Experimental Studies on Heat Transfer Augmentation Using TMT Rods with and without Baffles as ...

70 Pages·2012·1.63 MB·English

Experimental Studies on Heat Transfer Augmentation Using TMT Rods
with and without Baffles as Inserts for Tube Side Flow of Liquids

A thesis submitted in partial fulfilment of the requirements for the degree of

Bachelor of Technology
In
Chemical Engineering

Under the Guidance
of

Prof. S. K. Agarwal

By
Jitendra Kumar Patro
(Roll No. 108CHO41)
&
Abhinav Malviya
(Roll No. 108CH047)

Department of Chemical Engineering
National Institute of Technology
Rourkela
2012
National Institute of Technology
Rourkela

CERTIFICATE

This is to certify that the thesis entitled, “EXPERIMENTAL STUDIES ON HEAT
TRANSFER AUGMENTATION USING TMT RODS WITH AND WITHOUT
BAFFLES AS INSERTS FOR TUBE SIDE FLOW OF LIQUIDS” submitted by
Jitendra Kumar Patro & Abhinav Malviya in partial fulfilments for the requirements for
the award of Bachelor of Technology Degree in Chemical Engineering at National Institute
of Technology, Rourkela (Deemed University) is an authentic work carried out by them under
my supervision and guidance.
To the best of my knowledge, the matter embodied in this thesis has not been submitted to any
other University / Institute for the award of any Degree or Diploma.

Date

Prof.S.K.Agarwal
Dept .of Chemical Engineering
National Institute of Technology
Rourkela – 769008
ii
ACKNOWLEDGEMENT

We express our deepest appreciation and sincere gratitude to Prof. S. K. Agarwal for his valuable
guidance, constructive criticism and timely suggestions during the entire duration of this project
work, without which this work would not have been possible.

We would also like to thank Mr S.Majhi, and Rajendra Babu for their help in making baffles
for the inserts and also for teaching us balancing manometer.

Date:
Jitendra Kumar Patro

(108CH041)

Abhinav Malviya

(108CH047)
iii
ABSTRACT

This project deals with the introduction of TMT rods as inserts as passive augmentation device, in
the flow path of inner tube side liquid flow. The effect of turbulence on heat transfer & pressure
drop was compared with the values for smooth tube. The effect of baffles was also taken into
account and again a comparative study was made on the basis of varying the baffle spacing. All
the results and readings were compared with the standard data from the smooth tube. Whenever it
comes to enhance the heat transfer between the surfaces or in other words augmenting the heat
exchanger, the pressure drop does play an important role and becomes another important factor to
be considered and to be kept in mind.

Two TMT Rods (d = 8 mm, 10 mm) were used for the experimental purpose. In the beginning we
i
conducted the experiment without any insert to get the value for plane heat exchanger and
thereafter the experiment was repeated with TMT Rods ( d = 8mm, 10 mm) without any baffles
i
and with baffles with varying baffle spacing (β=10cm, 20cm, 30cm). The maximum value of
performance evaluation criteria R1 was found to be around 2.46 for 10mm insert with β = 10cm
and similarly the highest value for f /f was found to be around 21.
a o
The friction factor was found to be significantly high and that has been an area of concern and
which needs to be minimized.

iv
CONTENTS

Chapter Topic Page No.
Abstract iv
List of Figures vii
List of Tables viii
Nomenclature ix
Chapter 1 Introduction 1
Chapter 2 Literature Review 3
2.1 Classification of enhancement techniques 4
2.2 Performance Evaluation Criteria 6
Chapter 3 Present experimental work 12
3.1 Specifications of Heat exchanger used 13
3.2 Types of inserts used 13
3.3 Fabrication of inserts 16
3.4 Experimental Setup 16
3.5 Experimental Procedure 19
3.6 Standard equations used 22
Chapter4 Sample Calculations 23
4.1 Rotameter Calibration 24
4.2 Pressure drop & Friction factor calculations 27

v
4.3 Heat transfer coefficient calculation 25
Chapter 5 Results & Discussion 28
5.1 Friction Factor Results 29-31
5.2 Heat Transfer Coefficient Results 32-34
Chapter 6 Conclusion 35
Chapter 7 Scope for future work 38
References 40
Appendix 43
vi
LIST OF FIGURES

