![COMBUSTION OPTIMIZATION IN SPARK IGNITION ENGINES
Barhm Mohamad1, Gabor Szepesi2, Betti Bollo3
2,3Doctor of Mechanical Engineering
1, 2, 3 Miskolc University, Faculty of Mechanical Engineering and Informatics, 3515
Miskolc, Hungary
ABSTRACT
The blending technique used in internal combustion engines can reduce emission of toxic
exhaust components and noises, enhance overall energy efficiency and reduce fuel costs.
The aim of the study was to compare the effects of dual alcohols (methanol and ethanol)
blended in gasoline fuel (GF) against performance, combustion and emission
characteristics. Problems arise in the fuel delivery system when using the highly volatile
methanol - gasoline blends. This problem is reduced by using special fuel manifold.
However, the satisfactory engine performance of the dual alcohol–gasoline blends need
to be proved. The test fuels were GF, blend M35g65 (35 % methanol, and 65% GF by
volume), blend E40g60 (40% ethanol, and 6o% GF by volume). The blend M35g65 was
selected to match the vapor pressure (VP) of GF. The test fuels were a lean mixture with
excess-air ratio of λ=1.1. The reaction parameters are taken from literatures and fitting
calculations. Mathematical model and Computer software AVL program were
conducted on a naturally-aspirated, spark ignition engine. The results show that indicate
thermal efficiency (ITE) improved whereas the exhaust gas temperature (EGT) of the
blends reduced, which is a benefit that reduces compression work. The regulated
emissions were also reported. The blend E40g60 was recommended in preference to use
because the former had shortened combustion duration, high energy content and its VP
was selectively matched to that of GF's.
1. INTRODUCTION
Due to the multiple advantages, such as high specific power, low noise and vibration,
gasoline engine has been widely used as the power source of automobile. In China, about
80% of automobiles take the gasoline engine as power. Owing to the increasing energy
crisis and environment pollution, energy conservation and emission reduction have
become an important development strategy in the world. Therefore, to promote the fuel
economy and emission performance of gasoline engine is not only the requirement of
energy conservation and emission reduction, but also the demand for the survival of
traditional gasoline engine [6]. Only by continuously improving the combustion and
MultiScience - XXXI. microCAD International Multidisciplinary Scientific Conference
University of Miskolc, Hungary, 20-21 April 2017
ISBN 978-963-358-132-2
DOI: 10.26649/musci.2017.065](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-1-320.jpg)
![emission performance of gasoline engine, that allowed to study and Identify the noise
and vibrations occur from combustion process during change of exhaust gas behavior so
that the traditional gasoline engine continue to hold the leading position in the future
transportation. Environmentally friendly alternative or renewable fuels are taking the
center stage globally in the search for greener combustible fuels for use in internal
combustion engines [8].
Some of the chemical and physical properties of methanol, ethanol and gasoline are
presented in Table 1.
Table 1
Properties of methanol, ethanol and gasoline fuel. [1, 3]
Methanol Ethanol Gasoline
Molecular formula CH3OH C2H5OH -
Oxygen content
(%)
50 46 95–120
Density kg/m3 792 785 740
LHV MJ/kg 20 26.9 44.3
Octane number 111 108 >90
Auto-ignition
temp.(°C)
465 425 228–470
Stoichiometric A/F
(λ) ratio[kg/kg]
6.47 9.0 14.8
Latent heat kJ/kg 1103 840 305
Vapor pressure at
23.5 °C (kPa)
3.2 - 60–90
Blends in this study, the performance and combustion characteristics and regulated
emissions, for methanol gasoline blend designated as M35g65 (35% methanol and 65%
GF by volume (v/v)), The simulation results were evaluated by comparison with field
data collected from other experimental and mathematically evaluated [1, 7]. The other
blends tested were: E40g60 (40% ethanol and 60% GF by volume).
