The development of a new thermal modeling and heat transfer mechanisms of a compound parabolic concentrator (CPC) based on nanofluids

This paper analyzes heat transfer mechanisms in a compound parabolic concentrator solar collector by demonstrating a new thermal resistance network. Present study developed an analytical thermal model based on nanofluids. In addition, experimental data in similar conditions have been applied to validate and increase the reliability of the model. A laminar flow in the Reynolds number range of 726 to 1827 flows through the absorbent tube. The results were examined in four volumetric flow rates of 1, 1.5, 2, 2.5 L min(-1) and three concentrations of the SiO2/ethylene glycol-Water nanofluid with 0.5%, 1% and 1.5% volumetric fractions. The results revealed that the developed thermal model with an error percentage of less than 6% for the nanofluid was in good agreement with the experimental data. The mean error of the temperature difference between the thermal modeling and empirical data was estimated at 4.61%. Furthermore, the analysis pointed out that the increase in pumping power was less than 3.65%, whereas the thermal efficiency enhancement was up to 10.43% in the highest volumetric fraction of nanofluid. Since the thermal model is based on applying physical laws, it could be applied to other heat transfer fluids in various operative and environmental conditions. Likewise, the presented thermal model is a secure tool for designing and optimizing as well as controlling different energy parameters in compound parabolic concentrators.