INVESTIGATION OF 1-DIMENSIONAL ANALYSIS FOR TWO-STROKE SPARK IGNITION (SI) ENGINE
ZABIDI BIN MOHAMAD
A report submitted in partial fulfillment of the requirements for the award of the degree of Bachelor of Mechanical Engineering with Automotive
Faculty of Mechanical Engineering UNIVERSITI MALAYSIA PAHANG
NOVEMBER 2008
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SUPERVISOR’S DECLARATION
We hereby declare that we have checked this project and in our opinion this project is
satisfactory in terms of scope and quality for the award of the degree of Bachelor of
Mechanical Engineering with Automotive
Signature : ..........................................................
Name of Supervisor: Mr. Nik Mohd Izual Hj. Nik Ibrahim
Position : Lecturer
Date : ...............................
Signature : ................................................
Name of Panel : Mr. Devarajan A/L Ramasamy
Position : Lecturer
Date : ...............................
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STUDENT’S DECLARATION
I hereby declare that the work in this thesis is my own except for quotations and
summaries which have been duly acknowledged. The thesis has not been accepted
for any degree and is not concurrently submitted for award of other degree.
Signature : ……………………..
Name : Zabidi bin Mohamad
ID Number : MH 05054
Date : …………………
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ACKNOWLEDGEMENTS
I am grateful and would like to express my sincere gratitude to my supervisor
Mr Nik Mohd Izual Hj. Nik Ibrahim for his germinal ideas, invaluable guidance,
continuous encouragement and constant support in making this research possible. He
has always impressed me with his outstanding professional conduct, his strong
conviction for science, and his belief that this research is only a start of a life-long
learning experience. I appreciate his consistent support from the first day I applied to
graduate program to these concluding moments. I am truly grateful for his
progressive vision about my training in science, his tolerance of my naïve mistakes,
and his commitment to my future career. I also would like to express very special
thanks to my co-supervisor Mr Aguk for his suggestions and co-operation throughout
the study. I also sincerely thanks for the time spent proofreading and correcting my
many mistakes. I would like to acknowledge their comments and suggestions, which
was crucial for the successful completion of this study.
My sincere thanks go to all my friends and members of the staff of the
Mechanical Engineering Department, UMP, who helped me in many ways and made
my stay at UMP pleasant and unforgettable.
I acknowledge my sincere indebtedness and gratitude to my parents for their
love, dream and sacrifice throughout my life. I cannot find the appropriate words that
could properly describe my appreciation for their devotion, support and faith in my
ability to attain my goals.
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ABSTRACT
The project is based on two-stroke engine. The two-stroke engine will be
used as the testing engine that the performances can be determined. The objective of
this project is to investigate and analysis the performance of two-stroke engine using
a 1-Dimensional (engine gas dynamic) software. From this objective, the outcome of
the project can be determined by using the 1-Dimensional software. The outcomes
that need to be determined from this project are the performances of the engine. The
1-Dimensional software that was using in this project is GT-Power. GT-Power is
using to model and simulate the two-stroke engine. First, the parameters of the two-
stroke engine had been measured and then the modeling of the two-stroke engine had
been built and simulated. After simulation process, the performances of the engines
can be obtained right away. There are many information that can be taken from the
GT-Power after simulating the engine but for analyzing, only several data had been
chosen. Those data are pressure for scavenged port, in-cylinder and exhaust port,
temperature for scavenged port, in-cylinder and exhaust port, brake power, brake
torque, indicated mean effective pressure and brake specific fuel consumption. All of
this information had been analyzed and the optimum engine speed had been
determined at 1500 RPM to 2500 RPM because in this range, the brake torque and
brake power is maximum while the brake specific fuel consumption also low.
