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International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 1
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Numerical Investigation of New Cooling Method for
Clinker Flow in Parallel with Air flow at
Different Height Ratios
Nasr A. Jabbar1, M.J. ALshukri1, Wakkas Ali Rasheed1, Ihsan Y. Hussain2
1Department of Mechanical Engineering, Faculty of Engineering, University of Kufa, Najaf, Iraq 2Department of Mechanical Engineering, College of Engineering, University of Baghdad, Baghdad, Iraq
Abstract-- The properties of Portland cement depend on several
parameters, and the cooling method is one of these parameters.
When the effectiveness of cooling method increases, the
properties of Portland cement are enhanced. In the present work,
a new cooling method is suggested and numerical analysis is
made by CFD modeling using (FLUENT 6.3.26). Using the same
dimensions of cooling room in grate cooler, constant mass flow
rate of air and clinker, different porosity of clinker, and different
height ratios ( height of air / height of clinker), the numerical
results were calculated. The results show that the height ratio is
an important factor affecting the new cooling method and can be
used in order to decrease the length of cooling room or the time
of cooling process according to the porosity of clinker. The
maximum temperature of clinker with the lowest possible
porosity is much lower than the maximum temperature of
clinker with maximum porosity at a constant height ratio (H.R.).
Also, when the height ratio (H.R.) increases, the temperature of
clinker decreases at any point, also the rate of change between
clinker and air temperature decreases with increasing the height
ratio (H.R.).
Index Term-- Clinker; Cooling Process; Forced Convection;
Porosity; CFD. 1. INTRODUCTION
The production of Portland cement consists of three
fundamental stages [1,2]: (a) Preparation of the raw mixture,
(b) Production of the clinker, (c) Preparation of the cement.
The requirements of each stage are generally constant in spite
of the changes in properties of raw materials and operation
conditions. The production of the clinker is the most important
stage because there are several variables affecting on it.
Portland cement clinker is a hydraulic material composed
primary of calcium silicates, aluminates, and ferrites and it
remains the essential component of all standardized cements.
A clinker or clinker nodules are homogeneous material
produced from a finely ground, homogenized blend of
limestone, shale and iron ore. The properties of clinker
nodules (the phase composition of the clinker and the
morphology of the individual clinker phases) have a decisive
influence on the cement quality. These parameters are
controlled by the composition of the raw material (first stage),
and also by the combustion and cooling conditions during the
clinker burning process (second stage) [1,3]. One of the most
important parameters affecting in clinker production is the rate
of cooling [4]. Several studies were made to investigate the
effect of cooling rate on the composition and crystal structures
(crystallization of alite and belite) of clinker [5-9].
Generally, there are four types of clinker cooler (Rotary
cooler, satellite cooler, shaft cooler and grate cooler). The
grate cooler is the most important type because of its thermal
efficiency compares with other types of coolers [10]. Several
researchers studied the heat and mass transfer in the grate
cooler in order to control on clinker cooling process.
Touil [11] used finite element to simulate clinker cooling
process in grate cooler. Mujumdar [12] carried on overall heat
balance calculation of double-input and multiple-output to
analyze heat transfer in the grate cooler. Locher [13]
conducted a control model using the heat transfer analysis of
gas through the particle bed. He investigated the influence of
grate speed and particle size distribution on clinker cooling
process. Li [14] studied a chemical reaction of calcining
process of limestone and modeled the heat-mass transfer
coupling in this process. He found that solid particle size, inlet
flow velocity, and inlet gas temperature were important
parameters to the system characteristics. Zhang [15] simulated
using Fluent software and he found the optimal gas flow and
heat transfer in sinter circular cooler. In recent years, the
seepage heat transfer theory used in order to study and control
the clinker cooling as porous media at high temperature
[16,17].
1.1. NEW SUGGESTED COOLING METHOD The grate cooler consists of number of cooling rooms
depending on the size of grate cooler. These rooms arrange as
series and clinker enters each room (see Fig.(1)). The fresh air
(or cold air) generally enters from the bottom of the room and
the hot air sometimes flow parallel to the clinker (cold zone)
and another flow counter to the clinker (warm zone). These
cooling conditions produce sometimes warm clinker due to
change in mass flow rate of clinker and air, properties of raw
materials and working conditions, therefore; the clinker
properties will be bad relatively. In present work, the new
method suggests using the same rooms separately and
controlling on the mass flow rate of air of each room
depending on mass flow rate of clinker, input and output
temperature of clinker and the porosity of clinker.
The new suggested cooling method, used in present work,
assumed that:
1. The dimensions of the clinker cooling room are equal
to the dimensions of one stage in grate cooler (i.e.
height of room is 0.6 m and width of room is 1.8 m).
2. The mass flow rate of air and clinker is constant and
equal to 30 kg/sec [10].
3. The flow of air and clinker are parallel (see Fig.(1)).
4. The clinker is assumed as a porous media with
porosity (0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7).
