A STUDY ON 5 % AND 10 % BIO-BLENDED DIESEL

FUEL SPRAY DEPOSITION

KELVIN THENG SERN LUNG

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

ii

SUPERVISOR DECLARATION

“I hereby declare that I have read this thesis and in my opinion this report is

sufficient in terms of scope and quality for the award of the degree of Bachelor of

Mechanical Engineering (Automotive) with Honour”

Signature: ...................................

Supervisor: DR. YUSMADY BIN MOHAMED ARIFIN

Date: JUNE 2012

A STUDY ON 5 % AND 10 % BIO-BLENDED DIESEL

FUEL SPRAY DEPOSITION

KELVIN THENG SERN LUNG

This project is submitted to

Faculty of Mechanical Engineering

In partial fulfillment for

Bachelor Mechanical Engineering (Automotive) with Honour

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

JUNE 2012

iii

DECLARATION

“I hereby declare that the work in this report is my own except for summaries and

quotations which have been duly acknowledged”

Signature: ...................................

Author: KELVIN THENG SERN LUNG

Date: JUNE 2012

iv

ACKNOWLEDGEMENT

First of all, I would like to express the gratitude to Dr. Yusmady bin

Mohamed Arifin, as my supervisor who had given his expert guidance and full

commitment throughout this project.

Gratitude also goes to Faculty of Mechanical Engineering (UTeM) for giving

me the opportunity to undergo this final year project as part of my evaluation during

Bachelor Degree. Special thanks to En Fudhail bin Abdul Munir for his commitment

as Head of PSM which had guided all of the students following the proper

procedures during PSM implementation.

Last but not least, a lot of thanks to my family and friends for providing

encouragement and strength to me to always give the best. I would like to express

gratitude to all of who may involve either directly or indirect for all the support,

cooperation, guidance throughout this project.

v

ABSTRACT

Deposit formation inside a combustion chamber is a phenomenon that

contributes to various engine problems such as increase in emission, engine

performance reduction as well as engine damage. Due to higher viscosity, density

and distillation temperature compared to diesel fuel, utilization of bio-diesel fuel

increase the tendencies of deposit formation. The aim of this study is to investigate

the deposit formation for 5 % and 10 % Bio-Blended Diesel Fuel (B5 and B10) using

Fuel Spray Deposition Test (FSDT) apparatus. The deposit formation on hot surface

depends on spray interval, fuel types, wall surface temperature, chemical reaction

effect, heat transfer effect and cooling effect. Existing FSDT apparatus had been

improved and experiment had been conducted successfully for surface temperature

of 300 °C. In this study, it was found that deposition mass of both tested fuels was

increased. Deposition mass of B10 was found to be higher than B5, due to higher

value of density and viscosity. Deposit formation rate for both fuels was decreasing

as a function of time. However, B10 have higher deposit formation rate as compared

to B5 over time. Fuel deposit pattern onto the hot surface for both fuels differs to

each others, due to the atomization ability of the fuels. Hence, the utilization of lower

blends percentage of bio-diesel fuels had greater potential in reducing deposit

formation on a combustion chamber wall in an engine.

vi

ABSTRAK

Pemendapan dalam kebuk pembakaran ialah fenomena yang menyumbang

kepada masalah terhadap enjin seperti peningkatan emisi terhadap persekitaran,

pengurangan prestasi enjin dan kerosakan dalam enjin. Disebabkan bio-diesel

mempunyai kelikatan, ketumpatan dan suhu penyulingan yang lebih tinggi daripada

minyak diesel, penggunaan minyak bio-diesel dalam pasaran telah meningkatkan

kecenderungan dalam pembentukan pemendapan. Tujuan kajian ini adalah untuk

menyiasat pembentukan pemendapan bagi 5 % dan 10 % campuran bahan api Bio-

Diesel (B5 dan B10) dengan menggunakan radas Ujian Pemendapan Semburan

Bahan Api (FSDT). Pembentukan pemendapan terhadap permukaan panas

bergantung kepada selang masa semburan, jenis bahan api, suhu permukaan, tindak

balas kimia, kesan pemindahan haba dan kesan penyejukan. Radas FDST telah

dibaik pulih dan ujikaji telah selesai dijalankan bagi suhu permukaan 300 °C. Dalam

