A ray tracer model for analysis of solar concentrating systems
Keywords:
reflectors; receivers; flat mirror tiles; smooth mirror surfaces; interception ratioAbstract
This study describes a 3D ray tracer model for analysis of a small-scale solar concentrating system where thermal heat is collected for cooking purposes. Emitted sun rays were traced from the source through all reflections until they intercepted with the receiver or were lost. The algorithm of the ray tracer and its implementation in MATLAB is clearly described. The ray tracer was programmed to contribute to the development of small-scale concentrating solar energy systems with integrated heat storage units. The ray tracer was demonstrated for selected cases where continuous reflecting surfaces and flat mirror-tiled surfaces were compared. Off-focus sensitivity analysis was shown and this could provide guidelines for the required solar tracking accuracy. The flux distribution on the absorber was analysed and found to be concentrated on a small area on the target for continuous reflecting surfaces and having high intensities. However, for reflectors with mirror tiles, an elongated image was formed centred on the focal point with low intensities. Small misalignment of the reflector in the order 0.2° had minimal impact on the interception ratio, but any further increase in the tracking errors caused a sudden drop in the interception ratio to zero. Results showed that there is close agreement in flux distribution and the tracking error impact on interception ratio, when compared with the literature. This model could be a useful tool when designing the reflection and absorption components of solar concentrators for complex systems with several components in a non-symmetric 3D arrangement.
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Okello D., Foong C.W., Nydal O.J. and Banda E.J.K.B. 2014. An experimental investigation on the combined use of phase change material and rock particles for high temperature (≈350° C) heat stor-age. Energy Conversion and Management 79: 1-8.
https://doi.org/10.1016/j.enconman.2013.11.039
Heetkamp van den R.R.J. 2002. The development of small solar concentrating systems with heat stor-age for rural food preparation. Physica Scripta T97 2002: 99-106.
Nyeinga K., Nydal O.J., Okello D. and Banda E.J.K.B. 2016. Dynamic model of a small scale con-centrating solar cooker with rock bed heat storage. Journal of Energy in Southern Africa 27(1): 20-27.
https://doi.org/10.17159/2413-3051/2016/v27i1a1563
Okello D., Nydal O.J., Nyeinga K. and Banda E.J.K.B. 2016. Experimental investigation on heat extraction from a rock bed heat storage system for high temperature applications. Journal of Energy in Southern Africa 27(2): 30-37.
https://doi.org/10.17159/2413-3051/2016/v27i2a1339
Nyeinga K., Okello D. and Tabu B. 2017. Experimental investigation of thermal perfomance for selected oils for solar thermal energy storage and rural cooking application. Proceedings of SWC 2017 / SHC 2017 / ISES Solar World Congress, Abu Dhabi, UAE, 29 October – 3 November 2017.
https://doi.org/10.18086/swc.2017.14.05
Lugolole R., Mawire A., Lentswe K.A., Okello D. and Nyeinga K 2018. Performance comparison of three sunflower oil based sensible heat thermal en-ergy storage systems during charging cycles. Jour-nal for Sustainable Energy Technologies and As-sessment 30: 37-51. https://doi.org/10.1016/j.seta.2018.09.002
Mawire A. 2016. Performance of Sunflower oil as a sensible heat storage medium for domestic applica-tions. Journal of Energy Storage 5: 1-9. https://doi.org/10.1016/j.est.2015.11.002
Kanyarusoke K.E., Gryzagoridis J. and Oliver G. 2015. Are solar tracking technologies feasible for domestic applications in rural tropical Africa? Jour-nal of Energy in Southern Africa 26(1): 86-95. https://doi.org/10.17159/2413-3051/2015/v26i1a2224
Chikukwa A. and Lovseth J. 2009. Modeling of a novel volumetric absorber, suitable for compact so-lar concentrator with rock storage. Proceedings of ISES Solar World Congress, Johannesburg, 12-14 October 2009.
Dufie J.A. and Beckman W.A. 2006. Solar Engi-neering of Thermal Processes, third edition. John Wiley and Sons, Inc., Hoboken, New Jersey.
Mawire A., Abigail Phori A. and Taole S. 2014. Performance comparison of thermal energy storage oils for solar cookers during charging. Applied Thermal Engineering 73(1): 1323-1331.
https://doi.org/10.1016/j.applthermaleng.2014.08.032
Mobarak A. and Rahim A. A. 1990. Determination of focal flux distribution of a parabolic dish solar concentrator applying real shape. 12th Annual In-ternational Solar Energy Conference, ASME, 79-86.
