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A Comparison of Ethanol, Methanol and Butanol Blending with Gasoline and Relationship with Engine Performances and Emissions

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Worldwide, in recent years, it has been observed intensive research to find out alternatives to fossil fuels because world's fossil fuel reserves are limited. Alternative fuels are derived from resources other than petroleum. Alcohol based fuels may have been regarded as one of the alternative fuels because they have several physical and combustion properties similar to gasoline. The use of alcohol fuels or alcohol-blended fuels in gasoline has a great potential to reduce engine emissions. That is why this study is aimed to develop the model of a spark-ignited engine for predicting the effect of various fuel types on engine performances and emissions. The simulation tool AVL Boost was used to analyze the engine characteristics for different blends of ethanol, methanol, butanol and gasoline (by volume). The simulation results obtained from different fuel blends indicated that when alcohol–gasoline fuel blends were used, the brake power decreased and the brake specific fuel consumption increased compared to those of gasoline fuel. When fuel blends percentage increases, the CO and HC concentration decreases.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
DOI: 10.2507/29th.daaam.proceedings.073
A COMPARISON OF ETHANOL, METHANOL AND BUTANOL
BLENDING WITH GASOLINE AND RELATIONSHIP WITH
ENGINE PERFORMANCES AND EMISSIONS
Simeon Iliev
This Publication has to be referred as: Iliev, S[imeon] (2018). A Comparison of Ethanol, Methanol and Butanol
Blending with Gasoline and Relationship with Engine Performances and Emissions, Proceedings of the 29th DAAAM
International Symposium, pp.0505-0514, B. Katalinic (Ed.), Published by DAAAM International, ISBN 978-3-902734-
20-4, ISSN 1726-9679, Vienna, Austria
DOI: 10.2507/29th.daaam.proceedings.073
Abstract
Worldwide, in recent years, it has been observed intensive research to find out alternatives to fossil fuels because world's
fossil fuel reserves are limited. Alternative fuels are derived from resources other than petroleum. Alcohol based fuels
may have been regarded as one of the alternative fuels because they have several physical and combustion properties
similar to gasoline. The use of alcohol fuels or alcohol-blended fuels in gasoline has a great potential to reduce engine
emissions. That is why this study is aimed to develop the model of a spark-ignited engine for predicting the effect of
various fuel types on engine performances and emissions. The simulation tool AVL Boost was used to analyze the engine
characteristics for different blends of ethanol, methanol, butanol and gasoline (by volume). The simulation results
obtained from different fuel blends indicated that when alcoholgasoline fuel blends were used, the brake power decreased
and the brake specific fuel consumption increased compared to those of gasoline fuel. When fuel blends percentage
increases, the CO and HC concentration decreases.
Keywords: alternative fuels; methanol blends; ethanol blends; butanol blends; spark-ignition engine
1. Introduction
The exhaust gases from internal combustion engines (ICEs), affect environment and human life negatively and they
become a great problem. The most harmful pollutant gases, produced from engines, are carbon monoxide (CO), nitrogen
oxides (NOx), hydrocarbons (HC), and particles pollutants. Because CO2 emissions reason global warming, which is one
of the global environmental problems; it is estimate as a pollutant. Many researchers have focused to finding ways to
reduce emissions from fossil fuels. Among the alternatives, oxygenates have shown potential to reduce emission levels
without sacrificing power [1]. The use of fuel additives is very important because many of these additives can be added
to fuel in order to improve its efficiency and performance. Some of the most important additives to improve fuel
performance are oxygen containing organic compounds (oxygenates) [2]. Several oxygenates have been used as fuel
additives, such as methanol, ethanol, tertiary butyl alcohol and methyl tertiary butyl ether [3]. The use of oxygenated fuel
additives provides more oxygen in the combustion chamber and has a great potential to reduce emissions from spark
ignition (SI) and compression ignition engines [4]. Methanol, ethanol, butanol and biodiesel are main biofuels.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
The first four aliphatic alcohols (methanol, ethanol, propanol, and butanol) are of interest as fuels because they can be
synthesized chemically or biologically, and they have characteristics, which allow them to be used in current engines.
