Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Çekmer, ÖzgürHas files: Yes

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  • Article
    Citation - WoS: 32
    Citation - Scopus: 38
    Fully Developed Forced Convection in a Parallel Plate Channel With a Centered Porous Layer
    (Springer Verlag, 2012) Çekmer, Özgür; Mobedi, Moghtada; Özerdem, Barış; Pop, Ioan
    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 (Nu cl = 4. 12 and fRe cl = 24) are used to define heat transfer increment ratio (ε th = Nu p/Nu cl)and pressure drop increment ratio (ε p = f Re p/f Re cl) and observe the effects of an inserted porous layer on the increase of heat transfer and pressure drop. The heat transfer and pressure drop increment ratios are used to define an overall performance (ε = ε th/ε p) to evaluate overall benefits of an inserted porous layer in a parallel plate channel. The obtained results showed that for a partially porous filled channel, the value of ε is highly influenced from Darcy number, but it is not affected from thermal conductivity ratio (k r) when k r > 2. For a fully porous material filled channel, the value of ε is considerably affected from thermal conductivity ratio as the porous medium is in contact with the channel walls.
  • Article
    Citation - WoS: 19
    Citation - Scopus: 23
    Fully Developed Forced Convection Heat Transfer in a Porous Channel With Asymmetric Heat Flux Boundary Conditions
    (Springer Verlag, 2011) Çekmer, Özgür; Mobedi, Moghtada; Özerdem, Barış; Pop, Ioan
    An analytical study is performed on steady, laminar, and fully developed forced convection heat transfer in a parallel plate channel with asymmetric uniform heat flux boundary conditions. The channel is filled with a saturated porous medium, and the lower and upper walls are subjected to different uniform heat fluxes. The dimensionless form of the Darcy-Brinkman momentum equation is solved to determine the dimensionless velocity profile, while the dimensionless energy equation is solved to obtain temperature profile for a hydrodynamically and thermally fully developed flow in the channel. Nusselt numbers for the lower and upper walls and an overall Nusselt number are defined. Analytical expressions for determination of the Nusselt numbers and critical heat flux ratio, at which singularities are observed for individual Nusselt numbers, are obtained. Based on the values of critical heat flux ratio and Darcy number, a diagram is provided to determine the direction of heat transfer between the lower or upper walls while the fluid is flowing in the channel.
  • Article
    Citation - WoS: 18
    Citation - Scopus: 24
    Forced Convection Heat Transfer Inside an Anisotropic Porous Channel With Oblique Principal Axes: Effect of Viscous Dissipation
    (Elsevier Ltd., 2010) Mobedi, Moghtada; Çekmer, Özgür; Pop, Ioan
    An analytical study on laminar and fully developed forced convection heat transfer in a parallel-plate horizontal channel filled with an anisotropic permeability porous medium is performed. The principal axis of the anisotropic porous medium is oriented from 0 to 90 degrees. A constant heat flux is applied on the outer wall of the channel. Both clear (Newtonian) fluid and Darcy viscous dissipations are considered in the energy equation. Directional permeability ratio parameter A* is defined to combine both the effect of the dimensionless permeability ratio parameter K*=(K 1/K2) and orientation angle φ into one parameter. The effects of the parameter A*, the Darcy number Da and the modified Brinkman number Br* on the heat transfer and fluid flow characteristics in the channels are investigated and presented in graphs. The obtained results show that the parameters A*, Da and Br* have strong effects on the dimensionless normalized velocity and temperature profiles as well as on the Nusselt number. It is found that for a particular value of A*, called as critical value Acr*, the external heat applied to the surface of the channel is balanced by the internal heat generation due to viscous dissipation and the bulk mean temperature approaches the wall temperature. Hence, the Nusselt number approaches infinity for the critical values A cr*. © 2010 Elsevier Masson SAS. All rights reserved.