Fig. Page
Figure name
No No.
3.1a Photograph of 8mm insert and 10mm insert (without baffles) 14
3.1b Photograph of 8mm insert with baffles (β=10, 20, 30 cm) 14
3.2 Photograph of 10mm insert with baffles (β=10, 20, 30 cm) 15
3.3 Schematic Diagram for the experimental setup 17
3.4 Photograph of the experimental setup 18
3.5 Wilson chart 21
4.1 Viscosity vs. Temperature 25
4.2 Temperature in different RTDs 26
4.3 Prandtl Number vs. Temperature 27
5.1 Friction Factor vs. Reynolds number for Smooth Tube 29
Friction factor vs. Reynolds number for Smooth tube, inserts with baffles
5.2 or without baffles. 30

fa/fo vs. Reynolds Number for 8mm inserts with or without baffles and
5.3 10mm inserts with or without baffles 31

Heat transfer coefficient vs. Reynolds Number for smooth tube
5.4 32

Heat transfer coefficient vs. Reynolds Number for Smooth tube, inserts with
5.5 33
or without baffles
Performance evaluation criteria, R1 vs. Reynolds Number for inserts
5.6 with or without baffles. 34

vii
LIST OF TABLES

Table. Page
Table name
No No.
2.1 Performance Evaluation Criteria 7
2.2 Performance Evaluation Criteria of Bergles et.al 8
2.3 Summaries of important investigations of twisted tape in laminar flow 9
6.1 Range of R1, fa/fo for different inserts 36
A.1.1 Rotameter Calibration 44
A.1.2 RTD Calibration 44
A.2.1 standardisation of smooth tube (f vs. Re) 45
A.2.2 friction factor vs. Re for 8mm inserts (without baffle) 45
friction factor vs. Re for 10mm inserts( without insert)
A.2.3 46

friction factor vs. Re for 8mm inserts with β = 30cm
A.2.4 46

friction factor vs. Re for 8mm inserts with β = 20cm
A.2.5 47

friction factor vs. Re for 8mm inserts with β = 10cm
A.2.6 47

A.2.7 friction factor vs. Re for 10mm inserts with β = 30cm 48
A.2.8 friction factor vs. Re for 10mm inserts with β = 20cm 48
A.2.9 friction factor vs. Re for 10mm inserts with β = 10cm 49
A.3.1 Standardisation of smooth tube (hi vs. Re) 50
A.3.2 Heat transfer coefficient vs. Re for 8mm inserts 51
viii
A.3.3 Heat transfer coefficient vs. Re for 10mm inserts 52
A.3.4 Heat transfer coefficient vs. Re for 8mm inserts with β = 30cm 53
A.3.5 Heat transfer coefficient vs. Re for 8mm inserts with β = 20cm 54
A.3.6 Heat transfer coefficient vs. Re for 8mm inserts with β = 10cm 55
A.3.7 Heat transfer coefficient vs. Re for 10mm inserts with β = 30cm 56
A.3.8 Heat transfer coefficient vs. Re for 10mm inserts with β = 20cm 57
A.3.9 Heat transfer coefficient vs. Re for 10mm inserts with β = 20cm 58
ix
NOMENCLATURE

A Heat transfer area, m2
i

A Cross- section area of tube with twisted tape, m2
xa

A Cross-section area of tube, m2
xo

C Specific heat of fluid, J/Kg.K
p

d ID of inside tube, m
i
d OD of inside tube, m
o
f Fanning friction factor, Dimensionless

f Friction factor for the tube with inserts, Dimensionless
a

f Theoretical friction factor for smooth tube, Dimensionless
o

g acceleration due to gravity, m/s2

Gz Graetz Number, Dimensionless

h Heat transfer coefficient, W/m2°C

h Heat transfer coefficient for tube with inserts, W/m2°C
a
h Heat transfer coefficient for smooth tube, W/m2°C
o
h(exp) Experimental Heat transfer coefficient, W/m2°C
i
h(theo) Theoretical Heat transfer coefficient, W/m2°C
i
L heat exchanger length, m
LMTD Log mean temperature difference, °C

m Mass flow rate, kg/sec

Nu Nusselt Number, Dimensionless
Pr Prandtl number, dimensionless
Q Heat transfer rate, W

x