Recent Researches in Engineering Mechanics, Urban & Naval Transportation and Tourism
Mixtures of Gasoline-ethanol and gasoline –methanol in a two stroke
outboard low output engine.
CHARALAMPOS ARAPATSAKOS, MARIANTHI MOSCHOU
Department of Production and Management Engineering
Democritus University of Thrace
V. Sofias Street, 67100, Xanthi
GREECE
[email protected]
Abstract: - This work deals with the examination of a two stroke outboard low output engine from the
viewpoint of pollution and consumption, using as fuel gasoline-ethanol and gasoline-methanol mixtures. A
series of laboratory instruments were used for the realisation of the experiments
Key-Words: - Gasoline - ethanol, Gasoline –methanol, Gas emissions, Two stroke outboard engine
understanding of the use of these two alcohols we
must examine them separately. Fuel ethanol is an
alternative fuel that is produced from biologically
renewable resources that it can also be used as an
octane enhancer and as oxygenate. Ethanol (ethyl
alcohol, grain alcohol, ETOH) is a clear, colorless
liquid alcohol with characteristic odor and as
alcohol is a group of chemical compounds whose
molecules contain a hydroxyl group, -OH, bonded
to a carbon atom. It is produced by the process of
fermentation of grains such as wheat, barley, corn,
wood, or sugar cane. In the United States ethanol is
made by the fermentation of corn [5,6]. By the
reaction of fermentation simple sugars change into
ethanol and carbon dioxide with the presence of
zymase, an enzyme from yeast. Ethanol can also be
made from cellulose that is obtained from
agricultural residue and waste paper [6]. It is a
high-octane fuel with high oxygen content (35%
oxygen by weight) and when blended properly in
gasoline produces a cleaner and more complete
combustion. Ethanol is used as an automotive fuel
either by itself or in blends with gasoline, such as
mixtures of 10% ethanol and 90%gasoline, or 85%
ethanol and 15% gasoline [9,10,11]. Many countries
around the world use ethanol as fuel. For example,
in Brazil ethanol is produced by using as raw
material sugarcane and many vehicles use ethanol as
fuel. Also in Canada and in Sweden ethanol is
highly promoted as fuel because of the many
environmental benefits that ethanol has. When
gasoline is used as fuel hydrocarbons (HC) escape
to the atmosphere. Many hydrocarbons are toxic and
some, such as benzene, cane cause cancer to
humans. If ethanol is used as fuel hydrocarbons are
not being produced because ethanol is an alcohol
1 Introduction
The possible increases of the price of crude oil, the
abrupt oil market changes, the finite of reserves, as
well as the environmental pollution led to the
reevaluation of the importance of the rural and
forestall factor as a renewable resources supplier.
Important quantities of ethanol are produced every
year to be used as fuel [1]. Ethanol has a high octane
number, which means it can be used as a fuel
additive, or as a substitute either as pure alcohol or
as mixture of gasoline-alcohol [2].
Alcohol is produced in laboratories in many ways.
Practical interest occurs in producing ethanol from
the rich in sugar plants. ‘‘Alcoholic fragmentation’’
is the splitting of single sugars, type C6H12O6,
mainly glucose and fructose, to CO2 which is
catalysed by the zymasse enzyme. Raisins, molasses
and starchy roots or fruits like potatoes, corn, barley
and others are used for this purpose.
Nowadays mixtures of gasoline - alcohol are used
in USA mainly as car fuel (gasohol), either to fight
the energy crisis or to decrease environmental
pollution, because of the limited CO, HC emissions.
Compared to pure gasoline, the gasoline-alcohol
mixtures produce smaller calorific output. This is
due to the fact that the use of these mixtures in
petrol engines reduces the power of the engine [2,4].
The power decreases in principle, increases in
proportion to the alcohol percentage in gasoline.