kajian ini, didapati bahawa jisim pemendapan bagi kedua-dua bahan api yang diuji

menunjukkan peningkatan. Disebabkan ketumpatan dan kelikatan yang lebih tinggi,

B10 menghasilkan jisim pemendapan yang lebih tinggi daripada B5. Kadar

pembentukan pemendapan bagi kedua-dua bahan api berkurang dengan masa. Tetapi,

B10 mempunyai kadar pembentukan pemendapan yang lebih tinggi daripada B5,

berkadar dengan masa. Corak pemendapan bagi kedua-dua bahan api menunjukan

perbezaaan disebabkan oleh keupayaan pengabusan bahan api tersebut. Maka,

penggunaan bahan api yang mempunyai peratusan pencampuran bio-diesel yang

lebih rendah mempunyai kecenderungan dalam pengurangan pembentukan

pemendapan pada dinding kebuk pembakaran bagi sesuatu enjin.

vii

TABLE OF CONTENT

CHAPTER TITLE PAGE

SUPERVISOR DECLARATION ii

DECLARATION iii

AKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF ABBREVIATIONS xiii

LIST OF SYMBOLS xv

LIST OF APPENDICES xvi

CHAPTER 1 INTRODUCTION 1

1.1 Background 1

1.1.1 Bio-Diesel Fuel 2

1.1.2 Fuel Deposition 3

1.2 Problem Statement 4

1.3 Objectives 5

1.4 Scopes 5

CHAPTER 2 LITERATURE REVIEW 6

2.1 The Effect of Bio-Diesel Fuel Properties 6

2.1.1 Viscosity 7

2.1.2 Specific Gravity and Density 9

viii

CHAPTER TITLE PAGE

2.2 Concerns Using Bio-Diesel Fuel 10

2.2.1 Emissions 10

2.2.2 Impact on Engine Performance 12

2.3 Engine Deposition Phenomena 13

2.3.1 Fuel Spray/Wall Impingement 13

2.3.2 Regime Transition 14

2.4 Deposits and Precipitate Formation 16

CHAPTER 3 METHODOLOGY 19

3.1 Introduction 19

3.2 Tested Fuel 20

3.3 Problems with Current Fuel Spray Apparatus 22

3.4 Modification of Current Fuel Spray Apparatus 24

3.4.1 Fuel Spray Chamber 24

3.4.2 Fuel Tank 26

3.5 Experimental Set Up and Procedures 28

3.5.1 Fuel Spray Deposition Test (FSDT)

Apparatus 28

3.5.2 Procedures 30

CHAPTER 4 RESULTS & DISCUSSIONS 33

4.1 Introduction 33

4.2 Experimental Results 33

4.2.1 Bio-Diesel Fuel Deposition on a Hot Surface 33

4.2.2 Deposition Characteristics of B5 and B10 35

4.2.2.1 Deposit Formation Characteristics

for B5 36

4.2.2.2 Deposit Formation Characteristics

for B10 36

ix

CHAPTER TITLE PAGE

4.3 Discussions 38

4.3.1 Deposit Formation Rate, R in Relation to

Tested Fuels 38

4.3.2 Deposit Formation Mechanisms 40

4.3.3 Fuel Properties on Deposit Formation

for Bio-Diesel Fuels 40

4.3.4 Deposition Pattern Due to Fuel Properties 41

4.4 Problems Faced 42

4.4.1 Fabrication of FDST Apparatus 42

4.4.2 Time Constraint During Experimental

Setup 42

4.4.3 Effect of Bio-Diesel Fuel Vapors to

the Surrounding 42

CHAPTER 5 CONCLUSION & RECOMMENDATIONS 44

5.1 Conclusions 44

5.2 Recommendations 45

5.2.1 Hot Plate Design and Dimensions with

Types of Heater Plate Used 45

5.2.2 Filtering System to Reduce the Effect

of Fuel Vapors 46

REFERENCES 48

APPENDICES 54

x

LIST OF TABLES

NO. TITLE PAGE

2.1 ASTM Standards of Bio-Diesel and Petro-Diesel Fuels 12

2.2 Regime Transition Conditions 15

3.1 Properties of Tested Fuels 21

3.2 Summarized Comparison of FSDT Apparatus Before

and After Modification 27

xi

LIST OF FIGURES

NO. TITLE PAGE

1.1 Basic Transesterification Process 2

1.2 Transesterification of Triglycerides with Alcohol 2

1.3 Fuel Deposition Phenomena inside Combustion Chamber 3

2.1 Bio-Diesel Fuel Properties and Their Associated Impact on

