The document describes a proposed experiment to test a scaled-down prototype of a heat exchanger for wind turbines. The experiment aims to verify theoretical calculations by collecting experimental data on parameters like temperature, pressure, and heat transfer. A liquid flow system and air sampling system will circulate water and air through the prototype to measure performance and compare results to predictions. The experiment objectives are to manufacture and test the prototype, modify a wind tunnel for measurements, design a liquid flow circuit, and compare experimental and theoretical values.
It is basic information about what is critical thickness and why we should we know this. Then there is critical thickness formula for cylindrical pipe and spherical shell.
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Simple explanation: Working of HVAC Thermostat:
https://youtu.be/pxNEUGHeNac
Simplified: Working of Packaged Air-cooled AC Plant
https://youtu.be/rJnGwioN2nQ
Simplified: Working of Frost-Free Refrigerator
https://youtu.be/4Afk8M0v1Y8
Trailer-Animated Heat Load Calculations
https://youtu.be/lwfouMDxBvg
5-Mins Course on AHU
https://youtu.be/a1KEEzW31-U
4-Mins Course on Chillers
https://youtu.be/jKeHw2ICDmc
It is basic information about what is critical thickness and why we should we know this. Then there is critical thickness formula for cylindrical pipe and spherical shell.
⭐ Are you Core EPC engineer with Big Dreams & Want To Succeed In Life? ⭐
We the SCHOLENBERG INTERNATIONAL wants to help you achieve these dreams with our GLOBAL brand
JOIN NOW: https://sbgblv.com/
With 100+ Chapters on HVAC Basics, HVAC Oil & Gas Design Format, Heat Load Calculations, Psychometric Chart, P-H Diagram, Management Skills, Communication Skills - you can learn from the top most experts of EPC domain
When was the last time you faced with challenges that shook you to the core? Did you give up to the pressure? Or did you fight back and make it the biggest opportunity of your life. Do you know you can transform challenges into your biggest opportunities?
Ours is a story of grit and determination, a story from which you can learn how to leverage the challenges that life throws at you to create opportunities. A story of focus, belief, passion and motivation, Our story is the epitome of one where your self-belief creates opportunities in hard times, making you come out of any depression that you have.
If you are an MEP and EPC Professional looking for your purpose in life, success motivation in times of struggles and challenges, knowledge in time of confirmed resources then you must Join us: www.sbgblv.com
You can know more about us on our website - www.scholenberg.com
We, at Scholenberg International, passionately believes that a "well-defined" animation has power to re-shape the education. We are on a mission to find and showcase the best MEP Learning across the world .
What started as a simple company is now a fast-growing media platform that covers the most innovative MEP success stories with trainers from every conceivable background, including ISHRAE Excellence Award Winners, Ph.D. from IIT & Distinguished Professionals and consultant to Royal Court of Oman
Our goal is to unlock the potential of passionate MEP and EPC Engineers from rural and urban areas by inspiring them to overcome the setbacks they face in their career and helping them discover their true calling in life by means of our innovative approach towards life skills and Courses.
►Scholenberg on Facebook: https://www.facebook.com/scholenberg.3
►Scholenberg on Linkedin: https://www.linkedin.com/in/scholenberg-consulting-2567181b0/
►Scholenberg on Linkedin: https://www.linkedin.com/in/globalhvac/
Simple explanation: Working of HVAC Thermostat:
https://youtu.be/pxNEUGHeNac
Simplified: Working of Packaged Air-cooled AC Plant
https://youtu.be/rJnGwioN2nQ
Simplified: Working of Frost-Free Refrigerator
https://youtu.be/4Afk8M0v1Y8
Trailer-Animated Heat Load Calculations
https://youtu.be/lwfouMDxBvg
5-Mins Course on AHU
https://youtu.be/a1KEEzW31-U
4-Mins Course on Chillers
https://youtu.be/jKeHw2ICDmc
This presentation is on shell and tube heat exchanger in which its design parameters and its troubleshooting conditions designed for better understanding and learning of all
HEAT EXCHANGERS. Heat exchangers are devices that facilitate the exchange of heat between two fluids that are at different temperature while keeping them from mixing with each other.
2. Double Pipe Heat Exchangers
3. A typical double pipe heat exchanger basically consists of a tube or pipe fixed concentrically inside a larger pipe or tube They are used when flow rates of the fluids and the heat duty are small (less than 5 kW) These are simple to construct, but may require a lot of physical space to achieve the desired heat transfer area.
