Comparative Performance Analysis of Different Twisted Tape Inserts in the Absorber Tube of Parabolic Trough Collector

Comparative study on performance of different twisted tape inserts in the absorber tube of parabolic trough collector (PTC) are presented in this paper. The heat transfer equations for fully developed flow under quasi-steady state conditions have been developed in order to analyze the thermal characteristics and effect of operating parameters on system performance. The numerical simulations have been employed for five different twisted tape inserts with mass flow rate ranging from 0.06 kg/s to 0.16 kg/s. This study reveals, using of twisted tape insert has great promise for enhancing the performance of PTC. Results show that serrated twisted tape inserts with x= 2 yields the best performance among all inserts. The Nusselt number with serrated twisted tape insert (x=2) is found to be 3.56 and 3.19 times over plain absorber of PTC with mass flow rate of 0.06 kg/s and 0.16 kg/s respectively and the corresponding enhancement in thermal efficiency is 13.63 % and 5.41 % respectively. Also the exergy efficiency has been found to be 15.40 % and 16.46% and the corresponding enhancement factor is 1.12 and 1.05 respectively under conditions.