Heat exchangers are used in aero space engines have large heat transfer coefficient, large surface area per unit volume and low weight. The large surface area in compact heat exchangers is obtained by attaching closely spaced thin plate fins to the walls separating the two fluid. This study presents the airside performance of fin and tube compact heat exchangers with plain fin configuration. The effect of fin thickness, fin and tube material and fin spacing on the thermal-hydraulic characteristics is examined. Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow characteristics of a plain fin and tube heat exchanger using the Commercial Computational Fluid Dynamics Code ANSYS fluent 16.0. Heat transfer and fluid flow characteristics with consideration of air property variability which is caused by the air temperature change of the heat exchanger are investigated for Reynolds numbers ranging from 2622 to 10498. Temperature drop and heat transfer rate is simulated using standard k-epsilon model with air flow is taken as steady and turbulent. Results are compared for two different material GH3044,S66280 and find out optimum heat transfer rate. After selecting best material GH3044 , we investigate the temperature variation and heat transfer characteristics of three different fin thickness 0.08 mm,0.1mm and 0.2 mm and three different fin spacing 0.8mm,1.1mm and 1.6 mm. domain having 0.8 mm fin spacing shows 5 % increase in heat transfer as compared to 1.1 mm fin spacing. Fin thickness 0.2 mm is better as compared to the other fin thickness and shows 8 % increment in heat transfer as compared to 0.1 mm fin thickness.

1. J A B A L P U R E N G I N E E R I N G C O L L E G E , J A B A L P U R
(Established in 1947 as Government Engineering College, Jabalpur)
(Declared Autonomous by Government of Madhya Pradesh and University Grant Commission, New Delhi)
DEPARTMENT OF MECHANICAL ENGINEERING
A
DISSERTATION ON
Numerically Enhancement of heat transfer of fin and tube compact
heat exchanger used in aero space using CFD
Under The Guidance of
Prof. D S Rawat
Asst. Professor (Department of
Mechanical Engineering)
Presented by
Anurag chaubey
0201ME15ME05
ME- IV SEM (Heat Power)

2. CONTENT
 ABSTRACT
 INTRODUCTION
 LITERATURE REVIEW
 METHODOLOGY & MATERIAL USED
 COMPUTATIONAL FLUID DYANAMICS & GEOMETRY USED
 SOLID MODEL & MESHING
 GOVERNING EQUATIONS & BOUNDARY CONDITION
 MATHAMETICAL MODELAND DATA REDUCTION
 RESULT AND DISCUSSION
 CONCLUSION
 REFERENCES

3. Heat exchangers are used in aero space engines have large heat transfer coefficient, large surface area per
unit volume and low weight. The large surface area in compact heat exchangers is obtained by attaching closely
spaced thin plate fins to the walls separating the two fluid. This study presents the airside performance of fin and
tube compact heat exchangers with plain fin configuration. The effect of fin thickness, fin and tube material and
fin spacing on the thermal-hydraulic characteristics is examined. Three-dimensional CFD simulations are carried
out to investigate heat transfer and fluid flow characteristics of a plain fin and tube heat exchanger using the
Commercial Computational Fluid Dynamics Code ANSYS fluent 16.0. Heat transfer and fluid flow
characteristics with consideration of air property variability which is caused by the air temperature change of the
heat exchanger are investigated for Reynolds numbers ranging from 2622 to 10498. Temperature drop and heat
transfer rate is simulated using standard k-epsilon model with air flow is taken as steady and turbulent. Results
are compared for two different material GH3044,S66280 and find out optimum heat transfer rate. After selecting
best material GH3044 , we investigate the temperature variation and heat transfer characteristics of three
different fin thickness 0.08 mm,0.1mm and 0.2 mm and three different fin spacing 0.8mm,1.1mm and 1.6 mm.
domain having 0.8 mm fin spacing shows 5 % increase in heat transfer as compared to 1.1 mm fin spacing. Fin
thickness 0.2 mm is better as compared to the other fin thickness and shows 8 % increment in heat transfer as
compared to 0.1 mm fin thickness.
ABSTRACT

4. Introduction
• Heat exchangers are device that facilitate the exchange of heat between two fluid that are at different
temperature while keeping them from mixing with each other.
• heat exchanger are commonly used in practice in a wide range of application, for heating and air conditioning
systems in a household ,to chemical processing and power production in large plant.
• Type of Heat exchangers
1. Parallel flow heat exchanger
2. Counter flow heat exchanger
3. Cross flow heat exchanger
Mode of Heat transfer
• It may be defined as “the transmission of energy from one region to another as a result of temperature
gradient”
There are basic three mode of heat transfer:
1. Conduction
2. Convection
3. Radiation

