scholarly journals Effect of Secondary Air Injection on Bed-To-Wall Heat Transfer in a Clrculating Fluidized Bed.

1996 ◽  
Vol 29 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Yong Jun Cho ◽  
Won Namkung ◽  
Sang Done Kim ◽  
Sunwon Park ◽  
Pyung-Tchai Kim
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Air Injection ◽  
Wall Heat Transfer ◽  
Secondary Air Injection ◽  
Secondary Air

Gas mixing in a multi-stage conversion fluidized bed (MFB) with secondary air injection. Part I: an experimental study

RSC Advances ◽  
2016 ◽  
Vol 6 (43) ◽  
pp. 36642-36655 ◽  
Author(s):  
Rong Zhang ◽  
Zhenhua Hao ◽  
Zhiyu Wang ◽  
Xiaodong Huo ◽  
Junguo Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Air Injection ◽  
Gas Mixing ◽  
Cold Model ◽  
Stage Conversion ◽  
Multi Stage ◽  
Secondary Air Injection ◽  
Secondary Air

This paper investigated the distribution of secondary air after injection into a multi-stage conversion fluidized bed (MFB) cold model.

scholarly journals Improvement of Solid-Gas Interaction in Fluidized Bed Systems via Secondary Air- Injection

2017 ◽  
Vol 135 ◽  
pp. 00014
Author(s):  
Mohd Faizal Mohideen Batcha ◽  
Sulastri Sabudin ◽  
Jamal Hazri Zakaria
Keyword(s):  
Fluidized Bed ◽  
Air Injection ◽  
Secondary Air Injection ◽  
Secondary Air

Heat Transfer Enhancement in Electronic Modules Using Various Secondary Air Injection Hole Arrangements

1998 ◽  
Vol 120 (2) ◽  
pp. 342-347 ◽  
Author(s):  
B. A. Jubran ◽  
M. S. Al-Haroun
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Reynolds Numbers ◽  
Air Injection ◽  
Transfer Enhancement ◽  
Injection Hole ◽  
Secondary Air Injection ◽  
Secondary Air ◽  
Compound Angle

This paper reports an experimental investigation to study the effects of using various designs of secondary air injection hole arrangements on the heat transfer coefficient and the pressure drop characteristics of an array of rectangular modules at different values of free-stream Reynolds numbers in the range 8 × 103 to 2 × 104. The arrangement used is either one staggered row of simple holes or one row of compound injection holes. The pitch distances between the injection holes, as well as the injection angles, were varied in both the streamwise and spanwise directions. Generally, the presence of secondary air through the injection hole arrangement can give up to 54 percent heat transfer enhancement just downstream of the injection holes. The amount of heat transfer enhancement and pressure drop across the electronic modules is very much dependent on the design of the injection holes. The simple angle injection hole arrangement tends to give a better heat transfer enhancement and less pressure drop than the compound angle holes.

Assessment of Reynolds-Averaged Turbulence Models for Prediction of the Flow and Heat Transfer in an Inlet Vane-Endwall Passage

2004 ◽  
Vol 126 (3) ◽  
pp. 305-315 ◽  
Author(s):  
Hugo D. Pasinato ◽  
Kyle D. Squires ◽  
Ramendra P. Roy
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Leading Edge ◽  
Air Injection ◽  
Stanton Number ◽  
Computational Domain ◽  
Cooling Effectiveness ◽  
Vortical Structures ◽  
Secondary Air Injection ◽  
Secondary Air

Predictions of the flow and thermal fields in an inlet vane passage are obtained via solution of the incompressible Reynolds-averaged Navier-Stokes (RANS) equations. RANS predictions of the steady-state solutions are obtained using two scalar eddy viscosity models and full Reynolds stress transport to close the turbulent stress in the momentum equations. The turbulent heat flux is modeled using a constant turbulent Prandtl number. In the geometric configuration of the inlet vane passage, the hub endwall is flat. Calculations are performed for a baseline configuration and an additional configuration in which secondary air is injected through three small, angled slots positioned upstream of the vane leading edge. Solutions are obtained on unstructured grids with the densest mesh comprised of 1.9×106 elements. The simulations are assessed via an inter-comparison of predictions obtained using the different models, as well as through evaluation against experimental measurements of the Stanton number and cooling effectiveness on the hub endwall. The flow develops from a turbulent boundary layer at momentum thickness Reynolds number 955 prescribed at the inlet to the computational domain, 1.3 axial chord lengths upstream of the vane leading edge. The mean velocity at the inlet is prescribed to match an experimentally-measured profile with low freestream turbulence. For the case with secondary air injection, the blowing ratio was 1.3. Solid surfaces are isothermal at temperatures below that of the mainstream gas. Simulation results show that the vortical structures resolved by the models in the vicinity of the vane leading edge for the baseline case are relatively insensitive to the particular turbulence closure. The elevation in heat flux levels due to entrainment of higher temperature mainstream gas towards the endwall by the horseshoe vortex is captured, Stanton number distributions exhibit adequate agreement with measured values. While there are similarities in the coherent structures resolved by the models, details of their evolution through the passage lead to differences in heat transfer distribution along the endwall. Secondary air injection strongly distorts the flow structure in the vicinity of the leading edge, the vortical structures that develop in the calculations with air injection evolve primarily from the interaction of the fluid issuing from the slots and the mainstream flow. Elevated levels of cooling effectiveness predicted by the models correspond to larger areas of the endwall than measured, peak Stanton numbers are higher than the experimental values.

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