4. Double-pipe exchangers is the generic term covering a range of jacketed 'U' tube exchangers normally operating in countercurrent flow of two types which is true double pipes and multitubular hairpins. One fluid flows through the smaller pipe while the other fluid flows through the annular space between the two pipes. Two types of flow arrangement: Parallel flow Counter flow
5. • The fluids may be separated by a plane wall but more commonly by a concentric tube (double pipe) arrangement shown in fig. If both the fluids move in the same direction, the arrangement is called a parallel flow type. In the counter flow arrangement the fluids move in parallel but opposite directions. In a double pipe heat exchanger, either the hot or cold fluid occupies the annular space and the other fluid moves through the inner pipe. The method of solving the problem using logarithmic mean temperature difference is typical and more iteration must be done. So it takes more time for the problem to solve. Therefore another method is practiced for solving this type of problems. This method is known as Effectiveness and Number of Transfer Units or simply ε-NTU method.“Effectiveness of heat exchangers is defined as actual heat transfer rate by maximum possible heat transfer rate”.The LMTD method may be applied to design problems for which the fluid flow rates and inlet temperatures, as well as a desired outlet temperature, are prescribed.
6. Application of Double Pipe Heat Exchanger Pasteurization or sterilization of food and bioproducts Condensers and evaporators of air conditioners Radiators for internal combustion engines Charge air coolers and intercoolers for cooling supercharged engine intake air of diesel engines.
In this presentation on External Thermal Resistance we will look at the thermal resistance of various substrate types, thermal management with printed circuit boards, and examples that compare the thermal resistance of various substrate technologies.
This presentation is on shell and tube heat exchanger in which its design parameters and its troubleshooting conditions designed for better understanding and learning of all
HEAT EXCHANGERS. Heat exchangers are devices that facilitate the exchange of heat between two fluids that are at different temperature while keeping them from mixing with each other.
2. Double Pipe Heat Exchangers
3. A typical double pipe heat exchanger basically consists of a tube or pipe fixed concentrically inside a larger pipe or tube They are used when flow rates of the fluids and the heat duty are small (less than 5 kW) These are simple to construct, but may require a lot of physical space to achieve the desired heat transfer area.
4. Double-pipe exchangers is the generic term covering a range of jacketed 'U' tube exchangers normally operating in countercurrent flow of two types which is true double pipes and multitubular hairpins. One fluid flows through the smaller pipe while the other fluid flows through the annular space between the two pipes. Two types of flow arrangement: Parallel flow Counter flow
5. • The fluids may be separated by a plane wall but more commonly by a concentric tube (double pipe) arrangement shown in fig. If both the fluids move in the same direction, the arrangement is called a parallel flow type. In the counter flow arrangement the fluids move in parallel but opposite directions. In a double pipe heat exchanger, either the hot or cold fluid occupies the annular space and the other fluid moves through the inner pipe. The method of solving the problem using logarithmic mean temperature difference is typical and more iteration must be done. So it takes more time for the problem to solve. Therefore another method is practiced for solving this type of problems. This method is known as Effectiveness and Number of Transfer Units or simply ε-NTU method.“Effectiveness of heat exchangers is defined as actual heat transfer rate by maximum possible heat transfer rate”.The LMTD method may be applied to design problems for which the fluid flow rates and inlet temperatures, as well as a desired outlet temperature, are prescribed.
6. Application of Double Pipe Heat Exchanger Pasteurization or sterilization of food and bioproducts Condensers and evaporators of air conditioners Radiators for internal combustion engines Charge air coolers and intercoolers for cooling supercharged engine intake air of diesel engines.
In this presentation on External Thermal Resistance we will look at the thermal resistance of various substrate types, thermal management with printed circuit boards, and examples that compare the thermal resistance of various substrate technologies.
How SPEED Appliance is Effective in Torque Control, Space Closure and Sliding...Dr Sylvain Chamberland
Literature review on torque efficacy of self ligating bracket. How to close space with SPEED brackets? Sliding mechanics with SPEED.
Torque control, torquing moment, self-ligating bracket and torque, torquing moment, Enmasse retraction, space closure, sliding mechanics,
Fine Tubes’ oil and gas tubing are used in the most challenging subsea and downhole conditions in seawater and sour oil well environments. Materials used are Austenitic, Super Austenitic, Duplex, Super Duplex, Titanium and Nickel Alloys. Seamless tubes are used for hydraulic tube and instrumentation tube applications, in onshore control panels, topside processing facilities, on subsea manifolds and templates up to 2,500m below the sea’s surface. Seam welded & redrawn tubes with orbital joints are used for subsea umbilicals, subsea control lines and chemical injection tubes. We can produce straight tubes or tube coils up to 10,000 m long. Coiled tubing is also used in onshore or topside hydraulic and instrumentation systems where the longer coils result in fewer connections and can increase the integrity of the overall system. These high pressure tubes need to be able to withstand huge amounts of pressure which is why our stainless steel coils for onshore applications are rated for use up to 60,000psi.
