An experimental and three-dimensional numerical study on the convective heat transfer inside a trapezoidal duct under constant wall temperature

2008 ◽  
Vol 45 (3) ◽  
pp. 263-274 ◽  
Author(s):  
Nevzat Onur ◽  
Oğuz Turgut ◽  
Kamil Arslan ◽  
Özen Kurtul
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Wall Temperature ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Wall Temperature

Numerical Study of Turbulent Flow and Convective Heat Transfer Characteristics in Helical Rectangular Ducts

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Yunfei Xing ◽  
Fengquan Zhong ◽  
Xinyu Zhang
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Study ◽  
Rectangular Cross Section ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Axial Direction ◽  
Outer Wall ◽  
Centrifugal Effect

Three-dimensional turbulent forced convective heat transfer and its flow characteristics in helical rectangular ducts are simulated using SST k–ω turbulence model. The velocity field and temperature field at different axial locations along the axial direction are analyzed for different inlet Reynolds numbers, different curvatures, and torsions. The causes of heat transfer differences between the inner and outer wall of the helical rectangular ducts are discussed as well as the differences between helical and straight duct. A secondary flow is generated due to the centrifugal effect between the inner and outer walls. For the present study, the flow and thermal field become periodic after the first turn. It is found that Reynolds number can enhance the overall heat transfer. Instead, torsion and curvature change the overall heat transfer slightly. But the aspect ratio of the rectangular cross section can significantly affect heat transfer coefficient.

On the Convective Heat Transfer in a Tube of Elliptic Cross Section Maintained Under Constant Wall Temperature

1986 ◽  
Vol 108 (1) ◽  
pp. 33-39 ◽  
Author(s):  
M. A. Ebadian ◽  
H. C. Topakoglu ◽  
O. A. Arnas
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Convective Heat Transfer ◽  
Cross Section ◽  
Convective Heat ◽  
Wall Temperature ◽  
Elliptic Cross Section ◽  
Constant Wall Temperature ◽  
Elliptic Cross

The convective heat transfer problem along the portion of a tube of elliptic cross section maintained under a constant wall temperature where hydrodynamically and thermally fully developed flow conditions prevail is solved in this paper. The successive approximation method is used for the solution utilizing elliptic coordinates. Analytical expressions for temperature distribution and Nusselt number corresponding to the first cycle of approximation are obtained in terms of the ellipticity of the cross section. In the case of a circular section, the first cycle approximation of the Nusselt number is obtained as 3.7288 compared to the exact value of 3.6568. Representative temperature distribution curves are plotted and compared to those corresponding with constant wall heat flux conditions.

scholarly journals Effect of Thermophysical Properties Models on the Predicting of Convective Heat Transfer of Nanofluids With Considering Nanoparticles Migration

2010 ◽  
Author(s):  
Mohammad Mahdi Heyhat ◽  
Farshad Kowsary ◽  
Saeed Alem
Keyword(s):  
Heat Transfer ◽  
Physical Properties ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermophysical Properties ◽  
Numerical Study ◽  
Brownian Diffusion ◽  
Al2o3 Nanoparticles ◽  
Constant Wall Temperature ◽  
Transfer Behavior

In order to study the heat transfer behavior of the nanofluids, precise values of thermal and physical properties such as specific heat, viscosity and thermal conductivity of the nanofluids are required. There are a few well-known correlations for predicting the thermal and physical properties of nanofluids which are often cited by researchers to calculate the convective heat transfer behaviors of the nanofluids. Each researcher has used different models of the thermophysical properties in their works. The aim of the present paper is to study the convective heat transfer of nanofluids containing low volume concentration of Al2O3 nanoparticles with a regard to the migration of nanoparticles due to Brownian diffusion and thermophoresis. To do this, a two-component model has been used and a numerical study on laminar flow of alumina-water nanofluid through a constant wall temperature tube has been performed. Two different models have been adopted for predicting the thermophysical properties of nanofluids. All of the properties are assumed to be temperature as well as particle concentration dependent. The effects of these models on the predicted value of the convective heat transfer of nanofluid and the migration of nanoparticles have been discussed in detail.

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