5. Compact heat exchanger:
Compact heat exchanger can be characterized by its high ‘area density’ this means that is has a high ratio of heat
transfer surface to heat exchanger volume. So Compact heat exchange is characterized by high heat transfer
surface-area to volume ratios and high heat transfer coefficients compared to other exchanger types. The heat
transfer surface area is increased by fins to increase the surface area per unit volume.
Fig. 4- Schematic diagram of a compact fin and tube heat exchanger

6. LITERATURE REVIEW
Lingdong Gu [1] (2017) : Conducted Numerical studies to investigate the airside thermal-hydraulic
characteristics of bare tube bank and plain finned tube heat exchangers intended for use in aero-engine cooling.
The exchangers use small diameter tubes (3.0 mm) with compact tube layout and operate at high temperatures
with large temperature changes over the exchanger depth. Calculations are performed for frontal air velocities
between 5 and 20 m/s, airside heat transfer and pressure loss characteristics of bare tube bank and plain finned
tube heat exchangers are numerically predicted with consideration of the air property variations caused by the air
temperature variations.I:thesis bind filepapers1.pdf
Jeanette Cobian-Iniguesz [2] ( 2017) : In this paper, the hydrodynamic and heat transfer characteristics of
compact fin and tube heat exchanger have been investigated numerically by introducing a methodology of
analysis based on local and global energy balance from 3-D velocity and temperature field. The aim is to analyze
the influence of operating condition and the geometry parameters over tube fluid velocity via Reynolds number is
used as a parameter of operation .I:thesis bind filepapers2.pdf

7. Arafat A. Bhuiyan [3] (2012) :Three-dimensional CFD simulations are carried out to investigate heat transfer and
fluid flow characteristics of a four-row plain fin-and-tube heat exchanger using the Commercial Computational
Fluid Dynamics Code ANSYS CFX 12.0. Heat transfer and pressure drop characteristics of the heat exchanger
are investigated for Reynolds numbers ranging from 400 to 2000.I:thesis bind filepapers3.pdf
L.H.Tang, M.Zeng [4] (2009) : In the present paper they did investigation through experimentally on fin-and-tube
heat exchangers with the Reynolds number varies from 4000 to 10000,and the optimization of heat exchanger with
vortex generator (VGs) is also addressed and at high Reynolds numbers, best heat transfer performance achieved
by slit fin heat exchanger. The high angle of attack, low height and higher length of vortex generators will lead to
better overall performance of heat exchangers with VGs. The optimized vortex-generator fin can provide better
heat transfer performance than slit fin.I:thesis bind filepapers4.pdf

8. METHODOLOGY
• Study of heat exchanger used in the aero space engines and the parameters on which its performance is
dependent.
• Literature survey and find the scope of further research.
• Finding out the process parameters on which the performance parameters dependent.
• Develop the solid model of heat exchanger on the basis of geometry given in the base paper.
• After developing the solid model, numerical model of heat exchange is developed.
• Comparison of CFD model of heat exchanger with the analysis performed in the base paper.
• Three different materials are used for tubes and fins that is GH2132, GH3044, S66280 and find out the air exit
temperature for all three materials.
• With material having least exit temperature and high heat transfer rate, it considered the three different fin
having thickness 0.08 mm, 0.1 mm and 0.2 mm.
• Find out the effect of change in fin thickness on the air exit temperature and heat transfer rate.
• After finding the optimum fin thickness it also analyzed the effect of gap or space between two fins.
• Then finding out the effect of these parameter on the air exit temperature and heat transfer rate.

9. COMPUTATIONAL FLIUD DYANAMICS
• Computational fluid dynamics or CFD is the analysis of systems involving fluid flow, heat transfer and associated
phenomena by means of computer-based simulation. The technique is very powerful and spans a wide range of industrial
and non-industrial application areas. Computational fluid dynamics (CFD) simulation is conducted for a compact cross
flow type heat exchanger. The heat exchanger consists of cold fluid flows through a tube with finned flat plate for the air
stream. The three dimensional laminar and turbulent flows in both fluids regions are modelled by employing ANSYS
FLUENT 16.0. The continuity, momentum and energy equations are discretized by means of finite volume technique with
coupled boundary conditions. SIMPLE algorithm scheme is applied to link the pressure and velocity fields inside the
domain for both cold fluid and hot fluids. Uniform cross section fins and tube wall are governed by diffusion conduction
heat equation to analyse the heat transfer through fins tube wall. The standard k-ε model is used to model the turbulence
flow. some application of CFD are,
• Aerodynamics of aircraft and vehicles : lift and drag
• Power plant : combustion in internal combustion engines and gas turbines
• Turbo machinery: flows inside rotating passages, diffusers.
• Meteorology: weather prediction; etc.