5. The inlet temperature of cold air is 300K.
6. The inlet temperature of hot clinker is 1600K.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 2
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 1. Scheme of the clinker cooler.
Fig. 2. The Geometry and Conditions of the Cooling Room
In this method, the height ratio (H.R.), which defined as the
ratio between the height of air to the height of clinker
(Hair/Hclinker), is changed as (1, 1.5, 2, 2.5 and 3) in order to
study the effect of air height on the required length of cooler
when the clinker height decreases.
2. MATHEMATICAL METHODOLOGY
“A mathematical model is identified which is appropriate for
the description of steady, two-dimensional, convection in a
fluid-saturated porous medium. For theoretical studies of
convective heat transfer in fluid-saturated porous material, the
following assumptions are often made and used:
The natural convection and the radiation heat transfer
are neglected.
The medium is assumed to have constant, isotropic,
and homogenous characteristics and properties
(permeability, porosity).
It is allowed that the temperature of solid and fluid
phases be different.[18]
The steady-state fully developed forced convection is
desired.
The porosity of the medium is considered to be
uniform and constant.
Local thermal equilibrium (LTE) is valid.
Viscous dissipation are negligible [19].”
2.1. GOVERNING EQUATIONS
In convection heat transfer, the convection process is
governed by the basic conservation principles of mass,
momentum and energy; therefore to determine the flow and
temperature fields, they are in vector form [20]; a schematic of
the physical model and coordinate system is shown in Fig.(3).
Continuity Equation;
Momentum equations;
Energy Equation;
The energy equation describing temperature distribution of the
flow inside the gate is given by
For the solid and air temperature inside the porous medium
two energy equations;
𝑘 − ϵ Equation [21];
The 𝑘 − 𝜖 turbulence model equation is written as:
In these equations, (k) is the turbulent kinetic energy (μt) is the
turbulent viscosity (S) is the modulus of the mean rate-of-
strain tensor (𝑝𝑘) represents the generation of turbulence
kinetic energy due to the mean velocity gradients. (𝑝𝑏) is the
generation of turbulence kinetic energy due to buoyancy.
Fig. 3. Schematic of The Physical Model and Coordinate System
3. NUMERICAL MODEL
FLUENT(6.3.26) software was used to conduct CFD
modeling and simulation. The important part in all CFD is to
design geometry of the problem. GAMBIT software was
employed to draw the geometry and generate mesh. GAMBIT
offers graphical user interface to get inputs from user. The
numerical modeling is achieved by dividing the geometry into
a grid network. The mesh density used in this study was high
enough to assure all relevant flow feature [22]. The numerical
solution is obtained by dividing the domain of interest into a
grid network, The mesh density should be high enough to
capture all relevant flow feature.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 3
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
The mean cell count deviation (skewnees) for the current
model was 0%. Quadrilateral cells = 10800, and Face count=
21840, The user defined function was used to specify
properties of fluid and porous media ( clinker) (See Table(1)).
Table I
The Properties of Air and Clinker Used in This Work [10] Property Clinker Air
Density(kg/m3) 1350 342.1*t-1.0002
Viscosity(kg/m.sec) ------ 342.1t0.6769 *109 Heat Capacity
(J/kg.K)
0.632+4.62*10-4 t-
0.37*10-7 t2
0.97+1.37*t*10-4-4t2
Thermal
Conductivity
(W/m.K)
0.2 1*t1.6771*10-9
4. VALIDATION OF NUMERICAL MODEL
To belay of the results acquired from the present study, a
comparison was made with the results checked by prior
studies, which insure validity the program, the practical part of
the research [21] was simulated, The experimental
investigation of this research covered a set of experiments
executed to study the forced convection heat transfer from a
heated flat plate embedded in porous media with a constant
heat flux. The inquiry covered values of heat flux of (1000,
2000, 3000, 4000 and 5000 W/m²) and different velocities
values of (V=1.868, 3.451, 5.73 and 6.367 m/s).
The geometry of the design model consists of two regions of
interest. These are: the flow duct with dimensions (L=1872
mm x W=184 mm x H=333 mm). The smaller box with
dimensions (L=270mm x W=130mm x H=70mm), this box:
on base consist of heated Aluminum plate with dimensions
L=250mm x W=90mm and filled with porous media (glass
beads with diameter 12mm), as shown in figure (4). A
comparison between the experimental and theoretical results
has been made for one case, so figures (5a,b,c and d) show the
numerical and experimental results for temperature profile that
compared with each other. This figure is plotted for
temperatures with q"=5000W/m2 and all velocities above for
x-direction in the box. Figures present that the numerical
simulation follows the same trend as the results of
experimental work, with 5.6% variation.
