Multiple cylindrical inserts for parabolic trough solar collector

The use of insert flow is a promising technique for increasing the performance of parabolic trough solar collectors. The objective of this work is to investigate the use of multiple cylindrical longitudinal inserts in the parabolic trough solar collector LS-2 module. Totally 15 cases are investigated with a computational dynamic model developed in SolidWorks Flow Simulation. More specifically, the reference empty tube, one case with a single insert, eight cases with two inserts flow, three cases with three insert flow and two cases with four insert flow. It is found that the use of more inserts leads to higher thermal, exergy and overall efficiency performance of the collector. Moreover, it is found that the exact location of the inserts plays a significant role in the results. The pumping work is found to be generally low in all the cases, the fact that proves that the increase in the pressure drop is not so important in the total system performance. The global maximum efficiency is found for the case with the four inserts and in this case, the thermal efficiency is enhanced 0.656%, the thermal losses are reduced about 5.63% and the heat transfer coefficient is increased 26.88%. The results of this work can be used for the proper design of multiple inserts design in solar systems.