Comparative CFD Analysis of Shell and Serpentine Tube Heat Exchanger

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 02 | Feb -2017 www.irjet.net p-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1171
Comparative CFD Analysis of Shell and Serpentine Tube Heat
Exchanger
Subin Michael1 , Kiran K John2, Amal Krishnan2, K K Shanid2 and Melnus Mathew2
1 Assistant Professor,Department of Mechanical Engineering, Vimal Jyothi Engineering College,
Chemperi, Kannur-670632
2Department of Mechanical Engineering, Vimal Jyothi Engineering College, Chemperi, Kannur-670632
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Heat exchangers are the essential engineering
systems with wide variety of applications including nuclear
reactors, chemical factories, refrigeration systems etc. In this
study, we adopt a shell and tube heat exchanger having
serpentine type tubes instead of separate straight tubes.
ANSYS 16.2 Fluid Flow(Fluent) workbench is used to perform
computational fluid dynamics (CFD) simulations. The heat
exchanger geometry contains one serpentine tube of outer
diameter 30 mm and shell of diameter 200 mm. In this paper,
comparison is carried out by adopting different serpentine
tube materials (ASTM A 179 Carbon steel and C12200 copper
alloy). The changes in temperatureprofiles ineachofthecases
are taken into consideration for calculating effectiveness of
heat exchanger. Better insights on optimal material selection
for vital parts of a heat exchanger is obtained from
comparative CFD analysis by adopting distinct industrial
materials (ASTM A 179 Carbon steel and C12200 copper
alloy).
Key Words: CFD, shell and tube, serpentine tube, heat
exchanger, effectiveness
1.INTRODUCTION
Heat exchange can be occurred between fluids in
motion. It is one of the most important physical process. A
variety of heat exchangers are employed in different
situations. For example, in air conditioning systems, nuclear
plants, plywood companies etc.
The heat exchanger is intended to perform efficient
heat transfer from one fluid to another. It may be either by
direct contact or by indirect contact. In this study,ashelland
tube heat exchanger equipped with serpentine shaped tube
configuration is considered. Comparative CFD analysis is
performed by adopting two different serpentine tube
materials.
The two industrial materials adopted for study are
C12200 copper alloy and ASTM A 179Carbonsteel.Different
heat exchangers are named according to their area of
implementation. For example, condensers are heat
exchangers that are used tocondensevapours,similarlyheat
exchanger for boiling of liquids are referred to as boilers.
Effectiveness calculation is one of the technique for
performance analysis of heat exchangers.
Usman Ur Rehman [1] studied the flow and
temperature fields inside the shell and tubes. He resolved
them using a commercial CFD packageconsideringtheplane
symmetry. A set of CFD simulations is performed forasingle
shell and tube bundle and is compared with the
experimental results. An un-baffled shell-and-tube heat
exchanger design with respect to heat transfer coefficient
and pressure drop is investigated by numerically modeling.
Kwasi Foli [2], in his paper, describes two approaches
for determining the optimal geometric parameters of the
microchannel in micro heat exchangers. One approach
combines CFD analysis with an analytical method of
calculating the optimal geometric parameters of micro heat
exchangers. The second approach involves the usage of
multi-objective genetic algorithms in combinationwithCFD.
Brahim Selma [3] carried out a study to develop an
optimized heat pipe exchanger used to improve the energy
efficiency in building ventilation systems. The optimized
design is based on a validated model usedinsidea numerical
plan built on a design of experiments statistical procedure.
The numerical model, built using the open-source package
OpenFOAM, is validated through experimental
measurements done on a small-scale heat pipe industrial
exchanger. The results from the open source model are also
compared to the numerical predictions obtained from a
commercial code.
Nawras H. Mostafa [4], Qusay R. Al-hagag Presented
an approach to select the tube wall thickness distribution of
streamlined tubes intended for use in heat exchangers is
developed in this study. The main goal is to retain a
streamlined outer profile (resist deformation) and to
prevent strain failure due to the applied internal pressure.
The effect of the tube wall thickness distribution on shaped
tube efficiency is also considered.
Daniel Flórez-Orrego [5], in hiswork,heattransferin
a non-previously implemented cone-shaped helical
prototype with 15cm in maximum diameter, 7.5cm in
minimum diameter, 3/8" pitch and 40cmin axial length was
analyzed. An empirical correlation for the determination of
average Nusselt number along the duct, with Reynolds
ranging between 4300 and 18600 has been developed. Also,
numerical simulations were performed using ANSYS
FLUENT 12.1 software, where the governing equations of
mass, momentum and heat transport were solved
simultaneously.