TALAT Lecture 3205: The Fluidity of Molten MetalsCORE-Materials
This lecture introduces the concept of fluidity of molten metal and its influence on the production of castings. The students will understand the relevance of fluidity, the means by which this is measured and the effect of alloy type. Basic understanding of foundry processes, phase diagrams, basic physics and mathematics background is assumed
Innovation case study submitted by Emirates Aluminium during 3rd Continual Improvement & Innovation Symposium organized by Dubai Quality Group's Continual Improvement Subgroup to celebrate World Quality Day 2011.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Palestine last event orientationfvgnh .pptxRaedMohamed3
An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
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Macroeconomics- Movie Location
This will be used as part of your Personal Professional Portfolio once graded.
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Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Model Attribute Check Company Auto PropertyCeline George
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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2. 2
• Project Supervisor Professor Winoto SH
• Group members Tan Tze Peng Wilson
Clarence Chen Jun Jie
Chen Xianghao
Tan Bao Lun
Teh Ter Chen
Yeo Shu Feng Doreen
Ye Xiu Yin
3. 3
Scope of Presentation
• Introduction
• Heat Exchanger Model for Experiment
• Proposed Experiment
• Fouling of Heat Exchanger
• Conclusion and Recommendations
4. 4
1. Introduction
• Previous Semester
• Verification of Calculations
• Designing the Heat Exchanger for Experiment
• Procedures and Guidelines being drafted for the
experiment in wind tunnel.
• Comparison between Experimental and Theoretical
results.
• Fouling as a Menace in the Heat Industry.
• Innovative and cost-effective methods.
5. 5
Background
• We hope to be able to manufacture a heat exchanger which we have
previously designed and test it out via experiments.
• Our initial plan was to source for any local heat exchanger
companies to help fabricate the design. However we faced two major
constrains.
▫ The first constrain was that no local company fabricates plate-fin heat
exchangers.
▫ Secondly, the budget not enough to custom build a heat exchanger and
purchasing equipments for the wind tunnel testing.
• We have decided to do the theoretical calculation for the scaling
down as well as to brainstorm for innovative anti-fouling ideas.
• Facilitating our juniors who will undertake the project and carry out
the verification and testing of the heat exchanger
6. 6
2. Heat Exchangers Model for
Experiment
• Evaluation of Plate-Fin Surfaces
• Selection of Fin Configuration
• Scaling Law of Heat Exchangers
• Sample Calculation
7. Evaluation of Plate-Fin Surfaces
5 Categories of Plate-Fins
• Plain
• Wavy
• Offset strip
• Louver
• Pin Fin
8. Plain Fins
• Straight fins that are uninterrupted (uncut)
• Any complex shape can be formed as desired, depending on how the
fin material is folded.
• Rectangular and Triangular passages are most common
• Used in applications where the allowable pressure drop is low
• Preferred for very low Reynolds numbers applications.
▫ -with interrupted fins, at low Re, the advantage of the high heat
transfer coefficient value of the interrupted fins is diminished
while the cost remains high.
9. Wavy Fins
• Uncut surfaces in the flow direction, and have cross-sectional shapes
similar to those of plain surfaces. However, they are wavy in the flow
direction.
• The waveform provides effective interruptions to the flow and
induces very complex flows
- higher heat transfer coefficient for wavy fin to that of an
equivalent plain fin.
• However, the heat transfer coefficient for wavy fins is lower than that
for interrupted fins such as offset or louver fins.
• Since there are no cuts in the surface, wavy fins is preferred when
potential fouling or clogging problem might occurred.
10. Offset Strip Fins
• The fin has a rectangular cross section, and is cut into small strips of
length. Every alternate strip is displaced (offset) by about 50% of the
fin pitch in the transverse direction.
• Heat transfer coefficients for the offset strip fins are 1.5 to 4 times
higher than those of plain fin geometries. However, the
corresponding friction factors are also high.
• The ratio of j/f for an offset strip fin to j/f for a plain fin is about
80%.
• Offset strip fins are used in the approximate Re range 500 to 10000.
11. Louver Fins
• Louvers can be made in many different forms and shapes.
