Numerical study on the effects of geometrical parameters and Reynolds number on the heat transfer behavior of carboxy-methyl cellulose/CuO non-Newtonian nanofluid inside a rectangular microchannel

Abstract

Present work studies the effects of microchannel height and Reynolds number on the temperature distribution behavior, pressure drop, and Nusselt number of a non-Newtonian nanofluid. The nanofluid is an aqueous solution of carboxy-methyl cellulose with a 1 percent volume fraction of copper oxide (CuO) nanoparticle, which is flowed at four Reynolds numbers of 250, 500, 750 and 1000, respectively, inside a rectangular microchannel with different heights size. Three dimensions in the order of H = 1 mm, H = 1.5 mm, and H = 2 mm are used for the microchannel height. Generally, it is concluded that increment of channel height and Reynolds number reduce temperature, whereas they increase heat transfer rate and Nusselt number due to their role in reducing thermal and hydrodynamics boundary layers thickness and flow concentration within the microchannel. Moreover, this phenomenon increases collision between hot and cold fluids due to decreasing their interval layer thickness. Also, increasing Reynolds number amplifies the pressure drop along the microchannel as well as increasing microchannel height. Therefore, it is concluded that the maximum temperature value of 430 K and maximum pressure drop of 7000 Pa have belonged to the case of studies with minimum and maximum microchannel height, respectively. On the other side, the maximum value of temperature is related to the minimum Reynolds number of 250, whereas maximum pressure drop is related to the maximum Reynolds number of 1000.