Impact of alcohol–gasoline fuel blends on the exhaust emission of an SI engine

Renewable Energy 52 (2013) 111e117

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Impact of alcoholegasoline fuel blends on the exhaust emission of an SI engine Mustafa Canakci a, b, Ahmet Necati Ozsezen a, b, *, Ertan Alptekin a, b, Muharrem Eyidogan c a

Department of Automotive Engineering, Kocaeli University, 41380 Izmit, Turkey Alternative Fuels R&D Center, Kocaeli University, 41275 Izmit, Turkey c Automotive Technology Program, Vocational School, Karabuk University, 78050 Karabuk, Turkey b

a r t i c l e i n f o

a b s t r a c t

Article history: Received 9 February 2012 Accepted 29 September 2012 Available online 23 November 2012

In this study, the effect of ethanolegasoline and methanolegasoline blends on the engine performance and combustion characteristics has been investigated experimentally. In the experiments, a vehicle having a four-cylinder, four-stroke, multi-point injection system SI engine was used. The tests were performed on a chassis dynamometer while running the vehicle at two different vehicle speeds (80 km/h and 100 km/h), and four different wheel powers (5, 10, 15, and 20 kW). The measured emission values with the use of E5, E10, M5, and M10 have been compared to those of pure gasoline. The experimental results revealed that when the test engine was fueled with ethanolegasoline or methanolegasoline blends, CO, CO2, unburned HC and NOx emissions decreased for all wheel powers at the speed of 80 km/h. However, when the vehicle speed was changed to100 km/h, more complex trends occurred in the exhaust emissions for the fuel blends, especially for the wheel power of 15 kW. It was also seen that the airefuel equivalence ratio increased with the increase of ethanol and methanol percentages in fuel blends when compared to pure gasoline case. Ó 2012 Elsevier Ltd. All rights reserved.

Keywords: Gasoline Ethanol Methanol SI engine Emissions

1. Introduction Energy diversity is a vital factor for economic growth and environmental protection. Building a strong base of energy resources is necessary for concern the efforts which are made to search a potential alternate. Both ethanol and methanol can be produced from various biomass resources. It should be noted that methanol can be only produced from natural gas due to economic reasons [1e3]. Ethanol and methanol have low cetane number which may lead insufficient self-ignition quality for direct use of these alcohols in unmodified diesel engines. The key property of ethanol and methanol is their high octane number. The addition of ethanol or methanol to gasoline raises the octane value of gasoline and reduces engine knock, without affecting the efficiency of the catalytic converter [4]. Indeed, when Henry Ford designed his first automobile (Model T), it was built to run on both gasoline and pure

Abbreviations: bsfc, brake specific fuel consumption; CO, carbon monoxide; CO2, carbon dioxide; E5, 5% ethanol þ 95% gasoline (vol%); E10, 10% ethanol þ 90% gasoline (vol%); HC, hydrocarbons; M5, 5% methanol þ 95% gasoline (vol%); M10, 10% methanol þ 90% gasoline (vol%); NOx, nitrogen oxides; SAE, Society of Automotive Engineers. * Corresponding author. Department of Automotive Engineering, Kocaeli University, 41380 Izmit, Turkey. Tel.: þ90 262 3032288; fax: þ90 262 3032203. E-mail address: [email protected] (A.N. Ozsezen). 0960-1481/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.renene.2012.09.062