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ABSTRAK
Projek ini adalah berdasarkan enjin dua lejang. Enjin dua lejang akan
digunakan sebagai enjin ujian untuk mengetahui keupayaan enjin tersebut. Objektif
projek ini adalah untuk menyiasat dan menganalisa keupayaan enjin dua lejang
dengan menggunakan perisian 1-Dimensi. Melalui objektif ini, hasil projek ini boleh
diperolehi dengan menggunakan perisian 1-Dimensi. Hasil yang diperlukan daripada
projek ini adalah keupayaan enjin tersebut. Perisian 1-Dimensi yang digunakan
dalam projek ini adalah GT-Power. GT-Power digunakan untuk membina model dan
melakukan simulasi terhadap enjin dua lejang tersebut. Permulaannya, enjin dua
lejang tersebut diukur dan kemudian model enjin dua lejang itu dibina dan akhirnya
simulasi dilakukan. Selepas proses simulasi, keupayaan enjin tersebut dapat
diketahui terus. Terdapat banyak maklumat yang dapat diperolehi daripada GT-
Power hasil dari simulasi enjin tersebut tetapi untuk analisa, hanya beberapa data
yang dipilih. Data-data tersebut adalah tekanan pada lubang kemasukan, dalam
silinder dan lubang ekzos, suhu pada lubang kemasukan, dalam silinder dan lubang
ekzos, kuasa, daya kilas, tekanan efektif purata dan penggunaan spesifik bahan
bakar. Semua maklumat-maklumat ini akan dianalisa dan kelajuan optimum enjin
tersebut dicatatkan pada 1500 RPM hingga 2500 RPM kerana pada kelajuan ini, brek
tork dan brek kuasa adalah maksimum sementara penggunaan bahan bakar spesifik
adalah rendah.
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TABLE OF CONTENTS
Page
SUPERVISOR’S DECLARATION ii
STUDENT’S DECLARATION iii
ACKNOWLEDGEMENTS iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS vii
LIST OF TABLES xii
LIST OF FIGURES xiii
CHAPTER 1 INTRODUCTION 1
CHAPTER 2 LITERATURE REVIEW 3
2.1 Internal Combustion Engine 3
2.1.1 Introduction 3
2.1.2 Basic Parameters 3
2.1.2.1 Bore and stroke 3
2.1.2.2 Compression ratio 4
2.1.2.3 Mean piston speed 4
2.1.2.4 Air/Fuel ratios 4
2.1.3 Performance 5
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2.1.3.1 Brake torque and power 5
2.1.3.2 Mean effective pressure 5
2.2 Two-Stroke Engine 6
2.2.1 Introduction 6
2.2.2 Basic Operation 6
2.2.3 Combustion Process 7
2.2.4 Scavenging Process 7
2.2.5 Improvement 8
2.2.6 Advantages and Disadvantages 8
2.2.7 Research and Development 8
2.2.7.1 Introduction 8
2.2.7.2 Stratified scavenging 9
2.2.7.3 Leaner combustion technology and stratified scavenging 10
2.2.7.4 Engine scavenging optimization 12
2.2.7.5 Timing controlled auto-ignition 12
2.2.7.6 Active thermo atmosphere combustion 12
2.2.7.7 Finger ports method 13
2.2.7.8 Fuel injector 13
2.2.7.9 Reed valve 13
2.2.7.10 Comparison between computation and measurement 16
2.2.7.11 2-Dimensional analysis 17
2.3 1-Dimensional Analysis 19
2.3.1 Design of Experiment 19
2.3.2 GASDYN 19
2.3.3 IFP-ENGINE 20
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2.3.4 Ricardo’s WAVE 20
2.3.5 Quasi-Dimensional 20
2.3.6 Mathematical Modeling 21
2.3.7 Results Obtained 22
2.3.8 GT-Power 22
CHAPTER 3 METHODOLOGY 25
3.1 Introduction 25
3.2 Flowchart of the Project 25
3.3 Measuring the Engine’s Parameter 26
3.4 Mapping the Engine in 1-D 27
3.4.1 Firing 27
3.4.1.1 End environment 27
3.4.1.2 Pipe 28
3.4.1.3 Injector air-fuel ratio connection 28
3.4.1.4 Check valve connection 29
3.4.1.5 Engine crankcase 29
3.4.1.6 Ported valve connection 30
3.4.1.7 Engine cylinder 30
3.4.1.8 Engine crankshaft 30
3.4.2 Motoring 31
3.5 Simulation 31
3.6 Interpreting Data 34
3.7 Preparing Final Report 34
CHAPTER 4 RESULTS AND DISCUSSIONS 35
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4.1 Introduction 35
4.2 Firing 35
4.2.1 Pressure 35
4.2.1.1 Scavenged port 35
4.2.1.2 In-cylinder 37
4.2.1.3 Exhaust port 38
4.2.2 Temperature 39
4.2.2.1 Scavenged port 39
4.2.2.2 In-cylinder 40
4.2.2.3 Exhaust port 41
4.2.3 Brake Torque 43
4.2.4 Brake Power 44
4.2.5 Indicated Mean Effective Pressure (IMEP) 45
4.2.6 Brake Specific Fuel Consumption (BSFC) 46