10. MATERIAL USED
For the initial analysis the material taken is same as that taken by Lingdong [1]. So here GH2132 alloy (Fe-25Ni-15Cr) is
chosen as the fin material, whose thermal conductivity is set as 14.2 W/ ( 𝑚2.k). The material properties of GH2132 is shown in
the below table.
After analyzing the above material, two different materials are considered to increase the heat transfer rate. The two materials
considered are GH3044 and S66280. The material properties of these materials are shown in the table below:
Property of GH3044 Property of S66238
PROPERTY VALUE
DENSITY 7.99 g/cm3
SPECIFIC HEAT 447 j/kg
THERMAL CONDUCTIVITY 14.2 w/m-k
PROPERTY VALUE
DENSITY 8.89 g/cm3
SPECIFIC HEAT 440 j/kg
THERMAL CONDUCTIVITY 11.7 w/m-k
PROPERTY VALUE
DENSITY 7.98 g/cm3
SPECIFIC HEAT 460 j/kg
THERMAL CONDUCTIVITY 12.2 w/m-k

11. GEOMETRY USED
The solid model of heat exchanger is based on the geometry used in Lingdong [1]. The geometric specification of
heat exchanger used in the analysis is defining the tube bank configurations include the tube outside diameter (D),
transverse tube pitch (Pt), longitudinal tube pitch (Pl), and number of tube rows (N), fin pitch (𝐹𝑝 ) and fin
thickness (𝛿 𝑓). The geometric boundary condition is shown in the below fig.5.
Fig. 5 showing the geometric condition of tube

12. Based on the geometric condition given in the base paper the solid model of the heat exchanger is shown in the
below fig 6 (A) & (B).
(A) (B)
Fig. 6 (A) and (B) shows the solid model of compact heat exchanger used in the analysis

13. COMPUTATIONAL SOLID MODEL
The fin domain is inside this computational domain which is used to increase the heat transfer rate. The model
showing the fin inside the computational domain is shown in the Fig. 7 (A) & (B).
(A) (B)
Fig.7 - Solid model for computational analysis

14. MESHING
After developing the solid model of given geometry, it is then discretized into number of elements and nodes
because the numerical analysis is completely dependent on the elements and number of nodes.
Fig.8 - Mesh of the given geometry

15. Fig.9 - Top view of meshed solid model
Fig.10- Front view of the meshed solid model

16. • Here in this work the problem is defined by the law of mass, momentum and energy. The present study stretches from the
transitional range (2000<Re<4000) flow to turbulence range flow (Re > 4000). Equations that govern the problem of flow
are in the transitional range turbulence model.
• Turbulence consist of small scale fluctuation in the flow characteristics over time. It is a complex process, mainly because,
it is a three dimensional and unsteady. And it can have a significant effect on the characteristic of the flow. Turbulence
occurs when the inertia forces in the fluid become significant compared to viscous forces and is characterized by a high
Reynolds number.
• The continuity equation:
𝜕𝑢
𝜕𝑥
+
𝜕𝑣
𝜕𝑦
+
𝜕𝑤
𝜕𝑧
= 0
• The momentum equation:
In x-direction
𝜕𝑢
𝜕𝑡
+ 𝑢
𝜕𝑢
𝜕𝑥
+ 𝑣
𝜕𝑢
𝜕𝑦
+ 𝑤
𝜕𝑢
𝜕𝑧
= −
𝜕𝑃
𝜌𝜕𝑥
+
𝜇
𝜌
𝜕2
𝑢
𝜕𝑥2 +
𝜕2
𝑢
𝜕𝑦2 +
𝜕2
𝑢
𝜕𝑧2
GOVERNING EQUATION AND BOUNDARY CONDITIONS

17. • THE ENERGY EQUATION:
𝜕𝑇
𝜕𝑡
+ 𝑢
𝜕𝑇
𝜕𝑥
+ 𝑣
𝜕𝑇
𝜕𝑦
+ 𝑤
𝜕𝑇
𝜕𝑤
=
𝜆
𝜌𝐶 𝑝
𝜕2
𝑇
𝜕𝑥2
+
𝜕2
𝑇
𝜕𝑦2
+
𝜕2
𝑇
𝜕𝑧2
• BOUNDARY CONDITION:
The upstream boundary (inlet)
𝑢 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
𝑇 = 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
𝑣 = 𝑤 = 0
Fin and tube wall surface (no slip condition)
𝑢 = 𝑣 = 𝑤 = 0
T = 𝑐𝑜𝑛𝑠𝑡
The down stream boundary (outlet)(Newman boundary conditions)
𝜕𝑢
𝜕𝑥
=
𝜕𝑣
𝜕𝑥
=
𝜕𝑤
𝜕𝑥
= 0
Top symmetry boundary on the x-y plane
𝜕𝑢
𝜕𝑧
=
𝜕𝑣
𝜕𝑧
=
𝜕𝑇
𝜕𝑧
= 0
𝑤 = 0

