Experimental and numerical investigation of parabolic trough solar collector thermal efficiency enhanced by graphene–Fe3O4/water hybrid nanofluid

Abstract

This experimental study discusses and focuses on the working fluid because it is regarded as the most important factor influencing parabolic trough solar collector (PTSC) performance. To study the performance, two identical PTSCs were manufactured to use water and the graphene (G)–Fe3O4/water hybrid nanofluid (HNF) as working fluids with different concentrations. The two collectors were evaluated under the same conditions and based on experimental results that the average thermal efficiency and deviation between them not exceeding 0.11%. In addition, the HNF was prepared, and the effect of volume concentration and temperature on the viscosity and thermal conductivity of G–Fe3O4/water was studied. Test samples consisting of HNFs with volume concentrations of 0.01%, 0.05%, 0.1% and 0.2% were compared with water at a mass flow rate of 2 L/min. According to the results, the TE of the PTSC was improved by using a G–Fe3O4/water HNF. The thermal efficiency for G–Fe3O4 HNF was obtained for 0.2%, 0.1%, 0.05% and 0.01% VCs and reached 45.46%, 44.3%, 42.04% and 41.02%, respectively, while the collector efficiency with water was 40.41%. A numerical analysis of the performance of PTSC was also performed using ANSYS Fluent. The results obtained from the numerical and experimental work were in good agreement.