Thermohydraulic and entropy characteristics of Al2O3‐water nanofluid in a ribbed interrupted microchannel heat exchanger

Abstract

AbstractIn this study, an interrupted microchannel heat sink with rib turbulators was studied for its thermohydraulic effectiveness and entropy generation in a compact space. The rib edges are modified to enhance the overall functioning of the system by reducing the pressure drop. The working fluid used was Al2O3‐water nanofluid, and increasing the Reynolds number and nanoparticle concentration triggered a reduction in the heat sink's maximum temperature. These also offer a decrease in resistance to heat transfer, and there is an improvement in the evenness of the temperature of the interrupted microchannel heat sink, as regions with the likelihood of hot spot reduced drastically. At Re = 100, increasing the nanoparticle concentration from 0% to 4% enhanced the heat transfer coefficient by 38.41% for the interrupted microchannel heat sink‐base (IMCH‐B) configuration. Under similar conditions, the convective heat transfer coefficient for the interrupted microchannel heat sink‐fillet (IMCH‐F) increased by 43.69%. Furthermore, at 0.5% concentration, changing the Reynolds number from 100 to 700 augmented the heat transfer coefficient by 70.65%. Thus, the maximum temperature of the substrate's bottom surface was reduced by 53.83°C when the system was operated at Re = 700 and nanoparticle concentration of 4%. The IMCH‐C also showed relatively close results at all observed volume fractions. For the IMCH‐C, the maximum temperature of the bottom surface was reduced by 41.98°C at Re = 700 when compared with Re = 100% and 4% concentration. Although at high Reynolds numbers and concentrations, the pressure drops are higher, the performance enhancement criteria prove that the nanofluid is superior to water and the edge modifications show significant performance improvement. More importantly, the IMCH‐F heat sink showed the optimum performance based on the performance evaluation criteria at Re = 300 and (ie, at this point, the heat transfer coefficient is maximum and the pressure drop is minimum). On the other hand, the optimal thermodynamic performance was observed at Re = 700 and . The numerical results demonstrated a potential way to exploit nano‐suspensions for thermal applications, especially for high‐energy flux systems with compact space constraints.