Numerical Analysis on Hydrothermal Behavior of Various Ribbed Minichannel Heat Sinks with Different Hybrid Nanofluids

Abstract

Thermo-hydraulic behavior of the ribbed minichannel heat sink, having nine rectangular-shaped channels, is numerically investigated in the present study by using a multi-phase mixture model. Four different types of ribs (semi-circular, rectangular, triangular and trapezoidal ribs) and two hybrid nanofluids (Al2O3 + TiO2/DI water and Al2O3 + Cu/DI water) with a total nanoparticle volume concentration of 0.1% are considered. Heat transfer coefficient, Nusselt number, pressure drop, friction factor, performance evaluation criterion and thermal performance factor are evaluated for different Reynolds numbers (90–450) or flow rate (0.1–0.5 lpm). The maximum heat transfer coefficient (6690.12 W/m2 K) is observed for semi-circular ribs with Al2O3 + Cu hybrid nanofluid. The performance evaluation criterion is above 1 for all the cases except the plain channel with Al2O3 + TiO2 hybrid nanofluid at a lower flow rate. The combination of the semi-circular ribbed channel with Al2O3 + Cu hybrid nanofluid has a maximum performance evaluation criterion of 1.40 and that with Al2O3 + TiO2 hybrid nanofluid has a maximum thermal performance factor of 1.16. The thermal performance factor has an increasing trend with the flow rate for the semi-circular ribbed channel. The semi-circular ribbed channel shows better performance over other ribbed channels because the working fluid gets stuck and stagnant between two consecutive ribs in other ribbed channels, which leads to higher thermal resistance. © 2021, King Fahd University of Petroleum & Minerals.