4.3 Motoring 47
4.3.1 Pressure 47
4.3.1.1 Scavenged port 47
4.3.1.2 In-cylinder 48
4.3.1.3 Exhaust port 49
4.3.2 Temperature 50
4.3.2.1 Scavenged port 50
4.3.2.2 In-cylinder 51
4.3.2.3 Exhaust port 52
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CHAPTER 5 CONCLUSION 53
REFERENCES 55
APPENDICES 60
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xii
LIST OF TABLES
Tables No. Page
2.1 Engine specification 10
2.2 Summary of test results 11
2.3 Reed valve property data 14
2.4 Input for GT-Power reed valve component (main) 15
2.5 Input for GT-Power reed valve component (dynamics) 15
2.6 Input for GT-Power reed valve component (flow array) 15
2.7 Engine geometry 18
2.8 Engine performance prediction for 2500 RPM 24
4.1 Brake torque for variable engine speed 43
4.2 Brake power for variable engine speed 44
4.3 IMEP for variable engine speed 45
4.4 BSFC for variable engine speed 46
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xiii
LIST OF FIGURES
Figure No. Page
2.1 Stratified scavenging cylinder 9
2.2 Effect of the modified combustion chamber 11
2.3 Reed valve 14
2.4 Lift vs differential pressure 16
2.5 Flow vs differential pressure 16
2.6 Computed & measured pressure within cylinder & crankcase 17
2.7 Fixed places of the injector 17
2.8 Fuel-lost ratio in all cases 18
2.9 Combustion characteristics at 3000 RPM 21
2.10 GT-Power mapping for four-stroke engine 23
2.11 Graph pressure vs crank angle in-cylinder for 2500 RPM 23
2.12 Graph temperature vs crank angle in-cylinder for 2500 RPM 24
3.1 Flow chart of 1-D analysis for two-stroke engine 25
3.2 Solidworks drawing for two-stroke engine 26
3.3 1-D modeling for two-stroke engine 27
3.4 1-D modeling for two-stroke engine 31
3.5 RPM setting for 1-D simulation 32
3.6 Run simulation button 32
3.7 Running of the 1-D simulation 33
3.8 Open GT-Post button 33
4.1 Graph pressure (scavenged port) vs crank angle 35
4.2 Graph pressure (in-cylinder) vs crank angle 37
4.3 Graph pressure (exhaust port) vs crank angle 38
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4.4 Graph temperature (scavenged port) vs crank angle 39
4.5 Graph temperature (in-cylinder) vs crank angle 40
4.6 Graph temperature (exhaust port) vs crank angle 41
4.7 Graph brake torque vs engine speed 43
4.8 Graph brake power vs engine speed 44
4.9 Graph IMEP vs engine speed 45
4.10 Graph BSFC vs engine speed 46
4.11 Graph pressure (scavenged port) vs crank angle 47
4.12 Graph pressure (in-cylinder) vs crank angle 48
4.13 Graph pressure (exhaust port) vs crank angle 49
4.14 Graph temperature (scavenged port) vs crank angle 50
4.15 Graph temperature (in-cylinder) vs crank angle 51
4.16 Graph temperature (exhaust port) vs crank angle 52
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CHAPTER 1
INTRODUCTION
Two-stroke engine is commonly known as simple engine. Compared to four-
stroke engine, there are many advantages related to two-stroke engine. Mechanically
simple, low cost and low weight are the advantages that make the two-stroke engine
is the better engine but unfortunately in two-stroke engine lies a big disadvantage
that make it limited in production for most of the automobile and machining
industry. The disadvantage is the emission occurred in two-stroke engine that lead to
the pollution in the environment. Put aside the pollution factor, two-stroke engine
actually can provide more benefit whether to the manufacturers or the customers.
The engine that provide low weight and mechanically simple reduce the production
cost and time. Consequently, the manufacturers can produce more engines to be used
in the industry. As for the customers, the benefit that they can get is the reasonable
price with the high performance engine.
Before the manufacturers develop and produce the engine, they had to follow
the proper steps to make sure the probability of loss during the process can be
reduced to minimum. First step in the process is designing the engine by simulation.
