Exergy analysis of evacuated tube solar collectors: a review

The most recent studies show that different methodologies have been adopted to understand the concept of Exergy in general and exergy efficiency, exergy destruction, exergy losses, etc. in particular. The present paper reviews the concept of evacuated tube solar water heating systems (SWHSs) followed by fundamental laws of thermodynamics necessary to provide the concept of exergy analysis in detail. Mathematical modelling and experimental data provide the effect of mass flow rate, temperature gradient, inlet temperature, outlet temperature, collector efficiency, etc. on exergy. Finally, the exergy analysis and exergetic efficiencies along with exergy destruction sources for the evacuated tube collectors are presented.