Engine Operation, Storage and Transportation as Compared

to Fossil Diesel 6

2.2 Bio-Diesel Kinematic Viscosity Variations with Temperature 8

2.3 Kinematic Viscosity Variations with Bio-Diesel Blend

Percentage 8

2.4 Specific Gravity of Bio-Diesel and Its Blends with No. 2

Diesel Fuel 9

2.5 Direct Impact and Corresponding Interactions of Bio-Diesel

Fuel Properties on Emissions as Compared to Fossil Diesel 10

2.6 Diesel Engine Emission Characteristics for Operation

with Bio-Diesel 11

2.7 Schematic of Different Impact Regimes 14

2.8 The Amount of Precipitates Formed by SBO, CSO and PF

Based Bio-Diesel as Function of Bio-Diesel Fraction and

Temperature 18

3.1 Flow Chart of Methodology 20

3.2 Fuel Density Comparisons for Diesel and Bio-Diesel Fuels 21

3.3 Existing Fuel Spray Deposition (FSDT) Apparatus 22

3.4 Current Fuel Tank without Cover 22

3.5 Improper Fuel Hose Position 23

xii

NO. TITLE PAGE

3.6 Improper Fuel Spray Chamber Design 23

3.7 Comparison of Fuel Spray Chamber Between Before

and After Modification 24

3.8 Fuel Spray Chamber with Acrylic Cover and Sliding

Mechanism 25

3.9 Fuel Spray Chamber with Exhaust Fan and Aluminium Hoses 25

3.10 Jack System Use to Support and Adjust the Heater Plate

Position 26

3.11 Comparison of Fuel Tank between Before and After

Modification 27

3.12 Modified Fuel Spray Deposition Test (FSDT) Apparatus 28

3.13 Schematic Diagram of Fuel Spray Deposition (FSDT)

Apparatus 29

3.14 Dimension of the Aluminium Hot Plate 29

3.15 Distances between the Fuel Injector and Center of the Hot Plate 31

3.16 Hot Plate Placement onto the Support 32

3.17 Weight of Hot Plate Measurement Using Microbalance After

Cooled Down 32

4.1 Deposition Mass, M of B5 and B10 34

4.2 Visual Comparison for B5 and B10 Deposits 35

4.3 Deposit Formation Rate, R versus Time, T for Tested Fuels 38

4.4 General Features for the Single and Non-Single Droplet States

during Diesel and Bio-Diesel Fuel Droplet Evaporation 39

4.5 Evaporation Characteristics for Diesel Fuel, B100 and

Bio-Blended Diesel Fuels 39

4.6 Fuel Vapors Emitted from Exhaust Fan of the Spray Chamber 43

5.1 Charcoal Canister Used in Carburetor System 46

5.2 Fuel Vapor Canister Filter Made of Polyester Fibers 47

xiii

LIST OF ABBREVIATIONS

ASTM American Society for Testing and Material

BHA Butylated Hydroxyanisole

BHT Butylated Hydroxytoluene

CI Compression Ignition

CN Cetane Number

CO Carbon Monoxide

CO2 Carbon Dioxide

CSO Cottonseed Oil

CSOME Cottonseed Oil Methyl Ester

D2 No.2 Type Diesel Fuel

DC Direct Current

FAME Fatty Methyl Esters

FSDT Fuel Spray Deposition Test

HC Hydrocarbon

HCCI Homogeneous Charge Compression–Ignition

HP Horsepower

HSDI High Speed Direct Injection

ID Ignition Delay

La Laplace Number

max Maximum

MEP Maximum Evaporation Rate Point

min Minimum

NOx Nitrogen Oxides

PF Poultry Fat Based

PM Particulate Matter

PME Palm Methyl Ester

PrG Propyl Gallate

xiv

LIST OF ABBREVIATIONS

PSM Projek Sarjana Muda

SAE Society of Automotive Engineers

SBO Soybean Oil

SG Specific Gravity

SP Spray Penetration

TBHQ Tert-Butylhydroquinone

USA United States of America

UTeM Universiti Teknikal Malaysia Melaka

vol Volume

We Weber Number

wt Weight

xv

LIST OF SYMBOLS

L Length [m]

Characteristic Length [m]

μ Viscosity [mm2/s]

t Time [s]