It is to ensure the engine that will be developed can produce the desired output and
performance with the required size [4]. There are many types of designing the engine
whether using the 1-Dimensional, 3-Dimensional or even 2-Dimensional modeling
[12].
The basic modeling for the engine simulation is 1-Dimensional. In 1-D
modeling, it is all about mathematical, formula and calculation [49]. There is no
imaging about the shape of the engine like 3-D modeling, but it is critical in
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simulating engine. It is because the 1-D modeling can be the benchmark for either 3-
D modeling or developing the real engine. Other than that, the 1-D modeling also
simple and can be developed in short of time. So, the probability of loss money and
time when simulate using 3-D or develop the real engine can be reduced because the
engine had been successfully simulated by using 1-D. So, the process of developing
the engine can be continued without facing the big problems.
Actually, simulate, design and develop the real model is connecting to each
other. In case of two-stroke engine, the simulation of the engine is critical because
the designer must know all the parameter and geometry for the engine before
designing the engine. Otherwise, the output and performance of the engine cannot
match the required one.
In this project, the objective is to investigate and analysis the performance of
two-stroke engine using a 1-Dimensional (engine gas dynamic) software. As
mentioned before, the simulation of the engine is very important when designing and
developing the two-stroke engine. The purpose of this project is to ensure whether
the results obtained from the 1-D simulation approaching the results obtained from 3-
D simulation and experimentation of the real engine. Also, from this project, it can
be proved that whether the 1-D simulation can be used for the rapid prototyping.
Lastly, this project can prove whether there is any difference between the two-stroke
engine with firing and two-stroke engine with motoring.
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CHAPTER 2
LITERATURE REVIEW
2.1 INTERNAL COMBUSTION ENGINE
2.1.1 Introduction
The internal combustion engine with spark-ignition had been developed in
1876 by Nicolaus A. Otto. The compressed ignition or diesel engine had been
developed by Rudolf Diesel in 1892 [31]. The normal internal combustion engine is
generally one of two types, spark ignition petrol or gas engines and diesel engine
[13]. The conventional internal combustion engine basically can be classified by four
stroke and two stroke engine. In four stroke engine, the processes occurred in the
cycle are intake stroke, compression stroke, power stroke and exhaust stroke. In two
stroke engine, the processes involve only compression stroke and power/expansion
stroke [9][53].
2.1.2 Basic Parameters
2.1.2.1 Bore and Stroke
For conventional internal combustion engine, the piston reciprocates in the
cylinder between two fixed position called the top dead centre (TDC) and the bottom
dead centre (BDC) [9][19]. TDC is the position of the piston when it forms the
smallest volume in cylinder and BDC is the position of the piston when it forms the
largest volume in the cylinder. The distance between TDC and BDC is called the
stroke of the engine while the diameter of the piston is called the bore [9].
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2.1.2.2 Compression Ratio
There are also some other terms that must be understood first before
proceeding to the researching of the engine. The air-fuel mixture will enter the
cylinder through intake valve while the function of the exhaust valve is to expel the
combustion products from the cylinder. The minimum volume formed in the cylinder
when the piston is at TDC is called the clearance volume while the displacement
volume is the volume displaced by the piston as it moves between TDC and BDC
[9]. The compression ratio is the ratio of maximum volume formed in the cylinder to
the minimum volume [9][14] as shown in equation 2.1.
min
max
VV
r =
2.1.2.3 Mean Piston Speed
A parameter that important for calculation the engine behaviour as a function
of speed is the mean piston speed [53]. The formula is as shown in equation 2.2
LNU p 2=
where L stand for stroke and N stand for rotational speed of crankshaft.
2.1.2.4 Air/Fuel Ratios
In engine testing, the air mass flow rate and fuel mass flow rate are measured.
The ratio of these flow rates can be defined as shown in equation 2.3
f
a
f
a
mm
mm
AF&
&==
where ma stand for mass of air and mf stand for mass of fuel.
(2.1)
(2.2)
(2.3)
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2.1.3 Performance
2.1.3.1 Brake Torque and Power
Torque can be defined by a measure of engine’s ability to do work. The brake
torque can be measured by using a dynamometer [53]. The brake torque can be
measured using the equation 2.4
T = Fb
where F stand for force and b stand for the distance between centre of rotor and
force.
