cd6878_91

INVESTIGATION OF BIODIESEL FUEL PROPERTIES WITH THE

DISPERSION OF CARBON NANOTUBES

DINISH S/O THEGARAJU

Report submitted in partial fulfillment of the requirements

for the award of Bachelor of Mechanical Engineering with Automotive Engineering

Faculty of Mechanical Engineering

UNIVERSITI MALAYSIA PAHANG

JUNE 2012

vii

ABSTRACT

This project reports on the use of carbon nanotubes as additive.to the biodiesel fuel and

its effects to the operational characteristics of the fuel The objective of this project is to

investigate the properties of palm oil biodiesel dispersed with carbon nanotubes in order

to achieve improved operational characteristics and performance. In this study, the

tested fuels were prepared by dispersing CNT into the fuels at five different

concentrations of 0.5 % vol, 1.0 % vol, 1.5 % vol, 2.0 % vol, 2.5 % vol and have their

properties tested and be compared against standard fuels. Experimental results have

shown that the thermal conductivities and flash points of the fuels dispersed with CNT

have increased with higher concentration of CNT. The pour point data have shown

decremental values when dispersed with CNT at higher concentrations and the

dispersion of CNT has increased the cetane number and higher heating value of the

fuels. As a conclusion, dispersion of CNT as additive has improved the properties and

the operational characteristics of biodiesel fuel and its blends.

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ABSTRAK

Projek ini melaporkan mengenai pengunaan carbon nanotubes sebagai bahan tambahan

untuk meningkatkan prestasi biodisel kelapa sawit. Objektif projek ini adalah untuk

menyiasat sifat-sifat biodisel yang ditambah dengan zarah CNT untuk mencapai ciri-ciri

operasi yang lebih baik. Dalam kajian ini, bahan bakar yang diuji disediakan dengan

menambah CNT dengan lima kepekatan seperti berikut, 0.5 % vol, 1.0 % vol, 1.5 %

vol, 2.0 % vol, 2.5 % vol dan sifat-sifatnya diuji dan dibandingkan dengan minyak biasa

di pasaran. Hasil uji kaji ini menunjukkan bahawa koduktiviti terma dan titik kilat bagi

biodisel meningkat dengan peningkatan kepekatan CNT. Data titik tuang menunjukkan

penurunan apabila ditambah dengan CNT dengan kepekatan yang lebih tinggi dan

penambahan CNT menunjukkan peningkatan dalam nombor cetane dan nilai bakar

tinggi biodiesel. Sebagai kesimpulan, penambahan CNT sebagai bahan tambahan akan

meningkatkan sifat-sifat biodisel konvensional dan ciri-ciri operasinya.

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TABLE OF CONTENTS

Page

TITLE i

EXAMINER DECLARATION ii

SUPERVISOR DECLARATION iii

STUDENT DECLARATION iv

DEDICATION v

ACKNOWLEDGEMENT vi

ABSTARCT vii

ABSTRAK viii

TABLE OF CONTENTS ix

LIST OF TABLES xi

LIST OF FIGURES xiii

LIST OF SYMBOLS xv

LIST OF ABBREVIATIONS xvi

LIST OF APPENDICES xvii

CHAPTER 1 INTRODUCTION

1.1 Project Background 1

1.2 Problem Statement 2

1.3 Project Objective 2

1.4 Project Scope 2

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction 4

2.2 Background of Study 4

2.3 Biodiesel 5

2.3.1 Advantages and Disadvantages of Biodiesel 6

2.4 Biodiesel Production 9

2.5 Diesel Engine 11

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2.6 Carbon Nanotube 12

2.7 Cetane Number 15

2.8 Viscosity 19

2.9 Density 20

2.10 Higher Heating Value 23

2.11 Flash Point 23

2.12 Cold Flow Properties 25

2.13 Thermal Conductivity 25

2.14 Summary 27

CHAPTER 3 RESEARCH METHODOLOGY

3.1 Introduction 29

3.2 Flow Chart Description 31

3.2.1 Project Introduction 31

3.2.2 Literature Study 31

3.2.3 Sample Preparation 31

3.2.4 Determination of Key Fuel Properties 33

3.2.4.1 Higher heating value 33

3.2.4.2 Cetane number 34

3.2.4.3 Flash point 35

3.2.4.4Thermal conductivity 35

3.2.4.5 Weigh scale 36

3.2.4.6 Ultrasonication homogenizer 37

3.2.4.7 Glassware 39

3.5 Water Bath System 39

3.5.1 Water Bath System Container Design 40

3.6 Pour Point 42

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 44

4.2 Analysis of Water Bath System 44

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4.2.1 Effect of Stirring on Homogeneity and Temperature 44