2. MATHMATICAL MODEL
The parameters are taken from literatures experiments were performed using each single
alcohol–gasoline blends in turn at steady state (see Table 2). The multi-cylinder engine
was operated with pure gasoline, M35g65 and E40g60 to investigate the combustion and
exhaust emission characteristics. The speed was set to 2000 RPM as it represents the
operating condition for the average pulse width of fuel–mass injected for this engine
within the range 2000 RPM. The dependent variables included: in-cylinder pressure, heat
release rate (HRR) and emissions of NOx, UHC, CO, and CO2.](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-2-320.jpg)
![The gasoline – alcohol blends was selectedby a formula proposed by [2] to satisfy the
vapor pressure requirement for automotive fuels as follows:
𝐶𝑖 = (
𝑃 𝐺𝑎𝑠𝑜𝑙𝑖𝑛𝑒−𝑃𝑗( 𝐶𝑡𝑜𝑡)
𝑃𝑖( 𝐶𝑡𝑜𝑡)−𝑃𝑗( 𝐶𝑡𝑜𝑡)
) . 𝐶𝑡𝑜𝑡 (1)
Where,
Ci :volume fraction (v/v) % of the alcohol i,
Ctot : the total alcohol volume fraction (v/v) %,
Pgasoline : the vapor pressure of the base gasoline,
Pi(Ctot) : VP of the single alcohol i at Ctot,
Pj(Ctot) : VP of the single alcohol j at Ctot,
i and j : alcohol components i and j.
The volume of the solution depends on its composition, it is convenient to discuss
volumetric effects of Gasoline - Alcohol mixtures in terms of partial molar volume.
The partial molar volume, Vi, is defined as follows:
𝑉𝑖 = (
𝜕𝑉
𝜕𝑛 𝑖
)T, p, nj (2)
The equation above provided by Pecar & Dolecek can be stated by saying that Vi is the
change in total volume per mole of “i” added, when some amount of “i” is added to the
mixture at constant temperature, pressure and amount of other substances. Using partial
molar volumes, the total volume of a solution can be given by the following equation:
VT = V1n1 + V2n2 +…+ VNnN (3)
𝑉 𝑇 = (
𝜕𝑉
𝜕𝑛₁
)T, p, nj ∗ 𝑛1
+ (
𝜕𝑉
𝜕𝑛2
)T, P,nj*n₂+……+(
𝜕𝑉
𝜕𝑛 𝑁
)T, p, nj * 𝑛 𝑁 (4)
The total volume of the solution can be discovered by determining the partial molar
volumes of ethanol and gasoline, as well as the mass fractions of the mixture.
3. COMBUSTION SIMULATION
The BOOST program package consists of an interactive pre-processor which assists with
the preparation of the input data for the main calculation program. Results analysis is
supported by an interactive post-processor. The pre-processing tool of the AVL
Workspace Graphical User Interface features a model editor and a guided input of the
required data.](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-3-320.jpg)
![Table 3
Engine specification and parameters.
Engine type Four Stroke/ Spark Ignition Engine
Model GTE 0.5L
Bore [mm] 86
Stroke [mm] 86
Connecting rod [mm] 143.5
Compression ratio [–] 1:10.5
Number of cylinders 4
Number of valves 8
Fuel type Petrol-P
Fuel aspiration Naturally aspirated
Fuel delivery Multi-point injection
Fig.1
Engine structure and parts connection
4. RESULTS
It should be noted that in accordance with the literature data [2, 9, and 10] and calculation
in the software package, Ethanol-Gasoline blend was identified to have the potential of
generating a more appropriate atomization for internal combustion faster diffusion
velocity which enhanced local homogeneity. In comparison to the Methanol-Gasoline
blend due to a higher vapor pressure at high temperature conditions.](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-4-320.jpg)
![5. CONCLUSION
Fig.2,3,4 shows the simulation results. According to these results can see that the
ethanol-gasoline blend has a higher laminar flame propagation speed, which may make
combustion process finish earlier and thus may improve engine thermal efficiency. The
NOx emissions were decreased with ethanol blending due to the lower peak of in-
cylinder temperature by the combustion retardation. The LHVs of methanol and ethanol
are significantly lower than that of gasoline [12, 13]. However, the alcohol fuels show
higher octane numbers, which is favorable to achieve higher thermal efficiency. Studies
on the fuel consumption behavior between increased compression ratio and octane
number fuel, showed that an octane number increment of approximately 4–6 [11]. The
cooling effect itself can also contribute to increased knock tolerance and volumetric
efficiency. The vapor pressure of gasoline is higher and the boiling point is lower than
those of ethanol between the temperature ranges of 300–410 K. Therefore, engine
stability and emission problems under cold-start condition need to be taken care of when
implementing ethanol fuel. Combustion noise is generated due to pressure oscillations
created inside the combustion chamber due to sudden heat release because of combustion
of fuel. These pulses generate vibrations in the chamber walls, which radiate outwards
as combustion noise. Provides a comparison of this noise for different test fuels. It is
seen from this figure [Fig. 2b, 3b, 4b] that the noise generated by engine.
