Application of nanofluid flow in entropy generation and thermal performance analysis of parabolic trough solar collector: experimental and numerical study

This study investigates numerically and experimentally the flow and heat transfer characteristics of ZnO/EG-H2O nanofluid flow in a parabolic trough solar collector at different flow rates (between 20 lit h(-1) and 80 lit h(-1)) and nanoparticle volume fractions (phi = 1%, 2%, 3%, 4%). The effects of changes in parameters such as absorbed and heat loss parameters, collector efficiency, useful energy, and temperature differences between outlet and inlet have been investigated in the context of experimental results. To obtain meaningful results in the numerical study, a non-uniform heat flux distribution on the collector absorber has been generated by the Monte Carlo Ray Tracing method (MCRT) using the commercial code SOLTRACE. Friction factor, entropy generation, PEC number, Nusselt number, and Bejan number are the parameters studied. The ZnO/EG-H2O nanofluid significantly improves the efficiency of the collector, based on the findings obtained. The highest usable energy has been obtained at the flow rate of 80 lit h(-1) with 4% ZnO/EG-H2O nanofluid. The results suggest that the temperature differential rises when ZnO/H2O has been used compared to EG-H2O. Moreover, when ZnO/EG-H2O is used with the flow rate of 80 lit h(-1) and a volume fraction of 4% of nanoparticles, the Nusselt number increases by about 100% compared to EG-H2O as the working fluid. There is a negligible increase in the overall entropy production when ZnO/EG-H2O is utilized as opposed to the base fluid. Thus, the greatest possible nf may be suggested for parabolic trough solar collector. The goal of this study is to use the findings of ZnO/EG-H2O nanofluid research to parabolic trough solar collectors. The experimental data show that compared to traditional fluid, utilizing nanofluid results in significantly improved thermal performance. In this situation, it seems that nanofluid would be the best option.