Alcohols are liquid fuel and can work in the internal combustion engine (ICE) with gasoline without requiring major
modification. The three alcohols ethanol, methanol and butanol will be used as alternative fuels in pure form or in the
form of blending with conventional fuels in future to reduce the demand for conventional fuels [5]. Fossil fuels have some
disadvantages compared to alcohol fuels. This fuel has lower octane number and emits much more harmful emissions
than alcohol fuels. Due to having much more physical and chemical divers than alcohol, complex refining processes are
required to ensure the consistent production of gasoline from petroleum fuel [6]. Due to having high oxygen content, high
stoichiometric air/fuel ratio, high hydrogencarbon ratio and low sulphur content, alcohol emits less emission (Table 1).
On the combustion characteristics, the auto-ignition temperature and flash point of ethanol, methanol and butanol are
higher than those of gasoline, which makes it safer for transportation and storage [9]. Methanol, ethanol and butanol have
higher heat of vaporization than gasoline; this makes the temperature of the intake manifold much lower, which results
in cooling effect in the intake and compression stroke. As a result, the volumetric efficiency of the engine is increased
and the required amount of the work input is reduced in the compression stroke. Alcohols have high laminar flame
propagation speed, which may complete the combustion process earlier. This improves engine thermal efficiency [10].
Properties
Gasoline
Ethanol
Chemical formula
𝐶8𝐻15
𝐶2𝐻5𝑂𝐻
Molecular weight
111.21
46.07
Oxygen content, wt%
-
34.73
Density, g/cm3
0.737
0.785
Carbon content, wt%
86.3
52.2
Hydrogen content, wt%
24.8
13.1
Stoichiometric AFR
14.5
8.94
Lower heating value, Mj/kg
44.3
27
Heat of evaporation, kj/kg
305
840
Octane number (RON+MON)/2
87
100
Vapor pressure (psi at 37.7 OC)
4.5
2
Specific gravity (kg/dm3)
0,7430
0,7894
Auto-ignition temperature ( OC)
246-280
365
Table 1. Comparison of various properties of primary alcohol fuels with gasoline [7], [8]
Form Table 1, it can be said that about the latent heat of vaporization of these fuels, butanol is less attractive than
others are. For PFI (port fuel injection) systems, fuels with higher latent heat of vaporization have larger decreases in
temperature of intake charge with complete vaporization in the intake port. To match the combustion characteristics of
gasoline, the utilization of butanol fuel as a substitute for gasoline requires fuel-flow increases (though butanol has only
slightly less energy than gasoline, so the fuel-flow increase required is only minimal, maybe 10%). Higher oxygen content
and lower octane number of n-butanol need changes in initial engine calibration, determined with pure gasoline. In
addition, butanol has a higher laminar flame propagation speed than gasoline, which makes combustion process finish
earlier and improving the engine thermal efficiency. Moreover, the use of bio-based products in fuels is a strategic
government resolution in most European countries. According to the Act [11] and the EU Directive [12] bio-components
meet the criterion of reducing greenhouse gases, if it reaches a level of at least 35% until 31 December 2016, 50% from
1 January 2017 and at least 60% from 1 January 2018, for biofuels and bio liquids produced in installations in which
production started on 1 January 2017 or later. According to the Directive [12] biofuels should be used for reducing
greenhouse gas emissions to at least 6% by 31 December 2020, compared to the EU average of greenhouse gas emissions
throughout the life cycle per unit of energy from fossil fuels in 2010. BP and DuPont announced that they would start
selling n-butanol, under the name of biobutanol, as a gasoline-blending component in the UK while ethanol is already
commonly used. The Renewable Fuel Standard under the Energy Independence and Security Act of 2007 mandates an
increase in the volume of renewable fuel to be blended into transportation fuel from 9 billion gallons in 2008 to 36 billion
gallons by 2022 [13] and [14]. There is plenty of literature to various blends of ethanol, methanol, butanol and gasoline
utilization in gasoline engines. Altun et al. [15] studied the effect of 5% and 10% ethanol and methanol blending in
unleaded gasoline on engine performance and exhaust emission.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
Results indicated that M10 and E10 blended fuels demonstrated the best result in exhaust emission. The HC emission
of M10 and E10 are reduced by 13% and 15% and the CO emissions by 10,6 % and 9,8%, respectively. Increased CO2
emission for M10 and E10 compared with unleaded gasoline was observed. The ethanol and methanol addition to
unleaded gasoline demonstrated an increase of BSFC (brake specific fuel consumption) and a decrease of break thermal
efficiency in comparison to unleaded gasoline. In another study, Feng et al. [16] for pure gasoline and 35% by volume
butanol-gasoline blend. The results showed that engine torque, brake specific fuel consumption (BSFC) and CO and HC
emissions were better than those of pure gasoline at both full load and partial load with 35% volume butanol addition.
