TPV Emitter Using Sodium Radiation and IR Heat Recycling
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Solution Overview
Problem
Thermophotovoltaic (TPV) generators face inefficiencies in converting heat energy to electricity due to the broad spectrum of radiation emitted by traditional emitters, which limits the percentage of heat energy that can be captured and converted by photovoltaic cells.
Innovation Solution
A novel TPV design employs a material that emits characteristic radiation, such as sodium, and utilizes selective infrared mirrors and a counterflow heat exchanger to reflect and reheat infrared radiation, optimizing the conversion of heat energy into light within a narrow wavelength band compatible with photovoltaic cells, thereby enhancing energy capture and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional broad-spectrum emitters are used in TPV generators, then the emitter can generate visible and infrared light via blackbody radiation, but the conversion efficiency of heat energy to electricity is limited due to the broad spectrum not matching PV cell bandgap
Solution Approach 1:
The emitter is designed to emit radiation with specific local spectral characteristics (narrow wavelength band) rather than broad-spectrum blackbody radiation. This localized spectral quality matches the PV cell bandgap, improving energy conversion efficiency by ensuring the emitted radiation is optimally absorbed by the photovoltaic cells.
Solution Approach 2:
The spectral parameters of the emitted radiation are changed from broad-spectrum blackbody radiation to narrow-band characteristic radiation. By controlling the temperature and composition of the emitter, the radiation spectrum is tuned to match the PV cell absorption characteristics, thereby improving conversion efficiency.
2Loss of energy
If selective infrared mirrors are added to reflect unabsorbed infrared radiation back to the combustion chamber, then heat energy recycling is improved, but the device complexity increases
Solution Approach 1:
Selective infrared mirrors are introduced as intermediary components between the combustion chamber and PV cells. These mirrors reflect unabsorbed infrared radiation back to the combustion chamber, enabling heat recycling without directly modifying the emitter or PV cells. The mirrors act as mediators to recover energy that would otherwise be lost.
3Use of energy by moving object
If a counterflow heat exchanger is implemented to preheat reactants using combustion product heat, then overall energy efficiency is improved, but the device complexity and space requirements increase
Solution Approach 1:
The counterflow heat exchanger enables continuous heat recovery from combustion products and transfer to incoming reactants. This continuous thermal energy recycling maintains high temperature in the combustion chamber without additional energy input, improving overall energy utilization efficiency by eliminating thermal energy losses.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly improves the conversion efficiency of heat energy to electricity by ensuring that a higher percentage of heat energy is converted into electricity, with the use of sodium emitting 25% of radiant energy as characteristic D-lines, and further enhances efficiency by recycling heat energy multiple times.
Implementation Method 1
the use of a material that emits characteristic radiation is one novel element of an embodiment of the invention (in an embodiment that material is sodium)... These lines are emitted when an electron in a sodium atom which had been excited from the 3s orbital to the 3p orbital (the excitation having been effected by the heat of combustion), relaxes back into its ground state.
Implementation Method 2
mirrors that selectively reflect light wavelengths that are poorly absorbed by the PV cells
Implementation Method 3
a counterflow heat exchanger that extracts heat from the outflowing combustion products and uses it to preheat the reactants
Implementation Method 4
directing that radiation to fall on an array of photovoltaic cells... which, in turn, generate electricity
Data Source
AI summary
An apparatus for generating electricity via thermophotovoltaic (TPV) energy conversion is described. High efficiency is obtained by introducing a material into a combustion chamber that emits bright near-monochromatic visible light upon heating. This light is then directed to fall on an array of photovoltaic (PV) cells which convert the light to electricity. Heat and infrared radiation that is not absorbed by the PV cells is returned to the combustion chamber to further improve conversion efficiency.