REFERENCES
[1] L. Siwale, L.Kristóf, et al. “Performance, Combustion and Emission Characteristics
of N-Butanol Additive in Methanol-Gasoline Blend Fired in a Naturally-Aspirated
Spark Ignition Engine.” Fuel Processing Technology 118. Elsevier.2013.10.007.
[2] V.F. Andersen, et al., Vapor pressures of alcohol–gasoline blends, Energy & Fuels
24 (6) (2010) 3647–3654.
[3] R.C. Shanghua, R.C. Clemente, et al., Study of spark ignition engine fueled with
methanol/gasoline fuel blends, Applied Thermal Engineering 27 (2007) 1904–1910.
[4] V. Ganesan, Computer simulation of spark ignition engine processes, University
Press, (1996) 7371-0155.
[5] S. McAllister, J.Y. Chen, A.C. Fernandez-Pello, Fundamentals of combustion
processes, Springer, Berkeley CA, USA, 2011.
[6] A.N. Ozsezen, M. Canakci, Performance and combustion characteristics of alcohol–
gasoline blends at wide-open throttle, Energy 36 (5) (2011) 2747–2752.
[7] M. Eyidogan, et al., Impact of alcohol–gasoline fuel blends on the performance and
combustion characteristics of an SI engine, Fuel 89 (10) (2010) 2713–2720.](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-8-320.jpg)
![[8] W.-D. Hsieh, et al., Engine performance and pollutant emissionof an SI engine using
ethanol–gasoline blended fuels, Atmospheric Environment 36 (3) (2002) 403–410.
[9] R.-H. Chen, et al., Gasoline displacement and NOx reduction in an SI engine by
aqueous alcohol injection, Fuel 89 (3) (2010) 604–610.
[10] A.M. Liaquat, et al., Potential emissions reduction in road transport sector using
biofuel in developing countries, Atmospheric Environment 44 (32) (2010) 3869–
3877.
[11] C. Srinivasan, C.G. Saravanan, Study of combustion characteristics of an SI engine
fuelled with ethanol and oxygenated fuel additives, Journal of Sustainable Energy
and Environment 1 (2010) 85–91.
[12] Stephen R. Turns, An introduction to combustion concepts and applications, 3th
edition, McGraw - Hill, India (2012).