1.1 Effectiveness, (ε) of a Heat Exchanger:
Effectiveness of a heat exchanger is defined as ratio
of actual heat transferred to maximum possible heat thatcan
be transferred. It denotes the degreetowhichheatexchanger
is successful in producing desired heat transfer between
different fluids. It is a parameter showing feasibility of a heat
exchanger installation.
ε =
Substituting values of Qactual and Qmax possible from in
general equation, we get;
ε = =
2.CFD ANALYSIS
For any system, computational fluid dynamics (CFD)
analysis starts with the construction of required geometry
followed by mesh generation. Meshing is the discretization
of the domain into small volumes where the governing
equations are solved with the help of iterative methods.
Further modelling proceeds withassignmentofboundary
and initial conditions for the dominion and leads to
modelling of the entire system. At the end of iterative
solution steps, we can take the numerical and graphical
output of the analysis.
2.1 Geometry:
First, the fluid flow (fluent) module fromtheworkbench
is chosen. It is a counter-flow heat exchanger. Heat
exchanger geometry is built in the ANSYS Design Modeler.
Naming of various parts may be done in this step.
Fig -1: Main additional tube configurations used for
shell and tube heat exchanger
Table -1: Dimensions of Geometry
Fig -2: Isometric view of serpentine tube
Fig -3: complete model of shell and tube heat
exchanger
2.2 Mesh:
Fig -4: Meshing diagram of shell and tube heat exchanger
Heat exchanger length 1300mm
Shell outer diameter 200mm
Shell Thickness 3.2mm
Tube outer diameter 30mm
Tube Thickness 1.5mm
Number of serpentine tube 1

At first, a relatively coarser mesh is generated. The
mesh contains tetra cells and hexahedral cells (i.e., mixed
cells) having both triangular and quadrilateral faces at the
boundaries.
Care is taken to employ structured hexahedral cells
as muchas possible. It is meant to reduce numericaldiffusion
as much as possible by structuring the mesh in a good
manner, particularly near the wall region. In meshing stage,
itself; named selections are specified like cold inlet, cold
outlet, hot inlet, hot outlet etc. Heat transfer interfacescanbe
specified in this or it can be done in next stage of setup.
2.3 Fluent Setup:
The mesh is checked and quality is ensured. The
analysis type is altered to Pressure Based type. The velocity
formulation is assigned as ‘absolute’ and time to ‘steady
state’. Energy option is set toON. Viscous modelisselectedas
“k-ε model”. The create/edit option is clicked to add water-
liquid, copper, stainless steel, brass, ASTM A 179, C12200
materials to the list of fluid and solid respectively from the
fluent database. But vast majority of the industrial alloys are
unavailable in Fluent default data base. So, we have to create
a user defined database ‘.scm’ file and use it for material
assignment.
In eachanalysis,differentpartsoftheheatexchanger
geometry are assigned ascorrespondingfluid(eg:water)and
solids (eg: copper, stainless steel etc.) as per the comparison
criteria.
Boundary conditions are assigned according to the
need of the model. The inlet conditions are defined as ‘mass
flow inlet’ and outlet conditions are set as ‘outflow’. Two
inlets and two outlets are defined by considering hot fluid
side and cold fluid side.
Each wall is separately specified with respective boundary
conditions. Each wall is set to no slip condition. Except the
tube wall, other walls are set to zero heat flux condition.
Integral type surface monitor is assigned; field
variable is selected as temperature.Surfaceslikehotinlet,hot
outlet, cold inlet and cold outlet are selected. It is useful in
obtaining exact drop in temperature from inlet to outlet.
The details of boundary conditions are as follows:
Hot fluid inlet temperature (inner fluid),Thi= 365K
Cold fluid inlet temperature (outer fluid), Tci=300K
Hot fluid flow rate, mh=0.04 kg/s
Cold fluid flow rate, mc=0.05 kg/s
3.ANALYSIS RESULTS:
We have two cases considered in this comparative
analysis. In case I, ASTM A 179 Carbon steel is assigned as
inner tube material. In case II, C12200 copper alloy material
is taken as the inner tube material case ll. In both cases,
Stainless Steel is employed as the shell material.
Table -2: - CASE - I
Thermal Profile
Velocity Profile
Table -3: -Tabulation of Results
Effectiveness Calculation
Heat capacity of cold water, Cc = mc * Cpc
= 0.05*4179.725
= 208.98 W/K
Heat capacity of hot water, Ch = mh * Cph
= 0.04*4197.178
= 167.887 W/K
Inner material C12200 Copper alloy
Outer Material Stainless Steel
Fluid
Type
Mass
flow
rate, mc
(kg/s)
Specific heat
capacity,Cph
(J/kgK)
Inlet
Temp
(K)
Outlet
temp
(K)
Cold
Fluid
0.05 4179.725 300 326.83
Hot
Fluid
0.04 4197.178 365 339.26

