Mechanical Engineering / Makina Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4129

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Subject: search.filters.subject.Walls (structural partitions)

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  • Article
    Citation - WoS: 27
    Citation - Scopus: 28
    Effects of Wall-Located Heat Barrier on Conjugate Conduction/Natural- Convection Heat Transfer and Fluid Flow in Enclosures
    (Taylor and Francis Ltd., 2008) Hakyemez, Erinç; Mobedi, Moghtada; Öztop, Hakan Fehmi
    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 (10 3≤ Ra ≤ 10 6), 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 = 10 3), a location exists in the ceiling wall for which the dimensionless overall heat transfer rate is minimum.
  • Article
    Citation - WoS: 81
    Citation - Scopus: 89
    Visualization of Natural Convection Heat Transport Using Heatline Method in Porous Non-Isothermally Heated Triangular Cavity
    (Elsevier Ltd., 2008) Varol, Yasin; Öztop, Hakan Fehmi; Mobedi, Moghtada; Pop, Ioan
    Natural convection heat transfer in a porous media filled and non-isothermally heated from the bottom wall of triangular enclosure is analyzed using finite difference technique. Darcy law was used to write equations of porous media. Dimensionless heatfunction was used to visualize the heat transport due to buoyancy forces. Three different boundary conditions were applied for the vertical and inclined boundaries of triangular enclosures as Case I; both vertical and inclined walls were isothermal, Case II; vertical wall was adiabatic and inclined one was isothermal, Case III; vertical wall is isothermal and inclined one is adiabatic. A cosine function was utilized to get non-isothermal wall condition. The study was performed for different aspect ratios (0.25 ≤ AR ≤ 1.0) and Darcy-modified Rayleigh numbers (100 ≤ Ra ≤ 1000). It was observed that heat transfer enhancement was formed when vertical and inclined walls were isothermal while bottom wall was at non-uniform temperature. Heat transfer from bottom wall did not vary when the value of aspect ratio was higher than 0.50. In addition, heatline visualization technique was a useful technique for non-isothermally heated and porous media filled triangular enclosures. © 2008 Elsevier Ltd. All rights reserved.