18. Here in this analysis the frontal air entering the heat exchanger is at different speed because it
considered four different velocity of air that is 5, 10, 15 and 20 m/s. and Reynolds no. 2622 to 10498 but for the
initial analysis it is taken as 10 m/s. and the pressure is 0.84 MPa. The input of boundary condition into the
numerical analysis is shown in the figure. The temperature of air at the inlet of heat exchanger is 653.99 K.
During the analysis the temperature of tube and fin at the time of inlet is 298 K.
Fig. 11 - Value at the inlet of heat exchanger

19. MATHAMETICAL MODELS AND DATA REDUCTION
ASSUMPTIONS:
• The heat exchanger is a thin fin, horizontal compact heat exchanger.
• The fluid flow can be modeled as a three dimensional fluid flow through a computational domain.
• Viscous dissipation and viscous work are neglected.
• body forces are neglected.
• The pressure drop along the domain caused by momentum change and viscous friction is negligible.
Therefore, fluid pressure can be assumed uniform along the entire domain.
• Heat transfer from air to fin and tube through convection.
• Fluid properties are taken at mean temperature of inlet and outlet.

20. Maximum velocity of air flow inside the compact heat exchanger are given;
𝑉𝑚𝑎𝑥 =
𝑃𝑡×𝑉
2 𝑃 𝑑−𝐷
Where; D = diameter of tube
V = velocity of air at inlet
𝑃𝑡 = transverse distance in between the two tubes of same row
𝑃𝑑 = diagonal distance between the center of two tubes of adjacent row
Reynolds number;
𝑅𝑒 = 𝜌 𝑎𝑖𝑟 × 𝑉max 𝑎𝑖𝑟 × 𝐿 𝑐/𝜇 𝑎𝑖𝑟
Where; 𝜌 𝑎𝑖𝑟= Density of air
𝑉max 𝑎𝑖𝑟= Velocity of air
𝜇 𝑎𝑖𝑟= Dynamic viscosity of air

21. • To calculate the heat transfer rate at different velocity following formula used.
Q = 𝑚𝐶 𝑃∆𝑇
Where, m = mass flow rate of air.
C = specific heat of the air
𝛥T= change in temperature between inlet to outlet.
Mass flow rate of air,
𝑚 = 𝜌 𝑎𝑖𝑟 × 𝑉𝑎𝑖𝑟×𝐴 𝑐
To calculate ∆𝑇 𝑚 following formula mention in the base paper and Cengel and Gajar is used.
∆𝑇 𝑚=
𝑇𝑖𝑛 − 𝑇 𝑤 − 𝑇𝑜𝑢𝑡 − 𝑇 𝑤
𝑙𝑛 𝑇𝑖𝑛 − 𝑇 𝑤 / 𝑇𝑜𝑢𝑡 − 𝑇 𝑤
where,
𝑇𝑖𝑛= Temperature at inlet
𝑇𝑜𝑢𝑡= Temperature at outlet
𝑇 𝑤 =Temperature of the tube wall or fin .

22. To calculate heat transfer coefficient following formula is used .
Q = ℎ𝐴∆𝑇 𝑚ƞ0
Where, h = average heat transfer coefficient (W/𝑚2-k)
A = surface area of domain
∆𝑇 𝑚 = logarithmic mean temperature difference.
ƞ0 = surface efficiency or efficiency of computational domain
To calculate the surface area of domain following calculation is used.
A= L× 𝑊 − (
𝜋
8
× 𝐷2
) × 𝑁
Where L = length of fin .
W =width of fin
D = diameter of tube
N = no of tube in computational domain .
Efficiency of fin;
ƞ 𝑓 =
tan mr∅
mr∅
Surface efficiency ; ƞ0 = 1 − (1 − ƞ 𝑓)
𝐴 𝑓
𝐴