The question is how a two stroke low output
outboard engine behaves, from the viewpoint of
pollution and consumption, when mixture of
gasoline-alcohol has been used as fuel. Ethanol and
methanol are alcohols that can be used as fuels
instead of gasoline in automobile engines. For better
ISBN: 978-1-61804-071-8
268
Recent Researches in Engineering Mechanics, Urban & Naval Transportation and Tourism
that does not produce HC when is burned. The
reaction of hydrocarbons and nitrogen oxides that
are produced from the gasoline burning, in the
presence of sunlight leads to the formation of
photochemical smog. The use of ethanol as fuel can
contribute to the decrease of photochemical smog
since it does not produces hydrocarbons [11,12,13].
Vehicles that burn petroleum fuels produce carbon
monoxide (CO) because these fuels do not contain
oxygen in their molecular structure. Carbon
monoxide is a toxic gas that is formed by
incomplete combustion. When ethanol, which
contains oxygen, is mixed with gasoline the
combustion of the engine is more complete and the
result is CO reduction [14,15].
Using renewable fuels, such as ethanol,
there is also a reduction of carbon dioxide (CO2) in
the atmosphere. Carbon dioxide is non-toxic but
contributes to the greenhouse effect. Because of the
fact that plants absorb carbon dioxide and give off
oxygen, that balances the amount of CO2 that is
formed during combustion absorbed by plants used
to produce ethanol. This is why the use of ethanol
will partially offset the greenhouse effect that is
formed by carbon dioxide emissions of burning
gasoline [16,17]. Ethanol, as an octane enhancer,
can substitute benzene and other benzene-like
compounds, which are powerful liver carcinogens,
and reduce their emissions to the atmosphere.
Besides the environmental benefits, production and
use of ethanol, which is a renewable fuel, increases
economic activity, creates job openings, stabilizes
prices and can increase farm income. As a result
ethanol as an automotive fuel has many advantages.
Methanol (CH3OH) is an alcohol that is produced
from natural gas, biomass, coal and also municipal
solid wastes and sewage. It is quite corrosive and
poisonous. Methanol has lower volatility compared
to gasoline, which means that is not instantly
flammable. Usually methanol is used as a gasolineblending compound, but it can be used directly as an
automobile fuel with some modifications of the
automobile engine. Although there are many
feedstocks that are being used for the production of
methanol, natural gas is more economic. Methanol
is produced from natural gas with a technology of
steam reforming. By this method natural gas is
transformed to a synthesis gas that is fed to a reactor
vessel to produce methanol and water at the
presence of a catalyst. The reactions that represent
methanol production are the following [18,19]:
The main advantage of methanol as fuel is that is
being produced from resources that can be found
globally, while a large percentage of petroleum is
located in Middle East. Furthermore, the materials
needed for methanol production such as natural gas
or biomass, are renewable. This means that
methanol can also be cheaper and more
economically attractive than gasoline. When fossil
fuels are used in automobiles produce exhaust
emissions of hydrocarbons, carbon dioxide and
other gases that contribute to the greenhouse effect.
Methanol can give lower HC and CO emissions and
besides that the vehicles that use methanol emit
minimum particulate matter compared to gasoline,
which usually has damaging effect to humans. In
addition, methanol has high-octane content that
promotes better the process of combustion. Another
advantage of methanol is that if it does ignite can
cause less severe fires to the vehicle because is less
flammable
than
gasoline
[19,20].
Some
disadvantages that methanol has are the lower
energy content compared to gasoline, the fact that is
not volatile enough for easy cold starting and can
damage plastic and rubber fuel system components.
The vehicle that uses methanol for fuel must have a
large storage tank because pure methanol burns
faster than gasoline, and besides that, materials that
are not corrosive must make the storage equipment
[21,22,23]. Renewable fuels such as methanol and
ethanol will probably replace petroleum-based fuels
in the near future because petroleum reserves are not
sufficient enough to last many years. Also, the
severe environmental problems around the world
will eventually lead to the use of more
environmentally friendly technologies. The question
that is examined in this paper is how the mixtures of
gasoline-ethanol and gasoline-methanol behave in a
four-stroke engine from the aspect of emissions,
function and fuel consumption.