Ch < Cc, Cmin = Ch
Effectiveness,
ε =
=
= 0.5138
Table -4: - CASE- II
Thermal Profile
Velocity Profile
Table -5: Tabulation of Results
Effectiveness Calculation
Heat capacity of cold water, Cc = mc * Cpc
= 0.05*4180.83
= 209.041 W/K
Heat capacity of hot water, Ch = mh * Cph
= 0.04*4198.3
= 167.932 W/K
Ch < Cc , Cmin = Ch
Effectiveness,
ε =
=
= 0.6528
Variation of Effectiveness with
Different Tube Materials
Chart -1
CONCLUSIONS
Conclusions from comparative CFD analysis are as follows;
 The temperature profiles of each case under
comparison, point out that there occurs
considerable variation in shell side and tube side
temperature drop when tube material is altered.
 The comparison of ASTM A 179 carbon steel and
C12200 copper alloy materials reveal that C12200
copper alloy is the better tube material when
coupled with outer shell of Stainless Steel for a heat
exchanger.
 Thermal conductivity of C12200 copper alloy is
much higher than ASTM A 179 carbon steel
material, so, C12200 copper alloy offer higher heat
transfer characteristics.
 The effectiveness of heat exchanger is improved
when C12200 copper alloy is employed than ASTM
A 179 carbon steel by about 14%.
 Overall weight of tube assembly is increased by
about 12% percentage if we use copper alloy as
tube material by considering tube dimensions and
density of materials.
Inner material ASTM A 179 Carbon Steel
Outer Material Stainless Steel
Fluid
Type
Mass
flow rate,
m
(kg/s)
Specific heat
capacity,Cp
(J/kgK)
Inlet
Temp
(K)
Outlet
temp
(K)
Cold
Fluid
0.05 4180.83 300 334.088
Hot
Fluid
0.04 4198.3 365 342.616

Even if C12200 copper alloy tubes are better than A179
tubes in a heat transfer point of view, the industrial material
selection depends also on corrosion resistance, erosion,
vibration behaviour, fouling, mechanical properties etc.
REFERENCES
[1] Usman Ur Rehman, “Heat Transfer Optimization of
Shell-and-Tube Heat Exchanger through CFD Studies”,
Chalmers University of Technology (2011)
[2] Kwasi Foli, TatsuyaOkabe,MarkuOlhofer,YaochuJin and
Bernhard Sendhoff, “Optimization of micro heat exchanger:
CFD, analytical approach and multi-objective evolutionary
algorithms”, International JournalofHeatandMassTransfer
(2005)
[3] Brahim Selma “Optimization of an industrial heat
exchanger using anopen-sourceCFDcode”,Applied Thermal
Engineering (2013)
[4] Nawras H. Mostafa, Qusay R. Al-Hagag, “Structural and
Thermal Analysis of Heat Exchanger with Tubes of Elliptical
Shape”, University of Babylon
[5] Daniel Flórez-Orrego, “Experimental and CFD study of a
single-phase cone-shaped helical coiled heat exchanger: an
empirical correlation”- Proceedings of ‘Ecos 2012’, June 26-
29, 2012, Perugia, Italy
[6] J.S. Jayakumar, S.M. Mahajani, J.C. Mandal, P.K. Vijayan
and Rohidas Bhoi, “Experimental and CFDestimationofheat
transfer in helically coiled heat exchangers”, Chemical
engineering research and design (2008)
[7] Dilpak Saurabh P, Harshal Khond and Mandar M. Lele,
“CFD Analysis of a Triple Concentric Tube Heat Exchanger
having water flowing at three different temperatures”,
International JournalofCurrentEngineeringandTechnology
(2016)
[8] Swapnaneel Sarma (2012), “CFD Analysis of Shell and
Tube Heat Exchanger using triangular fins for waste heat
recovery processes”, ESTIJ (2012)
[9] Dr.B. Jayachandriah, M. Uday Kumar, R. Jagaesh, T M
Vamsi Krisha, “Fabrication and Design of Spiral Tube Heat
Exchanger”, American International Journal of
Contemporary Scientific Research

Comparative CFD Analysis of Shell and Serpentine Tube Heat Exchanger

More Related Content

Comparative CFD Analysis of Shell and Serpentine Tube Heat Exchanger