The objective of this work is to evaluate energetically and exergetically the use of internal longitudinal fins in parabolic trough collectors operating with air. Nine different finned absorbers are compared with the smooth absorber for various inlet temperatures up to 500℃. More specifically, the use of 4, 8, and 16 fins with lengths 5 mm, 10 mm, and 15 mm are examined. The simulation tool is Solidworks Flow Simulation and the examined parabolic trough collector is the Eurotrough module. According to the final results, the global maximum exergetic efficiency is 43.65% and it is achieved for 4 fins with 15 mm length, while the inlet temperature of the air is equal to 350℃ and the thermal efficiency is 67.98%. Moreover, in the cases of 8 and 16 fins, the optimum lengths exergetically are 10 mm and 5 mm respectively, a fact that proves the reverse relationship between the number of fins and the fin length. Finally, it is also important to be stated that greater number of fins and higher fin length not only lead to higher thermal performance but also to higher pressure losses; two factors are taken into consideration in the exergetic performance, which is the main evaluation index of this study.
An energy flow simulation tool for incorporating short-term PV forecasting in a diesel-PV-battery off-grid power supply system