ethanol [5]. In the past, ethanol had not been used widely due to its insufficient production and high production cost. But, nowadays, increasing global concern due to air pollution caused by internal combustion engines has generated much interest on the environmental friendly alternative fuels. So far, experimental studies [6e9] have been claimed that the ethanol or methanol blended fuels reduce exhaust emissions compared to gasoline fueled engine. Generally, in these studies, the reductions in the exhaust emissions have been associated with the oxygen content in ethanol and methanol. It is well-known that the physical and chemical properties of ethanol or methanol are completely different from those of gasoline. Especially, their energy contents are lower than that of gasoline, both on mass and volume basis. This property shows that the engine will need more amount fuel when it is fueled with ethanol or methanol blends to produce the same power output in a gasoline-fueled engine. This case will change airefuel ratio in the cylinder and exhaust emission levels. One of the most important properties of methanol or ethanol is the oxygenated atoms in their molecular compounds which provide significant reduction in the CO and HC emissions, but it may be adversely affect NOx emissions. Methanol has a heat of vaporization that is about 3 times higher than gasoline; ethanol has higher heat of vaporization about 2.5 times (see Table 1). It can be considered that the mixture temperature will be influenced because of the cooling effect from the vaporization of ethanol or methanol,

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Table 1 Some properties of the test fuels. Properties

Unleaded gasoline

Ethanol

Methanol

E5

E10

M5

M10

Typical formula Density (kg/m3 at 15  C) Kinematic viscosity (mm2/s at 40  C) Research octane number Motor Octane Number Heating value (kJ/kg) Latent heat of vaporization (kJ/kg) Autoignition temperature ( C) Copper strip corrosion (3 h at 50  C) Distillation % Initial boiling point 10 50 90 End boiling point Recovery (%)

C6.97H14.02 750.8 0.494 95 85 42,600 w380 w370 No.1A

C2H5OH 809.9 1.221 108.6 89.7 26,700 920 464 No.1A

CH3OH 796.0 0.596 108.7 88.6 19,850 1185 423 No.1A

C6.72H13.62O0.05 752.8 0.497 e e 41,799 e e No.1A

C6.47H13.22O0.1 755.4 0.572 e e 40,969 e e No.1A

C6.67H13.52O0.05 751.9 0.529 e e 41,462 e e No.1A

C6.37H13.02O0.1 754.1 0.545 e e 40,268 e e No.1A

45 54 96 168 207 96.0

78 78 78 79 79 99.2

64 64 64 65 66 99.2

46 53 79 162 208 96.8

46 53 66 160 207 96.7

42 48 91 163 207 96.4

43 48 81 165 206 96.4

especially for direct injection gasoline engine. However, this property makes the temperature on the intake manifold lower, and increases the volumetric efficiency in the port-injection gasoline engine [10]. At the same time, ethanol and methanol have low vapor pressure. When methanol or ethanol blends are used in a spark ignition engine, these properties can contribute to the amounts of unregulated pollutants like aldehydes [11] which play a major role in the formation of photochemical smog and are strong oxidants which can irritate the respiratory system of human beings [12]. Both methanol and ethanol have higher octane numbers than gasoline. The addition of ethanol to lead-free gasoline has resulted in an increase of fuel research octane number by 5 units for each 10% ethanol addition [13]. Nowadays, a novel approach to avoid the knock in direct injection gasoline engines is to use an alcohol such as ethanol or methanol [14]. In the literature, while some researchers have obviously shown the reductions in CO and HC emissions, NOx and CO2 emission results have not been clearly stated. Al-Hasan [15] investigated the effect of gasolineeethanol blends on the exhaust emissions of an SI engine at three-fourth throttle opening position and variable engine speed. In that study, E20 gave the best results with respect to the exhaust emissions. Using ethanolegasoline blends caused to significant reduction in exhaust emissions about 46.5% and 24.3% of the mean average values of CO and HC emissions, respectively. On the other hand, CO2 emissions increased about 7.5%. Similar results were obtained by Hsieh et al. [16] who studied the effect of ethanol addition to gasoline on the performance and emissions of an SI engine. They claimed that using ethanolegasoline blends may cause reductions in CO and HC emissions in the range of 10e90% and 20e80%, respectively, while CO2 emission increases 5e25% depending on engine running conditions. They also reported that NOx emission is closely related to the airefuel equivalence ratio, and NOx emission reaches to maximum level when the equivalence ratio closes to the stoichiometric conditions. Yanju et al. [17] tested 10, 20, 85% methanolegasoline blends in an SI engine. The result indicated that CO and NOx emissions decreased with the increase of methanol fraction in the fuel blend. NOx emissions of M10 and M20 are approximately equal to those of gasoline. However, the use of M85 leads to a reduction in NOx about 80%. Varde et al. [18] investigated the combustion and exhaust emissions characteristics of ethanolegasoline blends containing 10, 22 and 85% ethanol in a two-valve automotive SI engine. In that study, the alcohol blends improved CO emissions marginally at stoichiometric aire fuel ratio. The NOx levels for the E10 and E22 show close resemblance to the emission levels for gasoline. However, E85 showed significant reduction in the NOx levels. The use of E85 in the engine

