Three flux-type models for three-dimensional radiative heat transfer were applied to the prediction of the radiative flux density and the source term of a box-shaped enclosure problem based on data reported previously on a large-scale experimental furnace with steep temperature gradients. The models, which are a six-term discrete ordinate model and two Schuster-Schwarzschild type six-flux models, were evaluated from the viewpoints of both predictive accuracy and computational economy by comparing their predictions with exact solutions produced previously. The comparison showed that the six-flux model based on angular subdivisions related to the enclosure geometry produces more accurate results and is computationally less expensive than the other two models.


Experimental thermal performance characterization of flat grooved heat pipes
Alijani, Hossein; Çetin, Barbaros; Akkuş, Yiğit; Dursunkaya, Zafer (TAYLOR & FRANCIS INC, 530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA, 2015-06-15)
The thermal characterization of aluminum flat grooved heat pipes is performed experimentally for different groove dimensions. Three heat pipes with groove widths of 0.2 mm, 0.4 mm, and 1.5 mm are used in the experiments. The effect of the amount of the working fluid is extensively studied for each groove width. The results reveal that, although all three succeed in dissipating the heat input through the phase change of the working fluid by continuous evaporation and condensation, the effectiveness of the he...
Analysis of single phase convective heat transfer in microtubes and microchannels
Çetin, Barbaros; Yüncü, Hafit; Department of Mechanical Engineering (2005)
Heat transfer analysis of two-dimensional, incompressible, constant property, hydrodynamically developed, thermally developing, single phase laminar flow in microtubes and microchannels between parallel plates with negligible axial conduction is performed for constant wall temperature and constant wall heat flux thermal boundary conditions for slip flow regime. Fully developed velocity profile is determined analytically, and energy equation is solved by using finite difference method for both of the geometr...
Analysis of single phase convective heat transfer in microchannels with variable thermal conductivity and variable viscosity
Gözükara, Arif Cem; Güvenç Yazıcıoğlu, Almıla; Department of Mechanical Engineering (2010)
In this study simultaneously developing single phase, laminar and incompressible flow in a micro gap between parallel plates is numerically analyzed by including the effect of variation in thermal conductivity and viscosity with temperature. Variable property solutions for continuity, momentum and energy equations are performed in a coupled manner, for air as a Newtonian fluid. In these analyses the rarefaction effect, which is important for the slip flow regime, is taken into account by imposing slip veloc...
Numerical simulation and analytical optimization of microchannel heat sinks
Türkakar, Göker; Okutucu Özyurt, Hanife Tuba; Department of Mechanical Engineering (2010)
This study has two main objectives: The performance evaluation of existing microchannel heat sinks using a CFD model, and the dimensional optimization of various heat sinks by minimizing the total thermal resistance. For the analyses, the geometric modeling is performed using the software GAMBIT while the thermal analysis is performed with FLUENT. The developed model compares very well with those available in the literature. Eight different metal-polymer microchannel heat sinks are analyzed using the model ...
Numerical and experimental investigation of forced filmwise condensation over bundle of tubes in the presence of noncondensable gases
Ramadan, Abdul-Ghani M; Yamalı, Cemil; Department of Mechanical Engineering (2006)
The problem of the forced film condensation heat transfer of pure steam and steam-air mixture flowing downward a tier of horizontal cylinders is investigated numerically and experimentally. Liquid and vapor-air mixture boundary layers were solved by an implicit finite difference scheme. The effects of the free stream non-condensable gas (air) concentration, free stream velocity (Reynolds number), cylinder diameter, temperature difference and angle of inclination on the condensation heat transfer are analyze...
Citation Formats
N. Selçuk, “EVALUATION OF FLUX MODELS FOR RADIATIVE-TRANSFER IN RECTANGULAR FURNACES,” INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, pp. 1477–1482, 1988, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/31223.