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© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 188
PERFORMANCE ANALYSIS ON DOUBLE PIPE
HEAT EXCHANGER USING WIRE COILED AND PIN
WIRE COILED TURBULATOR INSERTS
S.Shanmugapriya1, M.Ganesh karthikeyan2, Dr.M.Prabakar3 and S. Senthilkumar4 1Thermal Engineering, TRPEC, Trichy, India
2,3,4Mechanical Engineering, TRPEC, Trichy, India
Abstract—The heat exchanger is an important device in
almost all of the mechanical industries as in case of
process industries it is key element. Thus from long time
many researchers in this area are working to improve the
performance of these heat exchangers in terms of heat
transfer rate, keeping pressure drop in limit by using
various techniques. This project work deals with of such
techniques keeping focus on passive augmentation
techniques used in heat exchangers. Here the wire coiled
turbulator and pin wire coiled turbulator are used to
enhance the heat transfer rate in the double pipe heat
exchanger by changing the flow of a liquid. Tests to be
conducted at various mass flow rates by controlling the
flow control valve, for the following valve opens (25%,
50%, 75%, 100% valve open). Results may indicate that
the heat transfer rate enhances inversely with the pitch
of the wire coiled turbulator and directly proportional to
the mass flow rate.
Index Terms—Double pipe heat exchanger, Plain Tube,
Wire coiled turbulator inserts, Pin wire coiled turbulator
inserts, Pressure drop, Friction Co-efficient.
I. INTRODUCTION
Heat transfer can be increased by active and passive
techniques. In the active techniques external power is
required to increase the heat transfer. For the passive
technique method no external energy is required for
the enhancement of heat transfer. Wire coiled coil
matrix turbulator (WCCMT), taper wire coiled coil
matrix turbulator, and pin wire coiled turbulators are
falls under the category of passive techniques. In this
experimental work, turbulators are used to increase the
heat transfer. Three different types of wire coiled
turbulators (shown in figs.) are used to increase the
heat transfer. Due to the insertion of turbulators there
is increase in pumping power due to the pressure drop.
But when compared to enhancement in heat transfer
the increase in pumping power is very less.
II. TURBULATORS
Heat exchangers with the convective heat transfer of
fluid inside the tubes arefrequently used in many
engineering applications. In order to augment heat
transfer andincrease the system efficiency, turbulators
with different geometries have been developedand
many experimental investigations have been
conducted to determine theirthermodynamic
characteristics. The turbulators, when they are inserted
into the flow, provide redevelopment ofthe boundary
layer and increase the heat transfer surface area and
cause enhancement ofconvective heat transfer by
increasing turbulence. Thus, more compact and
economicheat exchanger with lower operation cost
can be produced. On the other hand, when
thesedevices placed into the flow they deteriorate the
flow.
Major Applications for Turbulators:
1. Oil Coolers
2. Highly viscous liquids
3. Gas or Air heaters/coolers
4. Static Mixers
5. Falling Film Evaporators
6. Inline reactors
7. Prevention of scale formation on tube.
a) Wire coiled and Pin Wire coiledturbulators:
The wire coiled turbulator is the old war horse of the
Turbulator world and ofcourse we make them in large
quantities. This type is also featured in the HTRI
softwareas a generic product so customers can do their
own design. (A type of wire Turbulator isalso featured
but as a proprietary product of Calgavin and
customized as per theirconfigurations.) We can give
all standard and a large range of custom pitches and
offerthem in almost all materials. While in most cases
the flexible wire type is a preferredoption, in the case
© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 189
of retrofitting, where there is a lower flexibility with
regards toredesigning the existing equipment, this is
very often a low pressure drop reasonableefficiency
solution. So that I have selected wire coiled and pin
wire coiled turbulatorsformy research work.
b) Specifications of Wire Coiled Turbulator:
Fig. 1.Wire Coiled Turbulator
L = length of the wire coiled turbulator(1500 mm)
P = pitch (5mm, 10mm, 15mm)
D1 = Outer Diameter of the wire coil
turbulator(18mm)
D2 = inner Diameter of the wire coil turbulator.(6mm)
c) Wire Coiled Turbulator for Various Pitch:
Fig. 2 Wire coiled turbulator for 5mm pitch
Fig. 3 Wire coiled turbulator for 10mm pitch
Fig. 4 Wire coiled turbulator for 15mm pitch
d) Pin wire coiled turbulator:
Fig. 5 Pin wire coiled turbulator for 15mm pitch
III. EXPERIMENTAL SETUP AND
PROCEDURE
a) Double pipe heat exchanger:
A simplest form of heat exchanger is double pipe Heat
Exchanger where two pipes are constructed one inside
the other. One fluid flows in each of the pipes and gets
heated or cooled as per the application.
The major use of double pipe heat exchangers is
for sensible heating or cooling of process fluids
where small heat transfer areas (50 m2) are
required. This configuration is also suitable when
one or both fluids are at high pressure.
Double pipe heat exchangers Can operate
between 0.5KW~150KW.