also resulted in a reduction in HC levels relative to pure gasoline, but E85 produced significantly higher levels of acetaldehydes by comparison with pure gasoline and lower ethanol blends, particularly at light engine loads. Qi et al. [19] studied the effect of methanolegasoline blends and they added ethanol as the cosolvent to obtain stable homogeneous liquid phase on exhaust emission of SI engine. The results show that the HC emission for M25 (gasoline containing 19 vol% methanol and 6 vol% ethanol) was higher and the NOx emission was lower than those of gasoline and M10 (gasoline containing 8.5 vol% methanol and 1.5 vol% ethanol) for all engine loads. Under low and moderate loads, the CO emission obtained from gasoline was higher than that of methanolegasoline blends, but under high loads, that of M25 was higher. Information in the literature is plentiful for SI engine related to the use of methanol and ethanol blends with gasoline. However, few systematic studies exist about the combustion properties of ethanolegasoline and methanolegasoline blends. In our previous study [20], the effect of alcoholegasoline (E5, E10, M5, and M10) blends on the combustion characteristics (cylinder gas pressure, heat release etc.) has been discussed. The objective of this study is to provide the information about the effect of the ethanol-e gasoline and methanolegasoline blends on the exhaust emission characteristics. 2. Materials and methods Ethanol and methanol were blended with pure gasoline to prepare four different fuel blends on a volume basis which are E5, E10, M5, and M10. Ethanol and methanol, with a purity of 99%, were purchased from Merck distributor in Turkey. Fuel specification of the pure gasoline and alcoholegasoline blends were determined in the Fuel Laboratory at Kocaeli University. The fuel properties of alcohols were obtained from the manufacturer companies and literature [21e24]. Some properties of the test fuels are shown in Table 1. The tests were conducted on a vehicle placed on a chassis dynamometer. The engine specifications of the test vehicle are shown in Table 2. All fuel tests were performed without any modifications on the test engine. The test vehicle has a five-speed manual transmission. The tests were carried out at the speed-4 with the gear ratio of 1:1. Four different wheel powers (5e20 kW with an increment of 5 kW) at two vehicle speeds (80 and 100 km/h) were selected for the tests. The mass flow rate of air was monitored with a sharp edged orifice plate and digital manometer. Two different digital thermocouples

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113

3.2. Emission results

Table 2 Specifications of the test engine. Model of vehicle

1.4i SI engine e Honda Civic

Engine type Cylinder volume Compression ratio Bore and stroke Cylinder head Maximum torque Maximum power

Water-cooled, four-stroke, multi-point injection 1398 cm3 10.4/1 75  79 (mm) 16 valves, SOHC 130 Nm @ 4300 rpm 66 kW @ 5600 rpm