[13] V. Ganesan, Internal combustion engines, 3th edition, McGraw - Hill, India (2011).](https://image.slidesharecdn.com/d15barhmmohamad-191027230258/85/COMBUSTION-OPTIMIZATION-IN-SPARK-IGNITION-ENGINES-9-320.jpg)
COMBUSTION OPTIMIZATION IN SPARK IGNITION ENGINES
- 1. COMBUSTION OPTIMIZATION IN SPARK IGNITION ENGINES Barhm Mohamad1, Gabor Szepesi2, Betti Bollo3 2,3Doctor of Mechanical Engineering 1, 2, 3 Miskolc University, Faculty of Mechanical Engineering and Informatics, 3515 Miskolc, Hungary ABSTRACT The blending technique used in internal combustion engines can reduce emission of toxic exhaust components and noises, enhance overall energy efficiency and reduce fuel costs. The aim of the study was to compare the effects of dual alcohols (methanol and ethanol) blended in gasoline fuel (GF) against performance, combustion and emission characteristics. Problems arise in the fuel delivery system when using the highly volatile methanol - gasoline blends. This problem is reduced by using special fuel manifold. However, the satisfactory engine performance of the dual alcohol–gasoline blends need to be proved. The test fuels were GF, blend M35g65 (35 % methanol, and 65% GF by volume), blend E40g60 (40% ethanol, and 6o% GF by volume). The blend M35g65 was selected to match the vapor pressure (VP) of GF. The test fuels were a lean mixture with excess-air ratio of λ=1.1. The reaction parameters are taken from literatures and fitting calculations. Mathematical model and Computer software AVL program were conducted on a naturally-aspirated, spark ignition engine. The results show that indicate thermal efficiency (ITE) improved whereas the exhaust gas temperature (EGT) of the blends reduced, which is a benefit that reduces compression work. The regulated emissions were also reported. The blend E40g60 was recommended in preference to use because the former had shortened combustion duration, high energy content and its VP was selectively matched to that of GF's. 1. INTRODUCTION Due to the multiple advantages, such as high specific power, low noise and vibration, gasoline engine has been widely used as the power source of automobile. In China, about 80% of automobiles take the gasoline engine as power. Owing to the increasing energy crisis and environment pollution, energy conservation and emission reduction have become an important development strategy in the world. Therefore, to promote the fuel economy and emission performance of gasoline engine is not only the requirement of energy conservation and emission reduction, but also the demand for the survival of traditional gasoline engine [6]. Only by continuously improving the combustion and MultiScience - XXXI. microCAD International Multidisciplinary Scientific Conference University of Miskolc, Hungary, 20-21 April 2017 ISBN 978-963-358-132-2 DOI: 10.26649/musci.2017.065
- 2. emission performance of gasoline engine, that allowed to study and Identify the noise and vibrations occur from combustion process during change of exhaust gas behavior so that the traditional gasoline engine continue to hold the leading position in the future transportation. Environmentally friendly alternative or renewable fuels are taking the center stage globally in the search for greener combustible fuels for use in internal combustion engines [8]. Some of the chemical and physical properties of methanol, ethanol and gasoline are presented in Table 1. Table 1 Properties of methanol, ethanol and gasoline fuel. [1, 3] Methanol Ethanol Gasoline Molecular formula CH3OH C2H5OH - Oxygen content (%) 50 46 95–120 Density kg/m3 792 785 740 LHV MJ/kg 20 26.9 44.3 Octane number 111 108 >90 Auto-ignition temp.(°C) 465 425 228–470 Stoichiometric A/F (λ) ratio[kg/kg] 6.47 9.0 14.8 Latent heat kJ/kg 1103 840 305 Vapor pressure at 23.5 °C (kPa) 3.2 - 60–90 Blends in this study, the performance and combustion characteristics and regulated emissions, for methanol gasoline blend designated as M35g65 (35% methanol and 65% GF by volume (v/v)), The simulation results were evaluated by comparison with field data collected from other experimental and mathematically evaluated [1, 7]. The other blends tested were: E40g60 (40% ethanol and 60% GF by volume). 2. MATHMATICAL MODEL The parameters are taken from literatures experiments were performed using each single alcohol–gasoline blends in turn at steady state (see Table 2). The multi-cylinder engine was operated with pure gasoline, M35g65 and E40g60 to investigate the combustion and exhaust emission characteristics. The speed was set to 2000 RPM as it represents the operating condition for the average pulse width of fuel–mass injected for this engine within the range 2000 RPM. The dependent variables included: in-cylinder pressure, heat release rate (HRR) and emissions of NOx, UHC, CO, and CO2.