• The j factors are higher for louver fins than for the offset strip fin at
the same Reynolds number, but the f factors are even higher than
those for the offset strip fin geometry.
• Since the louver fin is triangular, it is generally not as strong as an
offset strip fin which has a relatively large flat area for brazing.
12. Pin Fins
• Can be manufactures at very high speed continuously from a wire of
proper diameter.
• Surfaces compactness achieved by pin fin geometry is much lower
than that of offset strip or louver fin surfaces.
• The overall exchanger performance is also lower than other types of
surfaces.
• Potential application for pin fins is at very lower Reynolds number
(Re<500).
• Due to vortex shedding behind the round pins, noise and flow
induced vibration may be a problem.
13. Selecting of Fin Configuration
Optimize Heat Exchanger Design based on the following factors:
• Pressure Drop
• Heat Transfer
• Size
• Weight
• Cost
To help us in our selection of the best fin configuration, we plotted
graphs for comparing different fin configurations under the listed
factors. From there we will be able to study the different fin types and
formulate a table as a basis for comparison.
14. Pressure Drop
If pressure drop and heat transfer are the most critical factors, then the
heat transfer per unit of pressure drop (i.e. j-Colburn factor divided by
f-friction factor) will show a good comparison between different types
of extended surface.
Heat Transfer over Pressure Drop Figure
of Merit
0.6
0.5
j/f (j-colburn / f- friction)
0.4
plain fin
0.3 strip fin
louvered fin
0.2 wavy fin
pin fin
0.1
0
0 2000 4000 6000 8000 10000 12000
Reynolds Number
15. Size
If size is the overall driving design factor then a good figure of merit is
heat transfer per unit height.
Size Figure of Merit
0.0035
Heat Transfer per unit height
0.003
0.0025
0.002 pin fin
louvered fin
0.0015
strip fin
wavy fin
0.001
plain fin
0.0005
0
0 2000 4000 6000 8000 10000 12000
Reynolds Number
16. Weight
If weight is the overall driving design factor, then a good figure of merit
is heat transfer per unit weight.
17. Cost
In general, pin fins, which are incorporated directly into the casting of
the heat exchanger, are the least expensive.
The other fin type cost about the same with some minor differences in
set up costs.
Fins
Cost
Configuration
Increasin
Pin fins 1
g cost
Plain fins 2
Wavy fins 3
Offset Strip fins 4
Louvered fins 5
18. Comparison of All Parameters
Ranking 1 being the most desirable and ranking 5 being the least desirable
Fins
∆P Size Weight Cost Average
Configuration
Plain fins 1 5 4 2 3
Louvered fins 3 2 1 5 2.75
Offset Strip fins 2 3 3 4 3
Wavy fins 4 4 2 3 3.25
Pin fins 5 1 5 1 3
Our Selection
Plain fins for water-side (taking fouling into consideration)
Using excel to find the best combination for air-side fin type
20. The following ratios apply to the geometric
parameters:
Hydrauli Length Surface Flow Volume
c Area, As area, Ac
Diameter
dh2 = dh1/N L2 = L1 /N As2 = As1/N2 Ac2 = V2 =
Ac1/N2 V1/N3
where N = scaling factor
21. Assumptions
• The number of tubes in the heat exchanger is the
same.
• The physical properties are fixed, based on the
inlet conditions.
• The inlet temperatures are fixed.
• Each flow stream is treated the same.
22. 4 scenarios
1. Same mass flow rate, (for each stream)
1. Same Reynolds Number, Re
1. Same flow velocity, G
1. Same pressure drop, ∆P
Based on the book:
Compact Heat Exchangers, Selection, Design and Operation
by J.E. Hesselgreaves
23. Resultant Parameters
We aim to find the following:
• Q2, heat load removed by the prototype(scaled
down model).
• The pressure drop ∆p.
25. Sample Calculations
• Flow regime of the original 3x3x0.15 m3 heat
exchanger is laminar
• Hence, when applying the scaling laws, flow regime
of the prototype must be consistent, ie, laminar
• Keep Reynolds Number the same
• Nusselt number for laminar flow,
• If turbulent, NuD = 0.023ReD0.8Pr0.4 (Dittus-Boelter)
31. Sample Calculations
• Ratio of pressure drops
Where f = Fanning friction factor
• With ∆P2 known, we can size the pump.
