Journal of Environmental Engineering & Sustainable Technology
Vol. 04 No. 01, July 2017, Pages 44-49
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EXHAUST EMISSIONS OF 4 STROKE SPARK IGNITION ENGINE WITH
INDIRECT INJECTION SYSTEM USING GASOLINE-ETHANOL FUEL
Mega Nur Sasongko1, Widya Wijayanti1, Fernando Nostra Damus G1,
1
Department of Mechanical Engineering, Brawijaya University
Correspondence author: [email protected]
ABSTRACT
Gasohol can be replaced in the spark ignition
engine (SI engine) as gasoline substitution
having lower emissions exhaust gas, making it
more environmentally friendly. The aim of
study was to investigate the effect of gasolineethanol ratio on the gas exhaust emission of SI
engine injection system. In this study, it was
used the 4-stroke gasoline engine injection
system by using the injector as a fuel input
device. The engine had a 124.8 cc singlecylinder engine with compression ratio of
9.3:1. The variations of gasohol were gasohol
E0, E10, E20, E30, E40, E50, E60, E70, E80,
E90 and E100 with range of speeds; 1500
rpm, 2000 rpm, 2500 rpm, 3000 rpm, 3500
rpm, 4000 rpm, 4500 rpm and 5000 rpm. The
research was run by rearranging the standard
ECU to obtain the AFR stoichiometric of each
gasohol mixture. The exhaust emissions were
measured by using the Stargas-898. The
results show that the addition of ethanol
content was able to increase the CO2
emissions, however, it would decrease the CO
and HC levels. Compare to the gasoline fuel,
gasohol has a lower emission of CO, HC and
higher of CO2 and O2 emissions.
Keywords : gasohol, 4 stroke-spark ignition
engine, injection, emission
1. INTRODUCTION
In recent years, the energy needs tend to
increase drastically such as the increasing of
petroleum, natural gas and coal demand in the
transportation sector, industry and household.
High consumption levels greatly affect the
environmental effects as the energy
conversion process effects. It makes the
environment dangerous emissions producing
toxic gas like CO, HC, and NOx emissions.
Unfortunately, we face the problem now. The
fossil fuels have dominant contributions to
support the problem. It is the trigger to
produce CO as gas poisoning that can be
characterized with dizziness, headache and
nausea. More severe conditions: decreasing
the body movements, disruption of the
cardiovascular system, and heart attack.
But the growth of vehicle production
increase significantly, so that the pollutants
released into the environment will be huger. It
is needed a solution to overcome it. It is
required some innovations to reduce the level
of exhaust pollution at vehicles, mainly at
gasoline engine. One of ways to overcome the
problem if it is used the electronic control
injection system, so that the exhaust gas
emission can be controlled. And now, the
equipment is developing by some engine. It is
expected that the mixing of air and fuel can
reach homogeneous conditions, so that the
combustion will be in perfect condition. The
use of the device can reduce the percentage of
HC and CO emissions around 22% and 55%.
As the development of motor fuel today is
indeed leading to the injection system,
however, the usage of the injection system
still needs to improve to overcome the
problem. Therefore, the environment can be
safe from the transportation sector problems.
Beside the injection systems, the fuel
types also have the major factors to influence
the exhaust gas emissions. Consequently, an
alternative energy source is needed to be
replaced the more environmentally friendly
fuel.
Ethyl-alcohol (ethanol) is one of widely
used as alternative energy fuel today. Ethanol
has a very abundant source of raw materials in
Indonesia, promising source of renewable
energy in the future. Ethanol has many
advantages as a substitute of gasoline fuel
such as; ethanol is an environmental friendly
because it has a lower emission compared to
the fossil fuel. In addition, ethanol has an
oxygen content of 34% of the weight of the
compound making the excess air in the
combustion process. Then, it is the reason
45
Journal of Environmental Engineering & Sustainable Technology
Vol. 04 No. 01, July 2017, Pages 45-49
why it is important to use ethanol as the fuels,
due to obtain a high engine performance and
environmentally friendly exhaust emissions.
However, because the engine usually is fueled
by gasoline, firstly, we will investigate the
fuel mixing the gasoline-ethanol (gasohol)
fuels. The gasohol is conducted to understand
the performance of SI engine before the
ethanol will be replaced in the future. The use
of gasohol has several advantages like low
toxic gas emissions. It is because gasohol
contains 34% oxygen insuring to produce the
perfect combustion. However, the gasohol
fuel has some disadvantages Ethanol tends to
cause highly corrosive in engine and a lower
calorific value of the ethanol so that the
performance of the gasohol will be lower than
that of gasoline fuel. So, it is important to mix
the ethanol and gasoline as the substitute fuel.
