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The energy and exergy performance of a parabolic dish collector is investigated experimentally and theoretically. The e ect of receiver type, inlet temperature and mass ow rate of heat transfer uid (HTF), receiver temperature, receiver aspect ratio and solar radiation are investigated. To evaluate the e ect of the receiver aperture area on the system performance, three aperture diameters are considered. It is deduced that the fully opened receivers have the greatest exergy and thermal e ciency. The cylindrical receiver has greater energy and exergy e ciency than the conical one due to less exergy destruction. It is found that the highest exergy destruction is due to heat transfer between the sun and the receivers and counts for 35 % to 60 % of the total wasted exergy. For three selected receiver aperture diameters, the exergy e ciency is minimum for a speci ed HTF mass ow rate. High solar radiation allows the system to work at higher HTF inlet temperatures. To use this system in applications that need high temperatures, in cylindrical and conical receivers, the HTF mass ow rates lower than 0.05 and 0.09 kg/s are suggested, respectively. For applications that need higher amounts of energy content, higher HTF mass ow rates than the above mentioned values are recommended.

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The removal of xylene vapors was studied in a biofilter packed with a new hybrid (scoria/compost) packing material at various inlet loads (IL) and empty bed residence times (EBRT) of 90, 60, and 40s. The best performance was observed for EBRT of 90s, where a removal efficiency of 98% was obtained under steady state condition for inlet xylene concentration of 1.34 g m−3, while a maximum elimination capacity of 97.5 g m−3 h−1 was observed for IL of 199.5 g m−3 h−1. Carbon dioxide production rates and the microbial counts for xylene-degraders followed xylene elimination capacities. Overall look to the results of this study indicates that the scoria/compost mixture could be considered as a potential biofilter carrier, with low pressure drop (here <4 mm H2O), to treat air streams containing VOCs.

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