measured the temperatures of engine oil and exhaust gases. The relative humidity, ambient temperature and pressure of the test room were measured using a hygrometer, a thermometer and a barometer, respectively. The engine was sufficiently warmed up at each test and the engine oil temperature was maintained at 70e 80  C. The engine was allowed to run for a few minutes until it reached to steady-state conditions, and then, the data were collected subsequently. Exhaust emissions such as CO, CO2, unburned HC and NOx were sampled from the engine-out and they were measured by an exhaust gas analyzer (Capelec Cap 3200). Calibration of each analyzer was done before each test. Each test was repeated three times and the results of the three repetitions were averaged. Table 3 shows the specifications of the exhaust emission equipment and experimental uncertainties. 3. Result and discussions 3.1. Performance results In this study, the brake wheel power and brake specific fuel consumption (bsfc) were corrected depending upon the atmospheric conditions as defined in SAE (Society of Automotive Engineers) standard [25], since the engine tests had been carried out in different days. The comparison of bsfc and exhaust gas temperature for the test fuels is given in Fig. 1. At 80 km/h, the bsfc amounts of E5, E10, M5 and M10 were increased by 2.8%, 3.6%, 0.6% and 3.3%, respectively, on average, compared with those of pure gasoline. Similarly, the increases in the bsfc of E5, E10, M5 and M10 occurred at the vehicle speed of 100 km/h, on average, which are 0.2%, 1.5%, 1.1% and 1.2% compared to pure gasoline, respectively. The decreases in exhaust gas temperatures for E5, E10, M5 and M10 at the vehicle speed of 80 km/h are 0.2%, 0.5%, 1.6% and 1.1%, respectively. At the vehicle speed of 100 km/h, the decreases in the exhaust gas temperatures for E5, E10, M5 and M10 are 0.3%, 1%, 1.4% and 1.1%, respectively. As seen in Table 1, ethanol and methanol have higher latent heat of vaporization than that of gasoline. Namely, more heat is required to vapor the fuel mixture of alcohole gasoline. This situation causes a reduction in the exhaust gas temperature. In addition, as already mentioned in our previous paper [20], the heat release of gasoline is higher than those of the blends after the 30 crank angle. This is thought to be the reason of the exhaust gas temperature of gasoline being higher than those of the blends. Table 3 The exhaust emission equipment and experimental uncertainties. Measuring instruments and technology

Emission

Error

Uncertainties

Capelec Cap 3200 (Infra-red)