Double pipe heat exchangers have an outer pipe
I.D of 50 to 400 mm at a nominallength of 1.5 to
12.0 m per hairpin. The O.D of the inner tube may
vary between 19 to 100 mm.
b) Reasons for selection:
The heat transfer coefficient and pressure drop are the
most significant variables in reducing the size and cost
of a heat exchanger. An increase in the heat transfer
coefficient generally leads to another advantage of
reducing the temperature driving force, which
increases the second law efficiency and decreases
entropy generation. Thus, research in this area
captivated the interest of a number of researchers. So,
the double pipe heat exchanger is selected.
The experimental setup is shown in fig. 6. It consists
of hot and water reservoir, Rota meter, thermocouples,
pumps, flow control valves and two concentric tubes
in which hot water flows through the inner tube
(Copper tube, d= 33 mm, L= 1550 mm) and cold water
flows in counter flow through annulus.The outer tube
is made of MS steel and it’s insulated with the asbestos
© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 190
rope to minimize the heat loss with surroundings. Six
RTD Pt 100 type temperature sensors with ±0.1 °C
accuracy are used to measure the inlet and outlet
temperature of the hot and cold water.The water is
heated using 3 KW water heaters in the hot water tank
and the desired temperature controller. The water at
constant temperature is taken from the tank using the
centrifugal pump to the test section.
c) Experimental procedure:
The hot and cold water tank is filled with the
required level water.
The heater is switched on through the main power
supply of the setup.
The RTD (Relational Temperature Detector) is set
with the required temperature of hot water inlet.
Fig. 6Experimental setup
In this experiment there are two flow control
valves are used in that two initially one flow
control valve is closed and another one is open
this allow the fluid to fill in the container by using
this we measure the flow rate.
After that both the flow control valves are open
the cold water is entered into the inner pipe of the
setup.
The hot water is entered into an outer tube of the
heat exchanger through flow control valve.
The sensor measures the hot water and inlet and
outlet temperature and indicates in the
temperature indicator.
After taking the required readings the gate valves
is adjusted to the initial position.
Finally the heater and main power is switch OFF
and the water is drained.
d) Specifications:
(1) Inner Tube of the double pipe:
i.Material - Copper
ii.Inner diameter - 33 mm
iii.Outer diameter - 38 mm
iv.Length - 1550 mm
(2) Outer pipe of the double pipe:
i.Material - Mild steel
ii.Inner diameter - 63.5 mm
iii.Outerdiameter - 66.5 mm
iv.Length - 1450 mm
v.Insulation material - Asbestos
(3) Heater:
i.Capacity of heating coil – 1000W
ii.Number of heating coil - 3 no’s
(4) Pump:
i.Type - Centrifugal pump
ii.Power - ½ HP
iii.Number of pumps - 1no’s
iv. Cold water pump - 1no’s
e) Digital temperature indicator:
i. Sensor - RTD-Pt 100
ii. Number of sensors - 6 no’s
iii. Range - 0-199.9 °C
iv. Display unit - Digital LED)
v. Number of Channel - 10
f) Digital temperature controller:
i. Sensor - k-type
ii. Number of sensors - 6 no’s.
iii. Range - 0-400 °C
© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 191
iv. Display unit -Digital (LED)
g) Hot and cold water tank:
i. Length - 0.47 m.
ii. Breadth - 0.47 m.
iii. Height - 0.75 m.20 liter container(used for
drinking water storage)
PVC pipe 0.5’’(length~1m)
Funnel (for feed input)
Rubber or plastic cap (to seal container)
Cap 0.5” (to seal effluent pipe)
Pipe (for gas output, was used LPG pipe) (1.5m)
Tyre tube (for store the biogas)
T- junction
M–seal
Black paint (to absorb heat energy from surroundings)
IV. DATA REDUCTION EQUATIONS
1. The average inside heat transfer coefficient and the
mean Nusselt number for the plain and the wire coiled
matrix turbulator cases are evaluated as:
Q = m Cp (T0 – Ti) = hi Ai (∆Ti) m
Where, Ai = π Di L
(∆Ti) m = (TMW-Ti) – (TMW-Ti)
ln (TMW-Ti)
(TMW-Ti)
TMW=TW/2
2. The average inside heat transfer co efficient
hi = (Q / Ai (∆Ti)m)
3. Nusseltnumber, friction factor, pressure drop
equations (plain tube):
Δp = 4fLVc2
2D2
4. Nusselt number, friction factor, pressure drop
equations (Plain tube with coiled turbulators):
Δp = 4fLVc2
2D2
V. RESULT AND DISCUSSION
The present experimental results on heat transfer and
friction characteristics in a plain tube are first
validated in terms of Nusselt number and friction
factor. It is important to compare the experimental
results obtained for the fully developed turbulent flow
for various turbulator inserts. At 25% valve open, with
a pitch of 5 mm, the wire coiled turbulators without
bonding have resulted in almost 2 times enhancement
when compared with plain tube. On the other hand, for
pitches of 10 mm and 15 mm the enhancement were
1.75 times and 1.5 times, respectively. At 50% valve
open, with a pitch of 5 mm, the wire coiled turbulators
without bonding have resulted in almost 1.83 times
enhancement when compared with plain tube. On the
other hand, for pitches of 10 mm and 15 mm the
enhancement were 1.66 times and 1.33 times,
respectively. At 75% valve open, with a pitch of 5 mm,
the wire coiled turbulators without bonding have
resulted in almost 1.75 times enhancement when
compared with plain tube. On the other hand, for
pitches of 10 mm and 15 mm the enhancement were
1.63 times and 1.37, respectively. At 100% valve
open, with a pitch of 5 mm, the wire coiled turbulators
without bonding have resulted in almost 1.63 times
enhancement when compared with plain tube. On the
other hand, for pitches of 10 mm and 15 mm the
enhancement were 1.45 times and 1.27 times,
respectively.
