Single Phase Heat Transfer Of Water-Ethanol Mixture In Microchannel

Abstract

Numerical simulations were conducted to understand the effect of property variations by changing the composition of the binary mixture on the thermal performance of the microchannel heat sink. To get the property variations, the properties of pure fluids are taken as dependent on temperature, and the binary mixture property variations are taken as dependent on the composition of the binary mixture. A constant heat flux is applied over the bottom wall of a square microchannel having a hydraulic diameter of 0.4 mm. The flow condition of the binary mixture is taken as laminar. The pure fluids simulations have shown that at the same flow conditions as the Reynolds number, ethanol as a coolant gave a better average Nusselt number, followed by water, FC-72, and methanol. As the conventional theory suggests, in forced convection flows, the average Nusselt number mainly depends upon the Reynolds number of flow and the Prandtl number of coolant. From the simulation results of the binary mixture of water-ethanol, the dependency of thermal performance over the prandtl number can be justified. The variation of the average Nusselt number over the different concentrations of ethanol in the water-ethanol binary mixture has shown that the mixture gives better thermal performance over the pure fluids due to an increment in the Prandtl number of the binary mixture over the pure fluids. The maximum average Nusselt number is found at 60% volume concentration of ethanol, and this value increases as the Reynolds flow increases.