4.3 Thermal Conductivity Analysis 46

4.4 Flash Point Analysis 50

4.5 Pour Point Analysis 52

4.6 Cetane Number Analysis 54

4.7 Higher Heating Value Analysis 56

CHAPTER 5 CONCLUSION AND RECOMMENDATION

5.1 Introduction 59

5.2 Conclusions 59

5.3 Recommendations 61

REFERENCES 63

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LIST OF TABLES

Table No. Title Page

2.1 Properties of biodiesel and vegetable oil 6

2.2 Properties of carbon nanotubes and other common materials 14

2.3 Cetane number of biodiesel esters 17

2.4 Oxidization effect of methyl esters on cetane number 18

2.5 Thermal conductivities of various solids and liquids 26

2.6 Thermal properties of biodiesel and diesel mixtures 27

3.1 Volume concentration of CNT in biodiesel 32

3.2 Specification of the weigh scale 37

4.1 Homogeneity of water temperature with and without stirring effect 45

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LIST OF FIGURES

Figure No. Title Page

2.1 Emissions of biodiesel compared with petro-diesel 7

2.2 A schematic diagram for biodiesel production 10

2.3 Comparison of fuel prices 10

2.4 CNT shapes 13

2.5 Relationship between cetane number and ignition delay 15

2.6 Relationship between viscosity and methyl ester amount in

biodiesel fuel 20

2.7 Relationship between density and methyl ester amount in

biodiesel fuel 22

2.8 Relationship between density and temperature of biodiesel 22

2.9 Relationship between flash point and number of atoms and number

of double bonds in fuel chains 24

3.1 Final year project flow chart 30

3.2 Samples of CNT-biodiesel blends 33

3.3 Oxygen bomb calorimeter 34

3.4 Octane meter 34

3.5 Petrotset machine 35

3.6 KD2PRO apparatus and the reading probe 36

3.7 Relationship between particle size and total particle surface 38

3.8 Scientz ultrasonic homogenizer 39

3.9 Water Bath Machine 40

3.10 Sample container holding steel plate with the clamp 41

3.11 Water bath system water container design 42

3.12 K46100 pour point and cloud point apparatus 43

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3.13 Sample container containing sample fuel during pour point testing 43

4.1 Dye dispersion in water without stirring effect 45

4.2 Dye dispersion in water with stirring effect 46

4.3 Thermal conductivity of D100 without CNT in relation to

temperature 47

4.4 Thermal conductivity of B100 in relation to temperature 48

4.5 Thermal conductivity of D20 in relation to temperature 48

4.6 Thermal conductivity of D10 in relation to temperature 49

4.7 Flash point of fuel blends in relation to various volume

concentrations of CNT 51

4.8 Pour point of B100 in relation to various volume






4.11 Cetane number of fuel blends in relation to various volume


4.12 Higher heating values of fuel blends in relation to volume


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LIST OF SYMBOLS

% Percentage

C Degree Celsius

cm Centimeter

cP Centipoise

g Grams

kg Kilogram

m Meter

mm/s Millimeter per Square Second

Nm Nanometer

Pa Pascal

% vol Volume Percentage

W/m-K Thermal Conductivity

Density

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LIST OF ABBREVIATIONS

API American Petroleum Institutes

ASTM American Standard of Testing Materials

CNT Carbon Nanotube(s)

