REVIEW OF ASPECTS OF FUEL ECONOMY IN VESSELS OPERATION
BY
NWANERI EBERECHI JOHNMEL
AK17/ENG/MAE/044
DEPARTMENT OF MARINE ENGINEERING
APRIL, 2023
REVIEW OF ASPECTS OF FUEL ECONOMY IN VESSELS OPERATION
BY
NWANERI EBERECHI JOHNMEL
AK17/ENG/MAE/044
A RESEARCH REPORT SUBMITTED TO THE DEPARTMENT OF MARINE
ENGINEERING, FACULTY OF ENGINEERING, AKWA IBOM STATE UNIVERSITY,
IKOT AKPADEN, MKPAT ENIN L.G.A.
AKWA IBOM STATE, NIGERIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF BACHELOR
OF ENGINEERING (B.ENG) DEGREE IN MARINE ENGINEERING
SUPERVISOR: ENGR HOPE IKUE JOHN
APRIL, 2023
AK17/ENG/MAE/044
II
ABSTRACT
The challenge of high fuel consumption has been a problem that has faced different sectors
ranging from automobile to aviation down to the maritime sector. Apart from the cost associated
with high fuel consumption there are other problems such as emission of dangerous substances
that negatively affect the marine environment, atmosphere and eventually we humans. This
makes it paramount that means should be devised to help curtail this problem. There have been
various studies that has aimed at reducing the ever increasing consumption of fuel. This work
reviews some of the aspects such as fleet management, hull maintenance, use of contra – rotating
propeller and nanotechnology. It was observed at the end of this work that operating a fleet of
vessels based on the most efficient vessels is not always the best option. It could also be
observed that a heavily fouled hull can lead to a change in required shaft power of up to 86%.
Contra – rotating propeller also showed promise as they were proven to improve propeller
properties, engine properties and reduce exhaust emission significantly. Lastly, it could be seen
that addition of nanoparticles to fuel led to an improvement in engine parameters such as brake
thermal efficiency, ignition delay period, exhaust gas temperature and overall fuel consumption.
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III
ACKNOWLEDGEMENTS
My appreciation goes to the Almighty God, the giver of knowledge who in his infinite mercy has
made this report a success.
My sincere appreciation goes to the Head of Department of Marine Engineering, Dr. E, Antai. I
am also grateful to my departmental projects coordinator Engr. Yireobong Akpaba, and I also wish
to express my profound gratitude to my project supervisor Engr Hope Ikue John who devoted his
time to guide, teach and support me throughout the period of research and to my friends and
colleagues who made the period of attachment an unforgettable one.
I wish to express my deepest appreciation to other lecturers such as Prof. K. D. H Bob-Manuel,
Prof. E. A. Ogbonnaya, Engr. U. Ebong, Engr E. Williams, Engr. I. Akpadiaha, etc. for their
guidiance and knowledge imparted in me.
This acknowledgement will not be complete without my parents Mr. and Mrs Nwaneri Valentine
who contributed immensely to my welfare and moral well-being. I want to say that may God
Almighty bless you all immensely in Jesus name, Amen.
AK17/ENG/MAE/044
IV
DECLARATION
I, NWANERI, EBERECHI JOHNMEL (AK17/ENG/MAE/044) declare that this project
represents my original work and has not been previously submitted elsewhere or to any other
University for the award of a degree of any type.
----------------------------------Signature of Student
AK17/ENG/MAE/044
--------------------------Date
V
CERTIFICATION
This is to certify that this project on REVIEW OF ASPECTS OF FUEL ECONOMY was
undertaken by NWANERI, EBERECHI JOHNMEL of Reg. No: AK17/ENG/MAE/044 of the
Department of Marine Engineering, Akwa Ibom State University under my supervision and
haven met the standard requirements, has been hereby satisfactorily approved by the Department.
…………………………..
……………………………....
Date:………………………
Date:………………………
Engr Hope Ikue John
Engr. Dr. Emmanuel Antai
Supervisor
Head of Department
…………………………..
Date:………………………
Engr. Dr. Thaddeus C.
External Examiner
AK17/ENG/MAE/044
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DEDICATION
This Project report is dedicated to God Almighty for His grace, mercies, protection and guidance
for seeing me through the period of my research and writing of this project. I also dedicated this
report to my lovely parents and siblings for their financial and moral supports.
AK17/ENG/MAE/044
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LIST OF CONTENTS
Title Page
List of Contents
VIII
List of figures
X
List of tables
XI
CHAPTER ONE: INTRODUCTION
1
1.1
Background of study
2
1.2
Aim
2
1.3
Objectives
2
1.4
Statement of Problems
3
1.5
Research Goals
3
1.6
Scope/Limitation of Research
3
1.7
Contribution to Knowledge
3
CHAPTER TWO: LITERATURE REVIEW
4
2.1
Engineering Options for More Fuel Efficient Ships
4
2.2
Reduce required power for propulsion
5
2.2.1 Reduce resistance
5
2.2.2 Improve propulsion
7
2.3
Reduce required power for equipment on board
9
2.4
Increase use of renewable energies
10
2.5
Employ use of Nanotechnology
12
CHAPTER THREE: RESEARCH METHODOLOGY
13
3.1
Aspect 1: Fleet Management
13
3.2
Aspect 2: Hull Maintenance
17
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3.2.1 Materials and method used by Schultz
3.3
Aspect 3: Use of Optimum – contra Rotating propeller
18
20
3.3.1 Numerical model
22
3.4
25
Aspect 4: Application of nanoparticles to improve combustion properties
3.4.1 Experiment set up
26
CHAPTER FOUR: RESULTS AND DISCUSSION
27
4.1
Results from Schultz study
27
4.2
Result from the study of Mina, Manuel and Soares study on
4.3
Contra – rotating propeller
32
Review of result obtained from Hayder, Sinan and Miqdam study
34
4.3.1 Brake thermal efficiency
34
4.3.2 Ignition delay period
34
4.3.3 Exhaust gas temperature
36
4.3.4 Maximum pressure timing
37
4.4
40
Comparison/discussion on the various aspects reviewed
4.4.1 Fleet Management
41
4.4.2 Hull Maintenance
41
4.4.3 Use of Contra – Rotating Propeller
42
4.4.4 Application of Nanoparticles
42
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
44
5.1
Conclusion
44
5.2
Recommendations
45
REFERENCES
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IX
LIST OF FIGURES
Figure
Caption
page
2.1
Transport efficiency vs speed for various vessels
6
2.2
Mewis Duct
9
2.3
Energy efficiency monitoring for main engine
10
2.4
SolarSailor catamaran ferry
11
2.5
Towing kite harnessing wind energy
12
3.1
Ton - miles per barrel and annual cargo versus
operating speed for various units of a 10-ship fleet.
14
3.2
The CRP system at the stern of the model ship
21
3.3
Schematic diagram of the propeller optimization model used by
(Tadros, M., Vettor, R., Ventura, M. , & Guedes Soares, 2021)
23
3.4
Schematic diagram of optimization tool in calm water
24
4.1
The effect of added nanoparticles on brake thermal efficiency
34
4.2
The effect of added nanoparticles on ignition delay period
35
4.3
The effect of added nanoparticles on cylinder pressure
at start of ignition
4.4
The effect of added nanoparticles on the exhaust
gas temperatures
4.5
36
37
The effect of added nanoparticles on maximum
cylinder pressure timing
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X
LIST OF TABLES
Table
Caption
Page
3.1
Fleet characteristics
13
3.2
Operating Strategy Based on Attaining 20,000
Ton-Miles per Barrel
3.3
Operating Strategy Based on Attaining 22,500
Ton-Miles per Barrel
3.4
15
15
Operating Strategy Based on Maximizing Use of
Most Efficient Ships
16
3.5
Main characteristics of bulk carrier
22
3.6
Properties of the used nanoparticles
26
4.1
Predictions of the change in total resistance (Δ𝑅𝑇 ) for
an Oliver Hazard Perry class frigate (FFG-7) with
a range of representative coating and fouling conditions
at a speed of 7.7 𝑚𝑠 −1 (15 knots)
4.2
27
Predictions of the change in total resistance (Δ𝑅𝑇 ) for
an Oliver Hazard Perry class frigate (FFG-7) with
a range of representative coating and fouling conditions
at a speed of 15.4 𝑚𝑠 −1 (30 knots)
4.3
28
Predictions of the change in required shaft power (ΔSP) for
an Oliver Hazard Perry class frigate (FFG-7) with a range
of representative coating and fouling conditions
at a speed of 7.7 𝑚𝑠 −1 (15 knots)
4.4
29
Predictions of the change in required shaft power (ΔSP) for
an Oliver Hazard Perry class frigate (FFG-7) with a range
of representative coating and fouling conditions
at a speed of 15.4 𝑚𝑠 −1 (30 knots)
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XI
4.5
Optimum results for different configurations
4.6
Areas of effectiveness of aspects of fuel economy
reviewed in this paper
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41
XII
CHAPTER ONE
INTRODUCTION
Fuel oil of various fractions obtained from distilling petroleum (crude oil). These oils
include distillates (the
lighter
fractions)
and residues (the
heavier
fractions).
Fuel
oils
include heavy fuel oil, marine fuel oil (MFO), bunker fuel, furnace oil, gas oil (gasoil), heating
oils (such as home heating oil), diesel fuel and others.
All fuel oil applications create energy by burning fuel oil. Fuel oil combustion (oxidation reaction)
releases a large amount of heat, which can be used for steam generation, for example, in steam
boilers (wikipedia, n.d.). The high volume (pressure) of the combustion gases can be used to drive
an engine, or (less frequent for HFO, but widespread for gasoil) a gas turbine. When fuel oil is
burned, an amount of heat is released, which is defined by the specific energy (international unit
MJ/kg) of the fuel. Thermal plants use this heat to generate steam, which then drives steam turbines,
thus providing mechanical energy that can be used for propulsion or to be converted into electrical
energy. For marine engines and gas turbines, mechanical energy provided by the combustion gases
is used either directly for propulsion or converted into electrical energy for power plants. For larger
installations, cost efficiency optimization and environmental constraints led to the introduction of
co-generation. In co-generation, some of the electrical energy lost is used to generate low-pressure
steam, suitable for a wide range of heating applications (Vermeire, 2021).
In the maritime field fuel oils are classified in the following ways:

MGO (Marine gas oil) - Roughly equivalent to no. 2 fuel oil, made from distillate only

MDO (Marine diesel oil) - Roughly equivalent to no. 3 fuel oil, a blend of heavy gasoil that
may contain very small amounts of black refinery feed stocks, but has a low viscosity up to 12
cSt so it need not be heated for use in internal combustion engines

IFO (Intermediate fuel oil) - Roughly equivalent no. 4 fuel oil, a blend of gasoil and heavy fuel
oil, with less gasoil than marine diesel oil

HFO (Heavy fuel oil) - Pure or nearly pure residual oil, roughly equivalent to no. 5 and no. 6
fuel oil

NSFO (Navy special fuel oil) - Another name for no. 5 HFO

MFO (Marine fuel oil) - Another name for no. 6 HFO
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1.1 Background of Study
For the maritime community, faced with continuing uncertainty about fuel sources and availability,
together with drastic escalation of fuel prices, the years ahead will be a most challenging period.
