A device for thermal energy harvesting can use pulsed heat.
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1. A device for thermal energy harvesting comprising: a heat source that generates pulsed heat, wherein the pulsed heat is periodic, intermittent or oscillating;a heat engine thermally connected to the heat source by a first thermal conduit; anda heat sink thermally connected to the heat engine by a
1. A device for thermal energy harvesting comprising: a heat source that generates pulsed heat, wherein the pulsed heat is periodic, intermittent or oscillating;a heat engine thermally connected to the heat source by a first thermal conduit; anda heat sink thermally connected to the heat engine by a second thermal conduit,wherein the first thermal conduit and the second thermal conduit are distinct; wherein the heat source configures to achieve pulsed heat transfer across the heat engine;wherein the heat engine converts the pulsed heat; andwherein the heat sink dissipates heat. 2. The device of claim 1, wherein the pulsed heat is produced by a pulsed heat flux from the heat source. 3. The device of claim 2, wherein the pulsed heat flux includes a system that produces periodic heat. 4. The device of claim 3, wherein the system includes a periodically burning gas heater. 5. The device of claim 2, wherein the pulsed heat flux includes an intermittently flowing heat transfer fluid. 6. The device of claim 2, wherein the pulsed heat flux includes an oscillating heat flux. 7. The device of claim 2, wherein when the pulsed heat flux is on, the rate of temperature change for the heat source varies. 8. The device of claim 7, wherein when the pulsed heat flux is on, the rate of temperature change for the heat source is defined as: dTSdtclosed=Qmscs-(TS-TR)REmscswherein closed means that the pulsed heat flux is on, Q is input power, ms is mass of the heat source, cs is specific heat of the heat source, TS is the temperature of the heat source, TR is the temperature of the heat sink, and RE is the thermal resistance of the heat engine. 9. The device of claim 2, wherein when the pulsed heat flux is off, the rate of temperature change for the heat source varies. 10. The device of claim 9, wherein when the pulsed heat flux is off, the rate of temperature change for the heat source is defined as: dTSdtopen=(TS-TR)REmscswherein open means that the pulsed heat flux is off, TS is the temperature of the heat source, TR is the temperature of the heat sink, RE is the thermal resistance of the heat engine, ms is the mass of the heat source, and Cs is the specific heat of the heat source. 11. The device of claim 2, wherein the rate of temperature change for the heat sink varies. 12. The device of claim 11, wherein the rate of temperature change for the heat sink is defined as: dTRdtopen/closed=(1-ηE)(TS-TR)REmRcR-(TR-T∞)RRmRcRwherein open means that the pulsed heat flux is off, closed means that the pulsed heat flux is on, ηE is heat engine efficiency, TS is the temperature of the heat source, TR is the temperature of the heat sink, RE is the thermal resistance of the heat engine, mR is the mass of the heat sink, cR is the specific heat of the heat source, T∞ is ambient temperature, and RR is the thermal resistances between the heat sink and ambient. 13. The device of claim 2, wherein increasing the bulk Fourier number of the heat sink improves energy conversion efficiency. 14. The device of claim 2, wherein a smaller bulk Fourier number of the heat sink is preferred to improve output power. 15. The device of claim 2, wherein phase lag is maximized at a low bulk Fourier number of the heat source. 16. The device of claim 2, wherein power and efficiency optimum is at: an intermediate bulk Fourier number of the heat source;heat source temperature close to maximum temperature; andsmall phase lag. 17. The device of claim 2, wherein both power and efficiency increase with increasing bulk Fourier number of the heat source until the bulk Fourier number of the heat source reaches 1. 18. The device of claim 2, wherein when the bulk Fourier number of the heat source is smaller than 1, energy storage ratio is smaller than 1, the heat flux is delivered as sharply declining pulse, and the heat flux is on, the rate of temperature change for the heat sink varies. 