Analysis of particle deposition of nanofluid flow through porous media

摘要

A numerical investigation of nanoparticle deposition for flow through a partially filled channel subject to a constant heat flux boundary condition is presented. The discrete particle model (DPM) is utilized for the simulations. The Brinkman-Forchheimer extended Darcy model is used for the flow inside a saturated porous matrix. The effect of porous permeability (Da = 10~(-8)-10~(-4)), Reynolds number (Re = 500-2000), volume concentration (0%, 0.3% and 3%) and different particle forces on the deposition rate have been documented. The particle adhesion/detachment is solved with respect to the force balance considering drag, Saffman lift, Brownian, thermophoresis, gravity and Van Der Waals. Our results reveal that the mass deposition rate can be omitted when there is no porous media inside the channel. In addition, no heat transfer enhancement is noticed for low particle loading ＜1% of nanofluid compared to water for Da ≤ 10~(-5). It is found that, the porous permeability has a substantial role on nanoparticle mobility and a critical Reynolds number (500 ≤ Re ≤ 1000) exists where the entrapment rate is maximized. On the other hand, the particle velocities and mass deposition rates are high for volume concentration of 3% while accompanied by an increased rate of heat transfer and pressure drop, particularly for Da ≥ 10~(-5) when compared to 0.3% volume fraction. It was observed that increasing porous permeability to Da ≥ 10~(-4) decreases the deposition rate. The impact of different pertinent forces on the deposition was also considered, and our results establish that Brownian motion had the most dominant effect on the deposition rate in the presence of a porous medium.