FKM Faculty of Mechanical Engineering

FTP Federal Test Procedure

FYP Final Year Project

SWNTs Single-Walled Nanotubes

MWNTs Multi-Walled Nanotube

SAE Society of Automobile Engineers

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LIST OF APPENDICES

Appendix Title Page

A1 Gantt chart for Final Year Project 1 66

A2 Gantt chart for Final Year Project 2 67

B1 Thermal conductivity of D100 in relation to temperature 68

Thermal conductivity of B100 in relation to temperature 68

B2 Thermal conductivity of D20 in relation to temperature 69

Thermal conductivity of D10 in relation to temperature 69

C Fuel blends flash point in relation to various volume

concentration of CNT 70

D Fuel blends pour point in relation to various volume


E Fuel blends cetane number in relation to various volume


F Fuel blends higher heating value in relation to various volume


CHAPTER 1

INTRODUCTION

1.1 PROJECT BACKROUND

The worlds energy demand and supply has been pressurizing the availability of

crude oil. The dependence on fossil fuel is now in its critical stage as most the logistics

of the world require crude oil in order to move. The increasing usage of this fossil based

fuel has a degrading effect on the environment and climate through its polluting

combustion product. As the demand increases renewable form of fuel that is compatible

with current diesel engine (compression ignition engine) must be identified and the

potential candidate is the biodiesel from vegetable oils through transesterification.

Malaysia is a major producer of vegetable oils such as palm oil and palm oil can be

converted to biodiesel. Biodiesel has promising properties such as better cetane number,

flash point and emissions compared to fossil fuels but biodiesels suffer from metal

corrosion (Fazal et al., 2011) as oxygen content is higher in the fuel. Properties such

viscosity, higher heating value and cold flow properties are also lower than

conventional fossil fuel which affects its performance on a diesel engine. Biodiesel is

completely miscible with diesel allowing blending the fuels in any proportion without

modification of current engines. CNT is a form of pure carbon arranged in a cylindrical

shape in nanoscale dimensions and the dispersion in the blended fuel may improve the

fuel properties and the engine performance to CNT mix ratio in fuels is to be performed.

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1.2 PROBLEM STATEMENT

Biodiesel fuels derived from vegetable oils comparatively have lower heating

value compared to the diesel due to the excess of oxygen in biodiesel fuels. This reduces

the amount of power generated when biodiesel is used, and thus increasing fuel

consumption for the same power generation from a diesel engine. In order to improve

the properties of the biodiesel, CNT is prepared to be dispersed within the diesel-

biodiesel fuel mixture in order to produce better fuel performance such as the higher

heating value and cetane number. Dispersion of CNT will also increase the ratio of

carbon-oxygen in the fuel, thus improve the properties further. Existing research on the

CNTs effect on biodiesel fuels has not been fully established

1.3 PROJECT OBJECTIVE

For this project, the objectives to be achieved are listed as follows;

i. To investigate various properties of diesel and biodiesel fuel blends.

ii. To quantify the effect of CNT dispersion on the properties of diesel and

biodiesel fuels.

iii. To develop a water bath system to find the effect of temperature on CNT

added diesel and biodiesel blends on thermal conductivity.

1.4 PROJECT SCOPE

In this study, CNT particles are selected as additive due to their high thermal

conductivity. It is proposed to determine operational characteristics of biodiesels in

concentrations of 0.5 % vol, 1.0 % vol, 1.5 % vol, 2.0 % vol and 2.5 % vol. Testing of

the fuel will be evaluated as per the American Standards of Testing Materials (ASTM).

The following tests are planned to be conducted.

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i. The Cetane number of a fuel is to be measured the quality of the fuel and

is used to determine the ignition delay of the fuel.

ii. The Higher heating value is the energy contained by one gram of fuel

during combustion.

iii. Thermal Conductivity of biodiesel is to be measured under transient

conditions. This method of measurement is undertaken by many

researchers. The measurement of temperature change with time is used in

the determination of thermal conductivity of biodiesel.

iv. The Cold flow properties or the pour point is the lowest temperature at

which no movement of the specimen is observed is to flow out of the

container under the influence of gravity.

v. The flash point temperature of biodiesel is the lowest temperature at

which an ignition source causes the vapors of the biodiesel to ignite

under specific conditions.

CHAPTER 2

LITERATURE REVIEW

2.1 INTRODUCTION

A plethora of experiments and studies were devoted by researchers on fuels and this

chapter discusses the findings of other researchers publications and by doing so, the

foundation and development of this project is paved by giving a better understanding of

fuel properties and its characteristics. The focus of the literature study is on biodiesel and

the dispersion of CNT as an additive.

