Moghtada Mobedi

Effects of Wall-Located Heat Barrier on Conjugate Conduction/Natural-Convection Heat Transfer and Fluid Flow in Enclosures

The effects of a heat barrier, located in the ceiling wall of an enclosure, on conjugate conduction/natural convection are investigated numerically. The vertical walls of the enclosure are differentially heated and the horizontal walls are adiabatic. Heatline technique is used to visualize heat transport. The variations of average Nusselt number, dimensionless heat transfer rate through the ceiling wall, and dimensionless overall heat transfer rate are studied. Calculations are performed for different Rayleigh numbers (103 ≤ Ra ≤ 106), thermal conductivity ratios (1 ≤ K ≤ 100), dimensionless locations of the heat barrier (0 < X h < 1),and two dimensionless ceiling wall thicknesses (D = 0.05 and D = 0.20). For high thermal conductivity ratio (K = 100), the heat barrier considerably reduces the dimensionless overall heat transfer rate. The effect of the heat barrier on dimensionless heat transfer rate through the enclosure increases as the Rayleigh number decreases. For low Rayleigh number (i.e., Ra = 103), a location exists in the ceiling wall for which the dimensionless overall heat transfer rate is minimum.

Visualization of heat transport using dimensionless heatfunction for natural convection and conduction in an enclosure with thick solid ceiling

A conjugate conduction-(natural)convection problem is numerically studied in order to present the application of dimensionless heatfunction for entire computational domain including solid and fluid regions in an enclosure with thick solid ceiling. The modified dimensionless heatfunction for solid region is defined to provide continuity of dimensionless heatfunction on solid-fluid interface. The enclosure is differentially heated from vertical walls, and horizontal walls are adiabatic. Finite difference method is employed to solve the set of governing equations. The dimensionless governing parameters for computations are: Rayleigh number (from 10^3 to 10^6), dimensionless ceiling wall thickness (0.05 and 0.5) and thermal conductivity ratio (from 1 to 100). The obtained results shows that the heat and fluid flows in the enclosure are considerably influenced by Rayleigh number and thermal conductivity ratio. Dimensionless wall thickness comparatively has less effect on heat transfer rate through the cavity.

Fully Developed Forced Convection in a Parallel Plate Channel with a Centered Porous Layer

In this study, fully developed heat and fluid flow in a parallel plate channel partially filled with porous layer is analyzed both analytically and numerically. The porous layer is located at the center of the channel and uniform heat flux is applied at the walls. The heat and fluid flow equations for clear fluid and porous regions are separately solved. Continues shear stress and heat flux conditions at the interface are used to determine the interface velocity and temperature. The velocity and temperature profiles in the channel for different values of Darcy number, thermal conductivity ratio, and porous layer thickness are plotted and discussed. The values of Nusselt number and friction factor of a fully clear fluid channel (Nucl = 4.12 and fRecl = 24) are used to define heat transfer increment ratio

Effect of an inserted porous layer located at a wall of a parallel plate channel on forced convection heat transfer

({\varepsilon _{\rm th} =Nu_{\rm p}/Nu_{\rm cl})}

Comparison of Uniform and Non-uniform Pressure Approaches Used to Analyze an Adsorption Process in a Closed Type Adsorbent Bed

and pressure drop increment ratio

Using of Bejan's Heatline Technique for Analysis of Natural Convection in a Divided Cavity with Differentially Changing Conductive Partition

({\varepsilon_{\rm p} =fRe_{\rm p}/fRe_{\rm cl} )}