1. PRESSURE DROP AND HEAT TRANSFER CHARACTERISTICS OF
LOUVERED FIN HEAT EXCHANGERS
SUPERVISED BY:
MR. SHAHRIN HISHAM BIN AMIRNORDIN
PRESENTED BY:
DJAMAL HISSEIN DIDANE
2. Figure 1: Flat-sided tube and louvered
plate fin heat transfersurface [1].
INTRODUCTION
Heat exchangers are devices
that facilitate the exchange of heat
between two fluids that are at
different temperatures while
keeping them from mixing with
each other.
Louvered fin compact heat
exchangers are used extensively in
several automotive applications
such as radiators, oil coolers,
condensers, and charge air coolers
[1].
3. Figure 2: Section through typical
louvered-fin showing key
geometrical parameters [15].
INTRODUCTION cont’
In order to improve the
performance of the heat exchanger
fins are added on the air side.
These serve several purposes:
They increase the available
surface for heat transfer and
interrupt the growth of the
boundary layer forming along the
fin surface [1].
4. BACKGROUND OF STUDY
• More efficient in enhancing heat transfer.
• Able to interrupt the growth of the boundary
layer forming along the fin surface.
• Louvered fin appears to be the most suitable
type of fin for automotive applications.
Advantages of
louvered fin
[1]:
• The associated pressure drop when using
louvered fin is significant.
• Adding more fins will increase the material cost
Disadvantages
[3]:
5. PROBLEM STATEMENT
Heat exchanger is an important device in automotive and
air conditioning applications, therefore having an effective
heat exchanger will enhance the performance of the whole
system.
Past studies have shown that the flow in the heat
exchanger is strongly dependent on geometrical parameters.
Hence, by manipulating the geometrical parameters of the
fin, we will obtain a heat exchanger with maximum heat
transfer coefficient and the pressure drop is within the
allowable design limit[1].
6. OBJECTIVE
SCOPE OF STUDY
The objective of this study is to determine the pressure drop
and heat transfer characteristics of a louvered fin heat exchanger.
Simulation will be performed using ANSYS Fluent.
Validation will be conducted using the experimental result from
literature.
The Reynolds number (based on louver pitch) is 200-1000.
The air inlet temperature is 27 °C which is the room temperature.
7. LITERATURE REVIEW
Figure 3: Flow efficiency [15]
Flow
efficiency
• Flow efficiency is used to
describe the percentage of the
fluid flowing along the louver
direction.
• 100 % efficiency represents
ideal louver-directed flow
while 0% represents complete
duct-directed flow [14].
• As Reynolds number increases,
flow undergoes a transition
from duct directed flow (low
efficiency) to louver directed
flow (high efficiency) [11].
8. Figure 4: Section through louver array
indicating possible flow directions [15].
LITERATURE REVIEW cont’
Flow
behavior
• louvers act to realign the
air flow in a direction
parallel to their own
planes.
• the degree of alignment
with the louvers was a
function of Reynolds
number.
• At low Reynolds number
values, realignment would
be slight, but at high
Reynolds number it was
almost complete [15].
9. SUMMARY OF THE LITERATURE REVIEW
The flow efficiency is strongly dependent on the geometry,
especially at low Reynolds numbers.
The flow efficiency increases with the Reynolds number and louver
angle, but it decreases with the fin pitch and thickness ratio.
The heat transfer for louvered fins is more appropriately described
by a Reynolds number based on the louver pitch.
A louvered fin heat exchanger produced a 25% increase in heat
transfer and a 110% increase in pressure drop relative to a plain
fin.
Louvered-fin flow behavior is generally laminar in The ReLP range
tested (50-600) with vortex shedding occurring within the louver array
for ReLP > 400, depending on the model.
13. PRE PROCESSING
Define the model goal
Identity the model
domain
Design and create the
grid
PROCESSING
(FLUENT)
Set up the numerical
model
Compute and monitor the
solution
POST PROCESSING
Examine the result
Consider revisions to the
model
CFD ANALYSIS
15. PARAMETERS
No
Louver pitch = 0.7 mm Louver pitch = 1.4 mm
Reynolds number Velocity (m/s)
Reynolds
number
Velocity (m/s)
1 200 4.51 200 2.26
2 400 9.03 400 4.51
3 600 13.54 600 6.77
4 800 18.06 800 9.03
5 1000 22.57 1000 11.28
Table 2: Parameter for Numerical Study
Here is the geometrical parameters and velocity inputs been used throughout
this study.
The velocity adopted in accordance with the Reynolds number and louver pitch.
