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