32. For the Experiment
Parameters that we can control:
• Inlet temperatures, Twater,in Tair,in ≈Tamb
• Wind tunnel air speed, u2
• Fluid properties, e.g. cp
• Mass flow rate of water, determined from the
pump,
33. Discussions
• Unable to scale down DH
• Actual DH = 3.23 mm (wavy, air side) and DH = 2.87
mm (plain, water side)
• Difficult to manufacture
• After scaling down, flow passage will be too narrow
• Heat loss may not be through convection only
• Possibly through conduction
34. Suggestions
• Build a scaled down HX
• Maintaining the original DH
• Since the entire HX consists of stacks of plates
with the fins attached,
• Can conduct experiments to calculate how much
heat, qp, 1 plate can remove
• ∴Total heat load = N x qp
35. 35
3. Proposed Experiment
• Purpose
• Objectives
• Theory
• Experiment Setup
• Startup Procedure
• Tables and Program
36. Purpose
The purpose of this experiment is to collect
experimental data from a scaled down prototype of
the wind turbine and verify the data against
theoretical values derived from the excel spreadsheet
calculations to prove that it is within acceptable
range of heat energy dissipation by the actual heat
exchanger.
37. Objectives
1. Manufacture a smaller prototype of heat exchanger
based on the scaling down theory calculation
2. Modify and introduce measurement apparatus in
wind tunnel to accurately collect selected design
parameters and data.
3. Design and build a liquid flow system (hot side) to
accurately facilitate liquid-side flow and heat transfer
measurements.
4. Compare the experimental results against the
theoretical excel spreadsheet calculations.
38. Theory
Determination of surface characteristics:
In the experiment:
• the flow rates on both fluid sides of the exchanger are set at
constant predetermined values.
• Once the steady – state conditions are achieved, fluid
temperatures upstream and downstream of the test section
on both fluid sides are measured.
• The upstream pressure and pressure drop across the core on
the unknown side are also recorded to determine the friction
factors.
• The tests are repeated with different flow rates on the
unknown side to cover the desired range of Reynolds number
for the j vs. RE characteristics.
39. Heat capacity ratio For an unmixed –
unmixed crossflow exchanger, the relationship
will be:
40. For Cr 0,
the heat capacity rate is determined from the
measured mass flow rate on each fluid side and
the specific heats of the fluids at their average
temperatures. On the known side, the fluid
properties are evaluated at the average
temperature Ts. On the unknown side, the fluid
properties are evaluated at the log-mean
temperature.
41. The overall heat transfer coefficient Ua based on the total
airside surface area Aa is then evaluated from NTU as
The overall heat transfer coefficient Ua is considered as having
three components in series:
• Air side thermal resistance, including the extended surface
efficiency
• Wall thermal resistance
• Steam side thermal resistance, including the extended surface
efficiency
42. Then
The test cores are generally new, and no fouling
or scale resistance is on either side, so the
corresponding resistance is not included above.
The liquid side heat transfer coefficient must
also be evaluated separately for each core and
should be known a priori. However, the liquid
side resistance is generally a very small
percentage of the total resistance, and a
reasonable estimate will suffice.
43. The term in equation 1.3 is the extended
surface efficiency of the air side surface and is
related to the fin efficiency of the extended
surface by the following formula:
44. For many plate fin surfaces, the relation for the
straight fin with constant conduction cross
section may be used to a good approximation. In
that case:
Once the surface area and the geometry are known
for the extended surface, h and are computed
iteratively from equations 1.3 to 1.5.
45. The Stanton number St and the Colburn factor j
are then evaluated from their definitions:
The Reynolds number on the unknown side for
the test point is determined from its definition:
G= ρ V
46. Determination of the factor is made under steady fluid
flow rates. For a given fluid flow rate on the unknown f
side, the following measurements are made:
1. Core pressure drop
2. Core inlet pressure and temperature
3. Core outlet temperature
4. Fluid mass flow rate
5. Core geometrical properties.
47. Here Kc and Ke are sudden contraction and expansion
pressure loss coefficients presented in Appendix 1. Tests
are repeated with different flow rates on the unknown
side to cover the desired range of the Reynolds number.
The Reynolds number is determined in the same way as
described in determination of the airside film coefficient
h.
48.
49. Liquid Flow System
• Stainless steel piping
• Gear pump
• Resistive Heater (Watlow®)
• Mass flow rate meter (D25 MicroMotion®)
• Thermocouple (type T) x 2
50. Air Sampling System
Consist of
• Thermocouple (type T) x 2
A type T thermocouple with a
measurement range of -200
to 350 degree Celsius is placed at
the entrance of the wind
tunnel air outlet. And for the air
outlet temperature, a similar
thermocouple is place near the
outlet of the heat exchanger
fin.
