Thermodynamic optimisation of the integrated design of a small‐scale solar thermal Brayton cycle

Show simple item record Le Roux, Willem Gabriel Bello-Ochende, Tunde Meyer, Josua P. 2012-12-13T11:28:12Z 2013-09-30T00:20:04Z 2012-09
dc.description.abstract The Brayton cycle’s heat source does not need to be from combustion but can be extracted from solar energy. When a black cavity receiver is mounted at the focus of a parabolic dish concentrator, the reflected light is absorbed and converted into a heat source. The second law of thermodynamics and entropy generation minimisation are applied to optimise the geometries of the recuperator and receiver. The irreversibilities in the recuperative solar thermal Brayton cycle are mainly due to heat transfer across a finite temperature difference and fluid friction. In a small‐scale open and direct solar thermal Brayton cycle with a micro‐turbine operating at its highest compressor efficiency, the geometries of a cavity receiver and counterflow‐plated recuperator can be optimised in such a way that the system produces maximum net power output. A modified cavity receiver is used in the analysis, and parabolic dish concentrator diameters of 6 to 18m are considered. Two cavity construction methods are compared. Results show that the maximum thermal efficiency of the system is a function of the solar concentrator diameter and choice of micro‐turbine. The optimum receiver tube diameter is relatively large when compared with the receiver size. The optimum recuperator channel aspect ratio for the highest maximum net power output of a micro‐turbine is a linear function of the system mass flow rate for a constant recuperator height. For a system operating at a relatively small mass flow rate, with a specific concentrator size, the optimum recuperator length is small. For the systems with the highest maximum net power output, the irreversibilities are spread throughout the system in such a way that the internal irreversibility rate is almost three times the external irreversibility rate. en_US
dc.description.uri en_US
dc.identifier.citation Le Roux, WG, Bello-Ochende, T & Meyer, JP 2012, 'Thermodynamic optimisation of the integrated design of a small‐scale solar thermal Brayton cycle', International Journal of Energy Research, vol. 36, no. 11, pp. 1088-1104. en_US
dc.identifier.issn 0363-907X (print)
dc.identifier.issn 1099-114X (online)
dc.identifier.other 10.1002/er.1859
dc.language.iso en en_US
dc.publisher Wiley-Blackwell en_US
dc.rights © 2011 John Wiley & Sons, Ltd. The definite version is available at en_US
dc.subject Brayton en_US
dc.subject Solar en_US
dc.subject Entropy en_US
dc.subject Minimisation en_US
dc.subject Receiver en_US
dc.subject Recuperator en_US
dc.title Thermodynamic optimisation of the integrated design of a small‐scale solar thermal Brayton cycle en_US
dc.type Postprint Article en_US

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