23. Specimen calculation:
At velocity V = 10 m/s
Maximum velocity of air;
𝑉𝑚𝑎𝑥 =
𝑃𝑡×𝑉
2 𝑃 𝑑−𝐷
=
6×10
2 4.24−3
𝑉𝑚𝑎𝑥 = 24.15 m/s
Reynolds number;
Re =
𝜌 𝑎𝑖𝑟×𝑉max 𝑎𝑖𝑟×𝐿 𝑐
𝜇 𝑎𝑖𝑟
Re =
4.46 ×24.15× 1.609
3.28×10−5
Re = 5218
Mass flow rate of air;
𝑚 = 𝜌 𝑎𝑖𝑟 × 𝑉𝑎𝑖𝑟 × 𝐴 𝑐
𝑚 = 4.46× 10 × 3.3 × 10−6
𝑚 = 0.00147 kg/s
Heat transfer rate;
Q = 𝑚c𝛥T = 0.00147×1065.74×(653.99-440)
Q = 33.24 W

24. Log mean temperature;
∆𝑇 𝑚=
𝑇 𝑖𝑛−𝑇 𝑤 − 𝑇𝑜𝑢𝑡−𝑇 𝑤
𝑙𝑛 𝑇 𝑖𝑛−𝑇 𝑤 / 𝑇𝑜𝑢𝑡−𝑇 𝑤
∆𝑇 𝑚=
653.99−298 − 440−298
𝑙𝑛 653.99−298 / 440−298
∆𝑇 𝑚 =232. 83K
Efficiency of fin;
ƞ 𝑓 =
𝑡𝑎𝑛 𝑚𝑟∅
𝑚𝑟∅
The value of local heat transfer coefficient for material GH2132 at velocity 10 m/s calculated through numerical
analysis is 844.1536 W/m2 K.
We find the value of ,
m =
2×307.4
0.0486×0.68×10−3 = 4313.1477
ƞ 𝑓 = 0.6995

25. Surface efficiency ƞ0 = 1 − (1 − ƞ 𝑓)
𝐴 𝑓
𝐴
ƞ0 = 0.8534
Heat transfer coefficient h =
𝑚𝐶 𝑃ΔT
ƞ0 𝐴∆𝑇 𝑚
h =
33.24
0.8534×140.58×10−6 ×232.83
h = 989.115 W/𝑚2
𝐾
h = average heat transfer coefficient (W/𝑚2-k)
A = surface area of domain
∆𝑇 𝑚 = logarithmic mean temperature difference.

26. RESULT AND DISSCUSION
CASE 1. Velocity at 5 m/s
Here in this case velocity of frontal air is 5 m/s and the temperature of air at the inlet is 653.98 K for
material GH2132. After applying the boundary condition it is find out the air exit temperature. The contour plot
of air temperature distribution for this case shown in Fig.12.
Fig.12 - Contours of temperature for velocity 5 m/s for material GH2132

27. From the above analysis, it observe that the temperature of air at the exit of heat exchanger is 366 K from the
numerical analysis it also find out the change in velocities and velocity vectors .
Fig. 13 Contour of temperature distribution at the exit for velocity 5m/s

28. Velocity at 10 m/s
Here in this analysis the velocity of frontal air coming to heat exchanger is 10 m/s and the temperature of
air at the inlet is same as that of case 1, other boundary conditions will also remain same as that of case 1. The
temperature distribution profile for this case is shown in Fig. 14.
Fig. 14 Contours of temperature for velocity 10 m/s for material GH2132

29. Fig.15 Contour of temperature at the exit for velocity 10 m/s

30. Table showing the value of air exit temperature at different velocity and the value of heat transfer rate at
different velocity for material GH2132.
Table.1 Air exit Temperature at different Reynolds number of material GH2132
Reynolds
number
Velocity (m/s) Temperature of air at
the exit (K)
Heat transfer rate (W)
2622 5 421 18.15
5218 10 440 33.24
7873 15 449 47.9
10498 20 457 54.059

31. • The value of heat transfer coefficient for different velocity is shown in the below table. The Comparison of
temperature of air at the exit and heat transfer coefficient calculated through numerical analysis with the
value of temperature and heat transfer coefficient given in the base paper.
Table 2. Comparison of numerical values and base paper value
Reynolds
number
Velocity
(m/s)
Average Heat
transfer coefficient
(h) (W/m2K)
calculated through
numerical analysis
Heat transfer
coefficient
(h) (W/m2K)
from base
paper
Error
(%)
Heat transfer
rate (W)
calculated form
numerical
analysis
Heat transfer
rate (W)
values from
base paper
Error
(%)
2622.96 5 563 550 2.3 18.15 18 14.62
5218.98 10 989.115 985 4 33.24 31 7.2
7873.25 15 1351.3 1300 3.9 47.9 44 8.86
10497.96 20 1662.16 1600 3.8 54.059 52 3.95