CO CO2 HC NOx

0.001 %vol. 0.1 %vol. 1 ppm 5 ppm < 100ppm  5% > 100 ppm

2.1% 1.2% 1.6% 2.4%

CO and unburned hydrocarbon emission among the exhaust gases represent lost chemical energy that is not fully utilized in the engine [26]. CO concentrations are greatly dependent on the aire fuel ratio relative to the stoichiometric proportions. The variation in the CO emission for 80 km/h and 100 km/h vehicle speeds and different wheel powers is shown in Fig. 2. At the 80 km/h vehicle speed, the decreases in CO emission for E5, E10, M5 and M10 are 18%, 17%, 14% and 11%, on average, compared to pure gasoline, respectively. Ethanol and methanol are oxygenated fuels and they contain an oxygen atom in their basic form. When they are added to the fuel, they can provide more oxygen for the combustion process and lead to the so-called “leaning effect”. Due to the leaning effect, CO emission decreases significantly [16,19,27]. That is maybe the reason of CO reduction. On the other hand, CO emission increases with the rising of wheel power at 80 km/h vehicle speed. While CO emission of E5 and M10 increases at 5 kW, 10 kW and 15 kW wheel powers and 100 km/h vehicle speed, it decreases at 20 kW wheel powers, compared with those of pure gasoline. It is observed that there is a decrease in CO emission for M5 and E10 at 100 km/h vehicle speed and all wheel powers. On average, the decreases in CO emission for E10 and M5 are 3% and 6% compared to pure gasoline, respectively. The oxygen content of the ethanol and methanol fuel blends improves the combustion process and lead to more complete combustion. Therefore, CO emissions decreased. It was also calculated that the increase in CO emission for M10 was 3%, on average, compared to pure gasoline. This increase may be explained with the high CO2 values of M10 at 20 kW. The airefuel equivalence ratios for the all test fuels at the vehicle speeds of 80 km/h and 100 km/h are given in Table 4. The airefuel equivalence ratio increases with the increase of ethanol and methanol percentages in fuel blends. The maximum airefuel equivalence ratio (1.22) was obtained for gasoline at 10 kW vehicle power and 80 km/h. Carbon dioxide (CO2) is one of the basic greenhouse gases, which is produced by the complete combustion of hydrocarbon fuel. CO2 formation is affected by the carbonehydrogen (C/H) ratio in the fuel. Stoichiometrically, combustion of a hydrocarbon fuel should produce only CO2 and water (H2O). The variation in the CO2 emission for 80 km/h and 100 km/h vehicle speeds and different wheel powers is shown in Fig. 3. The decreases in CO2 emission for E5, E10, M5 and M10 are 9.5%, 8%, 11.3% and 3%, on average, compared to pure gasoline, respectively. Researchers stated that CO2 formation depends on the C/H ratio in the fuel [28,29]. The main reason of this decrease is thought that C/H ratio and C content of methanol and ethanol are lower than gasoline. As seen in Fig. 3, in some cases, CO2 emission increased with the increase of ethanol and methanol fraction in the fuel blends. Ethanol and methanol have lower heating value than that of gasoline as shown in Table 1. Therefore, more oxygenated fuel is required to obtain the same brake power from the engine. Injected more fuel may cause increasing of CO2 emission. At the same time, as seen in Fig. 3, CO2 emissions of E5, E10 and M5 are lower than that of gasoline at all wheel powers. When M10 was used, an increase occurred in CO2 emission at 15 kW and 20 kW wheel powers at the speed of 100 km/h. When the average values were taken into consideration, CO2 emission of M10 increased only 0.3% compared with those of gasoline, while CO2 emissions of E5, E10 and M5 decreased by 4%, 3.7% and 7% at the vehicle speed of 100 km/h, respectively. Unburned HC emissions are caused primarily by unburned mixtures, which show improper mixing and incomplete combustion. They are one of the main sources of the photochemical smog

Brake spesific fuel consumption (g/kWh)

M. Canakci et al. / Renewable Energy 52 (2013) 111e117

Brake spesific fuel consumption (g/kWh)

114 1100

80 km/h

Gasoline E5 E10 M5 M10

1000 900 800 700 600 500 400 300 4

6

8

10

12

14

16

18

20

1100

100 km/h 1000 900 800 700 600 500 400 300 4

22

6

8

10

12

14

16

18

20

22

18

20

22

Wheel Power (kW)

Exhaust gas temperature ( C)

80 km/h

740

o

740

o

Exhaust gas temperature ( C)

Wheel Power (kW)

730 720 710 700 690 680 670

100 km/h

730 720 710 700 690 680 670 660

660 4

6

8

10

12

14

16

18

20

4

22

6

8

10

12

14

16

Wheel Power (kW)

Wheel Power (kW)

Fig. 1. Comparison of bsfc and exhaust gas temperatures for the test fuels at the vehicle speeds of 80 km/h and 100 km/h.

and ozone pollution. Generally, the main sources of engine-out unburned HC emissions are misfires, exhaust valve leakage, liquid fuel effects (especially during cold start and warm-up) and fuel or fuel/air mixture protected from the combustion process in crevices, oil films and deposits [30e33]. In this study, the unburned HC emission obtained from 80 km/h and 100 km/h vehicle speeds and different wheel power tests is shown in Fig. 4. When compared to pure gasoline, there is a significant decreasing trend in the unburned HC emissions for the all fuel

Table 4 The airefuel equivalence ratios for test fuels at the vehicle speeds of 80 km/h and 100 km/h. Test fuel Wheel power (kW) at the vehicle speed of 80 km/h

