Airbridge cell for ultra-efficient photovoltaic conversion of thermal radiation

2021 ◽  
Author(s):  
Tobias Burger ◽  
Dejiu Fan ◽  
Sean McSherry ◽  
Byungjun Lee ◽  
Andrej Lenert ◽  
...  
Keyword(s):  
Thermal Radiation ◽  
Photovoltaic Conversion

High-Efficiency Thermophotovoltaic System by Quasi-Monochromatic Thermal Radiation

2014 ◽  
Author(s):  
Asaka Kohiyama ◽  
Makoto Shimizu ◽  
Hiroaki Kobayashi ◽  
Fumitada Iguchi ◽  
Hiroo Yugami
Keyword(s):  
Thermal Radiation ◽  
Conversion Efficiency ◽  
Spectral Response ◽  
Detailed Balance ◽  
Total Efficiency ◽  
Emitter Temperature ◽  
Selective Emitter ◽  
Photovoltaic Conversion ◽  
Spectrally Selective ◽  
Photovoltaic Conversion Efficiency

Efficiency of solar-thermophotovoltaic (TPV) systems can be improved by controlling spectral property of thermal radiation to match the photovoltaic (PV) cells spectral response. We developed a spectrally selective emitter which can emit quasi-monochromatic thermal radiation to improve the efficiency of TPV systems. From the evaluation by the detailed-balance model for gallium antimonite (GaSb) TPV cells, the photovoltaic conversion efficiency over 50 % is achievable in the case of the emitter temperature over 1800K and emitter Q-value over 15. The numerical simulation based on Rigorous-Coupled Wave Analysis revealed that the quasi-monochromatic thermal radiation can be obtained by closed-end microcavity structure. A solar-TPV system equipped with a solar-simulator is fabricated to evaluate the effect of spectrally selective emitter. By using GaSb TPV cells and spectrally selective emitter based on dielectric layer coating, photovoltaic conversion efficiency of 26% and total efficiency of 7.7% are obtained at emitter temperature of 1654 K under 384 suns.

Characterizing the convective heat exchange with plastic shading nets under natural arid conditions

2019 ◽  
pp. 11-20
Author(s):  
Ahmed M Abdel-Ghanya ◽  
Ibrahim M Al-Helal
Keyword(s):  
Wind Speed ◽  
Thermal Radiation ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Convective Heat Exchange ◽  
Radiative Properties ◽  
Wooden Frame ◽  
Arid Conditions ◽  
Air Temperatures ◽  
Radiation Fluxes

Plastic nets are extensively used for shading purposes in arid regions such as in the Arabian Peninsula. Quantifying the convection exchange with shading net and understanding the mechanisms (free, mixed and forced) of convection are essential for analyzing energy exchange with shading nets. Unlike solar and thermal radiation, the convective energy, convective heat transfer coefficient and the nature of convection have never been theoretically estimated or experimentally measured for plastic nets under arid conditions. In this study, the convected heat exchanges with different plastic nets were quantified based on an energy balance applied to the nets under outdoor natural conditions. Therefore, each net was tacked onto a wooden frame, fixed horizontally at 1.5-m height over the floor. The downward and upward solar and thermal radiation fluxes were measured below and above each net on sunny days; also the wind speed over the net, and the net and air temperatures were measured, simultaneously. Nets with different porosities, colors and texture structures were used for the study. The short and long wave’s radiative properties of the nets were pre-determined in previous studies to be used. Re and Gr numbers were determined and used to characterize the convection mechanism over each net. The results showed that forced and mixed convection are the dominant modes existing over the nets during most of the day and night times. The nature of convection over nets depends mainly on the wind speed, net-air temperature difference and texture shape of the net rather than its color and its porosity.

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