Power can be defined as the rate at which work is done [53]. The brake power
can be calculated using the equation 2.5
P = 2p�NT
where p� stand for angular speed, N stand for crankshaft rotational speed and T stand
for torque.
2.1.3.2 Mean Effective Pressure
The other important terms that frequently used in conjunction with
reciprocating engine is the mean effective pressure (MEP). It is a fictitious pressure
that, if it acted on the piston during the entire power stroke, would produce the same
amount of net work as that produced during the actual cycle [9]. MEP can be
calculated using equation 2.6.
minmax VVW
MEP net
−=
(2.6)
(2.4)
(2.5)
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2.2 TWO-STROKE ENGINE
2.2.1 Introduction
Two stroke spark-ignition engine can be identified by the definition of both
zero-dimensional time-varying control volumes such as cylinder or crankcase and
one-dimensional devices like intake or exhaust manifold. The fundamental processes
like combustion, fluid dynamics and scavenging can be modelled using up-to-date
approaches [5].
2.2.2 Basic Operation
The operation of the two stroke engine is quite simple compared to four
stroke engine [8][9]. When the piston at TDC, the trapped air and fuel charge is
being ignited by the spark plug, producing a rapid rise in pressure and temperature
which will drive the piston down on the power stroke [8][14][16]. Below the piston,
the opened inlet port is inducing air from the atmosphere into the crankcase due to
the increasing volume of the crankcase lowering the pressure below the atmospheric
value [8][14].
Then, above the piston, the exhaust port has been opened. It will allow the hot
and high pressure exhaust gas to transfer from the cylinder to the exhaust ducts. As
the area of the port is increasing with crankshaft angle and the cylinder pressure is
falling with time, the exhaust duct pressure profile is increasing to a maximum value.
Below the piston, the compression of the fresh charge is taking place [8][14].
Next process, above the piston the initial exhaust process, referred to as
blowdown, is nearing completion and with the piston having uncovered the transfer
ports, this connects the cylinder directly to the crankcase through the transfer ducts.
If the crankcase pressure exceeds the cylinder pressure then the fresh charge enters
the cylinder. This process is known as scavenge process [8].
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Condition for the next process, in the cylinder, the piston is approaching the
trapping point or exhaust closure. The scavenge process has been completed and the
cylinder is now filled with a mix of air, fuel and exhaust gas. As the piston rises, the
cylinder pressure should also rise, but the exhaust port is still open and barring the
intervention of some unsteady gas-dynamic effect generated in the exhaust pipe, the
piston will spill fresh charge into the exhaust duct to the detriment of the resulting
power output and fuel consumption [8].
2.2.3 Combustion Process
For any engine, combustion process is the most important process. The right
time for the combustion process will lead to more power output and better fuel
consumption. An analysis about the combustion process and quick throttle opening
for two stroke engine had been studied. The outcome of the analysis is the exhaust-
pressure wave is heavily fluctuated and it was caused by fluctuation of combustion
velocity and duration for crank-angle [28].
The combustion chamber geometry is vital in spark ignition engine. The
combustion model using the equivalent integral length scale shows the amplified
turbulence effect of the bowl in a bowl-in-piston chamber. Also, the spark plug
location affects combustion significantly in the total burning duration and the
burning duration of a disc chamber is more dependent on a spark plug location than a
hemisphere chamber [39].
2.2.4 Scavenging Process
The important thing when talk about two stroke engine is scavenging system.
Scavenging is the operation of clearing the cylinder of burned gases and filling it
with fresh mixture combination between intake and exhaust process [31]. The
performance of the scavenging system is highly dependent on the dimensioning of
the inlet, transfer and exhaust port [14][23]. Scavenging and filling the cylinder with
a compressed fresh charge admitted through a scavenging port when the piston
approaches a bottom dead centre [16]. Actually, the power of two stroke engine is
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influenced by the scavenging efficiency [21][22][23]. There are ways of scavenging
the two stroke engine such as cross-scavenging, loop scavenging and uniflow
scavenging [21][40]. The best in scavenging efficiency is uniflow scavenging [21].
2.2.5 Improvement
To improve the performance and durability of two stroke engines, pressure,
volume and temperature of crankcase are the important parameters which need
optimisation. Investigation of the previous histories have been done with reference to
pressure fluctuations, backflow, Kadenacy effect, list approximation, ring sticking,
engine seizure, crankcase volume, crankcase temperature, cylinder barrel
temperature, engine speed and physical parameters of the engine [33].