51. Pressure Drop Measurement
Consist of
• Pressure differential Transducer (Validyne DP-103) x 2
To measure the pressure drop
across the heat exchanger, a
total of two differential pressure
sensors, one upstream and one
downstream, are incorporated
into the flow system.
52. Schematic diagram of Test Setup
2MX1M
P P
T T
HEAT
EXCHANGER
LEGENDS:
PUMP
MASS FLOW SENSOR
FILTER
HEATER
T THERMOCOUPLE
P PRESSURE DIFFERENTIAL SENSOR
53. Data Acquisition
Data Acquisition (DAQ)
Acquisition of signals &waveforms &processing the signals to obtain desired information.
Laboratory Virtual Instrumentation Engineering
Workbench (Labview)
Graphical approach allows non-programmers to build programs simply
by dragging & dropping virtual representations of familiar lab equipment.
54. Start Up Procedure
Power up the DAQ unit
Switch on the gear pump to start water circulation
Switching on the heater after full circulation of water
Set the heater to the specific heat load
Start Up Labview Program
Begin Data Aquisition
55. Lab Equipment
DAQ with Labview
Software
The NUS industrial
wind tunnel at
Mechanical
Department
56. Lab Equipment
Interior of a wind tunnel
The Wind turbine
and motor
57. 57
4. Fouling of Heat Exchangers
• Literature Survey
• General Methods of Fouling
• Heat Exchanger Cleaning
• Detailed Analysis of Anti-Fouling Methods
▫ Air Side
▫ Water Side
• Advantages and Disadvantages
58. 58
Literature Survey
• Fouling is defined as the accumulation of deposits on the
surface of the heat exchangers
• Deposits reduce the amount of heat transfer and thus
reducing the efficiency.
• In most of the cases, accumulation of deposits is from the
fluid itself.
59. 59
Deposition of Foulant
• Region A represents the initiation of adhesion
• Region B represents the steady growth of deposit on the surface.
• Region C shows that a steady state is reach between deposition and
removal.
60. 60
Why is Fouling bad?
Fin Cooler tubes severely corroded Deposits build-up on the inside of a heat Wall thinning led to this catastrophic
exchanger tube failure of an exchanger tube
• Fouling is highly related to conservation of energy
• Fouling decreases the efficiency leading to heavier
consumption of energy.
• Increase in the resistance also cause the pump to work
harder.
62. 62
Adhesion
• physical interaction between the foulant and the
heat exchanger surface.
• 3 types of interaction:
▫ long range attractive forces: Van Der Waals forces
▫ Bridging effect: mutual diffusion between substances
of the particle and the surface
▫ short range forces: adhesion at molecular level such as
hydrogen bonds and other chemical bonding
63. 63
Particulate Deposition
• Particle arriving at a surface can be by two
mechanism:
▫ gravitational and: stationary fluids
▫ particle transport within a fluid as it moves across the
surface onto which the particles deposit: Moving fluid
• transported by either or both of the following
mechanism:
▫ Brownian motion and
▫ turbulent diffusion
64. 64
Corrosion
• Corrosion means the breaking down of essential
properties in a material due to chemical reactions with
its surroundings
• origin of the corrosion is the fluid itself
• or a constitute of it: impurities
• Corrosion process is often accelerated by the presence of
scales or other deposit
• corrosion could also form a protection layer (oxide layer)
65. 65
Heat Exchanger Cleaning
• Circulation of Sponge Rubber Balls
• Brush and Cage System
• Air and Gas Injection
• Magnetic Devices
• Soot Blower
• Water Washing
• Galvanic Protection
66. 66
Circulation of Sponge Rubber Balls
• Sponge rubber balls which are slightly larger (by 2mm)
then the diameter of the condenser tubes are being
circulated to remove precipitates.
• Different types of sponge balls are available to suit different
heat exchanger e.g. rubber balls coated with a layer of
carborundum can be used for more heavy duty application.
• The automatic cleaning system is being controlled by a
Programmable Logic Controller.
• The system requires a source of water which has pressure
higher than the cooling water in the condenser inlet. This
water is used for soaking the balls and injecting them into
the Cleaning Systems.
68. 68
Brush and Cage System
• The operating method of this system is very similar to that of the
Sponge rubber Ball.
• It involves the use of a brush, made of wire or polymer filament
fitting into the size of the condenser tube.
• The brush is made to oscillate from end to end of the condenser tube
to remove the deposit by abrasion.
• The cage is located at the end of the tube to catch the brush after
cleaning.
• The addition of the brush and cage create restriction in the
flow, increasing the pressure drop across the condenser.