16. BOUNDARY CONDITION
No Name Type of boundary condition
1 Inlet Velocity inlet
2 Outlet Pressure outlet
3 Side wall Wall
4 Wall Periodic
5 Fin Wall
21. Difference of pressure drop between experiment
and simulation
Air
velocity
(m/s)
Experimental
work [1, 2]
Current work Difference
(%)
Pressure drop
(Pa)
Pressure drop
(Pa)
2.26 43.50 42.00 3.45
4.51 143.40 141.34 1.44
6.77 255.89 276.81 8.18
9.03 383.34 459.00 19.74
11.28 523.40 730.15 39.5
Average 14.46
2 4 6 8 10 12
0
100
200
300
400
500
600
700
800
Pressuredrop(Pa)
Reynolds Number (ReLp
)
Experimenatl
Numerical
Figure 9: Numerical and experimental pressure drop against Reynolds number
22. 200 400 600 800 1000
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Pressuredrop(Pa)
Reynolds number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
2 4 6 8 10 12
0
200
400
600
800
1000
1200
Pressuredrop(Pa)
Reynolds number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
Figure 11: Pressure drop against
Reynolds number at louver pitch 1.4 mm
Figure 10: Pressure drop against
Reynolds number at louver pitch 0.7 mm
PRESSURE DROP, ∆P
23. 200 400 600 800 1000
0.25
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
Heattransefercoefficient(W/m2.K)
Reynolds number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
200 400 600 800 1000
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
Heattransefercoefficient(W/m2.K)
Reynolds number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
Figure 12: Heat transfer coefficient versus
Reynolds number at louver pitch 0.7mm
Figure 13: Heat transfer coefficient versus
Reynolds number at louver pitch 1.4 mm
HEAT TRANSFER COEFFICIENT, h
24. 200 400 600 800 1000
0
2
4
EulerNumber(Eu)
Reynolds Number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
200 400 600 800 1000
2
4
6
8
10
EulerNumber(Eu)
Reynolds Number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
Figure 15: Euler number versus Reynolds
number at louver pitch 1.4 mm
Figure 14: Euler number versus Reynolds
number at louver pitch 0.7 mm
EULER NUMBER, Eu
Higher Euler number means that higher pressure drop occurred.
25. 200 400 600 800 1000
0.007
0.008
0.009
0.010
0.011
0.012
0.013
0.014
0.015
0.016
0.017
0.018
NusseltNumber(Nu)
Reynolds Number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
200 400 600 800 1000
0.008
0.010
0.012
0.014
0.016
0.018
0.020
0.022
0.024
0.026
0.028
NusseltNumber(Nu)
Reynolds Number (ReLp
)
Fp=1.65
Fp=2.02
Fp=3.25
Figure 17: Nusselt number versus
Reynolds number at louver pitch 1.4 mm
Figure 16: Nusselt number versus Reynolds
number at louver pitch 0.7 mm
NUSSELT NUMBER, Nu
Nusselt number is a ratio of convective to conductive heat transfer across the boundary.
A larger Nusselt number corresponds to more active heat convection between two boundary.
26. 200 400 600 800 1000
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St- Fp=1.65
f- Fp=1.65
200 400 600 800 1000
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St- Fp=2.02
f- Fp=2.02
Figure 19: Stanton number and friction factor
against Reynolds number for configuration 3
Figure 18: Stanton number and friction factor
against Reynolds number for configuration 1
STANTON NUMBER, St AND FRICTION FACTOR, f
27. 200 400 600 800 1000
0.02
0.03
0.04
0.05
0.06
0.07
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St- Fp=3.25
f- Fp=3.25
200 400 600 800 1000
0.0
0.2
0.4
0.6
0.8
1.0
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St- Fp=1.65
f- Fp=1.65
Figure 20: Stanton number and friction
factor against Reynolds number for
configuration 5
Figure 21: Stanton number and
friction factor against Reynolds
number for configuration 2
STANTON NUMBER, St AND FRICTION FACTOR,f
28. 200 400 600 800 1000
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St- Fp=2.02
f- Fp=2.02
200 400 600 800 1000
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
FrictionFactor(f)
StantonNumber(St)
Reynolds Number (ReLp
)
St-Fp=3.25
f- Fp=3.25
Figure 22: Stanton number and friction factor
against Reynolds number for configuration 4
Figure 23: Stanton number and friction factor
against Reynolds number for configuration 6
STANTON NUMBER,St AND FRICTION FACTOR,f
30. CONCLUSIONS
The major findings are summarized as follows:
Heat transfer rate increases when the fin pitch is increased. While the
opposite is true in the case of pressure drop.
Pressure drop and heat transfer increases when the louver pitch is
decreased.
The friction factor decreases with the increase in fin pitch. While the
opposite is true in the case of Stanton number.
Greater heat transfer values are obtained as the fin pitch is increased,
due to the increased heat transfer surface area.
Greater heat transfer and pressure drop values are obtained as the
Reynolds number is increased. That is due to the flow tends to be louver
directed flow at high Reynolds number and duct directed flow at low
Reynolds number, and this two behaviors have a huge impact on heat
transfer and pressure drop respectively.
![Figure 1: Flat-sided tube and louvered
plate fin heat transfersurface [1].
INTRODUCTION
Heat exchangers are devices
that facilitate the exchange of heat
between two fluids that are at
different temperatures while
keeping them from mixing with
each other.
Louvered fin compact heat
exchangers are used extensively in
several automotive applications
such as radiators, oil coolers,
condensers, and charge air coolers
[1].](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)