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.
Highlights
Heat exchangers are widely used in many industrial applications, for example in the chemical industry, power generation, food industry, environmental engineering, waste heat recovery, air conditioning and refrigeration [1]
Recent advances in nanotechnology have shown that the addition of nanoparticles in a base fluid, so-called nanofluids, used for the first time by Choi [2], for example, alumina nanoparticles (Al2O3), can significantly increase the heat transfer of nanofluids compared to conventional fluids
Sözen et al [7, 8] focused on improving heat transfer in plate heat exchangers, carrying out numerical and experimental investigations on the effects of nanofluids on the thermal performance of this type of heat exchanger, in this work the working fluids used are nanofluids based on kaolin and TiO2 deionized water
Summary
Heat exchangers are widely used in many industrial applications, for example in the chemical industry, power generation, food industry, environmental engineering, waste heat recovery, air conditioning and refrigeration [1]. Recent advances in nanotechnology have shown that the addition of nanoparticles in a base fluid, so-called nanofluids, used for the first time by Choi [2], for example, alumina nanoparticles (Al2O3), can significantly increase the heat transfer of nanofluids compared to conventional fluids (deionized water for example). The addition of these nanoparticles can change the thermal properties of the base fluid. The use of a nanomaterial with a concentration of 0.06% in the base fluid resulted in a 15.86% improvement in the convective heat transfer coefficient compared to water. The addition of high ribs can result in a higher friction factor than the corresponding microchannel with a constant rib
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