Page 63 - 9th Annual Research Report-web
P. 63

radiation.  In  addition,  the  issue  of  dust  accumulation  in  the  open  trough  configuration
               deteriorates the trough performance over time and therefore requires continues cleaning. The
               cleaning process is extremely complex owing to the profile of the trough and the presence of the
               receiving tube. This project investigates the performance of a novel trough design called Vacuum
               Parabolic Trough Collector (VPTC). The top side of the trough is covered by borosilicate sheets,
               the same material used for the outer tube of vacuum solar tubes. The trough is then sealed. This
               design is eliminating the drawbacks of the conventional trough collectors mentioned above in
               addition to minimizing the heat loss as a result of the wind gusting inside the trough. The cleaning
               issue is much easier since the VPTC will be covered by a flat borosilicate sheets for which a simple
               autonomous cleaning machine could be devised. The accumulated dust inside the tough can
               dramatically reduce the performance of system especially in Middle East region with the high
               occurrence of dusty days throughout the year. Work in this project will include building few VPTC
               troughs as well as convention troughs with vacuum focal tubes was compared in terms of their
               performances. In the first phase water was used as a heat transfer fluid, the new design parabolic
               trough collector showed a better performance than the conventional trough. In the second phase
               a mineral oil was used as a heat transfer fluid. Again, the new design parabolic trough showed a
               better performance than the conventional trough in term of the outlet temperature. During the
               third phase, a heat losses was carried out to compare both trough. The new design parabolic
               trough  showed  a  less  heat  losses  than  the  conventional  trough  because  the  new  trough
               represents a greenhouse effect since it is closed and sealed.

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