Numerical Analysis of Nanofluid Thermal Flows through a Model Heat Exchanger:

The present paper numerically analyzed the effect of nanoparticle volume fraction on thermal flows of Al 2 O 3 / Water nanofluids through a two-dimensional model heat exchanger channel. The trade-off relation between thermal conductivity and pressure drop in nanofluid flows was studied using numerical thermal flow simulation in which the dependence of both thermal conductivity and viscosity on the nanoparticle volume fraction and the distribution of nanoparticles in flows were considered. The Batchelor model and the Lu and Lin model were applied to models of viscosity and thermal conductivity of nanofluids, respectively. The results obtained are: (1) Nanofluids contribute to make an improvement of heat transfer without harmful effects to flow. (2) From the energy efficiency point of view, it was found that the use of nanofluids at low particle volume fractions was appropriate. This is because a remarkable increase in the temperature efficiency due to the addition of nanoparticles relative to an increase in the power required for flowing nanofluids in the channel is not expected at high particle volume fractions.