The prudent ship owner, naval architect, and marine engineer will have to recognize the changing
energy situation as one of the essential facts of economic life when making decisions in the design
and operation of their vessels (Scher R. M., 1980).
It is scant comfort that marine transport interests are not alone in the grip of the energy malaise;
there is hardly a part of the world's economy that does not feel the chill in some way. We are all
unfortunate enough, as the old Chinese proverb goes, to live in interesting times. Yet, within our
own industry there are several promising signs, indications that we can successfully adapt to the
new age of precious petroleum. Certainly, the problems that we will have to master in the coming
years are already under attack on many fronts: the development of more efficient machinery,
modified hull forms and improved coating systems for reduced resistance, the potential use of fuel
additives, and even the possible revival of commercial wind powered vessels. Further
improvements in over-all fuel efficiency may be realized through the widespread use of weather
routing and traffic control procedures, or by the rational reduction of speed and horsepower.
Finally, the avoidance of trips in ballast, where feasible, represents an important advantage in the
efficient use of fuel in marine transport; thus, the increasing popularity of multi-purpose cargo
vessels should be recognized as a potential energy saver (Benford, 1978).
The actual extent to which each of these factors will influence the future development of maritime
commerce is clearly beyond our scope. Indeed, if we could predict the future we might have
avoided the energy crisis entirely (Mortimer, 1974). Be that as it may, the purpose of this paper is
to research on methods that will help to improve the efficiency of fuel consumption. In this work,
hull fouling, fleet management, propeller selection and configuration then nanotechnology will be
studied in order to show how they can help to finesse the effect of high fuel consumption.
1.2 Aim
This project aims to review various aspects of fuel economy in operational vessels.
1.3 Objectives
i. To review a study on how fleet management can help to reduce fuel consumption.
ii. To review studies on how hull maintenance helps to improve fuel consumption.
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iii. To review studies on the use of contra – rotating propeller to reduce fuel consumption
iv. To review studies on the application of nanoparticles to reduce fuel consumption.
v. To carry out a comparative analysis on i – iv to decide which is the most effective.
1.4 Statement of Problem
The problem of high fuel consumption has been a problem for all engines not just marine engine
for a long time. Automobile vehicles, trains, airplane consumes a large amount of fuel and with
the increasing cost of fuel prices in all forms of transportation, the importance of studies to
optimize energy utilization cannot be stressed enough. This research aims to proffer solutions to
this ever growing problem.
1.5 Research Goals
The goal of this research is to contribute to some extent solutions that can be used to solve high
fuel consumption and reviewing some studies that has been proven to reduce this issue.
1.6 Scope/Limitation of Research
The scope of this paper will be to review studies that has been carried out on reducing fuel
consumption in vessels that majorly operate with diesel engines. Although there are too many
reasons for high fuel consumption in a vessel, this research will be confined to study on hull
maintenance, nanoparticles effect in engines that uses diesel as working fluid, how fleet
management can helps to predict and reduce high fuel consumption and how the use of contra –
rotating propeller help to reduce fuel consumption.
1.7 Contribution to Knowledge
This project will be contain information on some the problems of energy efficiency in vessel
operation, it will comprise of technologies that are already in play on vessels and will suggest how
a vessel should be run to optimize the energy the most.
This project work will also contribute knowledge of how to optimize fuel efficiency in vessels that
are already out at sea. The reader of this work will be enlightened on the employment of fleet
management in fuel economy, use of nanoparticles, contra – rotating propellers and how hull
maintenance plays a major role in determining the amount of fuel that will be consumed.
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CHAPTER TWO
LITERATURE REVIEW
2.1 Engineering Options for More Fuel Efficient Ships
According to the Second GHG Study of the IMO, 40 to 50 per cent of the total energy produced
on board a ship goes to propelling her. The rest is lost as heat and exhaust (Kitada, 2016). Ship
propulsion and resistance modification are some of the areas where there is potential for energy
efficient vessels. There are various ways to modify resistance component, example include
optimization of the ship hull form, viscous resistance can also be minimized through coating, air
lubrication etc.
Energy efficient ship design and operation are two key components of green shipping. Therefore,
despite the successful results of energy efficiency enhancement measures adopted during ship
design, there is still room for saving energy during ship operation. For example, fuel consumption
can be reduced with good voyage planning and/or ship handling. Weather routing, i.e., factoring
in the environmental conditions of various routes is a widely used example of voyage planning,
whereas trim optimisation and efficient ballast exchange processes are the common examples of
optimised ship handling. Maintenance of the hull and machinery is as important as voyage
planning and ship handling. Hulls that are not properly maintained or cleaned can result in
increased fuel consumption of up to 10 to 15 per cent, even 30 to 40 per cent in severe cases (Ölçer,
2016).
According to (Hochkirch, 2015) Mid-term and long-term fuel prices are expected to range from
500 to 1000 $/t including expected future surcharges for CO2 (carbon-dioxide) emissions.
Therefore ship operators will put higher pressure on ship owners to obtain fuel efficient ships.
These in turn will put pressure on ship yards to supply fuel efficient ships. As a result, we expect
to see a paradigm shift in designs and refits to improve the fuel consumption of ships.
There are any many ways to reduce fuel consumption. The following are discussed below:

Reduce required power for propulsion

Reduce required power for equipment on board

Substitute fuel power (partially) by renewable energies like wind and solar energy

Employ use of Nanotechnology
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Surveys on partial aspects of fuel saving options have been published before. Several HSVA
(Hamburg Ship Model Basin publications, (Hollenbach et al, 2007), (Mewis, F. & Hollenbach, U.
, Hydrodynamische Maßnahmen zur Verringerung des Energieverbrauches im Schiffsbetrieb,
2007), give rather comprehensive overviews of hydrodynamic options in design and operation of
ships. (K.H., 2007) discusses various approaches to recuperate energy losses from the main engine
to use them for on-board equipment. New hull form features are developed to improve the fuel
consumption for given payload, (Harries, S., Hinrichsen, H., & Hochkirch, K., 2007) We will
discuss more comprehensively the available options in the following, but recommend them
nevertheless for further studies.
2.2 Reduce required power for propulsion
We may use traditional hydrodynamic approaches to decompose the power requirements into
resistance and propulsion aspects. While propulsor and ship hull should be regarded as systems,
the structure may help to understand where savings may be (largely) cumulative and where
different devices work on the same energy loss and are thus mutually excluding alternative.
2.2.1 Reduce resistance
There are many ways to reduce the resistance of a ship. On the most global level, there are two
(almost trivial) options:

Reduce ship size: The lightship weight may be reduced for example by (expensive)
lightweight materials, more sophisticated structural design involving possibly formal
optimization and reducing the ship length. None of these options is straightforward. The ship
length should consider hydrodynamic aspect as well as production and weight aspects.
However, reducing the required power during the design stage by the assorted measures
discussed below will reduce in turn the weight of engines, power trains and fuel tanks and
yield considerable secondary savings due to smaller ship size.
 Reduce speed: Speed reduction is a very effective way to reduce fuel consumption and
emission. (Isensee, J., Bertram V., & Keil, H., 1997) pointed already out that transport
efficiency increases drastically with decreasing speed, Fig.1. HSVA reports fuel savings of
typically 13% for bulkers or tankers, 16-19% for containerships, for a speed reduction by 5%,
(Mewis, F. & Hollenbach, U. , Hydrodynamische Maßnahmen zur Verringerung des
Energieverbrauches im Schiffsbetrieb, 2007). Slow steaming reduces in itself fuel
consumption significantly. However, the ship is then operated in off-design, thus sub-optimal
condition. This offers assorted potential improvements to reduce the fuel consumption further:
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electronically controlled main engines allowed better efficiencies at slow steaming and reduce
also lubrication oil consumption; controllable pitch propellers allow better propeller efficiency
over a wider range of rpm; adapted new bulbous bows may reduce wave resistance
considerably. On the other hand, waste heat from exhausts and cooling water is considerably
reduced and may require reconfiguration of auxiliary engine systems for slow steaming. In
sum, a supporting engineering analysis is recommended when deciding on slow steaming for
a

longer
time.
Fig. 2.1: Transport efficiency vs speed for various vessels (modified Karman-Gabrielli diagram)
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2.2.2 Improve Propulsion
The propeller transforms the power delivered from the main engine via the shaft into a thrust power
to propel the ship. Typically, only 2/3 of the delivered power is converted into thrust power. A
special committee of the (ITTC, 1999) discussed extensively assorted unconventional options to
improve propulsion of ships and the associated problems in model tests. In short, model tests for
these devices suffer from scaling errors, making quantification of savings for the full-scale ship at
least doubtful.
- Operate propeller in optimum efficiency point: The propeller efficiency depends among others
on rpm and pitch. Fixed pitch propellers are cheaper and have for a given operating point a better
efficiency than controllable pitch propellers (CPPs). They may be replaced if the operator decides
to operate the ship long-term at lower speeds. CPPs can adapt its pitch and thus offer advantages
for ships operating over wider ranges of operational points. Several refit projects have been
reported, with savings up to 17% quoted due to new blades on CPPs, (N.N., Foul-release smoothes
hull efficiency , 2008a).
- Reduce rotational losses: For most ships, there is substantial rotation energy lost in the propeller
slipstream. Many devices have been proposed to recover some of this energy. These can be
categorized into pre-swirl (upstream of the propeller) and post-swirl (downstream of the propeller)
devices. Pre-swirl devices are generally easier to integrate with the hull structure.
Rudders behind the propeller recover automatically some of the rotational energy. Therefore
potential gains should always be considered with rudder behind the propeller to avoid overly
optimistic estimates. Pre-swirl devices include the SVA Potsdam (Potsdam model basin) preswirl
fin, pre-swirl stator blades, (Liljenberg, 2006), and asymmetric aft bodies, (Schneekluth, H. &
Bertram, V., 1998). Probably the best known post-swirl device is the Grim vane wheel,
(Schneekluth, H. & Bertram, V., 1998). The original Grim vane wheel is located immediately
behind the propeller generating extra thrust. The vane wheel is composed of a turbine section
inside the propeller slipstream and a propeller section (vane tips) outside the propeller slipstream.