But CO2 emission was worse than that of the original level of pure gasoline. Gravalos et al. [17] conducted several tests
with SI engine with lower to higher mass alcohol blends with fixed percentages of 1.9 % methanol, 3.5 % propanol, 1.5
% butanol, and 1.1 % pentanol, along with a varying percentage of ethanol from 2 % to 22 % in increments of 5 %. The
2 % ethanol blend produced maximum CO and HC emissions and lower CO2 and NOx emissions. In another experiment,
they removed the higher mass alcohols (i.e., propanol, butanol, and pentanol) and conducted experiments with just lower
mass alcohols. These lower mass alcohols produced lower HC, CO2, and NOx emissions and higher CO emissions
compared with the lower to higher mass alcohol blends. Costagliola et al. [18] examined 10% n-butanol (as well as
different ethanol blends) in a PFI engine showing similar benefits in CO, HC, and PM emissions as with ethanol, but also
similar increases in carbonyl emissions.
2. Research Methodology
The present paper aims to develop the 1-D combustion model of four-stroke port fuel injection (PFI) gasoline engine
for predicting the effect of methanolgasoline (M0, M5, M10, M20, M30 and M50), ethanolgasoline (E0, E5, E10, E20,
E30 and E50) and butanolgasoline (B0, B5, B10, B20, B30 and B50) fuel blends on the performance and emissions of
SI engine. For this purpose, a simulation of calibrated gasoline engine model was used as basic operating condition and
the laminar burning velocity correlations of methanolgasoline, ethanolgasoline and butanolgasoline fuel blends for
calculating the changed combustion duration. The engine performances: torque and specific fuel consumption were
compared and discussed.
2.1. Simulation Setup
Fig. 1. Layout of gasoline PFI engine model.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
The 1-D engine simulation model is developed by using the software AVL BOOST and has been employed to study
the performance of an engine working on methanol-gasoline, ethanol-gasoline and butanol-gasoline blends. The pre-
processing step of AVL Boost enable the user to model a 1-Dimensional engine test bench setup using the predefined
elements provided in the software toolbox. The various elements are joined by the desired connectors to establish the
complete engine model using pipelines. In (Fig.1), E1 represents the engine while C1, C2, C3 and C4 represent the number
of cylinders of the engine. MP1 to MP18 represent the measuring points. PL1, PL2, PL3 and PL4 represent the plenum.
SB1 and SB2 are for the system boundary. The flow pipes are numbered 1 to 34. CL1 represents the cleaner. R1 to R10
represent flow restrictions, CAT1 represents catalyst and I1 to I4 represent fuel injectors. The engine model used in this
simulation was performed on a four stroke, four cylinder spark ignition engine with port fuel injection. The gasoline
engine model was calibrated and described by Iliev [19] and its layout is shown in (Fig. 1) with engine specification
shown in Table 2.
Engine parameters
Value
Bore
86 (mm)
Stroke
86 (mm)
Compression ratio
10,5
Connection rod length
143,5 (mm)
Number of cylinder
4
Piston pin offset
0 (mm)
Displacement
2000 (cc)
Intake valve open
20 BTDC (deg)
Intake valve close
70 ABDC (deg)
Exhaust valve open
50 BBDC (deg)
Exhaust valve close
30 ATDC (deg)
Piston surface area
5809 (mm2)
Cylinder surface area
7550 (mm2)
Number of stroke
4
Table 2. PFI engine specification.
