FINAL2 PPT3

COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION
OF FLUID FLOW AND HEAT TRANSFER THROUGH A
SHELL AND TUBE HEAT EXCHANGER

GROUP MEMBERS
SAMIULLAH QURESH (G.L) 09ME08
QADIR NAWAZ (A.G.L) 09ME113
HIRA TABISH 09ME07
RAMESH KUMAR 09-08ME06
SALEEM ANWAR 09ME21
DEPARMENT OF
MECHANICAL ENGINEERING
MEHRAN UNIVERSITY OF ENGINEERING AND
TECHNOLOGY JAMSHORO

OUTLINE
 OBJECTIVES
 SHELL AND TUBE HEAT EXCHANGER
 COMPUTATIONAL FLUID DYNAMICS
 ANSYS SOFTWARE
 SIMULATION AND MODELLING PROCEDURE
 RESULTS
 CONCLUSION
 FUTURE WORK

OBJECTIVES
 To study heat transfer and fluid flow in shell and
tube heat exchanger.
 Simulation by using ANSYS 14.0 to investigate
heat transfer
 In counter flow and parallel flow
 With and without baffles
 At different mass flow rate
 Cross checked against experimental data

SHELL AND TUBE HEAT EXCHANGER
 To exchange heat between two fluids – heat exchanger
 Widely used type – shell and tube heat exchanger
 Consist of bundle of tubes enclosed in cylindrical shell
 To enhance heat transfer rate – baffles

COMPUTATION FLUID DYNAMICS(CFD)
 Science of predicting physical processes in fluid domain
 Solving mathematical models with help of computer
 More effective
 Simulation-based design instead of “build & test”
 Simulation of physical fluid phenomena that is
difficult for experiments

ANSYS SOFTWARE
 CAE software
 Combination of different tools of analysis
 ANSYS Design modeler – To create geometry
 ANSYS Meshing Client – to generate mesh
 ANSYS Fluent – CFD software

SIMULATION AND MODELLING PROCEDURE
1) GEOMETRY
 In ANSYS design modeler
 Simplified geometry – 2D

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

2) MESHING
Meshing is being carried out in ANSYS Meshing Client.
 Mapped Face Meshing - Quadrilateral element type
 Edge Sizing
 Shell and baffles side walls – 42 and 38 elements
 Upper and lower walls of Shell and tubes – 300 elements
 Inlet and outlet of Tubes - 18 elements

 Coarser meshing - 18330 elements
 Fine meshing - 73370 elements

3)PROBLEM SPECIFICATION
This step is being carried out in ANSYS Fluent.
 Solver – Pressure based
 Selection of models
 Energy
 K-ε standard viscous model
 Dual cell heat exchanger model
 Selection of materials
 Working fluid – water
 Tubes – Steel
 Shell / baffles – clear acrylic sheet

 Selection of Boundary condition
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

 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

 Governing Equation
 Conservation of Mass:
𝜕ρUj
𝜕xj
= 0
 Momentum :
Uj
𝜕Ui
𝜕xj
= −
1
ρ
𝜕P
𝜕xi
+
1
ρ
𝜕𝜏𝑖𝑗
𝜕xi
 Energy:
𝛻 . V ρE + p = 𝛻. [ keff 𝛻T + (τeff . V)]

RESULTS
1) PARALLEL FLOW WITHOUT BAFFLES
 Temperature Contours and Profile
 ΔT is large
 Decays with x
T

 Heat Exchanger Model Report
Variables Value
Shell side temp: difference (K) 4.06
Tube side temp: difference (K ) 1.85
Heat transfer rate (watts) 585.66
Overall HT coefficient (W/m2.K) 890
NTU 0.125
Effectiveness 0.11

2) COUNTER FLOW WITHOUT BAFFLES
 Temperature Contours and profile

 Effectiveness – 37% more than that in Parallel flow without
baffles
Variables Value
Shell side temp: difference (K) 5.39
Tube side temp: difference (K ) 2.43
Heat transfer rate (watts) 771
Overall HT coefficient (W/m2.K) 1202
NTU 0.169
Effectiveness 0.15

3) PARALLEL FLOW WITH BAFFLES
 Temperature contours and profile

 Simulated Effectiveness – 47% more than that in parallel flow
without baffles
Experimental Simulated % Diff:
Tube side Temp: difference 3.2 2.62 18.12
Shell side Temp: difference 7.2 5.72 20.55
Overall HT coeff: (W/m2.K) 1722 1310 23.9
NTU 0.242 0.184 23.9
Effectiveness 0.195 0.162 16.92

 Effect of mass flow rate on Heat Transfer
 Variation in hot mass flow rate
 To keep maximum heat transfer rate constant
 With increasing mass flow rate – effectiveness increases
Hot Mass Flow
Kg/sec
Overall HT coefficient
(W/m2.K)
NTU Effectiveness
0.038 1091 0.153 0.1335
0.076 1310 0.184 0.162
0.152 1327 0.186 0.168
0.228 1344 0.19 0.170

4) COUNTER FLOW WITH BAFFLES
 Temperature contours and profile

 Simulated effectiveness – 30% more than that in counter
flow without baffles.
Variables Experimental Simulated % Diff:
Tube side Temp: Difference 3.6 3.15 12.5
Shell side Temp: difference 7.7 6.92 10.12
Overall HT coeff: (W/m2.K) 1935 1623 16.11
NTU 0.27 0.228 15.55
Effectiveness 0.237 0.196 17.36

 Effect of mass flow rate on Heat Transfer
 With increasing mass flow rate – U increases
Hot Mass
Flow Kg/sec
Overall HT coefficient
(W/m2.K)
NTU Effectiveness
0.038 1184 0.166 0.143
0.076 1623 0.228 0.196
0.152 1687 0.237 0.207
0.228 1694 0.238 0.209

CONCLUSION
 Better heat exchanger effectiveness with baffles.
 Parallel flow – 47% increased
 Counter flow – 30% increased
 Effectiveness is 21% more in counter flow than
parallel flow
 Good agreement with experimental data and
theoretical concepts

FUTURE WORK
 Computational investigation of pressure drop in
shell and tube heat exchanger
 Computational investigation of heat transfer with
varying design of baffles

FINAL2 PPT3

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