The vane wheel became unpopular after several reports of mechanical failures, most notably for
the ‘Queen
Elizabeth 2’. IHI and Lips BV developed a modified vane wheel supported on the rudder,
overcoming the mechanical problems of the original Grim vane wheel, (N.N., Rudder horninstallation grim vane wheel reduces ship's energy consumption, 1992). Other post-swirl devices
are stator fins and rudder thrust fins. Stator fins are fixed on the rudder and intended for slender,
high-speed ships like car carriers, (Hoshino, T., et al., 2004). Rudder thrust fins are single foils
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attached at the rudder, proposed by Hyundai H.I. Typically 4% fuel savings are claimed for all
these devices by manufacturers. As all these devices target at the same energy loss, only one of
them should be considered. Gains are certainly not cumulative. CFD simulations are the suitable
tool to evaluate effects of these devices at full scale and aid their detailed design. Contra-rotating
propellers are a traditional device to recover the rotational energy losses, (Schneekluth, H. &
Bertram, V., 1998). More recently, podded drives and conventional propellers have been combined
to hybrid CRP-POD propulsion, (Ueda, N. & Numaguchi, H., 2006), claiming 13% fuel savings.
- Reduce frictional losses: Smaller blades with higher blade loading decrease frictional losses,
albeit at the expense of increased cavitation problems. A suitable tradeoff should be found using
experienced propeller designers and numerical analyses (Kitada, 2016).
- Reduce tip vortex losses: The pressure difference between suction side and pressure side of the
propeller blade induces a vortex at the tip of the propeller. This vortex (and the associated energy
losses) can be suppressed (at least partially) by tip fins similar to those often seen on aircraft wings.
The general idea has resulted in various implementations, differing in the actual geometric form
of the tip fin, (ITTC, 1999), namely contracted and loaded tip (CLT) propellers (with blade tips
bent sharply towards the rudder), Sparenberg-DeJong propellers (with two-sided shifted end
plates), or Kappel propellers (with integrated fins in the tip region).
- Reduce hub vortex losses: Devices added to the propeller hub may offer cost effective fuel
savings. Propeller boss cap fins (PBCF) were developed in Japan, (ITTC, 1999), (N.N., Propeller
boss cap with fins allows more efficient ship propulsion, 1991).
Publications of the patent holders report 3-7% gains in propeller efficiency in model test and 4%
for the power output of a full-scale vessel. Reported gains have to be considered with caution,
(Junglewitz, 1996). “The presence of the rudder significantly reduces the strength of the hub vortex
and hence the gain in propeller efficiency due to PBCF can be reduced by 10-30%”, (ITTC, 1999).
The Hub Vortex Vane (HVV), jointly developed by SVA Potsdam and Schottel, offers an
alternative to PBCF. The HVV is a small vane propeller fixed to the tip of a cone shaped boss cap.
It may have more blades than the propeller. The vendors claim increases of 3% in propeller
efficiency.
- Operate propeller in better wake: The propeller operates in an inhomogeneous wake behind the
ship. This induces pressure fluctuations on the propeller and the ship hull above the propeller,
which in turn excite vibrations. The magnitude of these vibrations poses more or less restrictive
constraints for the propeller design. A more homogeneous wake translates then into potentially
better propeller efficiency, for example by a larger propeller diameter or larger blade loading on
AK17/ENG/MAE/044
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the outer radii. For new designs, wake equalizing devices like Schneekluth nozzles (a.k.a. wake
equalizing ducts (WED)), Grothues spoilers, vortex generators, (Schneekluth, H. & Bertram, V.,
1998), may therefore improve propulsion and save fuel. For existing ships, despite several refits
more recent independent analyses shed doubts concerning the effectiveness of WEDs, Ok (2005).
“In conclusion, partial ducts [like WED] may result in energy saving at full scale, but this was not,
and probably cannot be proven by model tests”, (ITTC, 1999). The Mewis duct combines preswirl
fins and wake-equalizing duct, Fig.2. 4% savings appear realistic for full hulls like tankers or
bulkers.
Fig 2.2: Mewis Duct
2.3 Reduce required power for equipment on board
There are various options to save power in the assorted energy consuming equipment onboard
ferries. The saving potential depends on the ship type. Examples are in more efficient electronically
controlled pumps, HVAC (heat, ventilation and air conditioning) ventilation systems, and energy
saving lighting. Energy saving lamps not only reduce the energy requirements for lighting, they
also reduce the waste heat from the lamps and thus the energy needed by air conditioning systems
to cool lighted rooms. Avoidance of oversized main engines. Sea margins should be adapted to
ship type, ship size and intended operational trade. This is especially true f or fast ships. Sea
margins should be selected based on simulations or experience for specific ship types, but not
globally imposed. Margins for rare high-speed operation are expensive and may be better covered
by falling back on the auxiliary engine power (power take-in (PTI) via shaft generator). Detailed
engineering analyses can be used to assess feasibility and cost aspects of alternative configurations.
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For slow-steaming ships with controllable pitch propeller, it is better to reduce the brake mean
effective pressure than the rpm. Intelligent monitoring and simulation software can combine
engine supplier data and standard onboard monitoring data for a given operational profile to
determine optimum combinations of propeller pitch and rpm. (Hochkirch, 2015)
Fig 2.3: energy efficiency monitoring for main engine
2.4 Increase Use of Renewable Energies
Wind has been the predominant power source for ships until the late 19th century. Wind-assistance
has enjoyed a recent renaissance. Wind-assisted ships use predominantly other means of power
(typically diesel engines) and wind power plays only a secondary role. With increasing ship speed,
wind assistance makes less sense as increasingly efficient sails are needed. Constraints are initial
investment, space requirements, stability and required man-power for operation and maintenance.
Despite these constraints, several industrial projects have been realized in the past decade. Wind
kites have been brought to commercial maturity by the company Skysails, Fig.5, drawing also on
expert advice from Germanischer Lloyd. Kites harness wind power at larger heights without the
stability penalties of high masts. The development has enjoyed large media attention, and in 2007
the first prototype was tested successfully on the MS “Beluga Skysails” and the “Michael A”, N.N.
(2008b). Fuel savings in excess of 10% quoted by the manufacturer apply for slower ships. Flettner
rotors are another technology harnessing wind energy for ship propulsion. After 80 years of
obscurity, they have resurfaced in 2008 when Lindenau shipyards delivered a GL-class freighter
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10
equipped with Flettner rotors. These four cylinders, each 27 m tall and 4 m in diameter, are
predicted to save nearly half of the conventional fuel needed by the ship.
Solar energy may supply an environmentally friendly part to the total energy balance of a ship.
For inland ferries, solar power and fuel cells are an attractive option to have zero-emission ships.
For other ships, diesel and solar energy may be combined. Diesel-electric drive systems are already
quite common. Future ships may combine then diesel generators for 50% of the total power
consumed, fuel cells providing 30% and a solar generator accounting for the remaining 20%.
Solar-power and wind-power can be combined, using fixed sails equipped with solar panels. This
option is employed successfully on the SolarSailor ferries operated in Sydney and San Francisco,
Fig. 2.4. (Hochkirch, 2015)
Fig 2.4: SolarSailor catamaran ferry
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Fig 2.5: Towing kite harnessing wind energy
2.5 Employ use of Nanotechnology
Nanotechnology fuel treatment uses a multi-functional fuel additive which contains a molecular
catalyst that ensures maximum fuel efficiency. The additive can also reduce engine wear, meaning
the time between maintenance can be extended: particles work on existing carbon build-up within
the engine to effectively blast away residue. NanOx™ from Martek Marine is one of the most
exciting nanotechnology fuel treatments to hit the market and it’s being used by some of the largest
shipping companies across the globe, including; Yang Ming, NSNC Kazmortransflot & PDZ
Malaysia. Nano-clusters to improve viscosity by more than 30% for an improved fuel/air mix:
boosting engine power by more than 10%. Enhanced fuel atomisation in the tank & injectors offers
over 7% fuel savings and micro-explosions in the cylinders enable more complete combustion,
lowering emissions by 25% and enabling savings on C02 tax too. Nano-catalysts remove carbon
deposits and prevent future build-up, diminishing engine wear to reduce maintenance and spares
costs. (Marine, 2017)
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CHAPTER THREE
RESEARCH METHODOLOGY
3.1 ASPECT 1
Fleet Management
Fleet management refers to all actions that need to take place to keep a fleet running efficiently, on
time and within budget. Overall it is the process used by fleet managers to monitor fleet activities and
make decisions about proper asset management, dispatch and routing (mixtelematics, n.d.). A fleet
manager will normally make his operating decisions on a basis of maximizing annual profits or if
income is fixed, minimizing operating costs. During periods of acute fuel shortage, he may find it
desirable to base those decisions on the criterion of minimizing energy requirements (samsara, 2023).
Under this aspect of my work (Scher & Benford, 1980) proposes a technique that will allow a fleet
manager to achieve the goal of minimizing energy requirement. The proposal is illustrated by means
of the following numerical example.
The example illustrated analyzes a fleet manager that has agreed to carry 1,150,000 tons of coal each
year between two ports that are 12,000 miles apart. It is assumed that he has no other commitment
and no immediate prospect of any other. He has available to him a fleet of ten suitable bulk carriers,
some more energy efficient than others. The ships are identified as ship A – J.
Fleet Characteristics
Ship
Design speed
Annual Transport
Energy efficiency at
(Knots)
Capability
design sped
(1000 long tons)
(ton-mile per barrel)
17.6
3 × 190 = 570
9500
17.5
2 × 148 = 296
8000
16.5
3 × 105 = 315
9200
15.5
2 × 68 = 136
9700
A
B
C
D
E
F
G
H
I
J
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Total
1317
Table 3.1: Fleet characteristics
The table shows each ship's design speed and the number of tons of coal it could deliver each year if
operated at its design speed. The energy efficiency, in ton-miles of cargo per barrel of fuel, is also
shown. According to the table, the fleet if operated at full power will deliver 1,317,000 tons of coal
each year, which is about 14 percent above requirements. Since there are some extra capacity, the
manager is thus free to cut back on the number of ships he keeps in operation, or cut back on speed,
or some combination of those strategies. In the proposal made by (Scher & Benford, 1980) they
suggested a strategy that works by guessing at some maximum attainable value of ton – miles per
barrel (energy efficiency), then hold the same ton – miles per barrel for all ships and find a
corresponding speed and annual transport capability for each ship then sum up all the annual
capabilities for the individual ships. If the total is smaller than the requirements, this means that the
ships needs to be run faster by lowering the guessed at maximum attainable value of ton – miles per
barrel and vice versa. The values of speed and individual transport capability was taken from the
figure below.
Figure 3.1: Ton - miles per barrel and annual cargo versus operating speed for various units of a 10ship fleet.
AK17/ENG/MAE/044
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They started by guessing that the fleet can deliver the required 1,150,000 tons while attaining an
energy efficiency of 20,000 ton-miles per barrel. The table below shows the speed and annual
transport capability when operated at 20,000 ton – miles per barrel.
