PERFORMANCE EVALUATION OF DIRECT AND INDIRECT ABSORPTION LINEAR FRESNEL REFLECTORS OPERATING WITH NANOFLUIDS

Abstract

In this study, the performance of a linear Fresnel reflector (LFR) is analyzed using three types of nanofluids (Syltherm800-Cu, Therminol-Al2O3, and water-graphite ) as heat transfer fluids with a range of volume fraction of 0.01% to 6%. A comparison between pure-fluids and nanofluids is conducted regarding thermal efficiency, exergy efficiency, pumping power, and heat transfer coefficient. Nanofluids have a consistently positive impact on the thermal performance of solar collectors which as thermal efficiency enhancement was 4% and 3.3% for a volume fraction of 6% in the case of Therminol-Al2O3 and Sylthem-Cu ,respectively. Regarding the heat transfer coefficient, a constant improvement in values was found when using nanofluids, it reached a maximum of 44% and 35% at a volume fraction of 6% for Therminol Al2O3 and Syltherm-Cu, respectively. With regards to the direct absorption technology, nanofluids show a marked increase in optical and thermal performance, compared to the base-fluid.