Numerical Investigation of Nanofluid Forced Convection in Channels with Discrete Heat Sources

Abstract

Numerical simulation is performed to investigate the laminar force convection of Al₂O₃/water nanofluid in a flow channel with discrete heat sources. The heat sources are placed on the bottom wall of channel which produce much thermal energy that must be evacuated from the system. The remaining surfaces of channel are kept adiabatic to exchange energy between nanofluid and heat sources. In the present study the effects of Reynolds number ($\text{Re}=\mathrm{50,\; 100,\; 200,\; 400}$, and 1000), particle volume fraction ($\varphi =0$ (distilled water), 1 and 4%) on the average heat transfer coefficient (h), pressure drop ($\Delta P$), and wall temperature ($T_w$) are evaluated. The use of nanofluid can produce an asymmetric velocity along the height of the channel. The results show a maximum value 38% increase in average heat transfer coefficient and 68% increase in pressure drop for all the considered cases when compared to basefluid (i.e., water). It is also observed that the wall temperature decreases remarkably as Re and ϕ increase. Finally, thermal-hydraulic performance (η) is evaluated and it is seen that best performance can be obtained for $\text{Re}=1000$ and $\varphi =4$%.