Tabel 1. Characteristic of Gasoline dan
ethanol
Property
H/C ratio
Energy Content
(MJ/kg)
Liquid Density
(kg/l)
Liquid Energy
Density (MJ/l))
Boiling Point (oC)
Research Octane
Number
Motor Octane
Number
Stoichiometric airfuel ratio
Reid Vapor
Pressure (psi)
Gasoline
Ethanol
1.9
3.0
44
26.9
0.72-0.78
0.785
33
21.12
37-205
79
92-98
107
80-90
89
14.7
9.0
8-15
2.3
The gasoline engine used in this study is
a spark ignition engine with an injection
system where before it is combusted, the fuel
is sprayed in the burner by mixing process of
fuel and air. The injection system works by
mixing air and fuel on the stoichiometric state,
then it was inserted into the combustion
chamber by an inlet valve that the quantity is
measured by the airflow sensor controlled by
the ECM (Electronic Control Module). As a
result, it was able to determine the amount of
sprayed fuel by the injector.
46
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There are 2 types of fuel injection into
the combustion chamber in the technology; a
direct injection and indirect injection [6]. In
this study, we used the indirect injection in
which the gasohol was injected in the inlet
valve, afterwards, it would inserted to
combustion chamber with the air when the
suction step.
2. METHODOLOGY
The investigation results the gas exhaust
gas emissions. The result of this research is
the content of CO2, O2, CO, HC and λ (excess
air). The mixture of gasohol used is E0 to
E100 with a 10% increasing and the speed
was controlled by throttle openings from 1500
rpm to 5000 rpm with an increasing of 500
rpm.
Figure. 1 describes a schematic diagram
of experimental run. It was used a 4-stroke
cylinder with a compression ratio of 9.3: 1.
The experimental device was placed on a
buffer frame so that the test equipment was in
a static condition.
Figure 1. The experimental runs
The experimental devices consist of
1. Beaker glass
2. Fuel tank
3. Fuel pump
4. Injector
5. Exhaust
6. Stargas Analyzer tube
Journal of Environmental Engineering & Sustainable Technology
Vol. 04 No. 01, July 2017, Pages 45-49
Stargas Analyzer
Throttle
ECU
Accumulator
Engine frame
The gasoline and ethanol were mixed in
the beaker glass according to the desired
percentage. Then, it was put in the fuel tank.
Next, it was set the frequency and duty cycle.
The purpose of setting the frequency and duty
cycle was if the engine can be going on and
the combustion occurs in the stoichiometric
area. The duty cycle was the percentage of
injector openings in each inject fuel into the
combustion chamber. The greater the
percentage of the duty cycle, the more fuel
that was injected into the combustion
chamber. The amount of the duty cycle was
adjusted to each AFR level of ethanol in a
mixture of gasohol by comparing the air into
the combustion chamber and the amount of
fuel consumed in each unit of time. Then, the
experimental equipment was turned on, so
that the combustion process occurs inside the
combustion chamber.
The exhaust gas emission was measured
by Stargas Analyzer 898. It was able to
determine the emission content of CO2, O2,
CO, HC and λ (excess air), then it would be
analyzed.
with 3500 speed around 0.11% and the
highest CO concentration was found in
ethanol E0 with 1500 with value and the value
was 0.06%. Since the incomplete combustion
occurred, the production of CO emissions at
the exhaust gas tend to increased. The
incomplete combustion is mainly occurs when
the combustion takes place in the fuel-rich
conditions. The oxygen contained in the
ethanol fuel will reduce the incidence of
incomplete combustion due to insufficient
amount of oxygen in the air-fuel mixture. In
the present experiment, CO emissions in
exhaust gas may cause by the reducing of
combustion temperature result in the
incomplete combustion.
12
11
10
CO2 [%]
7.
8.
9.
10.
11.
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9
8
7
6
0 10 20 30 40 50 60 70 80 90 100
Ethanol [%]
1500 RPM
3500 RPM
2000 RPM
4000 RPM
2500 RPM
4500 RPM
3000 RPM
5000 RPM
3. RESULTS AND DISCUSSION
Figure. 2 shows the effect of ethanol
content on the CO2 emission. It explains the
relationship between gasohol content and CO2
exhaust gas emission in engine speed. When
the percentage of ethanol was increased, CO2
tends to rise. It can be seen that the lowest
CO2 content is found in ethanol E10 with
1500 rpm around 1.66%. Meanwhile, the
highest CO2 was found in ethanol E100 with
4500 rpm. And this condition, CO2
composition was 11.5%.
Figure. 3 explains the correlation
between the percentage of ethanol at gasohol
and the producing of CO content in the
various engine speeds. It can be seen that the
decreasing of CO appears from E0 to E100.
