Convection heat transfer of supercritical pressure carbon dioxide in a vertical micro tube from transition to turbulent flow regime

2013 ◽  
Vol 56 (1-2) ◽  
pp. 741-749 ◽  
Author(s):  
Pei-Xue Jiang ◽  
Bo Liu ◽  
Chen-Ru Zhao ◽  
Feng Luo
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Turbulent Flow ◽  
Flow Regime ◽  
Convection Heat Transfer ◽  
Supercritical Pressure ◽  
Convection Heat ◽  
Turbulent Flow Regime

Numerical Investigation of Buoyancy Effect on Mixed Convection Heat Transfer Deterioration of Supercritical Pressure Carbon Dioxide

2017 ◽  
Author(s):  
Guoli Tang ◽  
Zhouhang Li ◽  
Yuxin Wu ◽  
Qing Liu ◽  
Junfu Lyu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Mixed Convection ◽  
Pipe Flow ◽  
Convection Heat Transfer ◽  
Supercritical Pressure ◽  
Convection Heat ◽  
Temperature Peak ◽  
Heat Transfer Deterioration ◽  
Mixed Convection Heat Transfer

For supercritical pressure fluid upward pipe flow, turbulent mixed convection heat transfer deterioration, which is generally considered to be caused by buoyancy, is often put a deep concern for safety issues. The deterioration is typically characterized by a localized wall temperature peak. Sometimes, there will be another moderate temperature peak after the first one. However, due to the lack of reliable measure method, the understanding of the flow structure for these two localized temperature peaks were still limited. In order to investigate the detailed mechanism for these two peaks and further understand the effect of buoyancy, a numerical study of supercritical pressure carbon dioxide pipe flow mixed convection heat transfer deterioration was conducted in this paper. The SST k-omega model was selected as turbulence model. A variable turbulent Prandtl number model was adopted in the study to improve simulation accuracy. The variation of flow field and turbulence behavior were carefully analyzed. The results show that, the localized wall temperature rise is due to the suppressed turbulence in the near wall region. For the first localized temperature peak, the suppressed turbulence is due to the acceleration of near wall fluid. While for the second one, the restrained turbulence is due to the acceleration of core flow fluid.

Simulation of mixed convection heat transfer to carbon dioxide at supercritical pressure

2004 ◽  
Vol 218 (11) ◽  
pp. 1281-1296 ◽  
Author(s):  
S He ◽  
W S Kim ◽  
P X Jiang ◽  
J D Jackson
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Carbon Dioxide ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Turbulence Models ◽  
Supercritical Pressure ◽  
Convection Heat ◽  
Computational Simulations ◽  
Mixed Convection Heat Transfer

Computational simulations of turbulent mixed convection heat transfer experiments using carbon dioxide at supercritical pressure have been performed by solving the Reynolds averaged transport equations using an elliptic formulation. A number of two-equation low Reynolds number turbulence models have been used and the results have been compared directly with the experimental data. It has been shown that most of the models were to some extent able to reproduce the effects of the very strong influences of buoyancy on heat transfer in these experiments. However, the performance of the models varied significantly from one to another in terms of the predicted onset of such effects.

Modifying a meshless method to solving κ−ε turbulent natural convection heat transfer

2019 ◽  
Vol 31 (01) ◽  
pp. 2050014
Author(s):  
Nasrin Sheikhi ◽  
Mohammad Najafi ◽  
Vali Enjilela
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Numerical Methods ◽  
Turbulent Flow ◽  
Turbulent Viscosity ◽  
Convection Heat Transfer ◽  
New Technique ◽  
Test Cases ◽  
Convection Heat ◽  
Transfer Problems

The conventional meshless local Petrov–Galerkin method is modified to enable the method to solve turbulent convection heat transfer problems. The modifications include developing a new computer code which empowers the method to adopt nonlinear equations. A source term expressed in terms of turbulent viscosity gradients is appended to the code to optimize the accuracy for turbulent flow domains. The standard [Formula: see text] transport equations, one of the most applicable two equation turbulent viscosity models, is incorporated, appropriately, into the developed code to bring about both versibility and stability for turbulent natural heat transfer applications. The amenability of the new developed technique is tested by applying the modified method to two conventional turbulent fluid flow test cases. Upon the obtained acceptable results, the modified technique is, next, applied to two conventional natural heat transfer test cases for their turbulent domain. Based on comparing the results of the new technique with those of the available experimental or conventional numerical methods, the proposed method shows good adaptability and accuracy for both the fluid flow and convection heat transfer applications in turbulent domains. The new technique, now, furthers the applicability of the mesh-free local Petrov-Galerkin (MLPG) method to turbulent flow and heat transfer problems and provides much closer results to those of the available experimental or conventional numerical methods.

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