IRJET- Multi Tube Heat Exchanger in Counter Flow by using CFD Analysis

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 07 Issue: 01 | Jan 2020 www.irjet.net p-ISSN: 2395-0072
© 2020, IRJET | Impact Factor value: 7.34 | ISO 9001:2008 Certified Journal | Page 1763
MULTI TUBE HEAT EXCHANGER IN COUNTER FLOW BY USING
CFD ANALYSIS
Periyannan.L1, Saravanan.P2, Elayaraja.R3, Subramaniam.D4
1,3Assistant Professor, Department of Mechanical Engineering, Mahendra Engineering College, Mallasamudram,
Tamilnadu, India-637503.
2,4Professor, Department of Mechanical Engineering, Mahendra Engineering College, Mallasamudram, Tamilnadu,
India-637503.
----------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Heat exchanger is an important tool that is widely used in different industries such as operation, petroleum
refining, chemical, oil, power plant and paper, etc. Energy and material savings considerations as well as environmental
challenges in the sector have driven the demand for high performance heat exchangers. To order to improve the performance
of the heat exchanger, attention must be given to improving the heat transfer in the heat exchanger. In addition, the increase
in heat transfer allows a major reduction in the size of the heat exchanger. A high rate of heat transfer with a minimum space
requirement is sufficient for a compact heat exchanger. The counter-flow heat exchanger enhances the heat transfer
characteristics of the double pipe heat helical fins mounted on the outer surface of the inner tube and reduces the vibration
level by rotating the inner tube. Helical fins increase the heat transfer area and the rotation of the inner tube increases the
mixing of fluid particles required for the heat transfer convection mode. The heat pipe model is designed by the CREO
PARAMETRIC software and analyzed by the ANSYS software.
Key Words: Counter flow, Double pipe, Cooling fins, CERO, Ansys
1. INTRODUCTION
A heat exchanger is a device that is used to transfer thermal energy between two or more fluid, between a solid
surface and a fluid, or between solid particulates and a fluid, at different temperature and in thermal contact. In heat
exchangers, there are usually no external heat and work interactions.
Typical application involves heating or cooling of a fluid stream and evaporation or condensation of single or
multicomponent fluid streams. In other application, the objective may be to recover or reject heat, or sterilize, pasteurize,
fractionate, distil, concentrate, crystallize, or control a process fluid. In a few heat exchangers, the fluids exchanging are in
direct contact.
In most heat exchanger, heat transfer between fluids takes place through a separating wall or into and out of a
wall in a transient manner. In many heat exchangers, the fluid is separated by a heat transfer surface, and ideally they do
not mix or leak. Such exchangers are referred to as direct transfer type, or simply recuperate. In contrast, exchangers in
which there is intermittent heat exchange between the hot and cold fluid-via thermal energy storage and release through
the exchanger surface or matrix are refer to as indirect transfer type, or simply referred to as indirect transfer type, or
simply regenerators. Such exchangers usually have fluid leakage from one fluid stream to the other due to pressure
differences and matrix rotation/valve switching.
Common example of heat exchangers are shell and tube exchangers, automobile, radiators, condensers,
evaporators, air pre heaters, and cooling towers. If no phase change occurs in any of the fluids in the exchanger. There
could be internal thermal energy sources in the exchangers, such as in electric heaters and nuclear fuel elements.
Combustion and chemical reaction may take place within the exchangers, such as in boilers, fired heaters, and fluidized-
bed exchangers.

Figure 1. Double pipe heat exchanger
BASED ON FLUID ARRANGEMENT
 Counter flow
 Parallel flow
 Cross flow
Counter Flow
A counter flow heat exchanger is one in which the direction of the flow of one of the working fluids is opposite to the
direction to the flow of the other fluid. In a parallel flow exchanger, both fluids in the heat exchanger flow in the same
direction. The counter flow heat exchanger has three significant advantages over the parallel flow design.
Figure 2.Counter Flow
Parallel flow
A counter flow heat exchanger is one in which the direction of the flow of one of the working fluids is opposite to
the direction to the flow of the other fluid. In a parallel flow exchanger, both fluid in the heat exchanger flow in the same
direction.