2 Instrumentation and experimental
results
The tests were realised on an engine, type
EVINRUDE 4HP and volume 50cc, which is used
on small boats. For the measurement of exhaust
gases, an exhaust analyser was used, type HORIBA
MEXA 574E infrared radiation (Non Dispersive
Infra Red) with a 0 to 10% CO and 0ppm to
10.000ppm HC range. The engine was placed in a
container filled with tap water. The testings were
realised
using
different
gasoline-alcohol
mixtures(gasoline, gasoline-10%ethanol, gasoline20%ethanol, gasoline-30%ethanol and gasoline-
2CH4 + 3H2O CO + CO2 +7H2 (Synthesis gas)
CO + CO2 + 7H2 2CH3OH +2H2 + H2O
ISBN: 978-1-61804-071-8
269
Recent Researches in Engineering Mechanics, Urban & Naval Transportation and Tourism
500
1000
1500
2000
2500
3000
CO%
Figure 3. CO variation in relation to revolutions for
the different gasoline-methanol mixtures
gasoline
10%
20%
30%
0
500
1000
1500
2000
2500
3000
rpm
Figure 1. CO variation in relation to revolutions for
the different gasoline-ethanol mixtures
H C (p p m )
gasoline
10%
20%
30%
rpm
ethanol
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
methanol
2
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
0
H C (p p m )
CO%
10%methanol, gasoline-20%methanol, gasoline30%methanol), keeping the oil quantity stable, at
1:50. For each of the above mixtures, the engine
operated with different revolutions (500-1000-20003000rpm) and there was a continuous monitoring of
the exhaust gases, CO and HC, for each mixture and
number of revolutions separately. The second series
of experiments dealt with the fuel consumption,
which was measured separately for each mixture
always in relation to the different engine speed.
The environmental conditions, for all of the testings
above, were temperature 200C and pressure 1atm
with negligible fluctuations. The experimental
results are shown at the following figures:
1000
1500
rpm
2000
2500
3000
Figure 2. HC variation in relation to revolutions for
the different gasoline-ethanol mixtures
ISBN: 978-1-61804-071-8
20%
30%
500
1000
1500
rpm
2000
2500
3000
In figures 1,3, it is noticed that the increase in the
fuel alcohol percentage results in the CO reduction.
Figures 2, 4 presents the HC variation in relation to
motor engine speeds separately for each fuel
mixture. The increase in the alcohol fuel percentage
results in a HC increase, contrary to the CO
reduction illustrated figure 1and figure 3. The
increase of HC is probably caused by the production
of aldehydes during the combustion . The results of
the second series of experiments, shown on figure 5,
refer to the engine consumption in relation to the
revolutions and the fuel mixture.
20%
30%
500
10%
Figure 4. HC variation in relation to revolutions for
the different gasoline-methanol mixtures
gasoline
10%
0
gasoline
0
ethanol
4500
4000
3500
3000
2500
2000
1500
1000
500
0
methanol
4500
4000
3500
3000
2500
2000
1500
1000
500
0
270
Recent Researches in Engineering Mechanics, Urban & Naval Transportation and Tourism
9
8
consumption(ml/min)
7
6
5
4
3
2
1
0
500rpm
1000rpm
2000rpm
3000rpm
gasoline
4,9
5,4
6,2
7,1
10%
5,3
5,6
6,4
7,4
20%
5,7
5,9
6,6
7,6
30%
6,1
6,3
6,9
8,9
Figure 5. The variation of fuel consumption in relation of engine rpm and fuel (ethanol and methanol) mixtures
in consumption. Also, it must be mentioned that the
adjustment of the engine (air/fuel ratio) was that
which referred to the use of gasoline as fuel.
Comparing the mixtures of gasoline-ethanol and
gasoline-methanol it can be concluded that the
mixture of gasoline-methanol appeared better
behavior regarding to gas emissions, but the same
behavior regarding to fuel consumption.
In figure 5 it can be noticed that the engine
consumption increases in proportion to the %
alcohol fuel percentage. This is the result of ethanol
and methanol low calorific value, which means that
in order to achieve the same number using pure
gasoline, the fuel quantity in the combustion
chamber must be increased when we use a gasolineethanol and gasoline- methanol mixtures. It is
important to mention that there was no difference in
the fuel consumption among the mixtures of
gasoline-ethanol and gasoline-methanol.