Fig. 4. Model Geometry (all Dimensions in mm)
(a) V= (20%, 2.15 m/s)
(b) V=(40%, 3.451m/s)
(c) V= (70%, 5.73 m/s)
(d) V= (100%, 6.367 m/s)
Fig. 5. Experimental results versus Numerical results for temperature profile at q"=5000 W/m2,V=( 2.15,3.451,5.73 and 6.367 m/s)
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 4
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
5. RESULTS AND DISCUSSIONS
Figure (6) shows temperature distribution in cooling room (air
and clinker) at different height ratios (H.R.) when the porosity
of the clinker is (0.1). The temperature along the length of
cooling room for the solid phase (clinker) decreases in the
incident direction, however, for the fluid phase (air)
temperature; it increases along the length direction.
The response of the temperature to varying values of the
clinker porosity from 0.1 to 0.7 is illustrated in Figures (6) to
(12), and to represent the situation clearly, the temperature
lines for temperature at limited heights and at length of gate is
taken in figures (13) to (17), where the increasing porosity
leads to corresponding decrease in damping properties (the
rate of damping for fluid comes by three components which
are viscous, orifice and friction components) in the flow and
leads to decrease in resistance flow, and on the other side the
temperature of air decreases with an increase in porosity. It is
clear that when the average temperature decreases, it means
that the heat transfer rate increases. Because at low porosities
one observes that the resistance of the convective flow
becomes weaker because of an increase in the flow resistance
from the less permeable outer sub-layers. Also It can be seen
that the clinker temperature decreases when using the variable
porosity material along the length direction.
Also, when the height ratio (H.R.) increases, the temperature
of clinker decreases at any point, because more heat is
removed from the clinker. In the other hand, the rate of change
between clinker and air temperature decreases with increasing
the height ratio (H.R.). Consequently, the maximum
temperature inside the clinker region decreases. Same
behavior is also seen in Figures (7) to (12). This fact can be
Fig. 6. Effect of Height Ratio (H.R.) on Temperature Distribution in Cooling Room When ε=0.1.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 5
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
seen in Figures (13) to (17) when the height ratio (H.R.)
changes from 1 to 3.
The results also show that at a constant height ratio (H.R.), the
maximum temperature of clinker with the lowest possible
porosity is much lower than the maximum temperature of
clinker with maximum porosity. It is the main reason for
prevention of air flow through the void space of porous media.
In Fig (18), the comparison among temperatures variation at
the end of cooling room due to change in height Ratio (H.R.)
at different height (h) and different porosity (ε) is shown. It is
found that the convection heat transfer increases more slightly
at different height due to change in clinker porosity, which is
due to the high temperature gradient of the solid phase with
changing porosity effect.
This can be attributed to permeability of the porous region that
acts quite similar to a solid obstacle in low permeability vice
versa. The curves in figure (18) show that the maximum
temperature of clinker is inversely proportional with the height
Ratio (H.R), however a higher height Ratio (H.R) is the best
solution due to cooling rate enhancement which are required
as well as that the speed of cooling Clinker is an important
advantage [3, 23] .
Fig. 7. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.2.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 6
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Fig. 8. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.3.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 7
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 9. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.4.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 8
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 10. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.5.
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Fig. 11. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.6.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 10
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 12. Effect of Height Ratio (H.R.) on Temperature Distribution
in Cooling Room When ε=0.7.
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I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 13. Temperature Distribution Along Length of Cooling Room
at Different Height (h) When Height Ratio (H.R.)=1.
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 12
I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 14. Temperature Distribution Along Length of Cooling Room
at Different Height (h) When Height Ratio (H.R.)=1.5.
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I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 15. Temperature Distribution Along Length of Cooling Room
at Different Height (h) When Height Ratio (H.R.)=2.
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I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 16. Temperature Distribution Along Length of Cooling Room
at Different Height (h) When Height Ratio (H.R.)=2.5.
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I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 17. Temperature Distribution Along Length of Cooling Room
at Different Height (h) When Height Ratio (H.R.)=3.
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I J E N S 2018 IJENS JuneIJENS © -IJMME-7272-301804
Fig. 18. Temperature Variation at the End of Cooling Room due to Change in Height Ratio (H.R.) at Different Height (h) and Different Porosity (ε).
International Journal of Mechanical & Mechatronics Engineering IJMME-IJENS Vol:18 No:03 17
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6. CONCLUSIONS
The following conclusions may be drawn from this study:
1. The temperature along the length of cooling room for
the clinker is decrease in the incident direction, while
for the air temperature; it increases along the length
direction.
2. When the height ratio (H.R.) increases, the
temperature of clinker decreases at any point, also the
rate of change between clinker and air temperature
decreases with increasing the height ratio (H.R.).
3. With an increase in porosity, the temperature of air
decreases and the clinker temperature decreases
when using the variable porosity material along the
length direction.
4. At a constant height ratio (H.R.), the maximum
temperature of clinker with the lowest possible
5. porosity is much lower than the maximum
temperature of clinker with maximum porosity.
6. The convection heat transfer increases more slightly
at different height due to change in clinker porosity,
which is due to the high temperature gradient of the
solid phase with changing porosity effect.
The maximum temperature of clinker is inversely proportional
with the height Ratio (H.R), however a higher height Ratio
(H.R) is the best solution due to cooling rate enhancement.
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