Figure 3. Parallel Flow
Cross flow
A cross flow heat exchanger exchanges thermal energy from one airstream to another in an air handling unit (AHU).
A cross flow heat exchanger is used in a cooling and ventilation system that required heat to be transferred from one
airstream to another.
Figure 4. Cross flow
2. MATERIAL SELECTION
STEEL
Steel is an alloy of iron and carbon, and sometimes other elements. Because of its high tensile strength and low
cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and
weapons. Iron is the base metal of steel. Iron is able to take on two crystalline forms (allotropic forms), body cantered
cubic and face centred cubic, depending on its temperature. In the body-centred cubic arrangement, there is an iron atom
in the centre and eight atoms at the vertices of each cubic unit cell; in the face- centred cubic, there is one atom at the
centre of each of the six faces of the cubic unit cell and eight atoms at its vertices. It is the interaction of the allotropes of
iron with the alloying elements, primarily carbon that gives steel and cast iron their range of unique properties.

Figure 5. Steel
Steel property
Steel is an alloy, consisting mainly of iron, with a carbon content of 0.2% to 2.1% by weight. Though the use of
carbon is most common for the production of this metal alloy, other alloying materials like tungsten, chromium and
manganese are also used. The proportions and forms in which these elements are used, affect the properties of the steel that
is produced - increasing the carbon content for instance, increases its strength.
Mechanical properties of steel (outer pipe)
 Density - 8030 kg/m3
 Specific heat - 502.48 j/kg-k
 Thermal conductivity - 16.27 w/m-k
 Modulus of elasticity - 210,000 N/mm2
 Shear modulus - 81,000 N/mm²
 Poisson's ratio - 0.3
COPPER
Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a soft,
malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has
a pinkish-orange colour. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of
various metal alloys, such as sterling silver used in jewellery, cupronickel used to make marine hardware and coins, and
constantan used in strain gauges and thermocouples for temperature measurement.
Figure 6. Copper
Copper property
The word copper comes from the Latin word cuprum‟, which means „ore of Cyprus‟. This is why the chemical
symbol for copper is Cu. Copper has many extremely useful properties, including:

 Good electrical conductivity
 Good thermal conductivity
 Corrosion resistance
Mechanical property of copper (inner pipe)
 Density - 8978 kg/m3
 Specific heat - 381 j/kg-k
 Thermal conductivity - 387.6w/m-k
3. DESIGN OF DOUBLE PIPE HEAT EXCHANGER
Double Pipe Design
Double Pipe Heat Exchangers. In its simplest form, the double pipe heat exchanger, (also known as a concentric
pipe, hairpin, jacked pipe and jacketed U-tube heat exchangers), consists of a single tube mounted inside another. One fluid
flows in the inner pipe, while a second fluid flows in the outer pipe annuals. Double pipe heat exchangers come
into their own when a conventional shell and tube heat exchanger would be uneconomical. They are suited for
applications where either low flow rates, large temperature cross or small duties with high flow rates are involved. Their
size makes them particularly suitable for applications where space is at a premium. Multiple units can be set up in either
series or parallel and mounted vertically.
Their small diameter allows high pressure units to be built with thinner walls than would be achievable with
conventional shell and tube heat exchangers. A double tube heat exchanger is able to achieve pure counter current flow
thus allowing for a temperature cross to be achieved whereby the cold fluid can be heated above the exit temperature of
the hot fluid.
Normal Double Pipe Heat Exchanger Model:
Figure 7. Normal Double Pipe Heat Exchanger Model

Double Pipe Heat Exchanger with Helical Fins:
Figure 8. Double Pipe Heat Exchanger with Helical Fins
Dimension in Double Pipe Heat Exchanger
Figure 9. Dimension in Double Pipe Heat Exchanger
4. RESULT AND DISCUSSION
Purpose of CFD
The geometry and physical bounds of the problem can be defined using computer aided design (CAD). From there,
data can be suitably processed (cleaned-up) and the fluid volume (or fluid domain) is extracted.
The volume occupied by the fluid is divided into discrete cells (the mesh). The mesh may be uniform or non-
uniform, structured or unstructured, consisting of a combination of hexahedral, tetrahedral, prismatic, pyramidal
or polyhedral elements.
Boundary conditions are defined. This involves specifying the fluid behaviour and properties at all bounding
surfaces of the fluid domain. For transient problems, the initial conditions are also defined.
The simulation is started and the equations are solved iteratively as a steady-state or transient.