32. Fig.16 Comparison of heat transfer rate at different
Reynolds number of air
Fig.17 showing the comparison of heat transfer
coefficient for different Reynolds number of air
0
10
20
30
40
50
60
0 2000 4000 6000 8000 10000 12000
Heattransferrate(W)
Reynolds Number
Base paper
Numerical analysis
0
200
400
600
800
1000
1200
1400
1600
1800
0 2000 4000 6000 8000 10000 12000
Heattransfercoefficient(W/m2K)
Reynolds Number
Base Paper
Numerical analysis

33. GH3044 MATERIAL IS USED FOR FIN AND TUBE
The value of temperature at the exit for velocity 5 m/s is near about 357 K for the same geometrical parameter
of fin thickness of 0.1 mm and 1.1 mm fin spacing or domain. the temperature contour through the heat exchanger is
shown in the below Fig 18. The temperature distribution at the exit of heat exchanger shown in the below Fig.19. For the
further calculation average temperature is taken at the exit.
Fig. 18 contours of temperature at velocity 5 m/s for material GH2132

34. Fig.19 Temperature distribution of air at the exit for material GH3044

35. Likewise the above analysis it has calculate the temperature of air at the exit of heat exchanger for
different velocity. we have calculated the heat transfer coefficient, heat transfer rate and logarithmic mean
temperature difference. All the values for different velocity is shown in the below Table .
Table.3 Value of different parameters calculated through Numerical method for GH3044 material
Reynolds
number
Velocity of
air (m/s)
Temperature of air at
the exit of heat
exchanger (K)
Logarithmic
mean
temperature
difference (K)
Heat transfer
rate (W)
Heat transfer
coefficient
(W/m2K)
2622 5 357 165.23 23.10 994.5
5218 10 386 191.75 40.52 1503.2
7873 15 397 200.8 60.05 2127.28
10498 20 405 207.13 77.58 2664.3

36. S66280 MATERIAL USED FOR FIN AND TUBE
From the analysis, it is found that the temperature at the exit is near about 365 K for the same geometrical
parameter of fin thickness of o.1 mm and 1.1 mm fin spacing or domain. the temperature distribution at the exit of heat
exchanger is shown in the fig. below.
Case 1 at velocity 5 m/s:
Fig. 20 Contours of temperature at velocity 5 m/s for material S66280

37. Fig.21Temperature distribution of air at the exit for velocity 5 m/s for material S26680

38. We have calculated the value of heat transfer rate, logarithmic mean temperature difference and heat
transfer coefficient. All the value are shown in the below table.
Table.4 Showing the Values of different parameters at different Reynolds number
Reynolds
number
Velocity of
air (m/s)
Temperature of air
at the exit of heat
exchanger (K)
Logarithmic mean
temperature
difference (K)
Heat
transfer rate
(W)
Heat transfer
coefficient
(W/m2K)
2622 5 365 173.02 22.51 925.45
5218 10 390 195.098 41.12 1499.25
7873 15 401 204 59.12 2061.48
10498 20 415 214.77 74.46 2466.18

39. Fig.22 Comparison of heat transfer rate for different material at different Reynolds Number
0
10
20
30
40
50
60
70
80
90
0 2000 4000 6000 8000 10000 12000
Heattransferrate(W)
Reynolds Number
GH2132 material
GH3044 Material
S66280 Material

40. Fig.23 comparison of heat transfer coefficient for different material at different Reynolds Number.
0
200
400
600
800
1000
1200
1400
1600
1800
0 2000 4000 6000 8000 10000 12000
HeatTransfercoefficient(W/m2K)
Reynolds Number
GH2132 Material
GH3044 Material
S66280 Material

41. • From the above comparison graph, it is found that the temperature at the exit of heat exchanger is minimum
for material GH3044 at every velocity of air.
• Through this analysis, it is found that as the material density, specific heat and thermal conductivity changes,
the heat transfer capacity of the material also changes.
• From the analysis it is also observed that as the velocity of the air or Reynolds number increases the rate of
heat transfer also increases and it is high for material GH3044 at all velocity as shown in the comparison
graph.
• Through graph it is also analyzed that as the velocity of the air or Reynolds number increases the heat transfer
coefficient also increases and it is maximum in case of GH3044 material.
• So it is found that the material GH3044 shows the better heat transfer as compared to the material GH2132 and
S66280.
• Therefore further analysis of heat transfer rate for GH3044 material at different fin thickness and at different
fin spacing.

