Numerical and experimental investigation of alumina-based nanofluid effects on double-pipe heat exchanger thermal performances

Abstract In this study, we investigate the thermal behaviour of nanofluids in a double-pipe heat exchanger. It is about a counterflow configuration, designed to cool a lubrication unit of a thermoelectric power plant. The subject of this work is to evaluate the thermal performances of the exchanger by using a nanofluid based on alumina suspension comparing with deionized water. In order to evaluate the thermal performance of the studied configuration, we carried out numerical experiments in an application developed on COMSOL Multiphysics environment, these experiments are utilized to show the feasibility of this application. As result, we found that the nanofluid with an increase in its volume fraction leads to an increase in the overall exchange coefficient, the convective heat transfer coefficient, as well as the efficiency and the power of the exchanger. It is noted that an increase of 1% in volume fraction, can enhance the overall exchange coefficient, the power and the effectiveness of the exchanger by 17.62%, 1.473% and 10.80% respectively. Besides, it is noted that the increase in the concentration of nanofluids leads to a narrowing of the pinch points of the inlet and outlet temperatures, which means that nanofluids are more efficient in cooling temperatures than conventional fluids.