3. Result and discussion
The present study concentrated on the emission and performance characteristics of the methanol, ethanol and butanol-
gasoline blends. Different concentrations of the blends 0% Ethanol (Methanol, Butanol) E0 (M0, B0), 5% Ethanol
(Methanol, Butanol) E5 (M5, B5), 10% Ethanol (Methanol, Butanol) E10 (M10, B10), 20% Ethanol (Methanol, Butanol)
E20 (M20, B20), 30% Ethanol (Methanol, Butanol) E30 (M30, B30), 50% Ethanol (Methanol, Butanol) E50 (M50, B50)
and 85% Ethanol (Methanol, Butanol) E85 (M85, B85) by volume were analysed using AVL BOOST at full load
conditions for the speeds ranging from 1000 - 6500 rpm in the steps of 500 rpm.
3.1. Engine performance characteristics
The results of the brake power, and specific fuel consumption for methanol, ethanol and butanol gasoline blended
fuels at different engine speeds are presented here. Fig. 2 shows the influence of methanol, ethanol and butanol gasoline
blended fuels on engine brake power.
The brake power is one of the important factors that determine the performance of an engine. The variation of brake
power with speed was obtained at full load conditions for E5 (M5, B5), E10 (M10, B10), E20 (M20, B20), E30 (M30,
B30), E50 (M50, B50) and pure gasoline E0 (M0, B0), using the CFD results.
When the ethanol content in the blended fuel was increased, the engine brake power decreased for all engine speeds.
The brake power of gasoline was higher than those of E5-E50 for all engine speeds. The heating value of ethanol is lower
than that of gasoline and heating value of the blended fuel decreases with the increase of the ethanol content. As a result,
a lower power output is obtained [19] and [20].
When the methanol content in the blended fuel was increased (M5 and M10), the engine brake power slightly
increased. This can be explained by the fact that oxygenated fuels have a better combustion efficiency. When the methanol
content in the blended fuel was increased (M30 and M50), the engine brake power decreased for all engine speeds. The
heating value of the blended fuel decreases with the increase of the methanol content. As a result, a lower power output
is obtained. The brake power of gasoline was higher than those of M50 for all engine speeds.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
When the n-Butanol content in the blended fuel was increased, the engine brake power decreased for all engine speeds.
The brake power of gasoline was higher comparisons of B5 to B85 for all engine speeds.
Butanol addition to the gasoline does not affect engine power significantly, but especially at high engine speed (over
4000 min-1), there is a sharp reduction the power curves compared to pure gasoline (Fig. 2). The reason of this reduction
can be affected by the low calorific value of butanol. This may refer to some reasons as follows. Combustion characteristic
of n-butanol is different from gasoline since the latent heat of n-butanol is higher than that for gasoline (584 kJ/kg, 349
kJ/kg for n-butanol and gasoline, respectively). This means that the n-butanol absorbs more heat in order to evaporate and
burn.
Fig. 2. Influence of ethanol, methanol and butanol gasoline blended fuels on engine brake power.
Fig. 3 indicates the variations of the BSFC for methanol, ethanol and butanol gasoline blended fuels under various
engine speeds. As shown in this figure, the BSFC increased as the ethanol percentage increased. The reason is well known:
the heating value and stoichiometric air-fuel ratio are the smallest for this fuel, which means that for specific air-fuel
equivalence ratio, more fuel is needed. The highest specific fuel consumption is obtained at E50 (M50) blended fuel.
Also, a slight difference exists between the BSFC when using gasoline and when using ethanol, methanol and butanol
gasoline blended fuels (E5 (M5, B5), E10 (M10, B5) and E20 (M20, B5)). The lower energy content of ethanol, methanol
and butanol gasoline blended fuels causes some increment in BSFC of the engine when it is used without any modification.
The highest specific fuel consumption for butanol’s blended fuel is obtained for B50 blended fuel.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
Fig. 3. Influence of ethanol, methanol and butanol gasoline blended fuels on brake specific fuel consumption.
