Optical cavity for improved performance of solar receivers in solar-thermal systems
A principal loss mechanism for solar receivers in solar-thermal systems is radiation from the absorbing surface. This loss can be reduced by using the concept of directional selectivity in which radiation is suppressed at angles larger than the incident angle of the sunlight striking the absorber. D...
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| Format: | Article |
| Language: | en_US |
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Elsevier
2016
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| Online Access: | http://hdl.handle.net/1721.1/104836 https://orcid.org/0000-0001-8917-7547 https://orcid.org/0000-0002-3968-8530 |
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| author | Weinstein, Lee Adragon Kraemer, Daniel McEnaney, Kenneth Chen, Gang |
| author2 | Massachusetts Institute of Technology. Department of Mechanical Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Mechanical Engineering Weinstein, Lee Adragon Kraemer, Daniel McEnaney, Kenneth Chen, Gang |
| author_sort | Weinstein, Lee Adragon |
| collection | MIT |
| description | A principal loss mechanism for solar receivers in solar-thermal systems is radiation from the absorbing surface. This loss can be reduced by using the concept of directional selectivity in which radiation is suppressed at angles larger than the incident angle of the sunlight striking the absorber. Directional selectivity can achieve efficiencies similar to high solar concentration, without the drawbacks associated with large heat fluxes. A specularly reflective hemispherical cavity placed over the absorber can reflect emitted radiation back to the absorber, effectively suppressing emission losses. An aperture in the cavity will still allow sunlight to reach the absorber surface when used with point focus concentrating systems. In this paper the reduction in radiative losses through the use of a hemispherical cavity is predicted using ray tracing simulations, and the effects of cavity size and absorber alignment are investigated. Simulated results are validated with proof of concept experiments that show reductions in radiative losses of more than 75% from a near blackbody absorber surface. The demonstrated cavity system is shown to be capable of achieving receiver efficiencies comparable to idealized spectrally selective absorbers across a wide range of operating temperatures. |
| first_indexed | 2024-09-23T12:54:24Z |
| format | Article |
| id | mit-1721.1/104836 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T12:54:24Z |
| publishDate | 2016 |
| publisher | Elsevier |
| record_format | dspace |
| spelling | mit-1721.1/1048362022-10-01T11:49:32Z Optical cavity for improved performance of solar receivers in solar-thermal systems Weinstein, Lee Adragon Kraemer, Daniel McEnaney, Kenneth Chen, Gang Massachusetts Institute of Technology. Department of Mechanical Engineering Chen, Gang Weinstein, Lee Adragon Kraemer, Daniel McEnaney, Kenneth Chen, Gang A principal loss mechanism for solar receivers in solar-thermal systems is radiation from the absorbing surface. This loss can be reduced by using the concept of directional selectivity in which radiation is suppressed at angles larger than the incident angle of the sunlight striking the absorber. Directional selectivity can achieve efficiencies similar to high solar concentration, without the drawbacks associated with large heat fluxes. A specularly reflective hemispherical cavity placed over the absorber can reflect emitted radiation back to the absorber, effectively suppressing emission losses. An aperture in the cavity will still allow sunlight to reach the absorber surface when used with point focus concentrating systems. In this paper the reduction in radiative losses through the use of a hemispherical cavity is predicted using ray tracing simulations, and the effects of cavity size and absorber alignment are investigated. Simulated results are validated with proof of concept experiments that show reductions in radiative losses of more than 75% from a near blackbody absorber surface. The demonstrated cavity system is shown to be capable of achieving receiver efficiencies comparable to idealized spectrally selective absorbers across a wide range of operating temperatures. United States. Dept. of Energy (“Concentrated Solar Thermoelectric Power”, a DOE SunShot CSP Grant, under award number DE-EE0005806) 2016-10-14T18:44:42Z 2016-10-14T18:44:42Z 2014-07 2014-06 Article http://purl.org/eprint/type/JournalArticle 0038092X http://hdl.handle.net/1721.1/104836 Weinstein, Lee, Daniel Kraemer, Kenneth McEnaney, and Gang Chen. “Optical Cavity for Improved Performance of Solar Receivers in Solar-Thermal Systems.” Solar Energy 108 (October 2014): 69–79. https://orcid.org/0000-0001-8917-7547 https://orcid.org/0000-0002-3968-8530 en_US http://dx.doi.org/10.1016/j.solener.2014.06.023 Solar Energy Creative Commons Attribution-NonCommercial-NoDerivs License http://creativecommons.org/licenses/by-nc-nd/4.0/ application/pdf Elsevier Prof. Gang Chen |
| spellingShingle | Weinstein, Lee Adragon Kraemer, Daniel McEnaney, Kenneth Chen, Gang Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title | Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title_full | Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title_fullStr | Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title_full_unstemmed | Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title_short | Optical cavity for improved performance of solar receivers in solar-thermal systems |
| title_sort | optical cavity for improved performance of solar receivers in solar thermal systems |
| url | http://hdl.handle.net/1721.1/104836 https://orcid.org/0000-0001-8917-7547 https://orcid.org/0000-0002-3968-8530 |
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