In the present invention, we describe a simple ceramic gas burner for use in a cylindrical thermophotovoltaic generator in which the burner and IR emitter section consist of three concentric ceramic tubes, with the largest tube being the outer exhaust tube. Fuel and a small amount of primary air are injected from the bottom of the smallest tube and exit at the top of the infrared emitter section where they combine with secondary air coming down through a second ceramic tube with an intermediate diameter open at the bottom of the emitter section. Ignition is initiated at the bottom of this air injector tube. After ignition, combustion then moves up to the top of the fuel injector tube. The exhaust gases then pass down from the top of the emitter section inside the mid diameter tube to the bottom end of the emitter section and then back up between the mid diameter tube and the outer tube to the top of the emitter section. This double pass allows for both efficient heat transfer to the emitter and for a uniform heat transfer along the length of the emitter. This open ended tube design allows for a high conductance low pressure burner design using off-the-shelf ceramic tubing.
REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of U.S. patent application Ser. No. 08/047,477, filed, Apr. 19, 1993, now U.S. Pat. No. 5,383,976, which was a continuation-in-part of U.S. patent application Ser. No. 07/906,452, filed Jun. 30, 1992, now U.S. Pat. No. 5,312,521. These earlier applications and their listed references are incorporated herein by reference.
A thermophotovoltaic energy conversion device and a method for making the device. The device includes a substrate formed from a bulk single crystal material having a bandgap (E.sub.g) of 0.4 eV<E.sub.g <0.7 eV and an emitter fabricated on the substrate formed from one of a p-type or an n-type material. Another thermophotovoltaic energy conversion device includes a host substrate formed from a bulk single crystal material and lattice-matched ternary or quaternary III-V semiconductor active layers.
A mantle or emitter used to illuminate a photovoltaic cell. In one embodit, a tubular mantle or emitter is made of a composite structure including a rare-earth material, such as ytterbium oxide, covering a porous ceramic, such as alumina or zirconia, formed on a metal or ceramic support mesh. A hydrocarbon fuel-air mixture is forced into the mantle causing combustion and the rare-earth material to heat up to incandescent temperature, creating a highly radiant selective emitting surface. In another embodiment, a tubular burner-emitter having a mantle surrounded by an inner and outer glass tube permits the preheating of air used for combustion within a toroidal gap formed by the inner and outer glass tubes. In another embodiment, a tubular burner-emitter is used in combination with hinged photovoltaic cells or solar panels so that the photovoltaic cells can be positioned around the burner-emitter so that electromagnetic radiation from the burner-emitter causes the photovoltaic cells to create electrical energy. In another embodiment, a planar burner-emitter is used to illuminate a flat photovoltaic cell or panel. The present invention greatly enhances the efficiency and practicality of photovoltaic cells and permits electrical power to be generated continuously and independently of sunlight availability.
A thermophotovoltaic generator includes a stainless steel heat exchanger, a ceramic heat exchanger, a mixing chamber, a combustion chamber, an igniter, an infrared radiation emitter with counterflow, and an array of thermophotovoltaic cells surrounding the emitter and tube. The generator possesses both high conductance for the combustion gases and efficient heat transfer from the hot combustion gases to the emitter. The thermophotovoltaic cells have an IR response at least out to 1.7 microns and are fitted with simple dielectric filters. The emitter is an SiC spine disc emitter that is surrounded by at least one fused silica heat shield. Preferably, the thermophotovoltaic cells are GaSb cells, the infrared radiation emitter is a SiC blackbody emitter, and the dielectric filter is designed to transmit for wavelengths less than 1.7 microns and to reflect wavelengths between 1.7 and 4.0 microns. The filter can transmit again beyond 4.0 microns where the fused silica heat shields have suppressed the emitted energy.
A burner/emitter/recuperator assembly for providing a high temperature radiant emitting surface, includes an elongated fuel pipe in communication with a fuel source and extending toward the combustion chamber, and adapted to flow fuel from the fuel source to a nozzle end of the fuel pipe proximate the combustion chamber, a primary air pipe disposed around the fuel pipe and in communication with a relatively cool primary air source, a nozzle end of the primary air pipe being substantially coincident with the nozzle end of the fuel pipe, and a recuperator for preheating secondary air disposed around a distal portion of the primary air pipe and in communication with a secondary air source and a swirler downstream of the recuperator. The relatively cool air from the primary air source and fuel from the fuel source flow through the primary air pipe and the fuel pipe, respectively, and mix with the hot air from the recuperator and swirler, exterior to the fuel nozzle and the primary air pipe nozzle end, to maintain a relatively cool fuel pipe nozzle end, and a relatively hot flame in the combustion chamber.
A thermophotovoltaic power generating apparatus that heats an emitter by a combustion gas produced by fuel and air, and converts light radiated from the emitter into electric power by using photoelectric conversion elements. An air pipe is disposed in an internal hollow portion of the emitter, and a combustion gas supplier for supplying the combustion gas toward the emitter is disposed outside the emitter. The photoelectric conversion elements that receive radiated light are disposed further outside of the emitter. Therefore, residual heat of the combustion gas that has heated the emitter is utilized to heat the air needed for the combustion of fuel, and light radiated from the heated emitter is received by the photoelectric conversion elements. Thus, electric power generating efficiency can be improved.
