4. INTRODUCTION
To exchange heat between two fluids → heat
exchanger
Different types → Air conditioning , Power production,
Space heating
Widely used type → shell and tube heat exchanger
Consist of bundle of tubes enclosed in cylindrical shell
Efficient & energy saving heat exchanger →
Researchers conducts experimental and numerical
work
5. INTRODUCTION
In this study,
Experimental and CFD Investigation of Parallel and
Counter Flow in STHEx
CFD Software → ANSYS Fluent
Simulated result
Heat Transfer coefficient ,
Effectiveness
Compared with Experimental data
Also effect of mass flow rate → performance of heat
exchanger
6. M. Thirumarimurugan et al. [1] developed numerical model in
MATLAB
Predict outlets temperature
Simulated results compared
.Žarko Stevanović et al. [2] → 3-D numerical study
Fluid flow and heat transfer
Chen-Kim modification of k − ε model → good agreement with
experimental data
Optimal flow distribution → reduce pressure drop , enhance heat
transfer
Ender Ozden, and Ilker Tari [3] conducted → CFD study
Design of STHEx → baffle spacing, baffle cut
Simulated results compared → kern and Bell-Delaware methods
LITERATURE REVIEW
7. EXPERIMENTAL SETUP
Arm field HT33-XC-304 SHTHx → Heat transfer lab , MUET
Stainless steel tubes , acrylic transverse baffles and shell
Water heated in the vessel → electrical heater
Hot fluid passes through S.S tubes → pump
Tap water → Cold fluid
Experiment performed for Counter and parallel flow
Hot fluid → 𝑚 =0.076 kg/sec , Tin = 60°C
Cold fluid → 𝑚 =0.036 kg/sec , Tin = 24°C
8. Heat Exchanger Specification (provided by Armfield limited)
S.No Description Unit Value
1 Shell inner diameter mm 39
2 Shell wall thickness mm 3
3 Tube outer diameter mm 6.35
4 Tube wall thickness mm 0.6
5 Number of Tubes mm 7
6 Shell/Tubes length mm 150
7 Shell inlet/outlet length mm 10
8 Baffle height mm 34.5
9 Baffle Thickness mm 3
EXPERIMENTAL SETUP
9. SIMULATION AND MODELLING PROCEDURE
Geometry
Geometry in ANSYS design modeler
Simplified geometry – 2D
Actual Model
Simplified Model
10. SIMULATION AND MODELLING PROCEDURE
Meshing
Carried out in ANSYS Meshing Client
Whole fluid domain → Quadrilateral element type
Initially Coarser meshing → 18330 elements
Better Result → Fine meshing - 73370 elements
11. SIMULATION AND MODELLING PROCEDURE
Models and Governing Equation
According to system specification , some models need to be
adopted in CFD Software
In ANSYS Fluent → two built in HEx models
Heat Exchanger Model:
DUEL CELL heat exchanger model
Based on NTU method
Flow is turbulent → Turbulent model Should be selected
12. SIMULATION AND MODELLING PROCEDURE
Governing Equation
k-ɛ Turbulence Model
Turbulent kinetic energy k
Ui
𝜕k
𝜕xj
= vT
𝜕 Ui
𝜕xj
+
𝜕 Uj
𝜕xi
𝜕 Ui
𝜕xj
− ϵ +
𝜕
𝜕xj
v +
vT
σk
𝜕k
𝜕xj
Turbulent dissipation ɛ
Ui
𝜕ε
𝜕xj
= Cε1vT
ε
k
𝜕 Ui
𝜕xj
+
𝜕 Uj
𝜕xi
𝜕 Ui
𝜕xj
− Cε2
ε2
k
+
𝜕
𝜕xj
v +
vT
σε
𝜕ε
𝜕xj
Turbulent viscosity vT
𝑣 𝑇 = 𝐶𝜇
𝑘2
𝜀
14. BC Type Shell Tube
Intel Mass-flow 0.034 Kg/sec 0.076 Kg/sec
Outlet Pressure outlet 0 0
Wall No slip condition Zero heat flux Zero heat flux
Turbulence Turbulence intensity
Length scale
5.62%
0.007 m
4.24%
0.00036m
Temperature Inlet temperature 297 K 333K
SIMULATION AND MODELLING PROCEDURE
Boundary Conditions
Selected according to need of model
15. T
RESULT
Parallel Flow
Temperature contours
→ Shell Side
I
N
L
E
T
O
U
T
L
E
T
→ Tube side
I
N
L
E
T
O
U
T
L
E
T
16. Experimental Simulated Diff:
Tube side Temp: difference 2.8 2.6 7.14%
Shell side Temp: difference 6.2 5.7 8.06%
Overall HT co-eff: (W/m2.K) 1432 1310 8.55%
NTU 0.201 0.184 8.4%
Effectiveness 0.174 0.162 6.8%
RESULT
Comparison of simulated and experimental data
17. Effect of mass flow rate on Heat Transfer
Variation in hot mass flow rate
At 𝒎 𝒉𝒐𝒕 = 0.038 Kg/sec , U = 1091 W/m2.K , Effect: = 0.1335
With increasing mass flow rate – effectiveness increased
RESULT
20%
21.60%
23.15%
21%
25.80%
27.34%
0%
5%
10%
15%
20%
25%
30%
100% 200% 300%
Increment
Mass Flow Increment
U (W/m2.K) Effectiveness
18. RESULT
Counter Flow
Temperature contours
→ Tube side
I
N
L
E
T
O
U
T
L
E
T
→ Shell side
I
N
L
E
T
O
U
T
L
E
T
19. RESULT
Comparison of simulated and experimental data
Variables Experimental Simulated Diff:
Tube side Temp: Difference 3.4 3.15 7.35%
Shell side Temp: difference 7.5 6.92 7.7%
Overall HT coeff: (W/m2.K) 1765 1623 8.05%
NTU 0.248 0.228 8.06%
Effectiveness 0.208 0.196 5.76%
20. Effect of mass flow rate on Heat Transfer
Variation in hot mass flow rate
At 𝒎 𝒉𝒐𝒕 = 0.038 Kg/sec , U = 1184 W/m2.K , Effect: = 0.143
With increasing mass flow rate – effectiveness increased
RESULT
37%
42.00% 43.00%
37%
44.00%
46.00%
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
100% 200% 300%
Increment
Mass Flow Increment
U (W/m2.K) Effectiveness
21. CONCLUSION
Effect of Mass Flow rate
Effectiveness is increased with increase in hot fluid flow
Increment of effectiveness in counter flow is almost 90%
more than of that in parallel flow for same mass flow
increment
Effect of Flow Configuration
Effectiveness in counter flow is almost 20% to 25% more
than of that in Parallel Flow for same mass flow
CFD Analysis
Good agreement with experimental data and theoretical
concepts
22. [1] M. Thirumarimurugan, T.Kannadasan and
E.Ramasamy, Performance Analysis of Shell and
Tube Heat Exchanger Using Miscible System,
American Journal of Applied Sciences 5 (5): 548-552,
2008
[2] Žarko Stevanović , Gradimir Ilić, Nenad Radojković,
Mića Vukić, Velimir Stefanović, Goran Vučković,
Design of shell-and-tube heat exchangers by using
CFD technique – part one: thermo-hydraulic
calculation, FACTA UNIVERSITATIS Series:
Mechanical Engineering Vol.1, No 8, 2001, pp. 1091
– 1105
[3] Ender Ozden, Ilker Tari, Shell Side CFD Analysis of a
Small Shell And Tube Heat Exchanger, Energy
Conversion and Management, 2010: 51;1004-1014
REFERENCE
