Energy and Exergy Assessment of Nanofluids in Solar Energy Harvesting

Nanofluids were prepared in a water-base fluid using different types of nanoparticles that included CuO, Ag, ZnO, and MtNs at different concentrations.With the use of a solar simulator, experimental studies were performed to evaluate the thermal and exergetic efficiencies of the nanofluids.The nanofluid samples were subjected to an average heat flux of 800 W/m 2 .The photothermal conversion efficiency was shown to peak at relatively low concentrations for the different nanoparticles, and was shown to decrease with the increase in the nanofluid temperature.Whereas the exergetic efficiency was shown to increase with the increase in temperature, reaching a peak at a temperature close to 40 o C for all nanofluids, and declining afterwards.Compared to distilled water, the enhancement in the average exergetic efficiency of the tested nanofluids concentrations was shown to narrowly range between 57% and 69%, higher than that of the photothermal conversion efficiency that was seen to range between 28% and 66%.Compared to other nanoparticles, silver had the highest of the thermal and exergetic efficiency reaching an average enhancement of 66% in the photothermal conversion efficiency at a concentration of 0.31% by weight, and 68% in its exergetic efficiency at the same concentration.