Ship
Operating speed
Annual Transport
(Knots)
Capability
(1000 long tons)
A
B
15.2
3 × 177 = 531
14.5
2 × 138 = 276
13.6
3 × 94 = 282
12.5
2 × 58 = 116
Total
1205
C
D
E
F
G
H
I
J
Table 3.2: Operating Strategy Based on Attaining 20,000 Ton-Miles per Barrel
From the above table, it can be seen that the cumulative annual capability is above the required capability
(1,150,000 tons) so he increased the ton – miles per barrel by reducing the speed. He first increased the ton
– miles per barrel to 25,000 but it resulted in a cumulative annual capability of 1,110,000 tons which is
deficient to the desired annual capability. The desired annual capability was gotten by further reducing the
energy efficiency to 22,500 ton – miles per barrel which came between 0.5% of the required annual
capability. The operating strahtegy for each ship at 22,500 ton – miles per barrel is shown below.
Ship
Operating speed
Annual Transport
(Knots)
Capability
(1000 long tons)
A
B
14.6
3 × 171 = 513
14.0
2 × 132 = 264
C
D
E
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F
G
13.0
3 × 90 = 270
11.5
2 × 54 = 108
Total
1155
H
I
J
Table 3.3: Operating Strategy Based on Attaining 22,500 Ton-Miles per Barrel
The following formula was used to calculate the amount of fuel required in a year
Total fuel required =
𝑇𝑜𝑛𝑠 𝑝𝑒𝑟 𝑦𝑒𝑎𝑟 × 𝑑𝑖𝑠𝑖𝑡𝑎𝑛𝑐𝑒
𝑇𝑜𝑛−𝑚𝑖𝑙𝑒𝑠 𝑝𝑒𝑟 𝑏𝑎𝑟𝑟𝑒𝑙
For a total energy efficiency of design speed of 22,500 ton – miles per barrel the total fuel that will be
required for a year can be gotten as follows
Fuel required =
1,155,000 × 12,000
22,500
= 616,000 barrels per year
From the earlier analysis of (Scher & Benford, 1980) the fleet could deliver a total of 1,317,000 tons a
year if operating at design speed and maximum transport capability but the required delivery is just
about 1,150,000. A fleet manager might want to balance this up by taking away one or two of the least
efficient ships. From Table 3.1 the least efficient ships are D and E with 8,000 ton – miles per barrel,
let’s calculate the amount of fuel that will be required in a year if the fleet manager goes with this
strategy. The annual transport capability of the ships and their speed can be deduced from figure 3.1,
say ship E is left out, ship D will have to be adjusted accordingly to balance out the remaining capacity
of 1,150,000. This is illustrated in the table below
Ship
Design speed
(Knots)
Annual Transport Energy efficiency at
Capability
(1000 long tons)
design sped
Fuel required
(1000 barrel per year)
(ton-mile per barrel)
A
B
17.6
3 × 190 = 570
9500
720
13.6
129
24000
65
16.5
3 × 105 = 315
9200
411
C
D
F
G
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H
I
15.5
2 × 68 = 136
Total
1150
9700
168
J
1,364
Table 3.4: Operating Strategy Based on Maximizing Use of Most Efficient Ships
Table 3.4 shows the energy efficiencies at design speed. Suppose we rank our ships according to that
criteria then make maximum use of the most efficient ships (at design speed) and perhaps leave one
or more of the least efficient ships idle. Table 3.4 shows the results of that strategy. The total fuel
required comes to 1.364 million barrels which is over two times that required under (Scher & Benford,
1980) proposed method. Other plans you may conceive will, we guarantee, suffer the same fate,
although not necessarily to the same degree.
3.2 ASPECT 2
Hull Maintenance
Resistance is a major part of the reason vessels in operation burns excessive amount of fuel, these
resistance can arise from a rough hull which increases the friction between the hull of the vessel
and the water, In order to overcome this resistance the vessel engine requires more fuel to create
enough power. It is paramount that in order to ensure effective sail of the vessel that the resistance
due to friction between the hull and water must be kept at minimum, since it cannot be totally
eliminated. Vessels in general are designed and finished with fine hulls to make sure the vessel
does not encounter excessive resistance while sailing, this fine smoothness of the hull is usually
incapacitated due the growth on the hull of the submerged part of the vessel, these growth are as a
result of macro and microorganism such as bacteria, diatom, slime layers, barnacles, tubeworm
and algae leaves etc. that are present in the marine eco system. Since these growth are inevitable
as the vessel in operation is constantly submerged in water, therefore it is important to study the
degree to which these growth affect the vessel and proffer effective means of preventing them
from attaching themselves to the hull of the vessel. The main problem due to biofouling attached
to the hull is economic losses, climate change and damage to the environmental ecosystem (Schultz
MP, Bendick JA, & Holm ER, 2011).
In the last few decades there have been many studies that look into the effect of roughness on ships
hull (due to biofouling, anti-fouling coating, hull imperfection from shot blasting, or welding),
these include lab experiment, Computational Fluid Dynamics (CFD), and in-situation
AK17/ENG/MAE/044
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measurement on an operating ship. Some of these studies, particularly the experiment, involves
towing tank, wind tunnel, and direct measurement on an operating ship. To complement the
experimental investigations, studies using CFD allows engineers to study the phenomenal from
the different angle (M L Hakim, B Nugroho, M N Nurrohman, I K Suastika, & I K A P Utama,
2019). However due to the limit of resources available and time constraint this part of my work
will only review some of the work carried out in relation to observation and correlation of hull
roughness to high fuel consumption.
The first study to be considered is an experiment by (Schultz, 2007). Schultz made a full scale ship
resistance and powering prediction for antifouling coating systems with a range of roughness and
fouling conditions. His estimates were based on results from laboratory-scale drag measurements
and boundary layer similarity law analysis. In his work, predictions are made for a mid-sized naval
surface combatant at cruising speed and near maximum speed. The results indicate that slime films
can lead to significant increases in resistance and powering, and heavy calcareous fouling results
in powering penalties up to 86% at cruising speed. While the roughness and fouling conditions
considered in this work are only representative (not exhaustive) and the predictions are for a single
hull form, the methodology implemented here can be used for other fouling conditions and ship
hull forms for which laboratory drag data are available.
3.2.1 Materials and methods used by Schultz
Schultz made ship resistance and powering predictions based on scale model testing. Since
estimates of ship resistance and power requirements are typically made through towing tank tests
of a ship model that is geometrically similar to the full-scale ship. The total resistance (drag) of
the ship model, RTm, is made up of two primary components. These are the residuary resistance,
𝑅𝑅𝑚 , and the frictional resistance𝑅𝐹𝑚 (Gillmer TC & Johnson B., 1982).
i.e.
𝑅𝑇𝑚 = 𝑅𝑅𝑚 + 𝑅𝐹𝑚
(1)
The above equation is usually represented in its non-dimensional form and this is achieved by
dividing by the reference dynamic pressure and the wetted surface area. The quotient gotten is the
total resistance coefficient of the model (𝐶𝑇𝑚 ), similarly it is the sum of the residual coefficient of
the model (𝐶𝑅𝑚 ) and the frictional coefficient of the model (𝐶𝐹𝑚 ). The residuary resistance
coefficient of the model is a function of the Froude number (𝐹𝑟𝑚 ), also the frictional resistance
coefficient of the model is a function of the Reynolds number (𝑅𝑒𝑚 ), Therefore the total resistance
coefficient of the model is given as follows (Gillmer TC & Johnson B., 1982)
AK17/ENG/MAE/044
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𝐶𝑇𝑚 = 𝐶𝑅𝑚 𝐹𝑟𝑚 + 𝐶𝐹𝑚 𝑅𝑒𝑚
(2)
In order to accurately predict the resistance of the full-scale ship with model tests, it is desirable
to have dynamic similarity between the ship and the model. Equation 2 illustrates that in order to
accomplish this, both the Froude number and the Reynolds number would have to be matched
between the model and the ship. In practice, this is impossible to do. Instead incomplete dynamic
similarity is used in which the Froude number of the model and the ship are matched as shown in
Equation 3:
(𝐹𝑟𝑚 =𝐹𝑟𝑠 ) also known as
𝑈𝑚
√𝑔𝐿𝑚
=
𝑈𝑠
√𝑔𝐿𝑠
(3)
Where, g is acceleration due to gravity, 𝑈𝑚 is the model speed, 𝐿𝑚 is the model length, 𝑈𝑠 is the
ship speed and 𝐿𝑠 is the ship length. Towing tank tests were carried out at a range of model speeds
corresponding to full-scale ship speeds in accordance with Equation 3, as shown below:
Equation 4:
𝑈𝑚 =
𝑈𝑠
(4)
√𝜆
Where Scale ratio (λ) = Ls/Lm. The total resistance coefficient,𝐶𝑇𝑚 was measured at each speed.
The frictional resistance coefficient,𝐶𝐹𝑚 was obtained using the ITTC-1957 formula below
Equation 5:
𝐶𝐹𝑚 =
0.075
(𝑙𝑜𝑔10 𝑅𝑒𝑚 −2)2
(5)
The residuary resistance coefficient of the model,𝐶𝑅𝑚 was then found using Equation 2. Since the
residuary resistance is a function of the Froude number and 𝐹𝑟𝑚 =𝐹𝑟𝑠 in the model tests, it is
understood that 𝐶𝑅𝑚 =𝐶𝑅𝑠 . The frictional resistance coefficient of the ship, CFs, was also found
using Equation 5 by substituting Res for Rem. The total resistance coefficient of the ship,𝐶𝑇𝑠 is
given by the following equation (Gillmer TC & Johnson B., 1982):
Equation 6:
𝐶𝑇𝑠 = 𝐶𝑅𝑠 + 𝐶𝐹𝑠 + 𝐶𝐴
(6)
Where, 𝐶𝐴 is the correlation allowance. In Schultz work the effect of hull roughness was dealt
with separately and was accounted for in an added frictional resistance term, 𝛥𝐶𝐹𝑠 so the total
resistance coefficient of the ship, 𝐶𝑇𝑠 is:
Equation 7:
𝐶𝑇𝑠 = 𝐶𝑅𝑠 + 𝐶𝐹𝑠 + 𝐶𝐴 + 𝛥𝐶𝐹𝑠
(7)
Granville’s similarity law scaling was used to predict the change in frictional drag of a plate of
ship length in order to model the change in frictional resistance of the ship itself (ΔCFs).
AK17/ENG/MAE/044
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Schultz used data from (E. L. Woo, G. Karafiath, & Borda, 1983) which provides both full scale
trial powering data as well as model drag and propeller results for the US Navy Oliver Hazard
Perry class frigate (FFG-7). These data were used in order to assess the impact of coating
roughness and fouling on the shaft power requirements (SP) of an FFG-7 hull form. The FFG-7
has a waterline length of 124.4m with a beam of 14.3m and displaces 3779 metric tonnes. The fullscale trials were carried out in seawater with ρ =1022.3𝑘𝑔 𝑚−3 and ν =8.9761 × 10−7 𝑚2 𝑠 −1. The
ship model tests were conducted on a 1:20.82 scale model at the Naval Surface Warfare Center,
Carderock, MD, USA.