- 3. The gasoline – alcohol blends was selectedby a formula proposed by [2] to satisfy the vapor pressure requirement for automotive fuels as follows: 𝐶𝑖 = ( 𝑃 𝐺𝑎𝑠𝑜𝑙𝑖𝑛𝑒−𝑃𝑗( 𝐶𝑡𝑜𝑡) 𝑃𝑖( 𝐶𝑡𝑜𝑡)−𝑃𝑗( 𝐶𝑡𝑜𝑡) ) . 𝐶𝑡𝑜𝑡 (1) Where, Ci :volume fraction (v/v) % of the alcohol i, Ctot : the total alcohol volume fraction (v/v) %, Pgasoline : the vapor pressure of the base gasoline, Pi(Ctot) : VP of the single alcohol i at Ctot, Pj(Ctot) : VP of the single alcohol j at Ctot, i and j : alcohol components i and j. The volume of the solution depends on its composition, it is convenient to discuss volumetric effects of Gasoline - Alcohol mixtures in terms of partial molar volume. The partial molar volume, Vi, is defined as follows: 𝑉𝑖 = ( 𝜕𝑉 𝜕𝑛 𝑖 )T, p, nj (2) The equation above provided by Pecar & Dolecek can be stated by saying that Vi is the change in total volume per mole of “i” added, when some amount of “i” is added to the mixture at constant temperature, pressure and amount of other substances. Using partial molar volumes, the total volume of a solution can be given by the following equation: VT = V1n1 + V2n2 +…+ VNnN (3) 𝑉 𝑇 = ( 𝜕𝑉 𝜕𝑛₁ )T, p, nj ∗ 𝑛1 + ( 𝜕𝑉 𝜕𝑛2 )T, P,nj*n₂+……+( 𝜕𝑉 𝜕𝑛 𝑁 )T, p, nj * 𝑛 𝑁 (4) The total volume of the solution can be discovered by determining the partial molar volumes of ethanol and gasoline, as well as the mass fractions of the mixture. 3. COMBUSTION SIMULATION The BOOST program package consists of an interactive pre-processor which assists with the preparation of the input data for the main calculation program. Results analysis is supported by an interactive post-processor. The pre-processing tool of the AVL Workspace Graphical User Interface features a model editor and a guided input of the required data.
- 4. Table 3 Engine specification and parameters. Engine type Four Stroke/ Spark Ignition Engine Model GTE 0.5L Bore [mm] 86 Stroke [mm] 86 Connecting rod [mm] 143.5 Compression ratio [–] 1:10.5 Number of cylinders 4 Number of valves 8 Fuel type Petrol-P Fuel aspiration Naturally aspirated Fuel delivery Multi-point injection Fig.1 Engine structure and parts connection 4. RESULTS It should be noted that in accordance with the literature data [2, 9, and 10] and calculation in the software package, Ethanol-Gasoline blend was identified to have the potential of generating a more appropriate atomization for internal combustion faster diffusion velocity which enhanced local homogeneity. In comparison to the Methanol-Gasoline blend due to a higher vapor pressure at high temperature conditions.
- 5. Fig. 2.a Fig. 2.b Fig. 2.c a) NOx Formation of E40g60 blend (b) CO Formation of E40g60 blend (c) Exhaust gas velocity E40g60 blend NOx-Formation -5e-005 0 5e-005 0.0001 0.00015 0.0002 0.00025 0.0003 NOx-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) NOx-Formation Cylinder 1 (kg/s) E40g60 blend CO-Formation -0.01 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 CO-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) CO-Formation Cylinder 1 (kg/s) E40g60 blend Velocity 60 80 100 120 140 160 180 200 220 240 260 Velocity(m/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) Velocity MeasuringPoint 15 (m/s)
- 6. Fig. 3.a Fig. 3.b Fig. 3.c (a) NOx Formation of M35g65 blend (b) CO Formation of M35g65 blend (c) Exhaust gas velocity M35g65 blend CO-Formation -0.005 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 CO-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) CO-Formation Cylinder 1 (kg/s) M35g65 blend Velocity 60 80 100 120 140 160 180 200 220 240 260 Velocity(m/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) Velocity MeasuringPoint 15 (m/s) M35g65 blend NOx-Formation -0.0001 0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 NOx-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) NOx-Formation Cylinder 1 (kg/s)
