Thermal performance and entropy generation analysis of a high concentration ratio parabolic trough solar collector with Cu-Therminol®VP-1 nanofluid

This paper presents results of a numerical study on the thermal and thermodynamic performance of a high concentration ratio parabolic trough solar collector using Cu-Therminol®VP-1 nanofluid as the heat transfer fluid. A parabolic trough system with a concentration ratio of 113 and a rim angle of 80° has been used in this study. The thermal physical properties of both the base fluid and the copper nanoparticles have been considered temperature dependent. Inlet temperatures in the range 350-650 K and flow rates in the range 1.22-135 m³ h^-1 have been used. The numerical analysis consisted of combined Monte-Carlo ray tracing and computational fluid dynamics procedures. The Monte-Carlo ray tracing procedure is used to obtain the actual heat flux profile on the receiver's absorber tube, which is later coupled to a finite volume based computational fluid dynamics tool to evaluate the thermal and thermodynamic performance of the receiver. Results show that the thermal performance of the receiver improves as the nanoparticle volume fraction increases. The thermal efficiency of the system increases by about 12.5% as the nanoparticle volume fraction in the base fluid increase from 0% to 6%. The entropy generation rates in the receiver reduce as the nanoparticle volume fraction increases for some range of Reynolds numbers. Above a certain Reynolds number, further increase in the Reynolds numbers makes the entropy generation higher than that of a receiver with only the base fluid.