Performance of a parabolic trough solar collector

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dc.contributor.advisorHarms, T. M.
dc.contributor.authorBrooks, Michael Johnen_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
dc.date.accessioned2008-07-01T08:18:02Zen_ZA
dc.date.accessioned2010-06-01T08:34:10Z
dc.date.available2008-07-01T08:18:02Zen_ZA
dc.date.available2010-06-01T08:34:10Z
dc.date.issued2005-03en_ZA
dc.descriptionThesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005.
dc.description.abstractParabolic trough solar collectors (PTSCs) constitute a proven source of thermal energy for industrial process heat and power generation, although their implementation has been strongly influenced by economics. In recent years, environmental concerns and other geopolitical factors have focused attention on renewable energy resources, improving the prospects for PTSC deployment. Further work is needed to improve system efficiencies and active areas of research include development of advanced heat collecting elements and working fluids, optimisation of collector structures, thermal storage and direct steam generation (DSG). A parabolic trough collector, similar in size to smaller-scale commercial modules, has been developed locally for use in an ongoing PTSC research programme. The aim of this study was to test and fully characterise the performance of the collector. Specialised logging software was developed to record test data and monitor PTSC performance in real-time. Two heat collecting elements were tested with the collector, one unshielded and the other with an evacuated glass cover. Testing was carried out according to the ASHRAE 93-1986 (RA 91) standard, yielding results for the thermal efficiency, collector acceptance angle, incidence angle modifier and collector time constant. Peak thermal efficiency was 55.2 % with the unshielded receiver and 53.8 % with the glass-shielded unit. The evacuated glass shield offered superior performance overall, reducing the receiver heat loss coefficient by 50.2 % at maximum test temperature. The collector time constant was less than 30 s for both receivers, indicating low thermal inertia. Thermal loss tests were conducted and performance of the trough’s tracking system was evaluated. The measured acceptance angles of 0.43° (unshielded) and 0.52° (shielded) both exceeded the tracking accuracy of the PTSC, ensuring that the collector operated within 2 % of its optimal efficiency at all times. Additionally, experimental results were compared with a finite-volume thermal model, which showed potential for predicting trough performance under forced convection conditions.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/1821
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectDissertations -- Mechanical engineeringen
dc.subjectTheses -- Mechanical engineeringen
dc.subjectParabolic troughsen
dc.subjectSolar collectorsen
dc.subject.otherMechanical and Mechatronic Engineeringen_ZA
dc.titlePerformance of a parabolic trough solar collectoren_ZA
dc.typeThesisen_ZA
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