The data from the model tests were used to predict the full-scale shaft powering requirements of
the FFG-7 using the procedures highlighted above. The correlation allowance (CA) was taken to
be 0.0004 as suggested by (Gillmer TC & Johnson B., 1982) for a similar hull form. The change
in the frictional resistance coefficient (ΔCFs) resulting from the hull roughness was calculated
using similarity law scaling procedure (Granville, 1958; 1987) for Average coating roughness
(𝑅𝑡50 ) =150μm (equivalent sand roughness height (𝐾𝑠 ) =30μm).
3.3 ASPECT 3
Use of Optimum Contra – Rotating Propeller
The propeller selection is another area of interest in reducing fuel consumption and ensuring the
sustainability of the ship along the trips. Selecting the propeller at the maximum efficiency is
important to ensure a high propeller performance during the design and operation (Mina, Roberto
, Manuel, & Guedes , 2022). The propeller is the second component of the marine propulsion
system that directly affects the amount of power transmitted from the engine to the ship hull with
the first being the shaft. The selection of an effective propeller must be carefully performed to
ensure high technical efficiency, the required safety during the operation of the ship in calm waters
and in severe weather conditions, and to achieve a high level of economic benefit (Tadros, M.,
Vettor, R., Ventura, M., & Guedes Soares, Effect of different speed reduction strategies on ship
fuel consumption in realistic weather conditions., 2022).
Therefore, optimizing hull forms (Ventura, 2014) as well as ship transoms (Feng, Y., el Moctar,
O., & Schellin, T.E., 2021) are essential solutions to achieve an appropriate propeller inflow while
placing energy-saving devices (Stark, C., et al., 2022) forward of the propeller, such as pre-swirl
ducts (Andersson, J., et al., 2022), pre-swirl fins (Gaggero, S. & Martinelli, M., 2022), and vortex
generator fins (VGFs), can be effective solutions for improved energy efficiency.
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Besides the previous points, the selection of marine propellers including the type and size, coupled
with the engine performance is essential to improve propeller efficiency and reduce fuel
consumption (Nelson, M., et al., 2013). This process-based optimization can be performed by
comparing several types of propellers from different series and with different propeller shapes,
either ducted or non-ducted, to find the optimal fixed pitch propeller (FPP) performance.
The contra-rotating propeller (CRP) is another concept that was developed by Wagner (Wagner,
1929) to reduce engine loads and thus increase fuel economy. This concept is based on adding a
smaller propeller that rotates in the opposite direction, positioned aft of the main one. As the FPP
causes water circulation, placing two different propellers in front of each other assist in
neutralizing the water circulation. Therefore, the energy losses from the sideways forces due to
water circulation are recovered by the small propeller (aft propeller) and force the water to flow in
a horizontal direction parallel to the thrust direction. This system will create a larger thrust force
than in the case of a single FPP and increase the propeller efficiency. Figure 3.2 shows the
configuration of a CRP in a model ship.
Figure 3.2: The CRP system at the stern of the model ship
In this aspect of my work a more detailed review on the study of (Mina, Manuel , & Soares, 2022)
where they studied the effect of selecting a contra-rotating propeller (CRP) for a bulk carrier at the
engine operating point with minimum fuel consumption. Then Using a developed optimization
model, they selected the geometry of a CRP for different propeller diameters, the same propeller
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diameter as that of a fixed pitch propeller (FPP) installed on the bulk carrier, and at 90% of the
FPP diameter. Additionally, each case was optimized with both no-cup and heavy-cup
configurations.
3.3.1 Numerical model
The numerical model that is used to perform the simulation in this study is a propeller optimization
model that was previously developed by (Tadros, M., Vettor, R., Ventura, M. , & Guedes Soares,
Coupled Engine‐Propeller Selection Procedure to Minimize Fuel consumption at a specified
speed., 2021). This study considers the selection of a CRP for a bulk carrier of 154 m in length by
performing optimization procedures to identify the optimum propeller geometry. The
characteristics of the bulk carrier and the main engine installed are given in the table below.
Characteristics
Unit
Value
Length waterline
M
154.00
Breadth
M
23.11
Draft
M
10.00
Displacement
Tonnes
27,690
Ship
Service speed
Knots
14.5
characteristics
Maximum speed
Knots
16.0
Type of propellers
-
FPP
Number of propellers
-
1
Rated power
kW
7140
Engine builder
-
MAN Energy Solutions
Brand name
-
MAN
Engine
Bore
mm
320
characteristics
Stroke
mm
440
Displacement
Liters
4954
Number of cylinders
-
14
Rated speed
rpm
750
Rated power
kW
7140
Table 3.5: Main characteristics of bulk carrier.
A schematic diagram is presented in Figure 3.3 that shows the processing of data through the optimization
model. The model was developed to find the optimal propeller parameters and the operational point in order
AK17/ENG/MAE/044
22
to minimize the fuel consumption of the bulk carrier under different input parameters such as the ship design
speed (Vs), number of propeller blades (Z), type of propeller series and the percentage of propeller cupping.
The
model
complies
with
the
limitation
of
noise
and
cavitation
methods
applied.
Figure 3.3: Schematic diagram of the propeller optimization model used by (Tadros, M., Vettor, R., Ventura,
M. , & Guedes Soares, 2021)
AK17/ENG/MAE/044
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The procedure for the model used is described in the flow chart that follows
Figure 3.4: Schematic diagram of optimization tool in calm water.
(Mina, Manuel , & Soares, 2022) explains each procedure involved in the flow chart, readers may
refer to the article ‘Towards Fuel Consumption Reduction Based on the Optimum Contra-Rotating
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Propeller’ in the journal of marine science and technology for more information regarding the
numerical model.
3.4 ASPECT 4
Application of Nanoparticles to improve combustion properties
The application of nano-additive in liquid fuel is an interesting concept yet unexplored to its full
potential. Nanoparticles are small particles that ranges between 1 to 100 nanometers in size. They
are undetectable by eyes of human. To put into context, the average size of a nanoparticle is 0.1%
the thickness of a piece of paper. As the size of nanoparticles approaches atomic scale their
properties changes and they dominate the surface atoms of materials they are used with. Due to
their small size, nanoparticles have a large surface area to volume ratio in comparison to materials
like steel, aluminum etc. that are used to design engine components. For example, copper is
considered a soft material, with bulk copper bending when its atoms cluster at the 50nm scale.
Consequently, copper nanoparticles smaller then 50nm are considered a very hard material, with
drastically different malleability and ductility performance when compared to bulk copper. The
change in size can also affect the melting characteristics; gold nanoparticles melt at much lower
temperatures (300 °C for 2.5 nm size) than bulk gold (1064 °C) (TWI, 2020).
Researchers have discovered that mixing diesel with minimal proportions of metallic nanoparticles
results in effective fuel combustion and reduces the harmful exhaust emissions because these
nanostructures act as a catalyst for diesel combustion. Nanoparticles have a large surface-tovolume area, which increases the contact between the fuel and the oxidizer. Nanoparticles mixed
with diesel fuel to reduce the ignition delay time through the acceleration of chemical reactions by
reducing the evaporation time, consequently improving the ignition properties.
Due to the limited access to facility and economical constrain associated with carrying out a fully
detailed experiment on the effect of nanoparticles on fuel consumption, this work will only review
experiment done by (Hayder A. Dhahad, Sinan A. Ali, & Miqdam T. Chaichan, 2020) in detail
using nano-𝑇𝑖𝑂2 and nano-𝐴𝑙2 𝑂3 comparing them to the same engine when it runs on normal
diesel, while also reviewing similar works in order to fully understand the effect of nanoparticles
on diesel engines.
3.4.1 Experiment setup
3.4.1.1 Materials
Iraqi diesel fuel (molecular formula: C12.3H22.2) available at local fuel stations was used. This
fuel type has a dynamic viscosity of 2.778 × 10−3 (kg/ms), 844.3 kg/m3 density and a cetane
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number of 49. TiO2 and Al2O3 nanoparticles were utilized. The Table below illustrates the
properties of these nanoparticles. The nanoparticle size ranges from 30 nm to 50 nm. The
nanoparticles were added at mass fractions of 25, 50, 100 and 150 ppm. The mixing process was
carried out using an ultrasonic mixing tank. The process was performed for 1 hour to confirm
mixture stability and the homogenous distribution of the nanoparticles in the fuel.
Item
Nano-𝑨𝒍𝟐 𝑶𝟑
Manufacturer
Yurui chemical Co. Ltd
Appearance
White powder
Purity
99.9%
PH value
7.5
Crystal and type
a
Grain size(nm)
30-60
Bulk density(g/cm3)
4.43
Lose of drying %≤
0.21
Zeta potential (mV)
26.8
Molar mass (g/mole)
34.8
Melting point( ֯C )
2034
Thermal conductivity(w/mK)
290-380
Table 3.6: Properties of the used nanoparticles
Nano-𝑻𝒊𝑶𝟐
Hongwu Nanometer
White powder
99.78%
7.3
a
20-50
3.92
0.23
38.5
79.87
1943
300-770
3.4.1.2 Engine rig
The tests were performed employing water-cooled four-stroke with variable compression ratio and
a single-cylinder pilot diesel engine. The engine produces a maximum power of 3.7 kW when
running at 1500 rpm and full load. The diesel engine injector has a three-hole nozzle with a
diameter of 0.2 mm, and it operates at an injection pressure of 160 bar. A piezoelectric pressure
transducer (type Kistler Instruments, Switcher land, model 6613CQ09-01) was installed on the
cylinder head surface to equip measures of cylinder pressure.
3.4.1.3 Test procedure
After mixing the nanoparticles with the diesel fuel and confirming the homogeneity and stability
of the emulsion, the experiments were executed using the engine rig. The first set of experiments
was conducted to evaluate the highest useful compression ratio (HUCR) for the diesel used, that
is, 15.5:1. The tests were performed at this compression ratio to explore the effects of two types
of nanoparticles addition to Iraqi diesel. The selection of the HUCR rely on the maximum heat
release, and the best performance was achieved at this compression ratio.
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CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Results from Schultz’s study
The predictions of the full-scale powering of theFFG-7 from model test results were made for ship
speeds of 7.7𝑚𝑠 −1 (15 knots) and 15.4𝑚𝑠 −1 (30 knots), which correspond to a typical cruising
speed and nearly full speed, respectively. (Schultz, 2007) Presented the result in terms of change
in total resistance and change in shaft power for various hull conditions ranging from AF coating
to heavy calcareous fouling for ship speeds of 7.7𝑚𝑠 −1 and 15.4𝑚𝑠 −1. The table below shows the
result of Schultz prediction when the ship speed is at 7.7𝑚𝑠 −1
Δ𝑅𝑇 @
% Δ𝑅𝑇 @
𝑈𝑠 = 7.7𝑚𝑠 −1 (KN)
𝑈𝑠 = 7.7𝑚𝑠 −1
Hydraulically smooth surface
-
-
Typical as applied AF coating
4.6
2%
Deteriorated coating or
23
11%
Heavy slime
41
20%
Small calcareous
69
34%
Medium calcareous fouling
105
52%
Heavy calcareous fouling
162
80%
Description of condition
light slime
fouling or weed
Table 4.1: Predictions of the change in total resistance (Δ𝑅𝑇 ) for an Oliver Hazard Perry class
frigate (FFG-7) with a range of representative coating and fouling conditions at a speed of 7.7
𝑚𝑠 −1 (15 knots).
