Investigation of energetic and exergetic performances of parabolic trough collector with using different heat transfer fluids

Abstract

In this study energetic and exergetic performances of parabolic trough collector is theoretically investigated by using 120 l/min synthetic ''Dowtherm A'' oil, 1200 l/min Air at 100 bar (10 MPa) and 150 l/min molten salt which is mixture of 60 wt% sodium nitrate (NaNO3) and 40 wt% potassium nitrate (KNO3) which are widely used as heat transfer fluids. Fluids performance comparisons were performed with the LS-2 module, which is used with vacuum in annulus and Cermet as a selective coating. LS-2 module has 7.8 m receiver length and is 39 m2 aperture area. As a result, the maximum exergy efficiency of the molten salt, synthetic oil, Air to be 41.19% at 422 °C, 40.82% at 400 °C, 40.33% at 402 °C, respectively. The maximum exergy of air is higher than other working fluids up to 310 ° C but after about 310 ° C the exergy of the molten salt is higher than the others. The molten salt has the best energy efficiency at its operating temperatures (250 °C to 550 °C) than other working fluids.