42. EFFECT OF FIN THICKNESS
• After finding out the effect of material on the heat transfer rate, here it has also analyzed the effect of tube fin
thickness on the heat transfer rate and the temperature of heat exchanger. In order to find out the effect of fin
thickness, here it is considered the three different fin thicknesses for solid model and find out the temperature
of air at the exit.
• It is considered 0.08, 0.1 and 0.2 mm thickness fin during the numerical simulation. Model having fin
thickness 0.1 is already analyzed in base paper. In order to analyzed the effect of fin thickness, we have
considered four different velocity of air that is 5, 10, 15, 20 m/s or Reynolds No. 2622 to 10498 for analyzing
the effect of fin thickness on different parameters.
• Here we have calculated the different parameters that is heat transfer rate, heat transfer coefficient.

43. Table 5. Values of different parameters and heat transfer rate for different fin thickness
Reynolds
number
Temp. (K)
at the exit
for fin
thickness
0.08 mm
Temp. (K)
at the exit
for fin
thickness
0.1 mm
Temp. (K)
at the exit
for fin
thickness
0.2 mm
Temp.
(K)
at the exit
for fin
thickness
0.3 mm
Heat
transfer rate
(W) for
thickness
0.08mm
Heat
transfer
rate (W)
for
thickness
0.1 mm
Heat
transfer
rate (W)
for
thickness
0.2 mm
Heat
transfer
rate (W)
for
thickness
0.3 mm
2622 502 357 365 369 11.839 23.10 24.511 22.199
5218 505 386 384 389 23.2118 40.52 42.063 41.234
7873 509 397 398 402 33.883 60.05 61.8228 58.88
10498 515 405 404 406 43.3078 77.58 77.8912 77.27

44. Fig.24 Comparison of heat transfer rate for different fin thickness
0
10
20
30
40
50
60
70
80
90
0 2000 4000 6000 8000 10000 12000
HeattransferRate(W)
Reynolds Number
For Thickness 0.08 mm
For Thickness 0.1 mm
For Thickness 0.2 mm
For Thickness 0.3 mm

45. Table.6 Values of heat transfer coefficient for different fin thickness
Velocity of
air (m/s)
Reynolds
Number
Heat transfer
coefficient
(W/m2K) for
0.08 mm
Heat transfer
coefficient
(W/m2K) for
0.1 mm
Heat transfer
coefficient
(W/m2K) for
0.2 mm
Heat transfer
coefficient
(W/m2K) for
0.3 mm
5 2622.96 108.56 479.25 484.35 399.91
10 5248.98 208.366 800.25 809.458 614.37
15 7873.25 296.99 1127.53 1215.357 852.41
20 10497.96 382.074 1436.03 1445.658 1084.27

46. Fig.25 Comparison of heat transfer coefficient for different fin thickness
0
200
400
600
800
1000
1200
1400
1600
0 2000 4000 6000 8000 10000 12000
HeattransferCoefficient(W/m2K)
Reynolds Number
For Fin thickness 0.08 mm
For Fin thickness 0.1 mm
For Fin thickness 0.2 mm
For Fin Thickness 0.3 mm

47. Effect of Distance Between Two fins
• To analyzed the effect of change in gap in between the two adjacent fins here we have considered the three
different type of fins spacing solid modal. Here it considered 0.8, 1.1 and 1.6 mm distance in between the two
adjacent fins during the numerical simulation. Model having fins spacing 1.1 is already analyzed in base paper.
In order to analyzed the effect fins spacing, here we have considered the different velocity of air that is 5, 10,
15, 20 m/s or Reynolds number 2622 to 10498 and GH3044 material for tubes and fins. During the analysis the
fin thickness is remain constant.
• From the analysis it is found that as the space between the two adjacent fins get increases the temperature of
air at the exit get increased which means that the rate of heat transfer get reduce . Whereas with the decrease in
fin spacing the temperature of air at the exit get also decreases which means that the heat transfer rate get
increased. However, after the particular distance in between the fins. If we reduce the spacing beyond that the
heat transfer rate, get reduced. So in this case fin spacing 0.8 mm shows the better heat transfer as compared
to the 1.1 and 1.6 mm fin spacing which is showing in the table and graph.

