Simulation of mixed convection heat transfer in a horizontal channel with an open cavity containing a heated hollow cylinder

2012 ◽  
Vol 41 (4) ◽  
pp. 339-353 ◽  
Author(s):  
M.M. Rahman ◽  
S. Parvin ◽  
N.A. Rahim ◽  
M. Hasanuzzaman ◽  
R. Saidur
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Hollow Cylinder ◽  
Convection Heat Transfer ◽  
Open Cavity ◽  
Horizontal Channel ◽  
Convection Heat ◽  
Mixed Convection Heat Transfer

Investigation of Temperature Uniformity in an Open Cavity of Buoyancy Assisted Mixed Convection Heat Transfer With Multiple Discrete Inlet and Outlet Ports

2014 ◽  
Author(s):  
G. Yang ◽  
J. Y. Wu ◽  
Y. W. He ◽  
L. Yan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Temperature Gradient ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Open Cavity ◽  
Temperature Uniformity ◽  
Convection Heat ◽  
Grashof Number ◽  
Mixed Convection Heat Transfer

Turbulent buoyancy assisted mixed convection heat transfer in an open cavity with multiple discrete inlet and outlet ports is investigated experimentally. The side walls of the rectangular cavity are symmetrically heated with constant and uniform temperature. The temperature distribution in the interior of the cavity is presented and discussed for the Reynolds numbers of 3919 ≤ Re ≤ 35405, the Grashof numbers of 1.56 × 107 ≤ Gr ≤ 3.45 × 107, the Prandtl number of Pr = 0.71 and for various quantities of inlet and outlet ports ranging from 1 × 1 to 5 × 5 with the same total opening area. Increasing Reynolds number and decreasing Grashof number can improve the temperature uniformity in the cavity. As the dispersion of the inlet ports increases, the maximum temperature gradient of the fluids in the cavity is decreased while the average temperature gradient is increased. The effect of inlet/outlet forms, Reynolds number and Grashof number on the Nusselt number is also investigated.

Numerical Study on Mixed Convection Heat Transfer Enhancement in a Long Horizontal Channel Using Periodically Distributed Rotating Blades

2019 ◽  
Author(s):  
Mahmudul Islam ◽  
Shahriar Alam ◽  
Md. Shajedul Hoque Thakur ◽  
Mohammad Nasim Hasan ◽  
M. Ruhul Amin
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Prandtl Number ◽  
Mixed Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Horizontal Channel ◽  
Convection Heat ◽  
Rotating Blades ◽  
Mixed Convection Heat Transfer

Abstract A numerical study has been conducted on mixed convection heat transfer enhancement in a long horizontal channel provided with periodically distributed rotating blades. The upper wall of the channel is maintained at a constant low temperature (Tc) while the lower wall is kept hot at a constant high temperature (Th). A series of rotating blades having negligible thickness in comparison to its length is placed periodically along the centerline of the channel with the spacing between two successive blades’ rotational axes being equal to the height of the channel under consideration. The mathematical model of the present problem is governed by two-dimensional laminar transient continuity, momentum and energy equations. The governing equations are transformed to non-dimensional forms and then the moving mesh problem due to blade motion is solved by implementing Arbitrary Lagrangian-Eulerian (ALE) finite element formulation with triangular discretization scheme. Three different working fluids have been considered such as water, air and liquid Gallium that essentially cover a wide range of Prandtl Number (Pr) from 0.026 to 7.1. The dynamic condition of the rotating blades has been represented by Reynolds Number (Re) that is varied in the range of 1 to 500 and its effect on fluid flow and heat transfer has been investigated for the case of pure mixed convection heat transfer, characterized by Richardson number (Ri) of unity. Numerical results have been presented and analyzed in terms of the distribution of streamline and isotherm patterns, spatially averaged Nusselt number and normalized average Nusselt number variation along the hot wall for different parametric system configurations. The results of the present study show that, presence of rotating blades increases the heat transfer significantly in the channel. Heat transfer increases with increasing Prandtl Number (Pr) and the enhancement becomes more significant at higher Reynolds Numbers (Re).Power Spectrum analysis in frequency domain obtained from the FFT analysis indicates that, the rotating blade oscillation frequency and the oscillation frequency of Nusselt number differ at higher range of Reynolds Number (Re) and Prandtl Number (Pr). Therefore, dynamic condition of the rotating blades together with the thermophysical properties of working fluid play vital role in modulating the heat transfer characteristics and fluid flow behavior within the long horizontal channel.

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