Assessment of liquid metals as heat transfer fluid for parabolic trough solar collector

In this article, heat transfer characteristics of various heat transfer fluids (HTF's) such as water, therminol oil, molten salt and liquid metals are studied for parabolic trough solar collector. A three dimensional (3-D) numerical simulation of absorber for parabolic trough solar collector is carried out using commercial computational fluid dynamics software Fluent 16.0. The numerical model is solved based on K-S turbulent model with standard wall function. The influence of thermo-physical properties of HTF's on heat transfer rate from the absorber wall surface to the fluid is studied for various mass flow rates ranging from 0.5 kg/s to 1.5 kg/s insteps of 0.25 kg/s. The analysis is carried out for both uniform and non-uniform heat flux at the absorber wall surface. For both uniform and non-uniform heat flux configuration, liquid sodium offers better heat transfer characteristics among all the heat transfer fluids. Among all the heat transfer fluids, liquid sodium offers less temperature gradient (8.58 K) and therminol oil offers high temperature gradient (42.74 K) around the circumference of the absorber for the mass flow rate of 1 kg/s. Hence, liquid sodium offers significant benefits in terms of performance enhancement compared to other heat transfer fluids.