3.2. Engine emissions characteristics
Fuels consist of Hydrogen (H) and Carbon (C) molecules. During the combustion period in the engine cylinder, these
C and H molecules react with oxygen (O2) in the air and converted to the CO, CO2, HC. These exhaust tail emissions are
harmful for human health and environmental pollution. Carbon monoxide (CO) is colorless, odorless, tasteless gas which
is lighter than air. It is highly toxic to humans and animals in higher quantities. CO is a common industrial hazard resulting
from the incomplete burning of natural gas and any other material containing carbon.
The effect of the ethanol, methanol and butanol gasoline blends on CO emissions for different engine speeds is shown
in (Fig. 4). It can be seen that when ethanol, methanol and butanol percentage increases, the CO concentration decreases.
This can be explained by the enrichment of oxygen owing to the ethanol methanol and butanol, in which an increase in
the proportion of oxygen will promote the further oxidation of CO during the engine exhaust process. Another significant
reason for this reduction is that ethanol (C2H5OH), methanol (CH3OH) and butanol (C4H9OH) has less carbon than
gasoline (C8H18). The lowest CO emissions are obtained with blended fuel containing methanol (M50).
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
Fig. 4. Influence of ethanol, methanol and butanol gasoline blended fuels on CO emissions.
The effect of the ethanol and methanol gasoline blends on HC emissions for different engine speeds is shown in (Fig.
5). It can be seen that when ethanol, methanol and butanol percentage increases, the HC concentration decreases. The
concentration of HC emissions decreases with the increase of the relative air-fuel ratio. The reason for the decrease of HC
concentration is similar to that of CO concentration described above. The comparison of decrease of HC emissions among
the blended fuels indicates that methanol is more effective than ethanol and butanol. The lowest HC emissions are
obtained with blended fuel containing methanol (M50). When the complete combustion is more, the HC emission is
lower.
When using gasoline as fuel in a spark ignition engine, the unburned fuel hydrocarbons (HC) in the exhaust consist
mainly of unburned gasoline which itself largely consists of hydrocarbons. However, when using gasoline-Butanol blends
as fuel the uncombusted fuel constituents include both unburned gasoline (which consists mainly of hydrocarbons as
noted) and un-combusted Butanol. Thus, the HC emissions measured in the diluted exhaust consist of both hydrocarbons
and Butanol. From a legal perspective, HC emissions are regulated by law, but not butanol emissions. This means that
reported HC emissions from vehicles fueled with alcohol-gasoline blends are overestimated, due to the contribution of
the alcohol contents in the exhaust emitted from the vehicle, and the larger the alcohol contents present in the exhaust,
the greater the error in estimated HC emissions [21].
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
Fig. 5. Influence of ethanol, methanol and butanol gasoline blended fuels on HC emissions.
Nitrogen oxides (NO and NO2) are formed by the oxidation of nitrogen from the air in the combustion process. An
important parameter for the formation of nitrogen oxides is the combustion temperature (increased combustion
temperature results in increased nitrogen oxide emissions). Therefore, its probable formation is in very high temperature
regions, which are related to heat release [22]. It should be noted that nitrogen oxides (NOX) are regulated pollutants that
are determined jointly, as the sum of NO and NO2 contents rather than as individual components [23].
The effect of the ethanol, methanol and butanol gasoline blends on NOx emissions for different engine speeds is
shown in (Fig. 6). It can be seen that when ethanol and methanol percentage increases up to 30% E30 (M30), the NOx
concentration increases after which it decreases with increasing the ethanol (methanol) percentage but when n-Butanol
percentage increases up to 50% (B50), the NOx concentration increase after which it decreased with increasing n-Butanol
percentage. This can be explained by the improved combustion inside the cylinder resulting in an increased in-cylinder
temperature.
The higher percentage of ethanol (methanol, butanol) in gasoline reduces the in-cylinder temperature. The reasons for
the reduction in temperature are: 1. Latent heat of evaporation of ethanol (methanol, butanol), which decreases the in-
cylinder temperature when they vaporizes, 2. The more triatomic molecules are produced, the higher the gas heat capacity
and the lower the combustion gas temperature will be. However the low in-cylinder temperature can also lead to an
increment in the unburned combustion product.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
Fig. 6. Influence of ethanol, methanol and butanol gasoline blended fuels on NOx emissions.
