Conventional and advanced exergy analysis of solar flat plate air collectors

In this study, conventional and advanced exergy analyses have been executed on a simple flat plate collector and a flat plate collector with thin metal sheet. Mathematical models have been designed using energy balance equations developed for each component. The results of the present work are well in agreement with those of previous researchers. The effects of Reynolds number, channel depth and radiation intensity on the exergy annihilation of each component and process were investigated by conventional exergy analysis. To execute the advanced exergy analysis, the thermodynamic process was modified by the authors to comply with the problem. Using these two analyses, the decision maker is provided with the ability to determine the source and amount of each exergy annihilation; therefore, a rather realistic measure is achieved to potentially improve the efficiency. The results of conventional analysis indicated that the absorber plate-sun exergy destruction has the largest portion among all annihilations while the exergy loss from insulation has the smallest. The results of advanced exergy analysis revealed that most of the exergy annihilation in the absorber plate is unavoidable and endogenous whereas in the glass cover, a large amount of the exergy destruction can be avoided.