- 7. Fig. 4.a Fig. 4.b Fig. 4.c (a) NOx Formation of gasoline fuel (b) CO Formation of gasoline fuel (c) Exhaust gas velocity Gasoline NOx-Formation 0 2e-006 4e-006 6e-006 8e-006 1e-005 1.2e-005 NOx-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) NOx-Formation Cylinder 1 (kg/s) Gasoline CO-Formation -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 CO-Formation(kg/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) CO-Formation Cylinder 1 (kg/s) Gasoline Velocity 60 80 100 120 140 160 180 200 220 240 Velocity(m/s) 0 90 180 270 360 450 540 630 720 CRANKANGLE (deg) Velocity MeasuringPoint 15 (m/s)
- 8. 5. CONCLUSION Fig.2,3,4 shows the simulation results. According to these results can see that the ethanol-gasoline blend has a higher laminar flame propagation speed, which may make combustion process finish earlier and thus may improve engine thermal efficiency. The NOx emissions were decreased with ethanol blending due to the lower peak of in- cylinder temperature by the combustion retardation. The LHVs of methanol and ethanol are significantly lower than that of gasoline [12, 13]. However, the alcohol fuels show higher octane numbers, which is favorable to achieve higher thermal efficiency. Studies on the fuel consumption behavior between increased compression ratio and octane number fuel, showed that an octane number increment of approximately 4–6 [11]. The cooling effect itself can also contribute to increased knock tolerance and volumetric efficiency. The vapor pressure of gasoline is higher and the boiling point is lower than those of ethanol between the temperature ranges of 300–410 K. Therefore, engine stability and emission problems under cold-start condition need to be taken care of when implementing ethanol fuel. Combustion noise is generated due to pressure oscillations created inside the combustion chamber due to sudden heat release because of combustion of fuel. These pulses generate vibrations in the chamber walls, which radiate outwards as combustion noise. Provides a comparison of this noise for different test fuels. It is seen from this figure [Fig. 2b, 3b, 4b] that the noise generated by engine. REFERENCES [1] L. Siwale, L.Kristóf, et al. “Performance, Combustion and Emission Characteristics of N-Butanol Additive in Methanol-Gasoline Blend Fired in a Naturally-Aspirated Spark Ignition Engine.” Fuel Processing Technology 118. Elsevier.2013.10.007. [2] V.F. Andersen, et al., Vapor pressures of alcohol–gasoline blends, Energy & Fuels 24 (6) (2010) 3647–3654. [3] R.C. Shanghua, R.C. Clemente, et al., Study of spark ignition engine fueled with methanol/gasoline fuel blends, Applied Thermal Engineering 27 (2007) 1904–1910. [4] V. Ganesan, Computer simulation of spark ignition engine processes, University Press, (1996) 7371-0155. [5] S. McAllister, J.Y. Chen, A.C. Fernandez-Pello, Fundamentals of combustion processes, Springer, Berkeley CA, USA, 2011. [6] A.N. Ozsezen, M. Canakci, Performance and combustion characteristics of alcohol– gasoline blends at wide-open throttle, Energy 36 (5) (2011) 2747–2752. [7] M. Eyidogan, et al., Impact of alcohol–gasoline fuel blends on the performance and combustion characteristics of an SI engine, Fuel 89 (10) (2010) 2713–2720.
- 9. [8] W.-D. Hsieh, et al., Engine performance and pollutant emissionof an SI engine using ethanol–gasoline blended fuels, Atmospheric Environment 36 (3) (2002) 403–410. [9] R.-H. Chen, et al., Gasoline displacement and NOx reduction in an SI engine by aqueous alcohol injection, Fuel 89 (3) (2010) 604–610. [10] A.M. Liaquat, et al., Potential emissions reduction in road transport sector using biofuel in developing countries, Atmospheric Environment 44 (32) (2010) 3869– 3877. [11] C. Srinivasan, C.G. Saravanan, Study of combustion characteristics of an SI engine fuelled with ethanol and oxygenated fuel additives, Journal of Sustainable Energy and Environment 1 (2010) 85–91. [12] Stephen R. Turns, An introduction to combustion concepts and applications, 3th edition, McGraw - Hill, India (2012). [13] V. Ganesan, Internal combustion engines, 3th edition, McGraw - Hill, India (2011).