Numerical investigation of the performance of parabolic trough solar collector utilizing nanofluids as working fluids

Abstract

Parabolic trough solar collectors have been utilized to harvest solar energy for heating and power generation for ages. While several attempts have been made to improve the design and performance of solar collectors, little attention has been focused on enhancing the thermal conduction efficiency of the heat collection fluids. By adding nanofluids, a mixture of nanoparticles and base fluids, the thermal conductivity of the working fluids can be improved, and invariably the performance of the collectors can be enhanced. This paper presents a computational fluid dynamics (CFD) simulation of a parabolic trough solar collector in which pure water, CuO/water, and TiO2/water nanofluids were used as working fluids. The nanofluids were set at 5 vol.% while turbulent flow condition with non-uniform heat flux was applied at the outer surface of the receiver. At varying lengths and diameters, the heat profiles of the receiver were obtained using a general-purpose ray-tracing software (SolTrace). The results indicated 14% and 3.5% increase in the collector efficiency for TiO2/water and CuO/water nanofluids, respectively. The simulation results agreed with the existing experimental data within ±5% error. In addition, the performance of the solar collector when TiO2/water and CuO/water nanofluid was higher than pure water by 112% and 98%, respectively. It is, therefore, recommended that TiO2/water nanofluids be utilized for parabolic trough solar collectors, given the high energy demand occasioned by population explosion and COVID-19 pandemics.