• The other drawback of this system is that the reversal of the brush
would cause instability in the flow thus affecting the heat transfer
process.
69. 69
Air and Gas Injection
• Air and gas injection is usually used in areas where
accessibility is difficult e.g. shell side of shell and tube heat
exchanger.
• The injection of air reduces the formation of deposits on the
heat transfer surfaces.
• The surge of air creates a region of high turbulence near the
wall.
• This method is ineffective against deposits that requires
higher amount of force to remove.
• Extreme care has also to be taken when the process liquid is
volatile in nature; this is to avoid possibilities of forming
explosive mixtures.
70. 70
Magnetic Device
• The main application of magnetic devices is to eliminate
scale formation in pipes.
• It is could be supposed that slight soluble compounds
such as calcium carbonate (exist in water as charged
ion), could be affected by the application of an electric
field.
• One example is the use of hard water to rinse the treated
steel where the hard water could give rise to
precipitation of calcium phosphate and consequent scale
formation.
• Till date, this method is still not very commonly use and
there are still doubts and critics on this method.
71. 71
Soot Blower
• The fundamental of the soot blower is to remove soot that is
built up in steam boiler.
• Steam is channeled to the soot blower pipeline and a drain
valve will drain off any water in the steam (Ensures that steam
is dry).
• The drain valve is shut off, and the soot blower is turned on.
• The steam shoots out from the soot blower tube that is inside
the boiler fireside. Many small holes for the steam to emerge
are drilled along the length of the tube.
• As the tube rotates, the position of the steam jet will also
move with it. After a full rotation, all the areas around the soot
blower tube should be clear of soot. After completing the soot
blowing, the steam supply is shut off again.
73. 73
Water Washing
• Water washing of heat exchanger is the process of
introducing jets of water into the system. This has
been in practice over many years and is one of the
most commonly applied techniques in cleaning of
heat exchanger.
• It is important to note that the water used in this
technique is to be as pure as possible as any particle
in the water could deposit itself in the process;
increasing the foulant amount.
• The jets are introduced intermittently and the turn
off of this method could be that the thermal shock
from such action could cause cracking and
subsequent spalling of the foulant.
74. 74
Galvanic Protection
• Galvanic protection involves the study of electric
current that is involved in the corrosion of metal.
• By understanding how electric current is involve in
corrosion of metal, we look at various methods
applied in the industry to tackle corrosion problem.
• Methods of Galvanic protection include
▫ Cathodic Protection
▫ Sacrificial Anode Technique
▫ Impressed Current Technique
▫ Anodic Protection.
75. 1. fouling deposit provides additional thermal
resistance to heat transfer besides those originally
present due to the inherent design of the heat
exchanger
2. flow area is decreased and most foulant, having a
rough surface will result in an increased pressure
drop through the exchanger
76. • increased capital investment
• additional operating costs
• loss of production
• cost of remedial action
77. thermal resistance Rf across a solid barrier is given by
l is the solid thickness and kf is its thermal conductivity
heat flux q is given by
∆T is the change in temperature
78. • boundary layers, situated
between the deposits and the
fluids, provide small amount of
thermal resistance to heat flow
due to their almost stagnant
mode
• metal partition wall has good
thermal conductivity, negligible
temperature change at T3 and T4
• foulants have low thermal
conductivities, large temperature
differences required to transmit
heat across these depositions
79. we can write Rf in terms of the overall heat transfer coefficient for
fouling Uf
general formulas for overall heat transfer coefficient, including the
fouling factor, at the air and water side are respectively
80. • Besides increasing the thermal resistance, foulant layer have two
additional negative effects
• Firstly, once deposit reaches a significantly large thickness, cross-
sectional area for fluid flow reduced
• For the same volume flow, due to a smaller area, fluid velocity will
have to increase and for identical conditions the Reynolds number
will increase
• Secondly, increase in roughness of deposit
surface results in higher turbulence level,
and eventually a greater amount of heat
transfer
81. (three fundamental stages that describe process of deposition)
1. The diffusional transport of the foulant across the
boundary layers beside the solid surface within the
moving fluid.
2. Adhesion of deposit both to the surface and to
itself.
