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Numerical analysis on using compound parabolic couplers for direct transmission of concentrated solar radiation via optical fibre (Conference Presentation)
Author(s): Maryam Rahou; John Andrews; Gary Rosengarten
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Paper Abstract

A challenge in high-temperature solar thermal applications is transfer of concentrated solar radiation to the load with minimum energy loss. The use of a solar concentrator in conjunction with optical fibres has potential advantages in terms of transmission efficiency, technical feasibility and cost-effectiveness compared to a conventional heat transfer system employing heat exchangers and a heat transfer fluid. For transferring higher levels of concentrated flux it is necessary to employ multiple optical fibres or fibre bundles. However, the losses at the incident plane of a bundle due to absorption by the epoxy and cladding between the individual fibres in a bundle are substantial, typically over 60% of the overall transmission loss. The optical transmission of the system can thus be enhanced by employing a coupler between the concentrated solar radiation and the entrance to the bundle that reflects all incident light into the cores of individual fibres rather than allowing it to strike the interstitial spaces between the cores. This paper describes the design for such couplers based on multiple compound parabolic (CP) reflectors each with its exit aperture coinciding with the core of an individual fibre within the bundle. The proposed design employs external reflection from a machined metallic aluminium surface. This CP arrangement has the additional benefit of increasing the concentration ratio of the primary solar concentrator used. Simulation modeling using LightTools is conducted into a parabolic Cassegrain solar concentrator employing these CP couplers prior to a fibre bundle. The dependence of overall transmission and total optical efficiency of the system over lengths of the bundle up to 100 m are investigated quantitatively. In addition, the influence on transmission of the angular distribution of radiation intensity at the aperture of the couplers is studied.

Paper Details

Date Published: 2 November 2016
PDF: 1 pages
Proc. SPIE 9955, Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XIII—Commemorating the 50th Anniversary of Nonimaging Optics, 99550L (2 November 2016); doi: 10.1117/12.2237416
Show Author Affiliations
Maryam Rahou, RMIT Univ. (Australia)
John Andrews, RMIT Univ. (Australia)
Gary Rosengarten, RMIT Univ. (Australia)


Published in SPIE Proceedings Vol. 9955:
Nonimaging Optics: Efficient Design for Illumination and Solar Concentration XIII—Commemorating the 50th Anniversary of Nonimaging Optics
Roland Winston; Jeffrey M. Gordon, Editor(s)

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