48. Table 7. Values of different parameters and heat transfer rate for different fin spacing
Reynolds
number
Temperature
at the exit
for fin
spacing 0.5
mm
Temperature
at the exit
for fin
spacing 0.8
mm
Temperature
at the exit
for fin
spacing 1.1
mm
Temperature
at the exit
for fin
spacing 1.6
mm
Heat
transfer
rate (W)
for fin
spacing
0.5 mm
Heat
transfer
rate (W)
for fin
spacing
0.8 mm
Heat
transfer
rate (W)
for fin
spacing
1.1 mm
Heat
transfer
rate (W)
for fin
spacing
1.6 mm
2622 355 352 357 392 23.3 23.52 23.13 20.4
5218 386 382 386 420 41.75 42.37 41.71 36.45
7873 397 394 397 431 60.056 60.75 60.05 52.10
10498 408 403 405 438 76.647 78.2 77.58 67.3

49. Fig.26 comparison of heat transfer rate for different fin spacing
0
10
20
30
40
50
60
70
80
90
0 2000 4000 6000 8000 10000 12000
HeattransferRate(W)
Reynolds Number
For Fin Space 0.5 mm
For Fin Space 0.8 mm
For Fin Space 1.1 mm
For Fin Space 1.6 mm

50. Table 8. Values heat transfer coefficient for different fin spacing
Velocity
of air
(m/s)
Reynolds
Number
Heat transfer
coefficient
(W/m2K) for fin
spacing 0.5 mm
Heat transfer
coefficient
(W/m2K) for fin
spacing 0.8 mm
Heat transfer
coefficient
(W/m2K) for fin
spacing 1.1 mm
Heat transfer
coefficient
(W/m2K) for fin
spacing 1.6 mm
5 2622.96 735.48 819.32 479.25 510.08
10 5248.98 1761.449 1922.5 800.85 1135
15 7873.25 2293.66 2757.56 1127.53 1637.87
20 10497.96 3441.84 3929.109 1436.03 2134.4

51. Fig. 27 Comparison of heat transfer coefficient for different fin spacing
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 2000 4000 6000 8000 10000 12000
HeatTransferCoefficient(W/m2K)
Reynolds Number
For Fin Space 0.5 mm
For Fin Space 0.8 mm
For Fin Space 1.1 mm
For Fin Spacing 1.6 mm

52. CONCLUSION
• The airside heat transfer characteristics of plain finned tube heat exchangers are numerically predicted with
consideration of the air property variations caused by change in air velocity or Reynolds number .
• Here it also find out the effect of material on the temperature of air at the exit, for analyzing the effect it is
consider the different steel alloy which is GH2132, GH3044 and S66820.
• From the graph it is found that as the Reynolds number increases the value of heat transfer increases for all
the three material.
• GH3044 shows the maximum value of heat transfer as compared to the other material. From the graph it is
conclude that the value of heat transfer for GH3044 is on an average 15 % more than the GH2132 material.
• it is found that as the thickness of fin increases from 0.08 mm to 0.2 mm the heat transfer rate increases,
whereas beyond 0.2 mm thickness value of heat transfer again start decreasing.
• After analyzing the effect of different fin spacing it is found that as the fin spacing increases the heat transfer
decreases.

53. • It is concluded from comparison graph of fin thickness that the use of fin thickness 0.2 mm is better as
compared to the other fin thickness and shows 8 % increment in heat transfer as compared to 0.1 mm fin
thickness.
• Heat transfer increases with decrease in fin spacing, but after 0.8 mm fin spacing the heat transfer start
decreasing with decrease in fin spacing.
• Here computational domain having fin spacing 0.8 mm shows 5 % increase in heat transfer as compared to
1.1 mm fin spacing.
• After analyzing the effect of different material, fin spacing and fin thickness it is found that GH3044
material with fin thickness 0.2 mm having and fin spacing 0.8 mm is best combination to enhance the heat
transfer rate on the air side in the computational domain.

54. NOMENCLATURE
T Temperature (K) Q Heat transfer rate (W)
h Heat transfer coefficient (W/m2K) V Velocity of frontal air (m/s)
Re Reynolds number 𝜂 Fin efficiency
∆𝑇 𝑚 Logarithmic mean temperature difference (K)
L Length of fin . W Width of fin
D Diameter of tube
N No of tube in computational domain m Mass flow rate of air
C Specific heat of the air
𝛥T Change in temperature between inlet to outlet D Diameter of tube
𝑃𝑡 Transverse distance in between the two tubes of same row V Velocity of air at inlet
𝑃𝑑 Diagonal distance between the center of two tubes of adjacent row

55. 55
S.no. Title of Paper Name of Journal Volume and
Year of
Publication
1
A Conceptual Review Study and
Enhancement of Heat Transfer
in Compact Heat Exchanger JETIR
Volume 4, Issue 12, December
2017, JETIR (ISSN-2349-5162)
2 Numerically Enhancement of
heat transfer of fin and tube
compact heat exchanger used in
aero space using CFD
JETIR Volume 5, Issue 3, March 2018,
JETIR (ISSN-2349-5162)
PUBLICATIONS

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