Performance Evaluation of Heat Transfer and Friction
Factor Characteristics of Pipe in Pipe Fitted with
Helical Screw Tape Insert of different Material.
#1
Hemant P.Gawade,
PG Student: Mechanical Engineering Department
Padmabhooshan Vasantdada Patil Institute of Technology,
Bavdhan, Pune-21(India)
hemantgawade123@gmail.com
Abstract— Experimental investigation on heat transfer and
friction factor characteristics of circular tube fitted with helical
screw inserts of equal length of different material twist ratio
have been presented. The experimental data obtained were
compared with those obtained from plain tube published data.
In the present study would encompass all necessary activities
for benchmarking the existing application like solar power
plant with the current performance level and performance
standards to be set for arriving at the objectives of the
dissertation work. Recommendation of the best alternative
would follow the comparison of the results. Data over Testing
to be shared through a Test report for the experimentation
phase.
Key Words: Screw tapes; Thermal performance; Heat
Transfer Performance.
Introduction
A heat exchanger is a device that is used to transfer thermal
energy (enthalpy) between two or more fluids, between a solid
surface and a fluid, or between solid particulates and a fluid, at
different temperatures and in thermal contact. In heat
exchanges, there are usually no external heat and work
interactions. The basic concept of a heat exchanger is based on
the premise that the loss of heat on the high temperature side
is exactly the same as the heat gained in the low temperature
side after the heat and mass flows through the exchanger. Heat
exchanger simply exchangers the heat between those two
sides, as a result it is decreasing the temperature of higher side
and increasing the temperature of lower temperature side. Heat
exchangers are used in different processes ranging from
conversion, utilization & recovery of thermal energy in
various industrial, commercial & domestic applications. Some
common examples include steam generation, condensation in
power & cogeneration plants, sensible heating & cooling in
thermal processing of chemical, pharmaceutical & agricultural
products, fluid heating in manufacturing & waste heat
recovery etc. Increase in Heat exchanger’s performance can
lead to more economical design of heat exchanger which can
#2
Prof(Dr.). Rajendra K. Patil
Professor: Mechanical Engineering Department
Padmabhooshan Vasantdada Patil Institute of Technology,
Bavdhan, Pune-21(India)
rkpvpit@gmail.com
help to make energy, material & cost savings related to a heat
exchange process. The need to increase the thermal
performance of heat exchangers, thereby effecting energy,
material & cost savings have led to development & use of
many techniques termed as Heat transfer Augmentation. These
techniques are also referred as Heat transfer Enhancement or
Intensification. Augmentation techniques increase convective
heat transfer by reducing the thermal resistance in a heat
exchanger.
The technique of improving the performance of heat
transfer system is referred to as heat transfer augmentation or
intensification. This leads to reduce the size and cost of the
heat exchanger. Heat transfer enhancement technology has
been developed and widely applied to heat exchanger
applications; for example, refrigeration, automotives, process
industry, chemical industry etc. Many techniques of active and
passive techniques are available for augmentation. Also heat
augmentation techniques play a vital role for laminar flow,
since the heat transfer coefficient is generally low in plain
tubes. Vast literature is available on heat transfer
augmentation studies in tube fitted with twisted tape in
laminar flow. Helical screw-tape swirl flow generators shown
in Fig. 1 is a modified form of a twisted tape wound on a
single rod gives single way smooth direction of flow like
screw motion. The present paper reports the heat transfer and
friction factor characteristics of turbulent flow through a
circular tube fitted with full length helical screw inserts (twist)
of various twist ratio, and regularly spaced helical screw
inserts with different spacer length.
Technical details of helical screw-tape insert
The geometrical configuration of helical screw-tape
inserts is shown in Fig. 1a. The helical screw-tape inserts with
various twist ratio is made by winding uniformly a strip of 5
mm width over a 8 mm rod. These sheets wounded with pitch
values 20, 30, 40 mm. Due to these specifications we get
helical screw tapes of two different materials.
