Effect of Twisted Slice on Fluid Dynamics Performances of Fluid Media in Cracking Furnace Tube

2012 ◽  
Vol 516-517 ◽  
pp. 758-762
Author(s):  
Meng Han ◽  
Cheng Jiang Dong ◽  
Liang Gao ◽  
Feng He Liu
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Pressure Distribution ◽  
Circular Tube ◽  
Central Area ◽  
Wall Area ◽  
Fluid Media ◽  
Axial Velocity Distribution ◽  
Furnace Tube ◽  
Temperature And Pressure

Employing air at normal temperature and pressure as fluid media, the effect of twisted slice on fluid dynamics performances of fluid in cracking furnace tube was studied. The experimental results showed that boundary layer in cracking furnace tube fixed with twisted slice became thin, which leaded to the increase of heat transfer coefficient. So heat transfer was enhanced. Axial velocity distribution in central area of the tube fixed with twisted slice was smoother than that of circular tube, while velocity grad in near wall area was greater. Pressure drop increased in the tube fixed with twisted slice, whereas pressure distribution was even along axial length of the tube, in agreement with the pressure distribution in circular tube.

3D Simulation on Flow Behavior and Heat Transfer in a Circular Tube with Inclined Different Arrangement of Thin Rib

2012 ◽  
Vol 622-623 ◽  
pp. 628-632
Author(s):  
Amnart Boonloi ◽  
Withada Jedsadaratanachai ◽  
Pongjet Promvonge
Keyword(s):  
Heat Transfer ◽  
Test Section ◽  
Circular Tube ◽  
Flow Behavior ◽  
Central Area ◽  
Simple Algorithm ◽  
Vortex Flows ◽  
Drastic Increase ◽  
Rib Vortex ◽  
Volume Method

This work deals with periodic flow, friction loss and heat transfer characteristics in a constant temperature-surfaced circular tube fitted with rib vortex generators (RVG). The computations are based on the finite volume method with the SIMPLE algorithm implemented. The fluid flow and heat transfer behaviors are presented for Reynolds numbers ranging from 100 to 1000. To generate two main vortex flows through the tested section, the 45o RVGs are mounted repeatedly in in-line arrangements on the top and bottom walls and in the central area of the tested section. Effects of different RVG heights, BR in a range from 0.1D to 0.3D with a single pitch of 1.5D on heat transfer and friction losses in the test section are examined. It is apparent that the vortex flows created by the RVG exist and help to induce periodically impinging flows on a sidewall leading to drastic increase in the heat transfer rate over the test section. The computational results reveal that the optimum thermal performance is about 2.38 for using the RVG height of 0.2D for the RVG placed on the tube walls at the highest Re value.

Viscous Dissipation Effects on Developing Laminar Flow in Adiabatic and Heated Tubes

1975 ◽  
Vol 189 (1) ◽  
pp. 129-137 ◽  
Author(s):  
M. W. Collins
Keyword(s):  
Heat Transfer ◽  
Viscous Dissipation ◽  
Circular Tube ◽  
Recent Experimental Data ◽  
Nusselt Numbers ◽  
Developing Flow ◽  
Constant Wall Heat Flux ◽  
Finite Difference Solution ◽  
Viscosity Variation ◽  
Temperature And Pressure

A finite-difference solution is presented for the problem of laminar developing flow in a circular tube, allowing for viscous dissipation and viscosity variation with temperature. Predictions of temperature and pressure under adiabatic conditions compare reasonably with published experimental and analytical results. Polak's postulation of a hot slip zone is considered. Heat transfer, with constant wall heat flux, is also studied and it is concluded, with reference to some recent experimental data, that it is not necessary to postulate viscous dissipation as being a substantial aiding effect. Predicted Nusselt numbers are, in fact, reduced by allowing for the effect.

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