2.2 BACKROUND OF STUDY

Nanomaterials are now in the forefront of the additive development of fluids

because of their unique properties and performance increase has been achieved in spark

ignition engines by dispersing CNT in gasoline in terms of octane number and anti-knock

properties. Nanomaterials can act as a burning rate catalyst because when dispersed into

liquids as they accelerate the burning rate and promote clean burning, also particulate

matters and carbon monoxide are reduced (Kish et al., 2009). Biodiesels are a viable choice

as a fuel source because it has no aromatics and is 10 % to 20 % more in oxygen content

and also, biodiesel improves the lubricity which results in longer component life as it does

not undergo desulfurization unlike common fossil fuel which reduces emission but it loses

its lubricity. (Alptekin and Canakci., 2008). Ertan also postulated that biodiesel has higher

cost due to the cost of virgin oil but Malaysia as a producer of vast quantities of palm oil is

capable of producing cheap oil compared to expensive corn or soy derived biodiesels.

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Biodiesel is also nontoxic, renewable, biodegradable and environmentally friendly

(Verduzco et al., 2011). In addition, unlike oil and gas which have heavy foreign contents,

palm oil production is virtually 100% local. (Kalam and Masjuki., 2002)

2.3 BIODIESEL

The increasing awareness in the deteriorating properties of the ever growing

emissions and pollutants by combustion and the hike in fossil fuel cost due to its scarcity

will make biodiesel more acceptable. (Thielemann et al., 2007). Experts computed that

fossil fuel reserve depletion times for oil, coal and gas is approximately 35, 107 and 37

years which denotes that coal are available up to 2112 and the existing fossil fuel will

remain up until 2042. (Shafiee and Topal., 2008). To compensate for the rising energy

demand and the inevitable fossil fuel depletion, fuels such as biodiesel are in the pinnacle

alternative technologies as a viable replacement for diesel engines. The methyl ester of

palm oil, also known as palm oil diesel (POD) which is pure, made of 100% monoalkyl

ester is called neat fuel and is branded B100. Biodiesel blends can be designated by the

call sign BXX. The XX denotes the percentage of biodiesel in the blend (i.e., B90

describes a blend with 90% biodiesel and 10% diesel). . The comparison of properties of

vegetable oil biodiesel and standard specifications of diesel is given in Table 2.1. (Bajpai

and Tyagi., 2006). Table 2.1 indicates the properties of biodiesel in terms of kinematic

viscosity, cetane number, flash point, lower heating value and pour point for common types

of biodiesel and diesel.

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Table 2.1: Properties of biodiesel and vegetable oil

Vegetable

oil

Kinematic

viscosity at

38 (C)

(mm2/s)

Cetane

number

Flash

point

(C)

Lower

heating

value

(MJ/Kg)

Cloud

point

(C)

Pour

point

(C)

Peanut 4.9 56.4 176 33.6 5 -

Soybean 4.5 45 178 33.5 1 -7

Sunflower 3.6 63 127 31.8 4 -

Palm 5.7 62 164 33.5 13 -

Diesel 3.06 50 76 43.8 - -16

20 %

biodiesel

blend

3.2 51 128 43.2 - -16

Source: (Bajpai and Tyagi., 2006)

2.3.1 ADVANTAGES AND DISADVANTAGES OF BIODIESEL

It is a fact that the transportation network of the world are the highest consumer of

fossil fuel such as gasoline, diesel fuel, liquefied petroleum gas (LPG) and natural gas (NG)

and the alternative to this fuel must be feasible, economical relative to current production

techniques, environmentally acceptable and has good availability. However it is not wise to

look only at biodiesel, it is important to take into account other crucial factors such as raw

material and vehicle technology in order to assess the feasibility of biodiesel as a fuel.