Fig 1a : Copper Insert with Pitch 20 mm
Fig 1b:Copper Insert with Pitch 30 mm
water. Similarly a rotameters is provided to control the flow
rate of hot water from the inlet hot water tank. Cold water
flow rate is kept constant at 60,120LPH. Two pressure
tapings- One just before the test section and the other just after
the test section are attached to the U-tube manometer for
pressure drop measurement. Mercury (Hg) is used as the
manometric fluid. Four thermocouples measure the inlet &
outlet temperature of hot water & cold water (T1,
T4,T7,T10,T11) through a multipoint digital temperature
indicator.
Procedure
Fig 1c:Copper Insert with Pitch 40 mm
Fig: 1 Helical Screw Tape Insert of copper Material
Fig 2 a: Steel Insert with Pitch 20 mm
Fig 2 b :Steel Insert with Pitch 30 mm
Fig 2 c:Steel Insert with Pitch 40 mm
Fig:2 Helical Screw Tape Insert of Steel Material
Connect the plug pins to 220 V A.C stable electric supply.
Switch on the heater power supply. Heater is put on to heat the
water to 60 to 650C in a constant temperature water tank of
capacity 60litres. The tank is provided with a centrifugal pump
& a bypass valve for recirculation of hot water to the tank & to
the experimental setup. Start the pump and water at about
55°C is allowed to pass through the tube side of heat
exchanger at desired flow rate. Cold water is now allowed to
pass through the annulus side of heat exchanger in counter
flow direction at a 60,120LPH (mc=0.01657,0.033146
Kg/sec). The water inlet and outlet for both hot water & cold
water temperatures are recorded only after temperature of both
the fluids attains a constant value. The procedure was repeated
for different Hot water flow rates ranging from 60 to 300
LPH. The manometer reading is noted for each observation.
Calculations
Experimental set-up and procedure
The following photographs shows the experimental
A) Calculation for Reynolds Number
set up.
Reynolds Number (Re) =
 × v × di

B) Calculation For Heat Transfer Coefficient And Nusselt
Number
Heat transfer coefficient hInner =
Nusselt Number (Nu) =
Fig 3: Experimental Set Up
Photographs show the experimental setup. It is a
double pipe heat exchanger consisting of test section,
rotameters and water tank for supplying hot water with in-built
two heaters, pump & the measuring system. The test section is
a Plain copper tube with dimensions of 1000mm length, Inner
tube-22 mm ID, and 25 mm OD; Outer MS pipe- 44mm ID,
and 47 mm OD. The outer pipe is well insulated using 100
mm diameter glass wool to reduce heat losses to the
atmosphere. Two calibrated rotameters, with the flow range 30
to 300 LPH, are used to measure the flow of cold & hot water.
The water, at room temperature is drawn from tap of cold
q
A * LMTD
h × di
k
C) Pressure Drop and Friction Factor Calculation
1) Friction factor f =
Where Δp in N/m2
p × di × 2
L ×  × v2
=h in mm of hg × 133.33
Results and discussion
Results were discussed on the basis of heat transfer
performance different types Material used for screw tape.The
experimental system was validated by performing experiments
using pure water. The following results were obtained for
different Materials i.e. copper And M.S. shown as graphically.
Plain tube Results
Fig 5b: Variation of Friction factor Vs Reynolds Number
Above graph indicates variation of Friction factor Vs
Reynolds Number for cold water flow rate which is constant at
60,120LPH for Copper screw tape with 20 mm pitch.
Fig 4a: Variation of Nusselt Number Vs Reynolds Number.
Above graph indicates variation of Nusselt Number
Vs Reynolds Number for cold water flow rate which is
constant at 60,120LPH for plain tube.
Fig4b : Variation of Friction factor Vs Reynolds Number.
Above graph indicates variation of Friction factor Vs
Reynolds Number for cold water flow rate which is constant at
60,120 LPH for plain tube.
Material: Steel
Fig 6a: Variation of Nusselt Number Vs Reynolds Number
Above graph indicates variation of Nusselt Number Vs
Reynolds Number for cold water flow rate which is constant at
60,120 LPH for Steel Screw tape with 20mm pitch.
Helical Screw Tape Results
Material: Copper
Fig6b : Variation of Friction factor Vs Reynolds Number.
Above graph indicates variation of Friction factor Vs
Reynolds Number for cold water flow rate which is constant at
60, 120 LPH for Steel screw tape with 20 mm pitch.