Mass Flow using 4 LPM in Normal
Figure 10. Temperature Difference using 4 LPM in Normal
Comparative Reading of Normal Method:
Hot water Cold water
Flow Inlet Outlet Flow Inlet Outlet
LPM LPM
2 50 44.56 5 30 31.78
4 50 46.45 5 30 32.33
6 50 47.33 5 30 32.63
8 50 47.85 5 30 32.82
10 50 48.19 5 30 32.95
Table 1. Comparative Reading of Normal Method
The comparative reading of normal double pipe heat exchanger used in different flow value of hot water show the
reading in above table 1.The better result of 4 LPM mass flow rate graphically represented by Pressure, Velocity and
Temperature.
Comparative Reading of Helical Fins Method:
Hot water Cold water
Flow Inlet Outlet Flow Inlet Outlet
LPM LPM
2 50 43.28 6 30 32.22
4 50 45.17 6 30 33.20
6 50 46.15 6 30 33.81
8 50 46.78 6 30 34.25
10 50 47.23 6 30 34.58
Table 2. Comparative Reading of Helical Fins Method
The comparative reading of helical fins of double pipe heat exchanger used in different flow value of hot water
show the reading in above table 2 and temperature difference of different flow rate show in the figure 10. The better result
of 4 LPM mass flow rate graphically represented by Pressure, Velocity and Temperature.

Comparative Reading of Normal and Helical Fins Method
Mass Flow Rate
Hot Water
(LPM)
Mass Flow Rate
Cold Water
(LPM)
Normal Method Helical Fins Method
Hot Water
Outlet ( )
Cold Water
Outlet ( )
Hot Water
Outlet ( )
Cold Water
Outlet ( )
2 6 44.56 31.78 43.28 32.22
4 6 46.45 32.33 45.17 33.20
6 6 47.33 32.63 46.15 33.81
8 6 47.85 32.82 46.78 34.25
10 6 48.19 32.95 47.23 34.58
Table 3 Comparative Reading of Normal and Helical Fins Method
5. CONCLUSION
This research analyzes the heat transfer and flow properties of a tube-in-tube helical heat exchanger for
counterflow using the CFD technique. The consequence of the flow rate of mass in the inner tube. When we increase the
thickness of the fin, the temperature of the cold fluid at the outlet of the heat exchanger increases. The heat transfer
performance of a helical tube heat exchanger is greater than that of a straight tube heat exchanger. From the velocity and
temperature contours, it can be found that the velocity is higher towards the outer side of the coil, while the temperature is
higher towards the inner side of the coil.
6. REFERENCES
1. N. R. Chaudhari, F. N. Adroja (February 2014 ), “A Review on Design & Analysis of Double Pipe Heat Exchanger”
International Journal of Engineering Research & Technology, volume 3, issue 2
2. Jibin Johnson, Abdul Anzar V M (May 2015), “CFD Analysis of Double Pipe Heat Exchanger” International Journal
of Science, Engineering and Technology Research, volume 4, issue 5.
3. Kuruva umamahesh, k. venugopal (July 2015), “Design and Anaysis of Double Pipe Heat Exchanger Using
Computational Method” International Journal Of Professional Engineering Studies, volume5, issue 2
4. Sk.M.Z.M.Saqheeb Ali, k.Mohan Krishna (August 2015), “Thermal Analysis of Double Pipe Heat Exchanger by
Changing the Materials Using CFD” international journal of engineering trends and technology, volume 26, issue 2
5. Swathi Juturu , J. Kishore (September 2015), “Comparison of Effectiveness of Two Different Setups of Double Pipe
Heat Exchangers” international journal for research in applied science & engineering, volume 3, issue 9.
6. Madhav mishra, U. K Nayak (August 2016), “Experimental Investigations of Double Pipe Heat Exchanger with
Triangular Baffles” international research journal of engineering and technology, volume 3, issue 8.
7. Chetan Kharche, Sushila Pawade (December 2016), “Review of Dimple Tube Double Pipe Heat Exchanger Design”
international research journal of engineering and technology, volume 5, issue 2.
8. Rakesh C, Charan Nallode (July 2017), “Design and Performance Analysis of Double Pipe Heat Exchanger”
international journal of innovative research in science engineering and technology, volume 6, issue 7.
9. Patel Yogeshwari, Jayesh M Dhodiya (August 2017), “Analytical Solution of Compartment Based Double Pipe Heat
Exchanger Using Differential Transform Method” international research journal of enginnering and technology,
volume 4, issue 8.
10. Harsh Ladani, Rajkamal Sanepara (April 2018), “Design and Fabrication of Double Pipe Heat Exchanger Using
Different Heat Transfer Enhancement Techniques” international journal of technical innovation in modern
engineering and science, volume 4, issue 4.
11. Mohan, P. Sankar Ganesh (Oct 2018), “CFD Analysis of Double Pipe Heat Exchanger with and Without Dimples”
international research journal of engineering and technology, volume 5, issue 10.

BIOGRAPHIES
Periyannan.L
Assistant professor,
Mahendra Engineering College
Saravanan.P
Professor,
Elayaraja.R
Assistant professor,
Subramaniam.D
Professor,

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