19. The device of claim 2, wherein when the bulk Fourier number of the heat source is smaller than 1, the energy storage ratio is smaller than 1, the heat flux is delivered as sharply declining pulse, and the heat flux is on, the rate of temperature change for the heat sink is defined as: dTRdtclosed=(1-)Tmax-TR(t)TEmRcR-TR(t)-T∞RRmRcR(=∫0tcα(1-TR(t)/Tmax)dttc)wherein closed means that the pulsed heat flux is on, TR is the temperature of the heat sink, ηE is heat engine efficiency, Tmax is maximum temperature, TR(t) is the temperature of the heat sink at different time, TE is the temperature of the heat engine, mR is the mass of the heat sink, cR is the specific heat of the heat source, T∞ is ambient temperature, RR is the thermal resistances between the heat sink and ambient, tc is time when the heat flux is on, and α is fraction of Carnot efficiency. 20. The device of claim 2, wherein when the bulk Fourier number of the heat source is smaller than 1, the energy storage ratio is smaller than 1, and the heat flux is delivered as sharply declining pulse, the temperature of the heat sink changes with time. 21. The device of claim 20, wherein when the bulk Fourier number of the heat source is smaller than 1, the energy storage ratio is smaller than 1, and the heat flux is delivered as sharply declining pulse, the temperature of the heat sink at different time is defined as: TR(t)=RET∞+RRTmax(1-)RE+RR(1-)+Ket(RE+RR(1-))mRcRRRRE(K=-etcmRcRRR(etomRcRRR-1)RR(T∞-Tmax)(1-)(etc+tomRcRRR-etc(1-)mRcRRE)(RR+RR(1-)))wherein TR(t) is the temperature of the heat sink at different time, RE is the thermal resistance of the heat engine, T∞ is ambient temperature, RR is the thermal resistances between the heat sink and ambient, Tmax is maximum temperature, ηE is heat engine efficiency, e is a constant, mR is the mass of the heat sink, cR is the specific heat of the heat source, tc is time when the heat flux is on, and to is time when the heat flux is off. 22. The device of claim 2, wherein when engine-sink thermal resistance ratio is smaller than 1, pulse mode surpasses steady-state performance in both power and efficiency. 23. The device of claim 1, wherein the heat source has a bulk Fourier number that is characteristic heating time scale for the heat source and the heat sink has a bulk Fourier number that is characteristic cooling time scale for the heat sink. 24. A device of claim 1, wherein the heat engine includes a thermoelectric generator. 25. A device of claim 1, wherein the device includes a thermal resistor between the heat source and the heat sink. 26. A device of claim 1, wherein the device includes a thermal resistor between the heat sink and ambient temperature blocks. 27. A device of a gas-fired chiller comprising the pulsed heat flux of a device for thermal energy harvesting comprising: a heat source that generates pulsed heat, wherein the pulsed heat is periodic, intermittent or oscillating;a heat engine thermally connected to the heat source by a first thermal conduit anda heat sink thermally connected to the heat engine by a second thermal conduit,wherein the pulsed heat is produced by a pulsed heat flux from the heat source; wherein the heat source configures to achieve pulsed heat transfer across the heat engine;wherein the heat engine converts the pulsed heat; andwherein the heat sink dissipates heat,and a combustor configured to be switched on an off. 28. A device of an energy converter comprising the pulsed heat flux of a device for thermal energy harvesting comprising: a heat source that generates pulsed heat, wherein the pulsed heat is periodic, intermittent or oscillating;a heat engine thermally connected to the heat source by a first thermal conduit anda heat sink thermally connected to the heat engine by a second thermal conduit,wherein the pulsed heat is produced by a pulsed heat flux from the heat source; wherein the heat source configures to achieve pulsed heat transfer across the heat engine;wherein the heat engine converts the pulsed heat andwherein the heat sink dissipates heat. 29. A device for thermal energy harvesting comprising: a heat source that generates pulsed heat, wherein the pulsed heat is periodic, intermittent or oscillating;a heat engine thermally connected to the heat source by a first thermal conduit; anda heat sink thermally connected to the heat engine by a second thermal conduit;wherein the heat source configures to achieve pulsed heat transfer across the heat engine, wherein the pulsed heat is produced by a pulsed heat flux from the heat source and the pulsed heat flux includes an intermittently flowing heat transfer fluid or an oscillating heat flux;wherein the heat engine converts the pulsed heat; andwherein the heat sink dissipates heat.
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이 특허에 인용된 특허 (3)
Buezis, James G.; Kemp, Stephen J., Fireplace insert thermally generating electrical power useful for operating a circulating fan.
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