MHD mixed convection and entropy generation in a 3-D microchannel using Al2O3-water nanofluid

In this paper, mixed convection as well as second law of thermodynamics analysis in a three-dimensional microchannel filled with a nanofluid under a magnetic field are numerically studied. The temperature fields, variation of horizontal velocity, thermal resistance, pressure drop, Hartmann and Reynolds numbers are investigated. Moreover, heat, frictional and magnetic entropy generation are surveyed in different volume fractions. Analyzing the results of numerical simulations indicates that with increasing Hartmann number, maximum horizontal velocity along the centre line and the inlet and outlet thermal resistance decrease in the microchannel. On the other hand, by enhancing the strength of the imposing magnetic field, heat entropy generation mitigates, while frictional and magnetic ones increase. However, the increasing of two last is very small compared to heat entropy generation. The ratio of Nu(avg)/(pressure drop) is greater than 10. Therefore, the thermal gain of this microchannel fairly dominates the loss of pressure reduction. (C) 2014 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.