Table 4.1 for a ship speed of 7.7𝑚𝑠 −1 (15 knots). The results indicate that only a small resistance
penalty (2%) is expected to result from a typical AF coating compared to a hydraulically smooth
hull. With coating deterioration of a light slime layer, the impact on resistance begins to become
significant (11% increase in 𝑅𝑇 ). The resistance penalty continues to increase with the severity of
AK17/ENG/MAE/044
27
fouling until, for a heavy layer of calcareous fouling, the total resistance is nearly doubled at
cruising speed (80% increase in 𝑅𝑇 ).
The predictions of the change in total resistance for a ship speed of 15.4 𝑚𝑠 −1 (30 knots) are
shown in Table 4.2. The percentage increase in resistance due to hull roughness and fouling ranges
from 4 – 55%. It can be observed from the following table that the percentage increase in resistance
at this speed is lower compared to at 7.7𝑚𝑠 −1 this is due to the fact that at higher speeds the
residuary resistance becomes dominant compared to the frictional resistance.
Δ𝑅𝑇 @
% Δ𝑅𝑇 @
𝑈𝑠 = 15.4 𝑚𝑠 −1 (KN)
𝑈𝑠 = 15.4 𝑚𝑠 −1
Hydraulically smooth surface
-
-
Typical as applied AF coating
46
4%
Deteriorated coating or
118
10%
Heavy slime
192
16%
Small calcareous
305
25%
Medium calcareous fouling
447
36%
Heavy calcareous fouling
677
55%
Description of condition
light slime
fouling or weed
Table 4.2: Predictions of the change in total resistance (Δ𝑅𝑇 ) for an Oliver Hazard Perry class
frigate (FFG-7) with a range of representative coating and fouling conditions at a speed of 15.4
𝑚𝑠 −1 (30 knots).
Predictions of the change in required shaft power were also carried out. These are shown in Table
4.3 for a ship speed of 7.7𝑚𝑠 −1 (15 knots). It is important to note that the change in required shaft
power presented below accounts not only for the increase in total hull resistance but also for the
increased propeller loading at a given speed due to the hull fouling, which can lead to a significant
reduction in the propulsive coefficient for the heavier fouling conditions. These changes in
propulsive efficiency were calculated based on the open water propeller test results presented in
Woo et al. (1983). The powering results again indicate that only a small penalty (2%) is expected
to result from a typical, as applied AF coating compared to a hydraulically smooth hull. With
coating deterioration or a light slime layer, the impact on powering begins to become significant
AK17/ENG/MAE/044
28
(11% increase in SP). The powering penalty continues to increase with the severity of fouling until,
for a heavy layer of calcareous fouling, the required power is increased by 86%. The representation
of the effect of fouling on shaft power at 7.7𝑚𝑠 −1 is shown below in the following table.
ΔSP @
% ΔSP @
𝑈𝑠 = 7.7𝑚𝑠 −1 (KW)
𝑈𝑠 = 7.7𝑚𝑠 −1
Hydraulically smooth surface
-
-
Typical as applied AF coating
50
2%
Deteriorated coating or
250
11%
Heavy slime
458
21%
Small calcareous
781
35%
Medium calcareous fouling
1200
54%
Heavy calcareous fouling
1908
86%
Description of condition
light slime
fouling or weed
Table 4.3: Predictions of the change in required shaft power (ΔSP) for an Oliver Hazard Perry
class frigate (FFG-7) with a range of representative coating and fouling conditions at a speed of
7.7 𝑚𝑠 −1 (15 knots).
Description of
ΔSP @
% ΔSP @
% reduction in speed
condition
𝑈𝑠 = 7.7𝑚𝑠 −1 (KW)
𝑈𝑠 = 7.7𝑚𝑠 −1
for fixed
SP = 2.76104 kW
Hydraulically smooth
-
-
-
surface
AK17/ENG/MAE/044
29
Typical as applied AF
1004
4%
0.9%
2618
10%
2.7%
Heavy slime
4311
16%
4.0%
Small calcareous
6934
26%
5.8%
10,329
38%%
7.5%
16,043
59%
10.7
coating
Deteriorated coating or
light slime
fouling or weed
Medium calcareous
fouling
Heavy calcareous
fouling
The predictions of the change in required shaft power for a ship speed of 15.4𝑚𝑠 −1 (30 knots) are
shown in Table 4.4. The percentage powering penalty due to hull roughness and fouling ranges
from 4 – 59%. In general, the percentage increases at this speed are lower than at cruising speed
for the same reason as was discussed in the resistance results. Also presented in Table 4.4 is the
percentage reduction in speed at a fixed input shaft power of 2.76104 kW, the required shaft power
for the hydraulically smooth hull at 15.4 𝑚𝑠 −1 (30 knots). The analysis shows that the percentage
reduction in speed ranges from 0.9 – 10.7%. This corresponds to a speed loss of 0.14 𝑚𝑠 −1 to
1.6𝑚𝑠 −1 (0.28 – 3.2 knots). The table for 15.4𝑚𝑠 −1 is demonstrated below.
Table 4.4: Predictions of the change in required shaft power (ΔSP) for an Oliver Hazard Perry
class frigate (FFG-7) with a range of representative coating and fouling conditions at a speed of
15.4 𝑚𝑠 −1 (30 knots).
There has been other works that share similar ideology to that used by Schultz, for example
(Hundley LL & Tate CW, 1980) conducted a series of ship powering trials on USS Harold E. Holt,
a Knox class frigate. When operating with a clean propeller and a hull fouled with ‘light grass’
and 10 – 20% coverage of ‘incipient tube worm growth’, the required shaft power (SP) at 7.7 𝑚𝑠 −1
(15 knots) was 4525 kW. The SP after the hull was cleaned was 3650 kW. Therefore, the increase
in required power that can be attributed to the fouling is 24%. The fouling condition from Schultz
paper that best coincides with the pre-cleaning Holt power trial is the ‘small calcareous fouling or
weed’ condition. In this condition, the SP is predicted to be 2989 kW at 7.7 𝑚𝑠 −1 (15 knots).
AK17/ENG/MAE/044
30
(Haslbeck EG & Bohlander G, 1982) also conducted full-scale sea trials in order to quantify the
effect of slime layers on ship powering. In their study, power trials were conducted on the USS
Brewton, another Knox class frigate. The ship was coated with an ablative AF paint containing
both cuprous oxide and TBT and was subjected to fouling in Pearl Harbor, Hawaii for 22 months.
An initial hull inspection indicated the presence of a fairly heavy slime film with little to no
calcareous fouling. Power trials were conducted in which the shaft power and ship speed were
measured. Subsequently, the ship was cleaned and power trials were performed again. A difference
in required shaft power of 9% at a ship speed of 8.2 𝑚𝑠 −1 (16 knots) was measured between the
two power trials.
In recent times better and more detailed experiment has been conducted by (Turan, Demirel, &
Day, 2016) where they performed an experimental study of the resistance of flat plates covered
with artificial barnacles. Four flat plates having different surface conditions, including a smooth
reference plate and three different surface coverage of barnacles were towed at the Kelvin
Hydrodynamics Laboratory (KHL) of the University of Strathclyde. The plates were towed at
different speed ranges and the total resistances of the surfaces were measured. The resistance
values were then non-dimensionalised. The frictional resistance coefficients of all of the test
surfaces were then computed using assumptions that suggest the frictional resistance coefficients
of smooth surfaces obey the Karman-Schoenherr friction line (Schoenherr, K.E, 1932) and that the
residuary resistances of flat plates are not affected by surface roughness. Afterwards, roughness
function values of all of the test surfaces were calculated using an indirect method, following the
overall method of (Granville, 1987). Uncertainty estimates were made through repeatability tests,
with the uncertainty values found to be sufficient to ensure a reliable comparison.
Following this, the obtained roughness functions and roughness Reynolds numbers were employed
in an in-house code, developed based on the similarity law analysis of (Granville, 1958). The added
frictional resistance coefficients of a flat plate representing an LNG carrier were then predicted for
various ship speeds and an added resistance diagram was generated using these predictions. The
increases in the effective power of the LNG carrier were then predicted for a ship speed of 20 knots
using the added resistance diagram.
The added resistance diagram has a key advantage in that it captures the complex hydrodynamic
response of fouling in simple curves which can be implemented in a spreadsheet or a tool for lifecycle cost estimation. The main advantage of the proposed diagram is that it directly enables the
use of surface conditions, ship length and ship speed, rather than having to use hydrodynamic
AK17/ENG/MAE/044
31
parameters. By using such diagrams, one can easily estimate the added resistance, and hence the
fuel penalty, of a ship for a particular fouling condition given in this study. Therefore it becomes
very practical to calculate the effect of a range of fouling conditions on frictional resistance.
It is of note that this approach assumes a homogenous distribution of fouling on flat plates of ship
hulls, which may not necessarily be the case on real ship hulls. Therefore, additional results from
further immersion tests and experiments considering different types of fouling and their spatial
distributions would be beneficial to improve the diagrams. Having said that, (Turan, Demirel, &
Day, 2016) diagrams may be considered as a leap forward towards a universal model.
The most interesting part of their paper is that it not only proposes diagrams but it also provides
the algorithm of a prediction procedure showing how to develop such diagrams using the available
experimental data. Their study is an open access article under the journal ‘Transportation Research
Procedia’. More details on their study can be found under the fore mentioned journal.
4.2 Result from the study of Mina, Manuel and Soares study on Contra – rotating propeller
After establishing the numerical model in (3.3.1), the propeller type, CRP, was selected to perform
the optimization procedure. Different upper boundary conditions of propeller diameter were
selected to compare the selected CRP with the FPP. The first case was for an upper boundary equal
to the FPP (6 m), while the second one equaled 90% of the diameter of the FPP (5.4 m). Then,
each propeller was simulated in two cases; no cup and a heavy cup. All simulations were performed
for a five-blade propeller at a 14.5 knot designed speed. The results are presented in the table
below.