Seron F.J., Gutierrez D., Gutierrez G. and Cerezo E. 2005. Implementation of a method of curved ray tracing for inhomogeneous atmospheres. Comput-ers & Graphics 29: 95-108.
Ratzel A.C. and Boughton B.D. 1987. A computer code for analysis of point-focus concentrators with flat targets. SAND86-1866, Sandia National Labor-atories, Albuquerque, NM.
Nyeinga K., Banda E.J.K.B. and Nydal O.J. 2011. Ray tracer for analysis of solar concentrating sys-tems. Proceedings of Solar World Congress 2011 Kassel, Germany, 28 August – 2 September 2011.
https://doi.org/10.18086/swc.2011.25.22
Yan J., Cheng Z. and Peng Y. 2018. Effect of track-ing error of double-axis tracking device on the opti-cal performance of solar dish concentrator. Interna-tional Journal of Photoenergy 2018: 1-13.
https://doi.org/10.1155/2018/9046127
Ruelas J., Pando G., Lucero B. and Tzab J. 2014. Ray tracing study to determine the characteristics of the solar image in the receiver for a Scheffler-type solar concentrator coupled with a Stirling engine. Energy Procedia 57: 2858-2866.
https://doi.org/10.1016/j.egypro.2014.10.319
Spencer G.H. and Murty M.V.R.K. 1982. General ray-tracing procedure. Journal of the Optical Socie-ty of America 52: 630-678.
Te-Tan L. 2009. A skew ray tracing approach for the error analysis of optical elements with parabo-loidal boundary surfaces. Optik 120: 873-885.
Leutz R. and Annen H.P. 2007. Reverse ray-tracing model for the performance evaluation of stationary solar concentrators. Solar Energy 81: 761-767.
https://doi.org/10.1016/j.solener.2006.10.006
Chena C.F., Lina C.H. and Jan H.T. 2010. A solar concentrator with two reflection mirrors designed by using a ray-tracing method. Optik 121: 1042-1051.
https://doi.org/10.1016/j.ijleo.2008.12.010
Madessa H.B., Foong C. W. and Nydal O.J. 2011. Ray tracing for analysing transportation of concen-trated sun rays through a channel. Proceedings of ASES National Solar Conference 2011, Raleigh, North Carolina, USA, 17-21 May 2011.
Nydal O.J and Tesfay A. 2015. Ray tracing for eval-uation of the SK14 solar concentrator as a solar fry-er. Conference Proceedings, ISES Solar World Congress, Daegu, Korea, 8 – 12 November 2015.
Foong C.W., Nydal O.J., and Lovesth J. 2011. In-vestigation of a small-scale double reflector solar concentrating system with high temperature heat storage. Applied Thermal Engineering 31: 1801-1815.
https://doi.org/10.1016/j.applthermaleng.2011.02.026
Van Rooyen D.W., Heimsath A., Nitz P., and Platzer W. 2011. An optical model of the fix-focus Scheffler reflector. Proceedings of Solar World Congress, Kassel-Germany, 28 August – 2 September 2011.
https://doi.org/10.18086/swc.2011.28.30
Nydal O.J. 2014. Ray tracing for optimisation of a double reflector system for direct illumination of a heat storage. Energy Procedia 57: 2211-2220.
https://doi.org/10.1016/j.egypro.2014.10.188
Groulx D. and Sponagle B. 2010. Ray-tracing anal-ysis of a two-stage solar concentrator. Transactions of the Canadian Society for Mechanical Engineer-ing 34(2): 263-279. .
https://doi.org/10.1139/tcsme-2010-0016
Madessa H.B., Veslum T., Lovseth J. and Nydal O.J. 2011. Investigation of solar absorber for small-scale solar concentrating parabolic dish. Proceed-ings of Solar World Congress, Kassel-Germany, 28 August – 2 September 2011.
https://doi.org/10.18086/swc.2011.19.23
Wendelin T. 2003. SolTRACE: A new optical mod-elling tool for concentrating solar optics. Proceed-ings of the International Solar Energy Conference, 15-18 March 2003, Kohala Coast, Hawaii. New York, 253-260.
Radu A.A. and Mattox J. 1999. Ray tracing simula-tions for a modified compound parabolic concen-trator to be considered for the veritas project. Astro-particle Physics 11: 275-276.
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Copyright (c) 2019 Karidewa Nyeinga, Denis Okello, Ole Jorgen Nydal
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