Thermal Efficiency of Double Pass Solar Collector with Longitudinal Fins Absorbers

Problem statement: One of the most important components of a solar energy system is the solar collector. The performances of double-pass solar collector with longitudinal fins absorbers are analyzed. Approach: The study involves a theoretical study to investigate the effect of mass flow rate, number and height of fins on efficiency, which involves steady-state energy balance equations on the longitudinal fins absorber of solar collectors. The theoretical solution procedure of the energy equations uses a matrix inversion method and making some algebraic rearrangements. Results: The collector efficiency increases as the number and height of fins increases. For a mass flow rate 0.02-0.1kg/s, the double-pass solar collectors are efficiency about 36-73% in upper fins (type I), 37-75% in lower fins (type II) and 46-74% in upper and lower fins (type III). Conclusion: The efficiency of the collector is strongly dependent on the flow rate, efficiency increase is about 35%.