ρ Density [kg/m3][g/ml]

v Velocity [m/s]

σ Surface Tension [kg/s2]

V Voltage [V]

xvi

LIST OF APPENDICES

NO. TITLE PAGE

A Gantt Chart of PSM Implementation 54

B Density Measurement of Diesel and Bio-Diesel Fuels 55

C Fuel Properties of D2 and B5 56

D Electric Motor Specification Used in FSDT Apparatus 57

E Experimental Result of Deposition Mass, M for B5 at 300 °C 58

F Experimental Result of Deposition Mass, M for B10 at 300 °C 59

G Slope Calculation for Deposit Formation Rate, R of B5 and

B10 at 300 °C 60

1

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

Development of diesel engine had been evolved dramatically since its

invention around 1900’s. Throughout the industrial revolution era, diesel engine had

made its important roles and been widely used especially in transportation fields such

as heavy trucks, heavy machineries and most importantly, commercial vehicles.

Diesel engine had many advantages than gasoline type engines: high power-to-

weight ratio, higher thermal efficiencies, better fuel economies, simpler construction

and most importantly lower hydrocarbons (HC) emission.

However, emission from burned diesel fuel had brought major drawbacks

since it produce particulate emissions such as sulfates from sulfur contents inside the

fuel [1], as much as 20 to 50 times higher than conventional petrol-diesel [2]. This

had brought major concerns since it is harmful to the environments and most

importantly to publics. Typical proposed low-emissions fuel should have high cetane

number (CN), low boiling range, low aromatic compound and addition of oxygenates

[1]. Hence, some of the researchers had started to developing new alternatives fuels

from vegetable oils and cooking oils to produce bio-diesel. Bio-diesel, an alternative

fuel from diesel, is known as fatty acid methyl or ethyl esters formed from vegetable

oils or animal fats with alcohols through transesterification process [3]. It is

renewable, bio-degradable and oxygenated compared to conventional diesel fuel [4].

With the implementation of bio-diesel into the market, this had eventually reduced

the needs from fossil fuels which is depleting throughout the years.

2

1.1.1 Bio-Diesel Fuel

Bio-diesel (chemical name: fatty acid methyl esters (FAME), C14-C24 methyl

esters, is defined as a fuel comprised of mono-alkyl esters of long–chain fatty acids

derived from renewable lipid feedstock, such as vegetable oils or animal fats, for

used in compression-ignition (CI) diesel engine [5]. It is a type of alternative fuel that

had the potential to reduce emissions and green house effect. It is known as

“advanced bio-fuel” through the Energy Independence and Security Act of 2007 [3].

Bio-diesel is produced from transesterification process by reaction of fatty

acids such as glyceride with alcohol in presence of catalyst. The produced product,

which is long chain fatty acids that comprise of alkyl esters and glycerol.

Figure 1.1 Basic Transesterification Process [6]

Figure 1.2 Transesterification of triglycerides with alcohol [2]

3

Bio-diesel usually blended with petroleum diesel to make bio-diesel blends;

B100 is pure FAME, while B20, B5 and B2 are fairly common blend levels [3]. Bio-

diesel blends are classified through the letter B with followed numbers that denotes

the percentage of bio-diesel in the blend. For example, B20 of bio-diesel is consists

of 20 % of bio-diesel blends inside the fuel. However, for the conventional and

unmodified diesel engine, it can only operate with maximum of 20 % bio-diesel

blended fuel [7].

1.1.2 Fuel Deposition

Inside combustion chamber, large amount of fuel droplet was produced

during fuel injection process. This droplet will experience atomization and eventually

burned inside combustion chamber. However, due to some properties inside engine

such as ignition delay (ID) or excessive amount of fuel droplet, some of the fuel

droplet will not eventually burned up and cause impingement onto the wall surface of

combustion chamber and piston head. This repeating process will in turn produce

liquid fuel films [8], where deposit formation will produce onto combustion chamber

wall surface. Figure 1.3 below shows the common fuel deposits on top of the piston

bowl inside common diesel engine.

Figure 1.3 Fuel Deposition phenomena inside combustion chamber [9]

4

According to Werlberger and Cartellieri [10], they discovered that for small

bore direct injection diesel engine, more than 50 % of the fuel will impinged on the

top of piston bowl at high load conditions.

