Energy and exergy analysis of different solar air collector systems with natural convection

In this research work, mathematical models are presented for single and two-glass cover solar air collector systems with natural convection flow. These models are based on an analytical solution of energy balance equations for various elements of collectors. The results obtained from the present work and the experimental results of other researchers are in good agreement. The effects of a tin metal sheet suspended in the middle of the air channel, longitudinal fins with rectangular and triangular shapes, and depth and length variations of the channel on energy and exergy efficiencies of solar air collectors are also investigated. The results show that the collector with two-glass covers has a better performance than a single-glass collector, and it is analytically preferred by the first and second laws of thermodynamics. The results also illustrate that the collectors with triangular fins are more efficient in terms of energy than those with rectangular fins. (C) 2014 Elsevier Ltd. All rights reserved.