Heat transfer enhancement of nanofluids flow in microtube with constant heat flux

In this paper, laminar convective heat transfer in a two-dimensional microtube (MT) with 50 mu m diameter and 250 mu m length with constant heat flux is numerically investigated. The governing (continuity, momentum and energy) equations were solved using the finite volume method (FVM) with the aid of SIMPLE algorithm. Different types of nanofluids Al2O3, CuO, SiO2 and ZnO, with different nanoparticle size 25, 45, 65 and 80 nm, and different volume fractions ranged from 1% to 4% using ethylene glycol as a base fluid were used. This investigation covers Reynolds number in the range of 10 to 1500. The results have shown that SiO2-EG nanofluid has the highest Nusselt number, followed by ZnO-EG, CuO-EG, Al2O3-EG, and lastly pure EG. The Nusselt number for all cases increases with the volume fraction but it decreases with the rise in the diameter of nanoparticles. In all configurations, the Nusselt number increases with Reynolds number. (C) 2012 Elsevier Ltd. All rights reserved.