Inside small diesel engine, probability of impingement onto wall surface was

higher, due to factors such as higher injection pressure that leads to higher spray

penetration of fuel droplet [11], longer ID as compared to injection period [12], small

engine with smaller stroke between injector nozzle and piston head [13], and

incomplete combustion causing unburned fuel droplets, especially in the case for bio-

diesel fuel [2].

Wall surface temperature plays major role in fuel impingement. Higher wall

surface temperature will have less fuel impinge onto it than lower wall surface

temperature as discovered by Tang et al. in the case for bio-diesel [14]. Higher

volatility and heavier molecular mass fuel (density) will more likely to produce more

impingement on wall surface as experimental results discovered by Tat and Gerpen

[15].

1.2 PROBLEM STATEMENT

Engine deposition is the phenomena where deposit forms from unburned

fuels inside the combustion chamber. This in turns leads to increase in emission and

reduce engine performance [16]. Wall surface temperature was found to be one of

the main factors that affect the amount of deposit accumulated [14].

In this study, Fuel Spray Deposition Test (FSDT) was used to conduct an

experiment to investigate the deposit formation of B5 and B10 due to fuel spray

impingement on a hot surface.

5

1.3 OBJECTIVES

The main objective of this research is to investigate the deposit formation

tendency for bio-blended diesel (B5 and B10) fuel spray on a hot surface plate.

1.4 SCOPES

This study was focused on the investigation of deposit formation for B5 and

B10 on a hot surface due to fuel spray impingement. At first, the current design of

FSDT apparatus, fabrication method, as well as properties and behavior of fuel are

studied. Then, the current apparatus was improved and experiments were conducted

for further investigation.

The main scopes of this study are summarized as below:

i. Modify the existing fuel spray apparatus.

ii. B5 and B10 were used as the tested fuel for fuel spray deposition

investigation.

iii. Fuel injection pump was set at constant speed of 1450 rpm which is

corresponding to constant engine speed.

iv. Hot surface temperature was set at 300 °C corresponding to the wall

surface temperature that is before the MEP temperature of diesel fuel

[17].

6

CHAPTER 2

LITERATURE REVIEW

2.1 THE EFFECT OF BIO-DIESEL FUEL PROPERTIES

Through the transesterification process, bio-diesel fuel had experienced some

changes to its properties such as high density, high viscosity, high CN, lower heat

content and etc, as compared to conventional diesel fuel. Thus, this difference in fuel

properties will prone to have several impacts on engine operation as well as to the

environment. Figure 2.1 below shows the general impact of bio-diesel as compared

to diesel fuels.

Figure 2.1 Bio-diesel fuel properties and their associated impact on engine operation,

storage and transportation as compared to fossil diesel [18]

7

2.1.1 Viscosity

Viscosity of the blended bio-diesel plays major role in operation of CI engine.

It is an important factor in predicting the performance of potential alternatives diesel

fuel sources [3]. This is because minimum amount of viscosity from fuel is needed

due to possible of power loss caused by injection pump and injector leakage inside

engine. However, higher viscosity of fuels will cause poor combustion rate, due to

poor fuel injection atomization [16] that leads to deposit formation and high fuel

spray penetration (SP) inside cylinder. This in turn will causing engine oil diluted

with fuel itself that changing the engine oil properties [6].

Even though high fuel SP properties cause problems as above, it is found that

this properties leads to enhancing of power and torque produced onto the engine by

some researchers [6, 7]. Meanwhile, the higher viscosity and surface tension of bio-

diesel than diesel fuel prevent sufficient breaking of the bio-diesel during fuel

injection process.

However, according to Aydin and Bayindir [19], they reported that engine

torque was decreased when percentage of blends in CSOME (cottonseed oil methyl

ester) increased due to higher viscosity and lower heating value of CSOME. This in

turn raise up the probability of different feedstock has different properties throughout

percentages of bio-diesel blended.

High viscosity properties from vegetable oils and animal fats tends to cause

engine problems when used directly in common diesel engines [20-23], if the oils

and fats are transesterified using short-chain alcohols, the produced monoesters will

have viscosities that are almost identical to petroleum-based diesel fuel [24]. These

monoesters have come to be known as bio-diesel.

Tesfa et al. [4] studies the effect of temperature on density and viscosity on

three types of bio-diesel fuel – corn oil based, rapeseed oil and waste oil based for

various blended percentage. Figure 2.2 below summarize his findings of relationship

between different feedstock and bio-diesel blended.