References:
[1]. M. Kirik, “Alcohol as an Alternative Fuel “ The
Ontario Digest and Engineering Digest , pp. 29-31,
September 1997.
3 Conclusion
[2]. C I. Arapatsakos and P D. Sparis. “ Bioethanol Premium Gasoline Mixture Tests in Otto Engines”
Meeting of the Greek Section of Combustion
Institute, Athens, 1997
The use of gasoline-ethanol and gasoline-methanol
mixtures, from the pollution viewpoint, results in a
CO reduction and a HC increase. These effects
increase with the ethanol and methanol percentage
in the fuel. Finally, from the consumption
viewpoint, it was noticed that the increase in the
alcohol fuel percentage has as a result the increase
ISBN: 978-1-61804-071-8
[3].Swedish Motor Fuel Technology Co., Alcohol
and Alcohol Blends as Motor Fuel, Vol IIB, p. 8:39,
STU Information No. 580, 1986.
271
Recent Researches in Engineering Mechanics, Urban & Naval Transportation and Tourism
[4]. R.M Tillman, Blending, “ Distribution and
Marketing Aspects of Alcohols as Alternative
Fuels” Ontario , November 19, 1976.
[18]. Environmental Protection Agency ''Fact Sheet
CMS-7, EPA 400-F-92-009'', USA, August 1994
[19]. Methanol Institute, ''Methanol Production'',
Methanol Historical Pricing, Copyright 1996-2001
[5]. Koenig H Menrad and W. Bernhardt, “Alcohol
Fuels in Automobiles ”Alcohol Fuel Conference,
Inst. Chem. Eng. , Sydney, 9-11 August 1978.
[21]. E. R. Fanick, L. R. Smith, et al., '' Laboratory
evaluation of safety-related additives for neat
methanol fuel'', SAE paper No 902156, 1990.
[6]. Timothy T. Maxwell and Jesse C. Jones
''Alternative fuels: Emissions, Economics and
Performance'' Published by SAE, 1995.
[22]. J. Panzer, ''Characteristics of primed methanol
fuels for passenger cars'', SAE paper No 831175,
1983.
[7]. Keith Owen and Trevor Coley ''Automotive
Fuels Reference Book'' Second Edition, Published
by SAE, 1995.
[23]. M. Singh, '' A comparative analysis of
alternative fuel infrastructure requirements'', SAE
paper No 892065, 1989.
[8]. Fred Schafer and Richard van Basshuysen "
Reduced Emissions and Fuel Consumption in
Automobile Engines" Published by SAE, 1995.
[9]. Swedish Motor Fuel Technology Co., ''
Alcohols and alcohol blends as motor fuels'' Vol. II
B, p.8:39, STU information No 580,1986.
[10]. H. Menrad and M. Haselhorst, "Alcohol fuels",
Monograph.
Springer,
New York,
ISBN
3211816968,1981
[11]. Harrington, I.A.; Shishu, R.C.: A SingleCylinder Engine Study of the Effects of Fuel Type,
Fuel Stoichiometry and Hydrogen-to-Carbon Ratio
on CO, NO and HC Exhaust Emissions, SAE-Paper
730476.
[12]. K. Taschner, ''Who Needs Biofuels'' European
Environment Bureau Brussels 1993.
[13].D.J Rickeard and N.D.Thompson. ''A review of
the potential for biofuels as transportation fuels''
SAE paper No.932778, 1993.
[14]. U.E. Stumpf, "Brazilian Research on Ethyl
Alcohol as an Automotive Fuel" Alcohols Fuels
Conference, Inst. Chem. Eng., Sydney, 1978.
[15]. N.N.: U.S. EPA, Clean Air Facts, Nr. 3, 5, 9,
10, 15/1989, Washington, D.C.
[16]. N.N.:
Sept.1990
VDA-Jahresbeicht.
Auto
89/90,
[17]. "The Clean Fuels Report" J.E. Sinor
Consultants Inc., Niwot, Colorado, February 1991.
ISBN: 978-1-61804-071-8
272