The document describes an experimental study on heat transfer enhancement using dimpled surfaces. The objectives are to analyze the heat transfer rate from dimpled tubes under cross-flow and find the maximum rate by optimizing the spacing between tubes. The methodology involves passing hot water through dimpled copper tubes in a duct while blowing air across the tubes. Temperature measurements will be taken at various locations to calculate heat transfer parameters like heat transfer coefficient and Nusselt number. The results will help understand the effect of dimple geometry on heat transfer enhancement.

1. PRAJWAL KUMAR USN 4PA16MTP01
under the guidance of
Prof ABDUL RAZAK KALADGI
AN EXPERIMENTAL STUDY OF HEAT TRANSFER
ENHANCEMENT USING DIMPLED SURFACES
1/7/2023

2. Contents
1/7/2023
 Introduction
 Literature Survey
 Literature gap
 Objectives
 Methodology
 Experimental setup
 Results
 References

3. INTRODUCTION
1/7/2023
 To study experimentally the enhancement of heat
transfer through various geometries of dimpled
surface
 To check the heat transfer rate at different
spacing under cross flow analysis under the
principle of convection.
 Spacing dimension 12cm
 Tube material: Copper tube of 02 no’s

4. CONTINUED
1/7/2023
 Heat transfer from the surface is directly
proportional to area of the surface and
temperature difference between them.
 Enhancement of Heat transfer can be done by
dimples, fins , grooves, protrusions etc.
 Heat transfer enhancement techniques are used
in the areas of thermal power plants, in
automobiles, in chemical processing industries,
various electronic gadgets,HVAC systems, in
refrigerators, in heating and cooling of
evaporators, in the blades of gas turbines,
pharmaceutical industries etc.

5. CONTINUED
1/7/2023
 Different spacing will induce turbulence which
creates vertices that tends to increase the
thermal boundary layer.
 Dimples induces minimum pressure losses & flow
resistances.
 Based on various investigations it is found out
that there is 30 to 40% increase in heat transfer
rate in case of dimples.
 Presence of dimples will increase the area of heat
transfer of the flowing fluid which removes
excessive amount of heat from the surface of the
tubes.

6. LITERATURE SURVEY
1/7/2023
AUTHOR TYPE OF STUDY
SPECIFICATION
S
PARAMETERS
CHECKED
OBSERVATIONS
Vilas Apet
&. S L
Bose
Experimental
Heat Transfer
Enhancement
Plain tubes and
tubes with
spherical
dimples
Heat Transfer
Coefficient,
Reynolds
Number, Nusselt
Number
Heat transfer coefficient and
Nusselt Number increases if
dimple diameter decreases at
constant flow of air,
. Yogesh
Dhilip,
Shashank
Ram,
Mayur
Vasanth
Experimental
Heat Transfer
Enhancement
Plain tube and
tubes with
Dimples-Almond
shape geometry
Convective Heat
transfer
coefficient,
Reynold’s
number
Maximum increment b/w exp.
Heat transfer coefficient for
the dimple over plain tube
found to be 12.7%
. The exp. and numerical
results show that almond
shape dimple provides highest
heat transfer over plain tube
.

7. CONTINUED
1/7/2023
Dhananja
y R
Giram, A
M Patil.
Exp. and
theoretical
analysis of heat
transfer
augmentation.
Flat plate with
Varying dimples
Nusselt number,
Heat transfer
rate.
Maximum Nusselt number is
obtained for staggered
arrangement of dimples than
that of inline arrangement. As
dimple density of test plate
increases Nusselt number
also increases, Reynold’s
number range 3688 t0 5968.
Chethan
Kharche,
shusheela
Pavade, V
R Dhivare
Exp. And
theoretical Heat
transfer
enhancement
Double pipes
with Dimples
like Spherical,
triangular,
square,
trapezoidal etc
Heat transfer
area, friction
factor, turbulent
flow
Theoretical result show
increase in turbulence
intensity has higher
performance in dimple tube
compared to plain tube, in
spherical dimples show good
heat transfer characteristics
when used as surface
roughness and ellipsoidal
shape gives better result due
to prior vortex formation than
all other shapes.
AUTHOR
TYPE OF
STUDY
SPECIFICATION
S
PARAMETERS
CHECKED
OBSERVATIONS

8. CONTINUED
1/7/2023
5.Mr. Vilas
P Apet Dr.
Sachin L
Borse
Experimental
investigation of
forced
convection heat
transfer
enhancement in
dimpled tube.
4 copper tubes
with 4mm dia
and 4mm depth
and 8mm dia
and 4mm depth
with inline and
staggered
arrangement
Heat transfer
enhancement,
Thermal
performance
factor.
Staggered array facility
dimples have higher heat
transfer augmentation and
thermal performance factor
compared to inline,
convective heat transfer
coefficient is observed as
18% and Nusselt number
22%.(Reynold’s number
12000-26000)
6. Mr
Hasibur
Rahmon,
Mr. Abdul
Razak
Kaladgi.
Experimental
forced
convection heat
transfer analysis
on dimpled
surfaces
(different
arrangement)
Copper plate
with constant
dia dimples,
gradually
increasing and
gradually
decreasing dia
dimples.
Heat transfer
passive
technique’
Nusselt number,
Reynold’s
number.
Nusselt number increases
with Reynold’s number for all
three cases, constant
diameter dimpled plates has
higher heat transfer
compared to other cases
and has highest Nusselt
number
AUTHOR TYPE OF STUDY
SPECIFICATIO
N
PARAMETERS
CHECKED
OBSERVATIONS

9. LITERATURE GAP
1/7/2023
After investigating the journals we came to know
that
 Enhancement of heat transfer by cross flow
analysis
 Dimples of constant diameter at various
geometries of the tube section under maximum
optimum spacing.