Biodiesel is 100 % renewable and being plant based it does not emit sulfur and carbon

monoxide on burning and is nonpolluting, biodegradable and environmentally safe. The

cytotoxic and mutagenic effects of diesel engine using biodiesel shows that particulates and

vitro cytogenic and mutagenic effects were lower compared to diesel fuel. In view of the

environmental considerations, biodiesel is considered carbon neutral as all the carbon

dioxide released from the atmosphere are used for the growth of vegetable oil crops (carbon

is exhausted and absorbed in a closed cycle thus there will be no addition of carbon to the

atmosphere compared to diesel fuel as it releases trapped carbons to the atmosphere). It is

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known that the combustion of 1 liter diesel fuel gives 2.6 Kg of CO2 against 1 kg of

CO2/Kg of biodiesel (Bajpai and Tyagi., 2006). The literature states that the combustion of

biodiesel emit lesser pollution compared to diesel in which the emission of SO2, soot, CO,

hydrocarbons (HC), polyaromitic hydrocarbons (PAH), and aromatics as shown in Figure

2.1 which indicates the engine exhaust contains no SO2, and shows decreasing emissions of

pollutants. The NOx emissions are reported to be in the range between 10% compared to

diesel depending on engine combustion characteristics. This shows that biodiesel is similar

to diesel fuel in chemical and physical properties and has favourable engine performance

that makes it a better substitute for diesel fuel compared to battery power and hydrogen

power.

Figure 2.1: Emissions of biodiesel compared with petro-diesel


Hydrocarbons are reduced with biodiesel in diesel engines along with carbon

monoxide and particulate matter. The exhaust emission of total hydrocarbon is at an

average of 67 % lower for biodiesel, carbon monoxide at 48 % lower and particulate matter

at 47 % lower than diesel. This nulls the perspective that the dispersion of CNT will

increase pollution compared to diesel fuel as only a small percentage of CNT is dispersed.

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However nitrous oxide emissions stayed or are slightly increased. The melting temperature

of palm oil biodiesel (POD) is about 20 C which forms a clear liquid when blended with

diesel fuel. The fraction of POD in blends does not create any separation or any layering on

the inside wall of the fuel tank. This investigation was done in Malaysia, when the ambient

environmental temperature was 25 C 35 C. It is assumed that POD could be a good

alternative to partially replace the conventional diesel fuel (Kalam and Masjuki., 2002).

Biodiesels are subjected to oxidation through contact with the oxygen in the air and

hydroperoxides are formed by the reaction of oxygen with carbon atoms and most

vegetable oils contain anti-oxidants such as vitamin E that inhibit oxidation until it is

depleted causing the oxidation to process rapidly beyond the depletion of vitamin E. With

the presence of two or more double bonds in the fatty acid chain, biodiesel oxidize more

rapidly compared to biodiesel with one double bond thus the tendency to oxidize is greater

with the increase in the number of double bonds in the biodiesel chain. The important

consequence of oxidization is that the hydroperoxides are very unstable and tend to attack

the elastomers and it induces polymerization of esters and form insoluble gums and

sediments which causes filter plugging. This phenomenon is called fuel stability problem

and the oxidization is accelerated by heat and light. When biodiesels are distilled to remove

high boiling point materials such as glycerin, the natural antioxidants are also removed

causing accelerated oxidation. Biodiesel also show degradation when stored for a long time

along with humidity, pigments and enzymes which reduces oxidative stability. (Dantas et

al., 2010). The lubricating properties of the biodiesel increases the engine efficiency and

can eliminate the use of additives and reduce the failure of fuel injection pump which is

caused by inadequate fuel lubricity. Drivability is another important advantage of the

biodiesel where, the use of biodiesel causes smoothing of the engine where it runs quieter

and produces less smoke and existing engines can be used without any modification up to

20 % biodiesel in the fuel blend.

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2.4 BIODIESEL PRODUCTION

Biodiesel can be produced by chemically reacting vegetable oil or animal fat with

alcohol such as methanol. This reaction requires a catalyst such as sulfuric acid, sodium or

potassium hydroxide. This produces compounds called methyl esters. It is these esters that

came to be known as biodiesel. Biodiesel from vegetable oil is interesting for several

reasons such as it can replace diesel oil in boilers and internal combustion engines without

major adjustments, only a small decrease in performance was reported, almost zero

emission of sulfates, a small net contribution of carbon dioxide when whole life cycle is

considered from cultivation to conversion of biodiesel. In general, vegetable oils contain

triglycerides and monoglyserides and fatty acids. However the production cost of biodiesel

is not economically competitive with petroleum based fuels due to relatively high cost of

the lipid feedstock which are usually edible grade refined oils. The process of removal of

all glycerol and the fatty acid from the vegetable oil is called transesterification.

