Thermophotovoltaic technology

Claim 2

A narrow band thermal emitter comprising a rare earth metal oxide radiator member characterized in that said radiator member has a cross-sectional dimension in the range of five - thirty micrometers and said radiator member, when heated to about 1700°C, has a concentrated radiated flux over the 400 - 2500 nanometer wavelength range 'such that at least 50% of said radiated flux is within a band less than 400 nanometers in width.

Claim 3

The emitter of claim 1 further characterized in that the spectral irradiance profile of said emitter has a narrow radiated flux peak, said flux peak having a full width at half maximum of less than four hundred nanometers and said spectral irradiance profile of said emitter also having suppressed skirt characteristics such that, at wavelengths five hundred nanometers above and below said flux peak, the radiated flux levels of the skirts are less than ten percent of the radiated flux at said peak.,

Claim 4

The emitter of claim 2 further characterized in that said flux peak has a full width at half maximum of less than two hundred nanometers and that said suppressed skirt characteristics are such that, at wavelengths in the range of three - five hundred nanometers above and below said flux peak, the radiated flux levels of said skirts are less than five percent of the radiated flux at said peak.

Claim 5

The emitter of any preceding claim further characterized in that said emitter is composed of " interlocked filaments.

Claim 6

The emitter of claim 4 further characterized in that said filaments are composed of at least ninety-five weight percent of a host metal oxide.

Claim 7

The emitter of either claim 4 or 5 further characterized in that said filaments further comprise a rare earth metal oxide dopant material other than said host metal oxide.

Claim 8

The emitter of claim 6 further characterized in that said rare earth metal oxide dopant material is ceria.

Claim 9

The emitter of any preceding claim further characterized in that said metal oxide is in the form of structure that has a cross-sectional dimension in the order of ten micrometers.

Claim 10

The emitter of any preceding claim further characterized in that said metal oxide structure includes at least one oxide of a metal selected from the class consisting of erbium, holmium, neodymium and ytterbium.

Claim 11

The emitter of any preceding claim further characterized in that said emitter is a rare earth metal oxide fiber mantle that defines a hollow space.

Claim 12

The emitter of claim 10 further characterized in that said metal oxide fiber mantle is self-supporting and has an integral portion that is shrink-supported on a support tube.

Claim 13

The emitter of any preceding claim further characterized in that said emitter comprises ytterbia in the amount of at least about ninety-nine weight percent.

Claim 14

A thermophotovoltaic device comprising a photocell, a rare earth metal oxide radiator disposed in optically coupled relation to said photocell, and means for thermally exciting said radiator to cause it to emit radiation, said radiator, when heated to 1700°C, emitting radiation in a spectral irradiance profile that has a narrow radiated flux peak that is located less than four hundred nanometers below the electron production threshold of said photocell, said flux peak having a full width at half maximum of less than fou hundred nanometers and said relative spectral irradiance profile of said radiator also having suppressed skirt characteristics such that, at wavelengths five hundred nanometers above and below said flux peak, the radiated flux levels of said skirts are less than ten percent of the radiated flux at said peak.

Claim 15

A thermophotovoltaic device comprising a photocell, a rare earth metal oxide radiator disposed in optically coupled relation to said photocell, and means for thermally exciting said radiator to cause it to emit radiation, said radiator, when heated to 1700°C, emitting radiation in a spectral irradiance profile that has a narrow radiated flux peak that is located less than four hundred nanometers below the electron production threshold of said photocell, said flux peak having a full width at half maximum of less than fou hundred nanometers and said relative spectral irradiance profile of said radiator also having suppressed skirt characteristics such that, at wavelengths five hundred nanometers above and below said flux peak, the radiated flux levels of said skirts are less than ten percent of the radiated flux at said peak.

Claim 16

The thermophotovoltaic device of claim 13 further characterized in that said device has a photon conversion efficiency of more than fifty percent.

Claim 17

The thermophotovoltaic device of either claim 13 or 14 further characterized in that said radiator is composed of multi-filament metal oxide strands that have a cross-sectional dimension in the range of 0.05 - 0.3 millimeter.

Claim 18

The thermophotovoltaic device of any of claims 13-15 further characterized in that said radiator is a mantle composed of metal oxide filaments, each said filament having a cross-sectional dimension in the range of five - thirty micrometers.

Claim 19

The thermophotovoltaic device of claim 16 further characterized in that said mantle has an overall length in the range of about 0.5 - 4.0 centimeters and a diameter in the range of about 0.5 - 2.0 centimeters.

Claim 20

1 8 . The thermophotovoltaic device of either claim 16 or 17 further characterized in that said mantle is shrink-supported on a fuel supply conduit.

Claim 21

The thermophotovoltaic device of any of claims 13-18 further characterized in that said radiator is composed of filaments of an oxide of ytterbium, each said filament having a cross-sectional dimension in the order of ten micrometers; and said photocell is of the silicon type.

Claim 22

The thermophotovoltaic device of any of claims 13-18 further characterized in that said radiator is composed of filaments of an oxide of erbium, each said filament having a cross-sectional dimension in the order of ten micrometers; and said photocell is of the germanium type.