3. The removal of deposit from the surface.
82. By combining these three components, rate of deposition
growth can be defined as the difference between the rates
of foulant deposition and removal
83. • A = straight line
relationship, deposit thickness
increases at a constant rate with
time after the initial adhesion
period
• B = falling rate of deposition
thickening with time
• C = asymptotic curve like
curve B at the beginning but
reaches final plateau steady state
or asymptote (rate of deposition
= rate of removal)
84. Change in Heat Transfer
Coefficient
Change due to
Change due to Change due to change in
roughness of
thermal resistance of Re caused by presence
foulant
foulant of foulant
85. 85
Detailed Analysis of Anti-Fouling
Methods : Air Side : Sonic Technology
• Similar to vibration caused by sound energy to dislodge
the deposits off metal surfaces
• Device for producing the sonic wave can a sonic
horn, usually operating at audible frequency of
approximately 220 Hertz with intensity of about 130
decibels
• Low frequency resonant sound ranging from 0 to 20
Hertz capable of setting up sound field to remove
soot, loose and brittle dust particles in the air side of heat
exchanger
86. Sonic Technology (cont’)
• commercially available sonic horn model #CS-125
designed by IAC (Industrial Accessories Company)
• capable of removing build-up particulates using a
fundamental frequency of 125 Hertz and SPL (Sound
Pressure Level) of 146 decibels, operating at 10 seconds
every 5 to 10 minute interval
• cleaning device can be used to clean agglomerated dust
on collector plates of an electrostatic precipitator, which
is similar in structure to a plate fin heat exchanger
87. Corona Discharge
• ionizes the fluid so as to create a plasma around
the electrode
• may be positive or negative
• Neutralises static charges on the surfaces of the
heat exchanger’s plate fins
• Benefit of keeping the fin surfaces neutral in
charge
88. 88
Water Side : Electronic Anti-
Fouling Technology
• Most prominent is formation of scales
• Hard water is heated
• Degradation in the performance
• Decrease the flow rate or increase the pressure
drop
• Solution :Electronic Anti-fouling technology
90. Electronic Anti-fouling technology
• Induced electric field to increase the ions and crystals
collision frequency
• Produces a pulse input current to create time-varying
magnetic fields inside the pipe
Cross section of pipe where induced electric field oscillates
with time
91. Electronic Anti-fouling technology
• Resulting in collision, precipitation as well as
coagulation.
• Converted into insoluble mineral crystals of
submicron sizes, easily removed
• Level of Super-saturation of the water will
decrease
• Scale-causing mineral ions and particles were
eliminated from the water
94. 94
Conclusion and Recommendations
▫ Conclusions
Heat Exchanger Model for Experiment
Proposed Experiment
Fouling of Heat Exchanger
▫ Recommendations for Future Work
95. 95
Conclusions : Heat Exchanger Model
for Experiment
• Manufacturability constrains.
• If we are to scale down the hydraulic diameter, Dh, by a desired scaling factor, it’s
almost impossible to fabricate such small passage.
• We suggest to build a smaller heat exchanger keeping the geometrical data (Dh)
unchanged. From this smaller size prototype,
• Two most important date: Heat transfer coefficient h, which relates to the Stanton
number St and the Colburn factor j, and the flow friction factor f, necessary for
pressure drop analysis.
• After obtaining the experimental h and f, the rating of heat exchanger procedure can
then be applied to calculate the experimental heat load Q and pressure drop ∆P.
• Furthermore, if manufacturability is not an issue, the hydraulic diameter of the
chosen fin type may be varied and better h and f can be obtained.
96. 96
Conclusions : Proposed Experiment
• By using the experimental results, we are able to
determine Stanton number St, Colburn factor j
and the Reynolds number .
• This will enable us to find out the Q heat load of
the experimental heat exchanger, and based on
this heat load we can compare it with the heat
load derived from the excel spread sheet
calculation.
97. 97
Conclusions : Fouling of Heat
Exchanger
• With innovative methods employed on the air side and
water side of the heat exchanger
• We can be confident that fouling can be reduced, or even
eliminated.
• The use of sonic vibrations, coupled with the phenomena
of corona discharged air ions will safely prevent the
buildup of dust particles on the plate-fin surfaces.
• As for the water side, experiments have been conducted
to validate the theory being
• The downtime of the wind turbine can also be reduced
and maintenance can be done online.
98. 98
Conclusions : Recommendations for
Future Work
• With the stage set for the experiment to be conducted, our future
juniors undertaking this project can carry on from where we last left
off.
• The theory of the scaling laws can also be further analyzed and
researched in a much deeper scope.
• Feasibility study regarding the innovative method of anti-fouling for
the air and water side of the heat exchanger can also be conducted
• Purchase the equipment and implement it on a real heat exchanger.
• End result will be very beneficial to the industry and will indeed
benefit the future generations to come.
• On this note, there are still many areas of this project that has the
potential for future advancement.