Trasesterification is a better method because it is a simple and an easy operation. Figure 2.2

shows the chemical reaction between triglycerides and alcohol in the presence of the

catalyst to produce mono-esters. Depending on the fatty acid composition of the oil, its

cetane number can be determined at the starting stage. (Halek et al., 2009)

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Figure 2.2: A schematic diagram for biodiesel production


In some European countries, biodiesel oil are sold commercially, however in other

countries, biodiesels are not available commercially due to high cost and is primarily used

mainly for practical purposes and in reduce dependency on imported fuels. In Asia,

Malaysia produces 3000 metric tonnes per year for transit fleet, bus and cars therefore the

demand of biodiesel is there and is increasing. Although the general interest in using and

producing biodiesel is dependent on the regional prices of biofuel, labor, land, processing

plant and economic considerations must be evaluated. Figure 2.3 shows the comparison of

the cost of diesel fuel to the cost of the energy equivalent amount of palm oil and other

vegetable oil (Kalam and Masjuki., 2002) and from the figure it is clear that it is not yet

economical to use palm oil as well as other biodiesels.

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Figure 2.3: Comparison of fuel prices

Source: (Kalam and Masjuki., 2002)

2.5 DIESEL ENGINE

A diesel engine is a type of internal combustion engine where the standard diesel

engine operates on the principal that air in the engine cylinder is compressed to an

extremely high pressure and temperature at which time the fuel is injected into the

combustion chamber causing ignition. This is different from a gasoline engine which

compresses both the air and fuel at the same time. Once the air and fuel is compressed, the

gasoline engine relies on a spark to ignite the mixture causing combustion. The spark

ignition or gasoline engines need for electrical ignition requires the use of many

components such as spark plugs, ignition coil, distributor, and a carburetor. The mechanical

nature of the diesel engines design makes it simpler, more rugged, more versatile, and its

higher compression ratio makes it more efficient than the gasoline engine. It is because of

these basic principles of the diesel engines design that make it such a good candidate for a

near term solution to our renewable energy needs (Engine Manufacturers Association.,

2002).

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2.6 CARBON NANOTUBES

CNT were discovered by Sumio Iijima in 1991. CNTs are a particular arrangement

of carbon atoms similar in structure to graphene, a two dimensional counterpart of graphite.

A CNT is formed when the two-dimensional sheet of graphene is rolled into a seamless

cylinder. CNTs can range from 1 nm to 100 nm in diameter and have lengths in the

micrometer range. Based on the chemical arrangement of carbon atoms, a discrete number

of unique CNTs can be formed. Normally, these different types of CNTs are classified by

their chiral vector as displayed in Figure 2.4. The chiral vector is related to the

circumference of the nanotube, and based on the chiral vector, the nanotubes are

categorized as either semi-conducting or metallic. CNTs can also be classified as single-

walled, double-walled or multi-walled. A single-walled CNT is formed by a rolling a single

sheet of graphene into a cylinder. Double-walled and multi-walled CNTs are formed by

forming concentric cylinders from multiple layers of graphene. Dresselhaus provides a very

detailed description of the chemical arrangement of CNTs as well as the phonon transport

and related thermophysical properties (Eklund., 2000). Figure 2.4 is a schematic

representation of the construction of a nanotube by rolling up and infinite strip of graphene.

In (A) the chiral vector Ch = na1+ma2 connects two lattice points O and A on the graphene

sheet. An infinite strip is cut from the sheet through these two points, perpendicular to the

chiral vector. The strip is then rolled up into a seamless cylinder. T=t1a1 +t2a2 is the

translation vector of the tube. All different nanotubes have angles between 0 and 30.

Armchair tubes have angles of 30 (Ba), zigzag have angles of 0 (Bb) and all other tubes

are called chiral and have angles within 0 to 30 (Bc) as shown in Figure 2.4 (Popov.,

2004).

cd6878_91

Documents

dispersion of cnt

higher concentration

biodiesel production

disadvantages of biodiesel

project background

project objective

tested fuels

use of carbon nanotubes