Main
characteristics
Propeller type
Parameters
Ship
characteristics
Ship speed
Series
Cup
Diameter
Expanded
area ratio
Pitch
Speed
Thrust
Propeller
characteristics
AK17/ENG/MAE/044
Symbol
Unit
(-)
FPP
CRP
(6 m)
𝑉𝑠
(Kn)
14.5
14.5
(-)
(-)
D
EAR
(-)
(%)
(m)
(-)
0.00
6.00
0.47
Wageningen B – series
0.00
1.50
0.00
6.0
6.0
5.4
0.70
0.59
0.47
P
N
T
(m)
(RPM)
(KN)
6.58
75
576.4
9
5.55
73
576.49
CRP with
cup
(6 m)
14.5
8.08
48
576.49
CRP
(5.4 m)
14.5
6.76
70
576.49
CRP with
cup
( 5.4 m)
14.5
1.50
5.4
0.45
7.06
58
576.49
32
Torque
559.20
788.50
600.90
680.70
(%)
573.3
0
59
63
67
61
64
(-)
0.62
0.64
0.96
0.74
0.88
(-)
0.28
0.30
0.67
0.49
0.70
(-)
0.05
0.05
0.15
0.09
0.15
(-)
(-)
0.38
0.19
0.38
0.19
0.38
0.19
0.38
0.19
0.38
0.19
(m/s)
(-)
23.61
0.47
22.78
0.33
15.12
0.28
19.70
0.36
16.53
0.30
(kPa)
43.56
14.62
10.30
26.57
17.32
(%)
7.40
2.00
2.00
3.60
2.00
(m)
4.98
5.16
7.77
5.62
6.69
(-)
9.50
9.50
13.88
9.73
11.54
(RPM)
(kW)
(%)
(g/kWh)
(I/nm)
714
4682
65.6
192
688
4465
62.5
189
668
4151
58.1
191
678
4551
63.7
187
675
4321
60.5
189
Fuel
FC
74.17
consumption
Carbon
(g/kW608
𝐶𝑂2
dioxide
h)
Exhaust
Nitrogen
(g/kW- 6.68
𝑁𝑂𝑋
emission
oxides
h)
Sulphur
(g/kW- 9.59
𝑆𝑂𝑥
oxides
h)
Table 4.5: Optimum results for different configurations.
69.56
65.48
70.28
67.38
598
605
593
598
6.28
4.85
6.90
5.68
9.43
9.55
9.35
9.44
Cavitation and
noise criteria
Gearbox
characteristics
Engine
characteristics
Q
Open water
𝜂𝑜
efficiency
Advance
𝐽𝐴
coefficient
Thrust
𝐾𝑇
coefficient
Torque
𝐾𝑄
coefficient
Wake fraction
W
Thrust
t
deduction
factor
Tip speed
𝑉𝑡𝑖𝑝
Minimum
𝐸𝐴𝑅𝑚𝑖𝑛
expanded
area ratio
Average
PRESS
loading
pressure
Back
𝐶𝐴𝑉𝐴𝑉𝐺
cavitation
Minimum
𝑃𝐹𝐶
pitch
Gerbox ratio
GBR
Speed
Brake power
Loading ratio
BSFC
RPM
𝑃𝐵
LR
BSFC
(kN.m)
From table 4.5 above it can be observed that the CRP showed better fuel economy, as the propeller
was operated at a lower loading ratio than that of an FPP. This percentage was increased when the
model considered a cupping CRP. Compared to an FPP, a no-cup CRP unit could achieve a
reduction in fuel consumption by up to 6.2%, while a cupped CRP could achieve a reduction of up
AK17/ENG/MAE/044
33
to 11.7%. precisely, the no-cup CRP could reduce fuel consumption by 6.2% in the case of a 6 m
propeller and 5.2% in the case of a 5.4 m propeller, compared to an FPP, while a cupping propeller
fuel consumption was significantly reduced by 11.7% in the case of a 6 m and 9.2% in the case of
a 5.4 m propeller, compared to an FPP. It can be clearly seen that a cupping propeller performs
best in comparison to the no cupped CRP and FPP so I will recommend it if the fuel consumption
is to be improved on the bases of propeller configuration.
4.3 Review of result obtained from Hayder, Sinan and Miqdam study
4.3.1 Brake thermal efficiency
The figure below illustrate the effect of adding nano-TiO2 and nano-Al2O3 to diesel on the brake
thermal efficiency under variable load conditions and constant engine speed (1500 rpm). The
nanoparticles acted as catalysts for sintering because of their large surface area that provided a
wide interactive surface, which increased the speed of the chemical oxidation of fuel by air. The
improved fuel’s thermal conductivity increased the combustion speed due to and the enhanced
radiative heat transfer, which greatly enhanced the combustion efficiency. Regardless of the
nanoparticle added, the brake thermal efficiency displayed an improvement. Moreover, the highest
increase in efficiency was obtained when the weight ratio of the nanoparticles was 25 ppm. The
addition of nano-TiO2, however, yielded a better brake thermal efficiency (24.9%) than the
addition of nano-Al2O3 (21%). The addition of 25 ppm of nano-Al2O3 and nano-TiO2 increased
the brake thermal efficiency by 8.2% and 28.44%, respectively, compared to pure diesel, when the
engine was run at a partial load of 75%.
AK17/ENG/MAE/044
34
Figure 4.1: The effect of added nanoparticles on brake thermal efficiency.
4.3.2 Ignition delay period
Ignition delay affects the heat release rate and changes the engine’s performance, emissions and
noise rate characteristics. Moreover, ignition delay is dependent on the physicochemical
specifications of the air–fuel mixture. These properties and their overlaps occur simultaneously.
Figure 4.2 displays the nanoparticles addition effect on the ignition delay period at total load
conditions, as well as the effect of adding 25 ppm of the nanoparticles. Nano-TiO2 and nanoAl2O3 addition reduced the ignition delay period by 5.47% and 0.99%, respectively. Moreover,
the addition of the highly conductive nano-TiO2 greatly enhanced the evaporation process and
modulated fuel-air mixing rates. This result was due to the rapid absorption of the molecules to
the heat inside the combustion chamber and its transfer and distribution inside the liquid fuel
droplets. The output was a mixture suitable for ignition with a short ignition delay period.
Furthermore, the effect of nano-TiO2 was more evident than that of nano-Al2O.
AK17/ENG/MAE/044
35
Figure 4.2: The effect of added nanoparticles on ignition delay period.
Figure 4.3 represents the effect of adding nanoparticles with different mass fractions on the cylinder
pressure at the start of ignition. When the engine load increased causes the ignition delay period to
decrease, which results in reduction in the start ignition pressure. This pressure also decreased with
the addition of the nanoparticle fractions. The added nanoparticles improved the fuel’s cetane
number. The findings suggested that the effect of the addition of 25 ppm nano-TiO2 on the cylinder
pressure was more noticeable that that of the addition of nano-Al2O3 at the same mass fraction.
Figure 4.3: The effect of added nanoparticles on cylinder pressure at start of ignition.
4.3.3 Exhaust gas temperatures
Fig. 4.4 illustrates the effect of the addition of tested nanoparticles on exhaust gas temperatures at
variable engine loads. The addition of both types of nanoparticles causes a decrease in the delay
time, which results in lower exhaust gas temperatures for them compared to diesel fuel. The results
also showed that the exhaust gas temperatures of diesel fuel + nano TiO2 are less than the addition
AK17/ENG/MAE/044
36
of nano- Al2O3, and this difference increases with increasing the added quantity for both types
of nanoparticles. This decrease in the exhaust gas temperatures results in the addition of the nanoTiO2 due to the decrease in the maximum cylinder pressure in addition to the shorter delay in this
case compared to the nano-Al2O3 case. The addition of nano-Al2O3 causes an increase in the
exhaust gas temperature at all the tested loads due to the higher cylinder peak pressure.
Figure 4.4: The effect of added nanoparticles on the exhaust gas temperatures.
4.3.4 Maximum pressure timing (Pmax)
The figure that follows this paragraph illustrates the effect of nano-TiO2 and nano-Al2O3 addition
on the timing of Pmax inside the combustion chamber. The results were measured using a
piezoelectric pressure transducer. Fig. 5(A) shows that the maximum pressure approached the top
dead centre (TDC) by about 3֯–4֯. Pmax was closer to the piston’s TDC when nano-Al2O3 was
added than nano-TiO2 addition case. This result was attributed to the presumably larger premix
combustion fraction of Al2O3 in comparison with that of TiO2, which is indicative of a shorter
delay period. The figures present a diagram of cylinder pressure for multiple cases. The results
indicate that at the best mixing ratio of the nanoparticles and diesel (i.e. 25 ppm), the maximum
cylinder pressure increased more obviously with nano-Al2O3 addition than the case of adding
nano-TiO2. The reason for this behaviour can be considered as the shorter delay period when
adding nano-TiO2 to diesel fuel. Nanoparticles addition increase the area/volume ratio, which then
AK17/ENG/MAE/044
37
greatly improved the oxygen content, as reflected by the cylinder pressure. The figures also show
the status of the cylinder pressure of the diesel fuel when the Al2O3 and TiO2 nanoparticles were
added at rates of 50 (Fig. 5C and D), 100 (Fig. 5E and F) and 150 ppm (Fig. 5G and K) under 1500
rpm and 25% engine load. The results confirm that adding nanoparticles improves the physical
properties of the fuel, including the cetane number. At high mass fractions (50–100 ppm), the
diesel–nano-Al2O3 mixture approached the TDC, whereas the diesel–nano-TiO2 mixture drifted
AK17/ENG/MAE/044
38
away.
Figure 4.5: The effect of added nanoparticles on maximum cylinder pressure timing
AK17/ENG/MAE/044
39
To summarize (Hayder A. Dhahad, Sinan A. Ali, & Miqdam T. Chaichan, 2020) experiment, it dealt
with the effects of adding nano-TiO2 and nano-Al2O3 to Iraqi diesel fuel, which is characterised by
a low cetane number and a high sulphur content. Adding nano-TiO2 at a mass fraction of 25 ppm
yielded a higher increment in brake thermal efficiency (24.94%) compared with adding nano-Al2O3
with the same mass fraction (21%). Nano-TiO2 and nano-Al2O3 addition also shortened the ignition
delay period by 5.47% and 0.99%, respectively. Coming to the cylinder pressure, at the start of
ignition, the TiO2 nanoparticles exhibited a more satisfactory effect than the Al2O3 nanoparticles for
all loads. Amongst all mass fractions, the mass fraction of 25 ppm resulted in the most satisfactory
engine performance.
Similar experiments has been carried out by (Basha, 2014), in his work he dealt on investigating the
performance, combustion and emission characteristics of a single cylinder direct injection diesel
engine using Alumina nanoparticles blended diesel fuels. The results revealed that the application of
nanotechnology can be introduced in the area of internal combustion engines for improving the
performance on par with reduced emissions of the diesel engine. The conclusions of this investigation
are as follows:
1. The Alumina nanoparticles blended diesel fuels was stable for more than a week under idle
conditions.
2. Owing to the significant shortened ignition delay effect associated with the Alumina nanoparticles
blended diesel fuels, the magnitude of the peak pressure and the peak heat release rate were reduced
compared to that of neat diesel.
3. The brake thermal efficiency of Alumina nanoparticles blended diesel fuels were improved relative
to those of neat diesel particularly at the higher loads.
4. There was a marginal reduction of NOx, HC, CO and smoke emissions for the Alumina
nanoparticles blended diesel fuels compared to that of neat diesel fuel.