2.2.6 Advantages and Disadvantages
Although two stroke engine is known as simple and low cost engine [42][47],
its widest practical utilization only for low-output mopeds and motorcycles
[5][7][29][43]. Also, two stroke engine offered some advantages such as cost
reduction, specific output increase, NOx emission control, size and weight reduction
[5]. The two stroke engine also can generate the same power as four stroke engine as
the same size but at higher air/fuel ratios [15][44] and has better power to weight
ratio compared to four stroke engine [47]. The disadvantages of two stroke engine
are high emission and fuel consumption [34][44]. In the ported two stroke engine,
20-40% of the fresh charge passes unburned from the cylinder. This results in power
loss and a very high concentration of unburned hydrocarbons in the exhaust [34].
2.2.7 Research and Development
2.2.7.1 Introduction
To reduce the emission in two stroke engine, many ways had been developed.
Firstly, a pump operable to periodically pump air unmixed with fuel into the
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combustion chamber. Second, a fuel injector communicating directly with the
combustion chamber and inject fuel unmixed with air directly in the combustion
chamber. In the exhaust system, an exhaust manifold will communicate with the
combustion chamber and operable to produce a thermal reaction to reduce engine
exhaust emission [20].
2.2.7.2 Stratified Scavenging
The stratified scavenging had been applied to two stroke engine to improve
fuel consumption and reduce exhaust emission [35][37][41][43]. The stratified
scavenging system consists of long passages from crankcase to scavenging port and
the supplemental air system intake system directly to the scavenging port [30]. This
system is achieved by delivering the fuel into the rear transfer passage from a remote
mechanical fuel metering device, operated by intake manifold pressure as shown in
Figure 2.1. The outcome of the method is a 65% reduction in HC emission [29].
The stratified scavenging system for two stroke engine can be developed to
highest level to obtain greater results. Effective trapping was obtained by injecting
fuel into the crankcase and inducing air through an inlet at the top of the transfer
ducts. The results showed significant improvement over the standard homogeneous
scavenge engine. The brake specific fuel consumption was reduced by up to 22% and
the brake specific hydrocarbons by up to 55% [36].
Figure 2.1: Stratified scavenging cylinder [35]
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2.2.7.3 Leaner Combustion Technology and Stratified Scavenging
To improve the efficiency and decrease the emission cause by two stroke
engine, a research had been made. The objective of the research is to reduce the
hydrocarbon emission and improve the thermal efficiency of two stroke engine. Two
kind of engine had been used in this research. One is prototype two stroke cycle
engine with leaner combustion technology and air-head stratified scavenging
[29][30][41], the other one is current two stroke cycle engine with Schnurle
scavenging [41]. The specification of the engine had been listed in Table 2.1 [7].
Model Prototype Two-Stroke Current Two-Stroke
Displacement (cm3) 33.6 33.6
Bore (mm) 36 36
Stroke (mm) 33 33
Effective Compression Ratio 7.5 7.5
Intake Method Crankcase reed valve Piston valve
Scavenging Method Air-head stratified
scavenging
Schnurle scavenging
Ignition System CDI with CPU Transistor
Cooling Method Air Air
Rated Power (kW) 1.10 (target) 1.10
Rated Speed (rpm) 7000 7000
To obtain the result from this experiment, the apparatus like Bex-5100 G2
raw gas sampling and a dynamometer model PH-A03 had been used. The result of
the experiment had been shown in Figure 2.2 and Table 2.2 [7].
Table 2.1: Engine specification [7]
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Item R & D Target Prototype
Two-Stroke
Current Two-
Stroke
Mass Emission at THC - 42.9 230.3
Rated Speed (g/h) CO - 68.3 97.1
NOx - 2.80 2.71
Mass Emission at THC - 34.9 46.5
Idle Speed (g/h) CO - 27.4 38.2
NOx - 0.12 0.11
Weighted THC 67 44.6 208.4
Emission (g/kWh) CO 174 67.9 89.7
NOx 5.36 2.68 2.41
Thermal Efficiency % 18 20.6 13.6
Rated Power kW 1.10 1.05 1.13
Figure 2.2: Effect of the modified combustion chamber [7]
Table 2.2: Summary of test result [7]
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