Heat Transfer and Collector Thermal Efficiency of Magnesium Oxide/Water Nanofluids in Solar Flat Plate Collector Under Thermosyphon Conditions

The thermal efficiency, heat transfer, and friction factor of a solar collector circulated with water diluted MgO nanofluid under natural circulation have been estimated. The tests were run with particle loadings of 0.1%, 0.5%, and 1.0% between the hours of 10:00 and 3:30. The greatest increase in Nusselt number has been reported for 1.0% vol. of nanofluid to be 21.48% and 37.28% higher than water at Re of 143 and 346, respectively. Larger friction factor penalties of 1.14 times and 1.27 times, compared to water, were simultaneously reported for nanofluid concentrations of 1.0% vol. at Re numbers of 143 and 346, respectively. The collector efficiency was larger from 57.15% to 65.47% when used with water and at 1.0% vol. The relative variances of the formulae created to assess the friction factor and Nusselt number are within 2.5%.