications including lighting, cooking, heating water, electric power generation, and providing inexpensive photons to enhance chemical and physical reactions. A process for the preparation of a porous ceramic burner is described which comprises drawing a solution which contains metal oxide fibers onto a burner skeleton by use of a vacuum to form a base fiber layer. The base fiber layer is dried, after which an additional metal oxide fiber layer, the outer fiber layer, is added over the base fiber layer. In another embodiment of the invention, an intermediate fiber layer is placed over the base layer, prior to the addition of the outer fiber layer. The porous ceramic burners prepared in accordance with the present invention comprise a base fiber layer having a low emissivity in the range of the aluminum oxide, gallium oxide, thorium oxide, yttrium oxide, erbium oxide and zirconium oxide, and an outer fiber layer which is thermally stimulated to emit radiation of a specific wavelength above a threshold temperature wherein the burner produces from about 30,000 to about 3,000,000 watts/m.sup.2 and less than 20 ppm of NOx. An intermediate fiber layer is used to bond the outer fiber layer to the base fiber layer where desired.
A thermophotovoltaic generator for use in generating electricity using a or liquid fueled light emitter and an absorber with photocells, is provided. This generator includes a burner and mantle light emitter, and includes a multi-layer absorber having cylindrical layers of peripherally spaced tube units, each unit having end wall photocells which form a chamber that contains a dye.
Multiple low bandgap GaSb photovoltaic cell strings are mounted around the perimeter of a cylinder in parallel with the cylinder axis. These cell strings face radially inward and receive infrared (IR) radiation from a ceramic axial emitter and efficiently convert this radiation into DC electric power. Linear reflectors are associated with each cell string and serve to concentrate IR energy into the photovoltaic cells or to return it to the emitter. The ceramic emitter is heated from the inside by hydrocarbon combustion. A uniform temperature along the length of the emitter is maintained by staged addition of fuel in a special burner design. Regenerative air heating is also inherent in the burner design increasing its efficiency. Air for the combustion is supplied by a blower. Sliding contacts to the rotating shaft on the blower can be used for DC to AC conversion. The cell strings are cooled through a compact closed cycle convective liquid cooling loop. The resultant unit is a compact, quiet, light weight DC or AC electric power source.
