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COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION OF FLUID FLOW AND HEAT TRANSFER THROUGH A SHELL AND TUBE HEAT EXCHANGER
SUPERVISED BY:Dr. ABDUL FATAH ABBASI(ASSISTANT PROFESSOR )
GROUP MEMBERS
SAMIULLAH QURESH (G.L) 09ME08QADIR NAWAZ (A.G.L)09ME113HIRA TABISH 09ME07RAMESH KUMAR 09-08ME06SALEEM ANWAR 09ME21
DEPARMENT OFMECHANICAL 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 PROCEDURE1) 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) MESHINGMeshing 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 TubeIntel 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 intensityLength scale
5.62%0.007 m
4.24%0.00036m
Temperature Inlet temperature 297 K 333K
SIMULATION AND MODELLING PROCEDURE Governing Equation
k-ɛ Turbulence Model Turbulent kinetic energy k
Turbulent dissipation ɛ
Turbulent viscosity vT
SIMULATION AND MODELLING PROCEDURE Governing Equation
Conservation of Mass:
Momentum :
Energy:
RESULTS1) 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) 4.06Tube side temp: difference (K ) 1.85
Heat transfer rate (watts) 585.66Overall HT coefficient (W/m2.K) 890
NTU 0.125Effectiveness 0.11
2) COUNTER FLOW WITHOUT BAFFLES
Temperature Contours and profile
Heat Exchanger Model Report
Effectiveness – 37% more than that in Parallel flow without
baffles
Variables Value Shell side temp: difference (K) 5.39Tube side temp: difference (K ) 2.43
Heat transfer rate (watts) 771Overall HT coefficient (W/m2.K) 1202
NTU 0.169Effectiveness 0.15
3) PARALLEL FLOW WITH BAFFLES Temperature contours and profile
Heat Exchanger Model Report
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 0.13350.076 1310 0.184 0.1620.152 1327 0.186 0.1680.228 1344 0.19 0.170
4) COUNTER FLOW WITH BAFFLES
Temperature contours and profile
Heat Exchanger Model Report
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 0.1430.076 1623 0.228 0.1960.152 1687 0.237 0.2070.228 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
THANK YOU