The lowest CO concentration was look at E80
47
Figure 2. An increasing CO2 with the
percentage of ethanol at gasohol in various
engine speed
Figure. 4 explains the effect of the
ethanol contain at gasohol when it produced
HC emission. It was look like the previous
CO gas emissions that the increasing of
ethanol percentage would decline HC
emissions. The lowest level of HC was found
at E80 ethanol concentration with 4500 rpm
as 12 ppm (part per million) and the highest
ethanol was obtained at ethanol E0 with 1500
rpm and 160 ppm. Reducing HC emission
with increasing the ethanol addition in the fuel
indicated that the combustion performed in
the better condition.
Journal of Environmental Engineering & Sustainable Technology
Vol. 04 No. 01, July 2017, Pages 45-49
0.05
CO [%]
0.04
0.03
0.02
0.01
0
0 10 20 30 40 50 60 70 80 90 100
Ethanol [%]
1500 RPM
2000 RPM
2500 RPM
3000 RPM
3500 RPM
4000 RPM
4500 RPM
5000 RPM
Figure 3. A decreasing CO with the
percentage of ethanol at gasohol in various
engine speed
As a partially oxidized hydrocarbon due
to oxygen atom contained in the ethanol,
addition ethanol in the fuel blend could
increase the number of oxygen atoms for the
combustion process (leaning effect). Due to
the effects of leaning, the HC emissions will
decrease greatly as well as CO emissions.
percentage of ethanol was added. Therefore,
the graph shows that the lowest O2 levels was
found in ethanol E0 at 1500 rpm as 2.49% and
the highest O2 was gained in ethanol E100 at
4500 rpm as 9.26%.
Meanwhile, Fig. 6 explains the excess air
can be influenced by the percentage of ethanol
content in various the engine speed. It can be
seen, at each variation of ethanol content, the
content of excess air tends to rise starting
from ethanol E0 content, then decline to
ethanol E100. The lowest excess water
content was found on E10 ethanol level at
1500 rpm and the value was 1.012% and the
highest level was bring into being on ethanol
E80 at 3000 rpm with 1.08 value.
10
9
8
7
O2 [ % ]
0.06
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6
5
4
3
2
0 10 20 30 40 50 60 70 80 90 100
Ethanol [%]
HC [ppm]
180
160
140
120
100
80
60
40
20
0
2000 RPM
2500 RPM
3000 RPM
3500 RPM
4000 RPM
4500 RPM
5000 RPM
Figure 5. The produced O2 was influenced by
the percentage of ethanol content in various
the engine speed
0 10 20 30 40 50 60 70 80 90 100
Ethanol [%]
1500 RPM
2000 RPM
2500 RPM
3000 RPM
3500 RPM
4000 RPM
4500 RPM
5000 RPM
Figure 4. A decreasing HC with the
percentage of ethanol at gasohol in various
engine speed
In Figure. 5, it can be seen that the
produced O2 was influenced by the percentage
of ethanol content in various the engine speed.
The produced O2 would increase if the
48
1500 RPM
The gasohol fuel is very influential in
generating exhaust emissions causing
environmentally friendly. It is because each
molecule of ethanol has 34% oxygen, so that
the combustion process tends to form a high
CO2. Beside CO2, it will also leave a high O2
content. This is due to the actual burning AFR
tending to occur at a poor mixture. As a result,
C atoms will have the most possibility
opportunity to react with O2 to form CO2 in
the combustion reaction of gasohol. On the
contrary, the content of CO and HC which are
emissions
harmful
to
health
and
environmental balance will decrease in the
remain process of the burning gasohol.
Journal of Environmental Engineering & Sustainable Technology
Vol. 04 No. 01, July 2017, Pages 45-49
1.1
1.09
1.08
1.07
1.06
1.05
1.04
1.03
1.02
1.01
1
Journal of Energy Conversion and
Management (44) 1547-61.
Excess Air
BATA RM, Elord AC, Rice RW., Emissions
from IC engines fueled with alcohol–
gasoline blends: a literature review.
Transactions
of
the
ASME
1989;111:424–31.
0 10 20 30 40 50 60 70 80 90 100
Ethanol [%]
1500 RPM
3500 RPM
2000 RPM
4000 RPM
2500 RPM
4500 RPM
3000 RPM
5000 RPM
Figure 6. The generated excess air due to the
percentage of ethanol content in various the
engine speed
4. SUMMARY
In the investigation, it can be
summarized some important matters. Due to
the addition of ethanol content in gasohol, it is
able conclude that :
1. The addition of ethanol levels in the
gasohol content will increase CO2 caused
by lean mixture in combustion and
oxygen levels in ethanol that support that
combustion will be burned more
perfectly.
2. The addition of ethanol content in the
gasohol content will result in the
decreasing of CO and HC emissions.
Therefore, the poison exhaust gas
emissions can be reduced.
3. The addition of ethanol in the alcohol
content will result in the rising of O2
emissions due the higher oxygen levels in
the gasohol mixture.
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