Geometrical Modifications Of Absorber Tube Of Conventional Solar Parabolic Trough Collector Systems For Thermal Enhancement: A Complete Review

Abstract

This review covers most of the techniques of improving the performance of solar parabolic trough collector systems using innovative geometries, novel heat transfer techniques, numerical simulation, and experimental verification. Fundamentally, the research considers the impact of geometrical configurations including fins, inserts, and innovative receiver geometries on system performance, as well as thermal performance. The studies show that trapezoidal receivers, dimpled tubing, corrugated absorbers, and wire coil inserts have major contributions in determining heat transfer rates and thermal efficiency. The use of external and internal fins, dimpled tubing, and turbulators, including twisted tapes and wire coils, significantly improves thermal performance, with some configurations achieving a significant increase in efficiency up to 40.74%. A comparison shows that the optimal configurations are dependent on factors like aperture width, fin geometry, and nanofluid concentration. Additionally, the use of nanofluids, especially copper or titanium dioxide nanoparticles, greatly improves performance by increasing convective heat transfer coefficients. This work illustrates the benefits of nanofluids and hybrid nanofluids as heat transfer fluids which significantly reduce the thermal gradients and the stresses they generate. These results represent a necessary step towards our pursuit of the sustainable harvesting of solar energy, enabling cost-saving approaches to large-scale solar applications and extending the pursuit of global carbon neutrality.