4. Conclusion
The present paper demonstrates the influences of ethanol, methanol and butanol addition to gasoline on SI engine
performance and emission characteristics. General results concluded from this study can be summarized as follows:
When the ethanol and butanol content in the blended fuel was increased, the engine brake power decreased for all
engine speeds. When the methanol content in the blended fuel was increased (M5 and M10), the engine brake power
slightly increased and when the methanol content in the blended fuel was increased (M30 and M50), the engine brake
power decreased for all engine speeds. The BSFC increased as the ethanol (methanol, butanol) percentage increased.
Gasoline blended fuels show lower brake power and higher BSFC than those of gasoline. Also, a slight difference exists
between the BSFC when using gasoline and gasoline blended fuels (E5 (M5, B5), E10 (M10, B10) and E20 (M20, B20)).
When ethanol and methanol percentage increases, the CO and HC concentration decreases. The lowest CO and HC
emissions are obtained with blended fuel containing methanol (M50).
Ethanol and methanol gasoline blends the significant increase NOx emissions with the increase of ethanol and
methanol percentage. When ethanol and methanol percentage increases up to 30% E30 (M30), the NOx concentration
increases, followed by a decrease, after which it decreases with increasing ethanol (methanol) percentage.
Butanol gasoline blends the significant increase NOx emissions with the increase of butanol percentage. When butanol
percentage increases up to 50% B50, the NOx concentration increase after which it decreased with increasing butanol
percentage. The lowest NOx emissions are obtained with gasoline.
Future research should focus on examining different alcoholgasoline fuel blends and their comparison with ethanol,
methanol and butanol.
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29TH DAAAM INTERNATIONAL SYMPOSIUM ON INTELLIGENT MANUFACTURING AND AUTOMATION
5. Acknowledgments
The present document has been produced with the financial assistance of the Project 2018-RU-07 "Creation of a
complex mobile laboratory platform for research and approbation of environmentally friendly technical solutions".
We are also eternally grateful to AVL-AST, Graz, Austria for granting use of AVL-BOOST under the university
partnership program.
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... bioethanol has been widely used as a first-generation biofuel as a blend along with gasoline. Since it is an oxygenate which has a higher octane number, its addition can bring about better combustion and reduced exhaust emissions (Iliev 2018). Bioethanol on its whole cannot replace gasoline in the conventional spark-ignition-based internal combustion engine as it requires major modifications. ...
... Butanol (27 MJ/L) on the other hand is hydrophobic and its energy content is higher than ethanol (23.4 MJ/L) and relatively closer to gasoline (32 MJ/L) (Atsumi and Liao 2008). Butanol in some aspects provides better properties than gasoline like higher laminar flame propagation speed which leads to quicker combustion and increased engine thermal efficiency (Iliev 2018). The various physicochemical properties of gasoline, methanol, ethanol, and butanol are compiled in Table 1. ...
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... Some of specific properties of alcohols, such as high-octane number and high heath of evaporation, make them suitable for use in engines with a high CR [1]. Due to higher heat of vaporization volumetric efficiency improves due to cooling of fresh charge [2]. It is also decreasing in cylinder temperature and reduces the NOx emissions. ...
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Problems with environmental protection, depletion of oil reserves are most discussed topics of our time. In this regard, engine manufacturers are looking for different ways to decrease emissions and use alternative energy sources. The alcohols and alcohol additives as substitutes for fossil fuels are one way to address these problems. This study aims to develop a model of single-cylinder gasoline engine and study its characteristics when working with ethanol additives, by volume: 0% ethanol (E10), 25% ethanol (E25), 75% ethanol (E75) and 100% ethanol (E100). The operation of the engine with CR 6, 8 and 10 was studied.
