Exergetic, Energetic, and entropy production evaluations of parabolic trough collector retrofitted with elliptical dimpled receiver tube filled with hybrid nanofluid

In this paper, a numerical study was performed on a parabolic trough collector receiver tube containing elliptical dimpled fins with different elliptical ratios (ER = 0.66-1.66) under turbulent flow regime. The C++ code was developed to perform a non-uniform heat flux on outside of the receiver tube to get approximation real working conditions. Different mono and hybrid nanofluids and their combinations with different nanoparticle volume fractions (2.0 %TiO2/Syltherm800, 2.0 %Al2O3/Syltherm800, 0.5 %TiO2-1.5 %Al2O3/Syltherm800, 1.0 %TiO2-1.0 %Al2O3/Syltherm800, and 1.5 %TiO2-0.5 %Al2O3/Syltherm800) were used as a working fluid. The study provides a detailed analysis of the hydro-thermal characteristics, exergetic, and entropy production of the parabolic trough collector. 1.5 %Al2O3-0.5 %TiO2/Syltherm800 hybrid nanofluid shows the best increase in results obtained in this study using elliptical ratio of a/b = 5/3. The use of the elliptical ratio of a/b = 5/3, the average Nusselt number increases with 38 % compared to the receiver tube without elliptical dimpled fin. Total entropy generation was reduced up to 16.82 % for the elliptical ratio of a/b = 5/3. With the inserting elliptical dimpled fins of a/b = 5/3, the Performance Evaluation Criterion was detected as 1.81 compared to while the thermal efficiency increases from 74 % to 80 % at the lowest Reynolds numbers.

Automated summary

A numerical study was conducted on a parabolic trough collector receiver tube with elliptical dimpled fins to analyze its hydro-thermal characteristics under turbulent flow regime. Different mono and hybrid nanofluids with various nanoparticle volume fractions were used as the working fluid. The study provides a detailed analysis of the collector's exergetic and entropy production. The results show that the use of elliptical dimpled fins with an elliptical ratio of a/b=5/3 significantly increases the average Nusselt number, reduces entropy generation, and improves thermal efficiency.