At 25% valve open, with a pin wire coiled turbulator
without bonding have resulted in almost 2.5 times
enhancement when compared with plain tube. At 50%
valve open, with a pin wire coiled turbulator without
bonding have resulted in almost 2.16 times
enhancement when compared with plain tube. At 75%
valve open, with a pin wire coiled turbulator without
bonding have resulted in almost 2 times enhancement
when compared with plain tube. At 100% valve open,
© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 192
with a pin wire coiled turbulator without bonding have
resulted in almost 1.81 times enhancement when
compared with plain tube. On other hand the Nusselt
number, friction factor, and pressure drop are
indirectly proportional to the pitch.
Fig 7 Reynolds number Vs Experimental Heat
transfer co-efficient.
Fig 8 Reynolds number Vs Theoretical Heat
transfer co-efficient.
Figures 7 and 8 shows variation of Nusselt number
with Reynolds number for the different cases like plain
tube, wire coiled turbulator, taper wire coiled
turbulator, and pin wire coiled turbulator. It is
observed that the heat transfer rate is higher for pin
wire coiled turbulator while compare with other
turbulators.
Fig 9 Reynolds number Vs Experimental friction
factor.
Fig 10 Reynolds number Vs Theoretical friction
factor.
Figures 9 and 10 shows variation of friction factor with
Reynolds number for the different cases like plain
tube, wire coiled turbulator, taper wire coiled
turbulator,and pin wire coiled turbulator. It is observed
that the friction factor is higher for pin wire coiled
turbulator while compare with other turbulators.
0
5000
10000
15000
20000
25000
30000
0 100000
Exp
Hea
t tr
ansf
er c
o-e
ffic
ient
hex
p (
W/m
2K
)
Reynolds no
Reynolds no Vs Exp Heat
transfer co-efficient Plain
Tube
WCT
(5mm
Pitch)
WCT
(10mm
Pitch)
WCT
(15mm
Pitch)
0
1000
2000
3000
4000
5000
6000
0 100000Theo
reti
cal
Hea
t tr
ansf
er c
o-
effi
cien
t…
Reynolds no
Reynolds no Vs Theoretical
Heat transfer co-efficientPlain
Tube
WCT
(5mm
Pitch)
WCT
(10mm
Pitch)
WCT
(15mm
Pitch)
0
0.000001
0.000002
0.000003
0.000004
0.000005
0.000006
0 100000
fric
tion
fact
or
Reynolds no
Reynolds no Vs Exp friction
factorPlain Tube
WCT
(5mm
Pitch)WCT
(10mm
Pitch)WCT
(15mm
Pitch)Pin Wire
Coiled
Turbulator
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 100000
fric
tion
fact
or
Reynolds no
Reynolds no Vs Theoretical
friction factorPlain Tube
WCT
(5mm
Pitch)
WCT
(10mm
Pitch)
WCT
(15mm
Pitch)
Pin Wire
Coiled
Turbulator
© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 193
Fig 11.Reynolds number Vs Experimental
Pressure drop.
Figures 11 and 12 shows variation of pressure drop
with Reynolds number for the differentcaseslike plain
tube, it is observedthat the pressure dropis higher for
pin wire coiled turbulator while compare with other
turbulators.
Fig 12 Reynolds number Vs Theoretical Pressure
drop
VI. CONCLUSION
Experimental data obtained were compared with
those obtained from the theoretical data of plain tube.
The maximum Nusselt number for pitch 5 mm
was obtained which indicates that heat transfer
coefficient increases with the decreasing pitch of
the turbulator.
The friction factor also increases with the
decreasing pitch.
The above findings indicate that the use of wire
coiled coil matrix turbulator and pin wire coiled
turbulators in the tube-in-tube heat exchanger
enhances the heat transfer with considerable
pressure drop.
The experimental data which indicates the heat
transfer rate of pin wire coiled turbulator is
higher than the wire coiled turbulators.
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P.S.S. Srinivasan,Heattransfer and pressure
drop characteristics in a circular tube fitted
with and without V-cut twisted tape insert:
International Communications in Heat and
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[ 2 ] PaisarnNaphon, TanaponSuchana,Heat
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[ 3 ] Halit Bas, VeyselOzceyhan,Heat transfer
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[ 4 ] PaisarnNaphon,Second law analysis on the
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0
0.01
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0.06
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0 100000
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bar)
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WCT
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© June 2017 | IJIRT | Volume 4 Issue 1 | ISSN: 2349-6002
IJIRT 144608 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 194
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