10. OBJECTIVES
1/7/2023
 To analyze the Rate of heat transfer from the
dimpled tubes under the principle of cross flow
analysis.
 To find out the maximum rate of heat transfer by
enlarging optimum spacing between the dimpled
tubes.
 To investigate the rate of heat transfer
enhancement in dimpled parallel tubes of copper
material tubes.

11. METHODOLOGY
1/7/2023
 The main set up consist of a duct which has two
ends in it the convergent end as well as the
Divergent end.
 The dimpled copper tubes is placed vertically
inside it.
 Water is circulated from the collecting tank where
it is pumped by means of a suction pump on to
the container where immersion heater is
immersed which heats up the water in the
container.
 Gate valve is adjusted for slow movement of hot
water
 The Hot water is made to pass through two
copper tubes by means of hose pipe in order to

12. CONTINUED
1/7/2023
 Air is then made to pass through the duct in order
to absorb the heat from the tubes by the means
of a centrifugal blower.
 Flow velocity of air is controlled by using
anemometer and it is measured in m/s.
 The temperature of air at the inlet, outlet and on
the surface of the tubes needs to be measured.
 Optimum spacing of 12cm is maintained in the
dimpled tubes

13. FLOW ARRANGEMENT
1/7/2023

14. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
A RECTANGULAR DUCT OF LENGTH 300CM AND HEIGHT 20CM WIDTH
30CM MADE OF GALVANISED IRON (GI) SHEET OF THICKNESS IMM

15. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
FIGURE DETERMINING CONVERGING AND DIVERGING PART

16. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
Rectangular duct showing air damper

17. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
DIMPLED COPPER TUBE OF DIMPLE DEPTH 2MM AT A
DISTANCE OF IMM BETWEEN EACH DIMPLES

18. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
SLITS ARRANGED AT 12CM DISTANCE BETWEEN COPPER TUBES
FOR OPTIMAL SPACING BETWEEN THEM

19. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
Copper based ring thermocouple of k type with adjustable inner diameter. 7
mm which is fixed at tip of the pipe with 2 metre of Teflon cable.

20. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
CENTRIFUGAL BLOWER TO BE ATTACHED TO DIVERGENT

21. PLUMBING ARRANGEMENT
SET UP
1/7/2023
 Tank nipple out of threaded surface of ½ inch
 Female tank fitting of threaded end of 80mm
 Gate valve of ½ inch threaded PVC ball valve to
control the regulation of flow
 1/8 inch reduces pipe Elbow of 2 numbers at both
sides
 Pressure pipe T piece
 Hose collar of ½ inch

22. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
The sealing material is nitrile foam self-adhesive foam tape of width 2 inches x
thickness 3 mm and has a length of 9 meter are used to prevent the leakage of
air into the duct

23. EXPERIMENTAL
ARRANGEMENTS
1/7/2023
ANEMOMETER used to measure the speed of air while flowing inside the
duet.

24. RESULTS TO BE FOUND
1/7/2023
Sl
No
Water
Inlet
temp
Water
outlet
Temp
Air
Inlet
Temp
Air
outlet
Temp
Copp
er
Temp
Copp
er
Temp
Time taken
for Flow
(sec)
1 63 59 28 31 10 9 28
2 59 55 28 30 9 13 29

25. FORMULAES
1/7/2023
Heat transfer rate, q=mf Cp(To-Ti) W
Heat transfer coefficient, h=q/(A(Ts-Ta )) W/m2K
Reynolds number, Re=ρDu/µ
Nusselt number, Nu=hD/k
 Where p = density, 𝐶𝑝 = Specific Heat, 𝑚𝑓 = mass
flow rate, To & Ti = Temperature at inlet and outlet , K
= Thermal conductivity, A = Area of heat transfer D =
Characteristic length

26. REFERENCES
1/7/2023
 Sadighi Dizaji H, Jafarmadar S, Mobadersani F.
Experimental studies on heat transfer and pressure drop
characteristics for new arrangements of corrugated tubes
in a double pipe heat exchanger. I. 2015;96:211– 220.
 Bi C, Tang GH, MOE WQT. Heat transfer enhancement in
mini-channel heat sinks with dimples and cylindrical
grooves.Appl Therm Eng. 2016;55:121–132.
 Kathait PS, Patil AK. Thermo-hydraulic performance of a
heat exchanger tube with discrete corrugations. Appl
Therm Eng. 2014;66:162–170.
 . Poredoš P, Šuklje T, Medved S, Arkar C. An experimental
heat-transfer study for a heat-recovery unit made of
corrugated tubes. Appl Therm Eng. 2013;53:49–56.
 . FanJF ,Ding WK, HeYL, TaoWQ. Three-dimensional
numerical study of fluid and heat transfer characteristics of
dimpled fin surfaces. Numer Heat TransferAppl.
2012;62:271–294.

27. 1/7/2023
THANK YOU