Abstract
The purpose of this study is indicating the effect of mounting heat generating porous matrix in a close cavity on the Brownian term of CuO-water nanofluid and its impact on improving the Nusselt number.
Because of presence of heat source in porous matrix, couple of energy equations is solved for porous matrix and nanofluid separately. Thermal conductivity and viscosity of nanofluid were assumed to be consisting of a static component and a Brownian component that were functions of volume fraction of the nanofluid and temperature. To explain the effect of the Brownian term on the flow and heat fields, different parameters such as heat conduction ratio, interstitial heat transfer coefficient, Rayleigh number, concentration of nanoparticles and porous material porosity were investigated and compared to those of the non-Brownian solution.
The Brownian term cause to better cooling of porous matrix because of rising thermal conductivity. Mounting the porous material into cavity changes the temperature distribution and increases Brownian term effect and heat transfer functionality of the nanofluid. Besides, the effect of the Brownian term was seen to be greatest at low Rayleigh number, low-porosity and small thermal conductivity of the porous matrix. It is noteworthy that due to decrement of thermal conduction in high porosities, the impact of Brownian term drops severely makes it possible to obtain reliable results even in the case of neglecting Brownian term in these porosities.
The effect of mounting the porous matrix with internal heat generation was investigated on the improvement of variable properties of nanofluid.
Because of presence of heat source in porous matrix, couple of energy equations is solved for porous matrix and nanofluid separately. Thermal conductivity and viscosity of nanofluid were assumed to be consisting of a static component and a Brownian component that were functions of volume fraction of the nanofluid and temperature. To explain the effect of the Brownian term on the flow and heat fields, different parameters such as heat conduction ratio, interstitial heat transfer coefficient, Rayleigh number, concentration of nanoparticles and porous material porosity were investigated and compared to those of the non-Brownian solution.
The Brownian term cause to better cooling of porous matrix because of rising thermal conductivity. Mounting the porous material into cavity changes the temperature distribution and increases Brownian term effect and heat transfer functionality of the nanofluid. Besides, the effect of the Brownian term was seen to be greatest at low Rayleigh number, low-porosity and small thermal conductivity of the porous matrix. It is noteworthy that due to decrement of thermal conduction in high porosities, the impact of Brownian term drops severely makes it possible to obtain reliable results even in the case of neglecting Brownian term in these porosities.
The effect of mounting the porous matrix with internal heat generation was investigated on the improvement of variable properties of nanofluid.
| Original language | English |
|---|---|
| Journal | International Journal of Numerical Methods for Heat & Fluid Flow |
| Early online date | 29 Oct 2018 |
| DOIs | |
| Publication status | E-pub ahead of print - 29 Oct 2018 |
Keywords
- nanofluid
- brownian motion
- porous matrix
- dependent internal heat generation
- LTNE model