Claim 23

The'thermophotovoltaic device of any of claims 13-20 further characterized by the provision of a reflector system for collecting and directing the radiated flux from said radiator to said photocell.

Claim 24

The thermophotovoltaic device of any of claims 13-21 further characterized by the provision of radiation transmitting thermal isolation means interposed between said radiator and said photocell.

Claim 25

The thermophotovoltaic device of any of claims 13-22 further characterized in that said radiator, when heated to 1700°C, emits radiation in a concentrated portion of the.400 - 2500 nanometer wavelength range such that at least 50% of the radiated flux is within a band less than 400 nanometers in width, said flux peak has a full width at half maximum of less than two hundred nanometers and said suppressed skirt characteristics are such that, at wavelengths n the range of three - five hundred nanometers above and below said flux peak, the radiated flux levels of tht. skirts are less than five percent of the radiated flux at said peak.

Claim 26

A thermophotovoltaic device comprising: a photovoltaic device, said photovoltaic device having an electron production threshold, a fuel supply, a fuel supply conduit connected to said fuel supply and having an outlet port, a metal oxide fiber mantle supported on said fuel supply conduit adjacent said outlet port, said photovoltaic device being in optically coupled relation to said mantle, a fuel control for controlling the flow of fuel to said mantle through said conduit, and an igniter mechanism for igniting said fuel to cause said mantle to emit radiation that has a wavelength peak below said electron production.- threshold, said peak having a full width at half maximum of less than 400 nanometers and said mantle, when heated to about 1700°C, having a concentrated radiated flux output over the 400 - 2500 nanometer wavelength range such that at least 50% of said radiated flux is within a band less than 400 nanometers in width.

Claim 27

A thermophotovoltaic device comprising: a photovoltaic device, said photovoltaic device having an electron production threshold, a fuel supply, a fuel supply conduit connected to said fuel supply and having an outlet port, a metal oxide fiber mantle supported on said fuel supply conduit adjacent said outlet port, said photovoltaic device being in optically coupled relation to said mantle, a fuel control for controlling the flow of fuel to said mantle through said conduit, and an igniter mechanism for igniting said fuel to cause said mantle to emit radiation that has a wavelength peak below said electron production.- threshold, said peak having a full width at half maximum of less than 400 nanometers and said mantle, when heated to about 1700°C, having a concentrated radiated flux output over the 400 - 2500 nanometer wavelength range such that at least 50% of said radiated flux is within a band less than 400 nanometers in width.

Claim 28

25 . The thermophotovoltaic device of claim 24 further characterized in that said fuel is a liquid or gaseous fuel such as hydrogen, natural gas, propane, butane, isobutane or gasoline..

Claim 29

The thermophotovoltaic device of either claim 24 or 25 further characterized in that said mantle is composed of interlocked metal oxide fibers, each said fiber having a cross-sectional dimension in the range of five - thirty micrometers.

Claim 30

The thermophotovoltaic device of claim 26 further characterized in that said fibers of said mantle are composed substantially entirely of the oxide of a host metal selected from the group of ytterbium and erbium.-

Claim 31

The thermophotovoltaic device of any of claims 24-27 and further characterized by the provision of a reflector system for collecting and directing the radiated flux from said mantle to said photovoltaic device.

Claim 32

The thermophotovoltaic device of any of claims 24-28 and further characterized by the provision of radiation transmitting thermal isolation means interposed between said mantle and said photovoltaic device.

Claim 33

The thermophotovoltaic device of any of claims 24-29 further characterized in that said mantle, when heated to 1700°C, emits radiation in a spectral irradiance profile that has a narrow radiated flux peak that is located less than four hundred nanometers below the electron production threshold of said photovoltaic device, said flux peak having a full width at half maximum of less than four hundred nanometers and said relative spectral irradiance profile of said tantle also having suppressed skirt characteristics such :hat, at wavelengths five hundred nanometers above and below said flux peak, the radiated flux levels of said skirts are less than ten.,percent of the radiated flux at said peak.

Claim 34

The thermophotovoltaic device of claim 30 further characterized in that said mantle, when heated to 1700°C, emits radiation in a concentrated portion of the 400 - 2500 nanometer wavelength range such that at . least 50% of the radiated flux is within a band less than 400 nanometers in width, said flux peak has a full width at half maximum of less than two hundred nanometers and said suppressed skirt characteristics are such that, at wavelengths in the range of three - five hundred nanometers above and below said flux peak, the radiated flux levels of said skirts are less than five percent of the radiated flux at said peak.

Claim 37

The method of claim 32 further characterized in that said metal oxide radiator material is in the form of structure that has a cross-sectional dimension in the range of five - thirty micrometers.

Claim 40

The method of claim 35 further characterized in that said radiator is composed of an oxide of ytterbium; and said photocell is of the silicon type.

Claim 41

The method of claim 35 further characterized in that said radiator is composed of an oxide of erbium; and said photocell is of the germanium type.