PosterPDF Available

Abstract

The rate of airflow through a sugar beet clamp is central in the thermodynamic processes that occur during storage. It determines the rate at which ambient air and the air inside the clamp exchange through advection, and the rates at which heat and moisture transfer between the beets and the air. Computational Fluid Dynamics (CFD) is a method commonly used by engineers to model fluid dynamics and heat transfer processes in complex systems. Thanks to increased computing power and generous open source software communities, programming high-resolution CFD models is a much more accessible research avenue. Using the open source software programs R and Blender (physical model creation), OpenFOAM (CFD modelling), and ParaView (results visualisation), a series of CFD models of stylised sugar beet clamps were developed. Clamp size was modelled as either 7 m, 8 m, or 9 m wide at the base. The clamp was modelled as either uncovered, or covered with TopTex. Ambient wind velocity was taken as either 1, 5, or 10 m/s normal to the clamp length. The porous medium approach was adopted, and Darcy-Forchheimer (D-F) parametrization applied. The D-F values for the clamp region were fixed at values derived from previous research (Tabil et al, 2003), for small, large and mixed beet sizes. D-F values for TopTex were supplied by TenCate Industrial Fabrics. An additional model of a clamp with active ventilation was developed. The steady airflow profiles of eleven models are presented.
NBR Nordic Beet Research foundation,
Borgeby Slottsväg 11, SE-237 91 Bjärred
MODELLING AIRFLOW IN SUGAR BEET CLAMPS
WILLIAM ENGLISH 1, 2
1 NBR Nordic Beet Research foundation, Bjärred, SE; 2 Swedish University of Agricultural Sciences (SLU), Alnarp, SE. e-mail: we@nbrf.nu
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 9 m
BEET SIZE: Mixed
COVER: None
AMBIENT AIR SPEED: 1 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Mixed
COVER: TopTex
AMBIENT AIR SPEED: 1 m.s-1
CLAMP SIZE: 9 m
BEET SIZE: Small
COVER: TopTex
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Large
COVER: None
AMBIENT AIR SPEED: 10 m.s-1
CLAMP SIZE: 7 m
BEET SIZE: Large
COVER: None
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 7 m
BEET SIZE: Mixed
COVER: None
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Mixed
COVER: None
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Small
COVER: None
AMBIENT AIR SPEED: 5 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Mixed
COVER: TopTex
AMBIENT AIR SPEED: 10 m.s-1
CLAMP SIZE: 8 m
BEET SIZE: Mixed
COVER: TopTex
1 2
3 4 5
6 7 8
910
0
0,05
0,1
0,15
0,2
0,25
0,3
0,35
0,4
0,45
0,5
1357
AIR SPEED (m.s-1)
WIDTH (m)
1
2
3
4
5
6
7
8
9
10
MODEL
METHOD:
Computational Fluid Dynamics
Program: OpenFOAM
Temporal model: Transient
Turbulence model: k-epsilon
Solver: PIMPLE
Solution (U): linear upwind
Porous medium approach
Ambient Air Speed (Inlet):
-1 m.s-1, left to right
-5 m.s-1, left to right
-10 m.s-1, left to right
Clamp size:
-7 x 2.33 m
-8 x 2.67 m
-9 x 3.00 m
Beet size Darcy-Forchheimer coeffs.*
- Small: 530000 / 450
- Mixed: 100000 / 370
-Large: 520000 / 300
Cover Darcy-Forchheimer coeffs.**
-TopTex: 150000000 / 1400
Mesh: 2780 cells (2D)
Darcy-Forchheimer coefficients determine the
permeability of the porous medium. Higher
values indicate lower permeability (i.e. lower
airflow).
*Source: L. G. Tabil, J. Kienholz, H. Qi & M. V.
Eliason, (2003) “Airflow Resistance of
Sugarbeet, Journal of Sugar Beet Research,
Vol. 40 Issue 3 Pages 67-86
**Source: TenCate Industrial Fabrics
WITH ASSISTANCE FROM:
Air speed
m.s-1
ACTIVE VENTILATION. Inlet speed: 20 m.s-1. Mesh: 1.2 mill cells (3D). Ambient air speed: 0 m.s-1. D-F: 100000 / 370
INLET PAIRS (6 pairs in total)
3 m
BACKGROUND: The movement of air is a major driver of thermodynamic processes in post
harvest storage systems. It can have large impacts on the rates of heat and moisture
transfer.
PURPOSE: Present profiles of modelled air flow through naturally ventilated sugar beet
clamps, as affected by ambient air speed, clamp size, beet size, and cover type. Ambient
air flows left to right. Two profiles of an actively ventilated clamp are also presented.
CONCLUSIONS:
The model appears well behaved:
there is higher air flow in the porous
clamp region when there is higher
ambient air flow, a small clamp, larger
beets, and no cover. Ambient air speed
has the greatest effect on airflow in the
porous clamp region of the model. No
data is available for field validation.
1 m ABOVE GROUND
2.4 m
8 m
AIR SPEED IN CLAMP 1 m ABOVE GROUND
TO COMPARE…
SEE MODELS…
AMBIENT AIR SPEED 6, 7, 8
CLAMP SIZE 3, 4, 5
BEET SIZE 1, 4, 10
COVER 4, 7
EXTREMES 2, 9
KEY
ResearchGate has not been able to resolve any citations for this publication.
ResearchGate has not been able to resolve any references for this publication.