The proficiency of nanoparticles has been backed by other researches including (Karthikeyan S.,
Elango A., & Prathima A., 2014) reported that adding catalytic nanomaterials (such as adding nanoZnO to diesel) accelerated the fuel and air mixing process, and it reduced the ignition delay time.
(Silva R. D., Binu K.G., & Bhat T., 2015) Conducted a practical study by adding 80 mg/L of nanoTiO2 to diesel and reported a 25% reduction in CO emissions relative to conventional diesel. (M.E.M.
Soudagar, N.N. Ghazali, & M.A. Kalam, 2019) added nanographene oxide (GO) to a mixture of
diesel and butter biodiesel and used a surfactant sodium dodecyl sulphate to confirm stable and
continuous suspension of the GO nanoparticles in the mixture. Nanoparticles were added at rates of
AK17/ENG/MAE/044
40
20, 40 and 60 ppm. The results showed a clear reduction in the ignition delay period, which caused a
remarkable reduction in the combustion time. In addition, the heat release rate for the maximum load
condition and peak pressure were improved, thus increased brake thermal efficiency by 11.56% and
reduced the fuel consumption by 8.34%. The addition of 40 ppm of nano-GO reduced the
contaminants of unburnt hydrocarbons, smoke, CO and NOx by 21.68%, 24.88%, 38.662% and
5.62%, respectively. Lastly (A. Yas¸ar, A. Keskin, S. Yildizhan, & E. Uludamar, 2019) Studied the
effects of adding three types of nanoparticles, namely, Cu(NO3)2, TiO2, and Ce(CH3CO2)3⋅H2O,
to diesel in doses (25 and 50 ppm) on engine performance and emissions. The additions did not cause
any change in physical and chemical properties, except for a relatively slight rise in the fuel cetane
number. In their work, the addition of Ce(CH3CO2)3⋅H2O hydrate to diesel reduced the exhaust
emissions and caused low engine pressure.
4.4 Comparison/Discussion on the various aspect reviewed
Up until now some aspect of fuel economy study has been reviewed ranging from fleet
management to use of nanoparticles. This aspect of my work will carry out a comparative analysis
to know the areas where each of the aforementioned aspects are effective in a vessel. This is done
so because after going through all the aspects it can be seen that they can co-exist and their
combined effort will further reduce the amount of fuel consumed in a vessel. Table 4.6 shows the
aspects reviewed in this paper and the areas where they are effective
Areas of
Fleet
Hull
Use of
Application of
Effectiveness
Management
Maintenance
Contra – Rotating
Nanoparticles
Propellers
Reduction of fuel
Yes
Yes
Yes
Yes
No
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
consumption
Effect on
resistance
Improving engine
parameters
Reduction of
emission
Effect on
shaft/propeller
performance
AK17/ENG/MAE/044
41
Effect of ship
Yes
Yes
Yes
No
speed
Table 4.6: Areas of effectiveness of aspects of fuel economy reviewed in this paper.
4.4.1 Fleet Management
From the studies reviewed, it shows that fleet management can help to reduce fuel consumption
especially when tons – miles per barrel is adjusted. The proposal made by (Scher & Benford, 1980)
where ton – miles per barrel was adjusted to 22,500 ton – miles per barrel by adjusting the ship
speed this ultimately amounted to 616,000 barrels per year of fuel usage compared to 1,364,000
barrels per year if the fleet manager went with the most common strategy of using the most
efficient vessels. This strategy overall led to saving more than 100% on fuel consumption over a
years. When the amount of fuel consumed is reduced this will ultimately lead to reduction in
emission
The study reviewed on fleet management does not show any cognizance on increasing or reducing
resistance. The same can be said of this review in terms of engine parameters and effect on
propeller and shaft performance, although it will ultimately have an effect on resistance and engine
parameters if studied further but that is beyond the scope in this current paper.
4.4.2 Hull Maintenance
From all the studies reviewed it can be seen that a badly maintained hull or one which is fouled
depending on the extent of severity has the potential to increase fuel consumption by increasing
the resistance between the hull of the vessel and the sea. This added resistance will ultimately have
a toll on the shaft power. A reduced shaft power will reduce the speed at which thermal energy of
the engine is converted to mechanical energy in order to propel the vessel. Table 4.4 shows that
when the level of fouling increases for a fixed shaft power of 2.76104kW the speed of the vessel
reduces, for a heavy calcareous fouling for example the speed reduces by 10.7% in order for the
vessel to overcome this speed reduction and maintain the desired speed more fuel has to be
consumed and this will cause the fuel consumption to increase. From the studies reviewed it has
not been established that hull management plays a direct role in affecting the parameters in the
E/R of a vessel.
If the hull is properly maintained and the fuel consumption is brought back to an acceptable limit
this will help to reduce the emission from that particular vessel as less consumption of fuel equals
less emission of harmful substance from vessels. In terms of the shaft/propeller performance and
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ship speed, a badly maintained hull takes a big toll on the shaft and propeller performance and
speed as it can lead to a significant reduction in the propulsive coefficient and shaft power output.
Review of the study of (Hundley LL & Tate CW, 1980) stated that when operating with a clean
propeller and a hull fouled with ‘light grass’ and 10 – 20% coverage of ‘incipient tube worm
growth’, the required shaft power (SP) at 7.7 𝑚𝑠 −1 (15 knots) was 4525 kW. The Shaft power
after the hull was cleaned was 3650 kW. Therefore the increase in required power that can be
attributed to the fouling is 24%.
4.4.3 Use of Contra – Rotating Propellers
The contra-rotating propeller (CRP) helps to reduce fuel consumption, this backed by the study of
(Mina, Manuel , & Soares, 2022) where they observed that a no-cup CRP unit could achieve a
reduction in fuel consumption by up to 6.2%, while a cupped CRP could achieve a reduction of up
to 11.7%.
In terms of emissions, (Minami, Y. & Kano, T., 2005) showed that the use of a super marine gas
turbine (SMGT) coupled with a CRP could reduce CO2 emissions by 25%, nitrogen oxide (NOx)
emissions by 92%, and sulfur oxide (SOx) emissions by 73%. (Mina, Roberto , Manuel, & Guedes
, 2022) also showed that while using CRP, engine parameters such as engine speed, brake power,
loading ratio and BSFC improved by 7%, 13%, 13% and 3% respectively. They also showed
propeller characteristics such as speed, torque, open water efficiency, thrust coefficient improved
by 36%, 38%, 14% and 60% respectively when compared to a FPP for a fixed ship speed of 14.5
knots.
4.4.4 Application of Nanoparticles
Studies like that of (M.E.M. Soudagar, N.N. Ghazali, & M.A. Kalam, 2019) has backed the
capability of nanoparticles to reduce fuel consumption. In their study they added nanographene
oxide (GO) to a mixture of diesel and butter biodiesel and used a surfactant sodium dodecyl
sulphate to confirm stable and continuous suspension of the GO nanoparticles in the mixture.
Nanoparticles were added at rates of 20, 40 and 60 ppm. The results showed a clear reduction in
the ignition delay period, which caused a remarkable reduction in the combustion time. In addition,
the heat release rate for the maximum load condition and peak pressure were improved, thus
increased brake thermal efficiency by 11.56% and reduced the fuel consumption by 8.34%.
The study of (Hayder A. Dhahad, Sinan A. Ali, & Miqdam T. Chaichan, 2020) proves that
nanoparticles improves engine parameters. Their study which has been demonstrated in this work
shows that the addition of 25 ppm of TiO2 increased the brake thermal efficiency by 28.44% when
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compared to Iraqi diesel with the engine running at 75% part load, 25 ppm of Nano-TiO2 also
reduced the ignition delay period by 5.47%. In (M.E.M. Soudagar, N.N. Ghazali, & M.A. Kalam,
2019) study it was also established that the addition of 40 ppm of nano-GO reduced the
contaminants of unburnt hydrocarbons, smoke, CO and NOx by 21.68%, 24.88%, 38.662% and
5.62%, respectively.
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CHAPTER FIVE
CONCLUSION AND RECOMMENDATION
5.1
CONCLUSION
In conclusion, this project has shown that high fuel consumption is linked to not one but different
factors in a vessel ranging from fleet management, hull maintenance, use of contra - rotating
propellers and application of nanoparticles. It can be seen from this project that fleet management
achieves energy efficiency by reducing the ton - miles per barrel for a particular fleet of vessels,
this was proven to improve the fuel consumption by 121% over a year. It is also important to note
that the strategy used here was a simplified analysis and many variables has been left out.
Also hull maintenance which was another aspect of fuel economy discussed here was shows that
if the hull is not properly maintained it can lead to an increase in fuel consumption this is due to
an increase in resistance which also lead to a reduction in the shaft power out, this research found
that the shaft power of a vessel can be reduced by up to 86% if the vessel is heavily fouled. Contra
- rotating propeller which was also discussed here showed a great improvement in propeller
characteristics, engine characteristics, gearbox characteristics and a reduction in the emission from
a vessel by using a secondary propeller in the front of the main propeller, this is further enhanced
when the propeller is used with cup.
Additionally nanoparticles which was the last aspect discussed here was shown to reduce fuel
consumption by enhancing engine characteristics such as ignition timing, brake thermal efficiency,
maximum pressure in the cylinder and exhaust gas temperature. Nano-TiO2 showed a greater
improvement when tested with Iraqi diesel which is proven to have high sulphur content and low
cetane number, from the study reviewed nano-TiO2 increased brake thermal efficiency by 24.94%
and shortened ignition time by 5.47%.
Lastly it is important to note that improvement of fuel efficiency in a vessel can be achieved not
by following only one of the aspects reviewed in this project but from combination of different
methods and strategies which might have not been reviewed in this work.
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5.2
RECOMMENDATIONS
I am pleased to present the final report for my project work, this project provides a comprehensive
review of some aspects of fuel economy, the extent to which they affect fuel consumption and
extent to which they reduce fuel consumption. Based on the findings of this project, I would like
to make the following recommendation:
1. A contra - rotating propeller should be used where feasible because studies reviewed has
shown that they reduce fuel consumption by reducing the load on the engine.
2. The hull of the vessel should be properly maintained to avoid unacceptable level of fouling
on the vessel because studies that have been reviewed in this project has shown that a
heavily fouled hull is associated with an increase in fuel consumption of a vessel.
3. For the optimization of fuel in a vessel a fleet manager has to properly manage a fleet of
vessel by using strategies that best fit the characteristics of the vessel in his possession.
4. The problem of high fuel consumption can mostly be related to the engine of a vessel, from
the studies reviewed in this work nanoparticles helped to improve engine parameters so i
will recommend that it should be employed in order to improve the fuel efficiency of a
vessel.
5. I will also recommend that a combination of the different aspects reviewed in this work be
applied in order to achieve the most efficient fuel consumption.
I am confident that these recommendations will help to reduce the amount of fuel consumed for a
vessel in operation.
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