... Compared to methanol, ethanol is more compatible with existing fuel infrastructure. It has also a higher energy density 27 MJ/kg vs. 20 MJ/kg (Iliev, 2018). However, produced via gasification of biomass followed by chemical synthesis from synthesis gas, production of ethanol requires more synthesis steps compared to methanol. ...
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... It was found that an aviation piston engine can operate with any mixture of aviation gas (AVGAS) and ethanol [18]. However, a recent review emphasised the advantages of the fuel properties of butanol over methanol and ethanol for use in internal combustion engines [19,20]. ...
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... The reduction of available stocks of traditional fuels in recent decades has led to an increase in the use of renewable sources for the production of biofuels [5,6]. Unlike other renewable energy sources, biomass can be converted directly into liquid biofuels for transport [7,8]. The two most common types of biofuels are ethanol and biodiesel [9]. ...
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An experimental investigation of emissions characteristics of lower–higher molecular mass alcohol blended gasoline fuels is presented in this paper. The alcohol component of the blends consisted of methanol, ethanol, propanol, butanol and pentanol. Apparatuses used in the present study were a single cylinder spark ignition engine, a hydraulic dynamometer and an exhaust analyzer. The variables that were continuously measured include engine rotational speed (min−1), CO, CO2, HC and NO emissions. During variable load tests, the results indicate that CO and HC levels in the engine exhaust are reduced with the operation on alcohol gasoline blends. NO emissions with alcohol gasoline blends are higher than with gasoline.
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Alcohols with carbon numbers ranging from C1 to C5 were individually blended with unleaded test gasoline. All the alcohol-gasoline blends had the same oxygen mass content. The performance characteristics of the blends were quantified using a single-cylinder spark ignition engine. The knock-limiting spark timing was determined by analysis of the third derivative of the measured in-cylinder gas pressure versus crank angle. The engine operating conditions were optimized for each (C1-C5) blend with two different values of matched oxygen mass content (2.5 and 5.0 per cent). Emission mass rates of carbon monoxide (CO), nitric oxides (NOx), total unburned hydrocarbons (THCs), alcohols and aldehydes were quantified. The brake power specific rate emissions were compared with that of neat gasoline. Adding lower alcohols (C1, C2 and C3) to gasoline improved the knock resistance. Further improvement was achieved by increasing the oxygen content of the fuel blend. Blends with higher alcohols (C4 and C5) showed degraded knock resistance when compared with neat gasoline. Generally, all alcohol-gasoline blends showed reduction in CO emissions. Higher alcohol-gasoline blends with an oxygen mass content of 5.0 per cent showed a pronounced increase in NOx emission rates when operating at high compression ratios and 5° before top dead centre timing. This is attributed to their lower enthalpy of vaporization and higher flame temperature. All blends tested at optimized operating conditions showed reduction in THC emission rates. Unburned alcohol emission rates were higher for blends with higher content of alcohol, and aldehyde emissions were higher for all blends with formaldehyde as the main constituent.
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An experimental investigation of combustion characteristics of higher-alcohol/gasoline [unleaded test gas 96 (UTG 96)] blends is presented. Lower alcohols (methanol and ethanol) have been used in the past as fuel extenders by mixing them with gasoline, but relatively little work has been reported on higher alcohols (propanol, butanol and pentanol). All these alcohols can be produced from coal-derived syngas. Given the abundant coal reserves in the United States, use of such higher alcohols offers an attractive alternative to alleviate the country's growing needs for transportation fuels. Comparisons of knock limits, indicated mean effective pressure (i.m.e.p.), emissions and fuel characteristics between higher-alcohol/gasoline blends and neat gasoline were made to determine the advantages and disadvantages of blending alcohol with gasoline. All tests were conducted on a single-cylinder Waukesha cooperative fuel research (CFR) engine operating at steady state conditions and stoichiometric air-fuel ratio. The data show that higher-alcohol/gasoline blends have a greater resistance to knock than neat gasoline does, as indicated by the knock resistance indicator (KRI) and the (RON+MON)/2 antiknock index (where RON is the research octane number and MON the motor octane number). Ignition delay and combustion interval data show that higher-alcohol/gasoline blends tend to have faster flame speeds.