Fig5a: Variation of Nusselt Number Vs Reynolds Number.
Above graph indicates variation of Nusselt Number
Vs Reynolds Number for cold water flow rate which is
constant at 60,120LPH for Copper screw tape with 20mm
pitch.
As like this there are different readings have been
taken and on those results we comparing that for different
material having different pitch value i.e. 30 mm and 40 mm
Following graph show the variation for different Pitch value
and material.
Effect of Pitch Value
Fig7a: Variation of Nusselt Number Vs Reynolds Number.
Above graph indicates variation of Nusselt Number Vs
Reynolds Number for cold water flow rate which is constant at
60LPH, for Copper Screw Tape with pitch values 20,30 and
40 mm respectively. Above graph clearly indicates that as
pitch Value increases the Nusselt No. Decreases for different
Reynolds no. It shows maximum Nusselt no for 20 mm pitch
is 26.44.
Fig7b: Variation of Pressure Drop Vs Reynolds Number.
Above graph indicates variation of Pressure Drop Vs
Reynolds Number for cold water flow rate which is constant at
60LPH, for Copper screw tape with pitch values 20, 30, 40
mm respectively. Above graph clearly indicates that as pitch
Value increases the Pressure drop increases for different
Reynolds no.
Effect of Material
Fig8a: Variation of Nusselt Number Vs Reynolds Number
Above graph indicates variation of Nusselt Number Vs
Reynolds Number for cold water flow rate which is constant at
120 LPH, for Copper, and Steel screw tape with pitch value 20
mm Above graph clearly indicates that for Copper material
Nusselt no is maximum for most of the Reynolds no. So that
Copper inserts are more effective than the Steel inserts
Fig8b: Variation of Pressure Drop Vs Reynolds Number.
Above graph indicates variation of Pressure Drop Vs
Reynolds Number for cold water flow rate which is constant at
120LPH, for Copper and Steel screw tape with pitch values 15
mm.
Fig8c: Variation of Friction factor Vs Reynolds Number.
Fig 7c:Variation of Friction factor Vs Reynolds Number.
Above graph indicates variation of Friction factor Vs
Reynolds Number for cold water flow rate which is constant at
60LPH for Copper screw tape with pitch values 20, 30, 40 mm
respectively. Above graph clearly indicates that as pitch Value
increases the Friction factor also decreases for different
Reynolds no.
Above graph indicates variation of Friction factor Vs
Reynolds Number for cold water flow rate which is constant at
120LPH for Copper and Steel Screw tape with pitch values
20mm.
Conclusions
It can be found that enhancing heat transfer with
passive method using different types of Screw tape
construction in the inner tube of a double pipe heat exchanger
can improve the heat transfer rate efficiently. However, the
friction factor of the tube with the Screw tape insert also
increases. The increase in heat transfer and friction can be
explained by the swirling flow as a result of the secondary
flows of the fluid.
Following are the conclusions drawn from this
research, the effect of varying hot fluid flow rate (or Reynolds
Number) on the , Nusselt number & friction factor, and
comparative study for above said parameters different flow
regimes (i.e. 60LPH to 300LPH), the effect of varying fluid
flow rate. Similarly the comparative study among material,
pitch values for heat exchanger.
i) It is found that pressure drop increases as Reynolds
number increases for all screw tapes (i.e. by considering all
variation of the pitch) & friction factor decreases with increase
Reynolds number for all twisted tapes.
ii) Nusselt number increases as Reynolds number
increases for all tapes.
iii) From result tables and calculation it is also found
that Nusselt number for Copper Screw tape with pitch 20mm
40% increase as compared to plain tube heat exchanger and
Steel with pitch 20 mm is 25-32% increase more as compared
to plain tube heat exchanger.
iv) Experimental analysis shows, for Copper 20 mm
pitch value Nusselt number is more than remaining Five
Screw tapes.
v) Result shows that pitch value increases the
Nusselt number decreases; so that minimum pitch value (20
mm) has maximum Nusselt number but pressure drop is
maximum for minimum pith value (20 mm). Friction factor is
decreases pitch value increases.
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