Browsing by Author "Van der Merwe, Philippus Carel"
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- ItemSolar air receiver using a non-uniform porous medium(Stellenbosch : Stellenbosch, 2016-03) Van der Merwe, Philippus Carel; Hoffmann, J. E.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: A receiver concept for a CSP plant employing a Brayton cycle solar thermal power plant was designed and tested experimentally. The receiver aims to mimic the greenhouse effect and comprises of an annular configuration, with a transparent outer tube and an opaque inner tube. A porous medium in the annular space serves to trap radiation and transfers heat to air flowing through it. The receiver concept may be integrated in any CSP plant exploiting the Brayton Cycle, such as the SUNSPOT system. The receiver will be situated between the compressor and combustor with the aim being to increase the air temperature before it runs through the combustion chamber. A linear mirror system was developed to concentrate the solar radiation in the receiver tube, while air was used as the heat transfer fluid. The temperature of the air was measured at the outlet of the tube in order to determine the efficiency of the receiver tube. The projects aims towards determining the radiation properties of the porous medium by means of three different ways. The first modelled developed, was that of an analytical Matlab model and the second being a simulated CFD model. These results were compared to the experimental tested results. The study concluded that the receiver achieved an efficiency of 41 % without being optimized, while reaching an average temperature increase in the system of up to 40 °C. The radiation properties of the porous medium can, however, not be determined by taking temperature measurements. A separate test result will have to be constructed to determine these properties. The concept proves to be very promising although it only achieved an efficiency of 41 %. The large heat transfer area between the air and the porous medium proves to be a major advantage.