Computational fluid dynamic evaluation of heat transfer enhancement in microchannel solar collectors sustained by alumina nanofluid

Nanofluids have produced a wide range of researches for various cooling/heating purposes, owing to the enhanced thermophysical properties they bring by suspending nanoparticles in the base fluid. This work proposes a detailed computational fluid dynamic (CFD) study of heat transfer enhancement in microchannel solar collectors coupled with nanofluid. The accuracy of the numerical model is ensured through a reliable finite element analysis considering the complexity of the three-dimensional structure of microchannel solar collector. The thermophoretic motion induced by the suspension of Al2O3 nanoparticles was also evaluated to further understand the thermal enhancement observed in forced convection regimes. The accuracy of the model was first validated with respect to propylene glycol/water fluid, and then applied to evaluate the performance for Al2O3/water nanofluid. A detailed comparison of the performance of the two fluids with an assessment of the temperature and velocity profiles, was adopted to evaluate the thermal efficacy of adding nanofluids. A further investigation of the effect of solar collector inclination angles at the optimal volumetric concentration of the nanofluid was also done to determine the impact of the system geometry on the efficacy of the heat removal. It was established that the optimal heat removal is achieved at 2% nanoparticle concentration. Finally, it was also detected that increasing the inclination angle of the solar collector from 0 to obstructed the heat removal efficiency.