Gasoline E5 E10 M5 M10

0.65

5

10

15

20

5

10

15

20

1.07 1.08 1.09 1.03 1.05

1.22 1.09 1.13 1.06 1.09

1.12 1.1 1.11 1.08 1.1

1.12 1.14 1.15 1.13 1.15

1.1 1.07 1.08 1 1.12

1 1.07 1.08 1.04 1.1

1.08 1.08 1.1 1.09 1.1

1.1 1.11 1.12 1.1 1.13

0.65

Gasoline E5 E10 M5 M10

0.60

CO emission (ppm)

0.60

CO emission (ppm)

Wheel power (kW) at the vehicle speed of 100 km/h

0.55

0.50

0.45

0.55

0.50

0.45

100 km/h

80 km/h 0.40

0.40 5

10

15

Wheel power (kW)

20

5

10

15

Wheel power (kW)

Fig. 2. Comparison of CO emission for test fuels at vehicle speeds of 80 km/h and 100 km/h.

20

M. Canakci et al. / Renewable Energy 52 (2013) 111e117 14.4

115

14.4

100 km/h

14.0

14.0

13.6

13.6

CO2 emission (%)

CO2 emission (%)

80 km/h

13.2

12.8

12.4

12.0

13.2

12.8

Gasoline E5 E10 M5 M10

12.4

12.0

11.6

11.6 5

10

15

20

5

10

15

20

Wheel power (kW)

Wheel power (kW)

Fig. 3. Comparison of CO2 emission for test fuels at vehicle speeds of 80 km/h and 100 km/h.

blends. The average decreases in unburned HC emissions of E5, E10, M5 and M10, compared to pure gasoline, are 27%, 32%, 35% and 30% at 80 km/h vehicle speed, respectively. The oxygen content of the ethanol and methanol fuel blends remarkably improved the combustion efficiency. Thus, the HC emissions reduced when ethanol or methanol were added to gasoline. While HC emissions decrease with the increase of ethanol content in the fuel blend for the most test conditions, HC emissions of M10 increase compared to those of M5. The main reason for this situation may be explained by quenching effect due to methanol’s high latent heat of evaporation. Unburned HC emissions decrease linearly as the wheel power increases for the E5, E10 and M5 fuels at 100 km/h vehicle speed. The decreases in HC emissions of E5, E10, M5 and M10 are 12%, 16%, 10% and 17%, on average, compared to pure gasoline, respectively. When the reduction in HC emissions at 100 km/h test condition is compared with that of 80 km/h test condition, it is seen that the reduction in HC emissions decreased at 100 km/h test condition. In addition, HC emissions at 100 km/h were lower than those of 80 km/h test condition. When the speed is increased, the fueleair mixture becomes more homogenous. The temperature raised and combustion efficiency is improved. Thus, the HC emissions decreased at 100 km/h vehicle speed compared to 80 km/h test condition.

The oxides of nitrogen (NOx) in the exhaust emissions, a mixture of nitric oxide (NO) and nitrogen dioxide (NO2), are formed by the oxidation of nitrogen from the air in the combustion process. The formation of NOx is strongly related to the combustion temperature, the oxygen concentration and residence time for the reaction to take place [34e36]. If the concentration of NOx is above certain level and reactive hydrocarbons are also available in the atmosphere, smog is generated under strong sunlight. The variation in the NOx emission for 80 km/h and 100 km/h vehicle speeds and different wheel powers is shown in Fig. 5. It is seen that there is a decreasing tendency in NOx emissions with the use of the ethanol and methanol blends as compared to pure gasoline. The average decrease in NOx emissions of E5, E10, M5 and M10 compared to pure gasoline is 11%, 15.5%, 9% and 1.3% at 80 km/h vehicle speed, respectively. With the use of alcohol in gasoline, the combustion temperature is decreased due to high latent heat, their lower heating value and oxygen content, and this leads to the reduction in NOx emissions [18,37]. NOx emissions of M10 are higher than that of M5 at 80 km/h vehicle speed because M10 has more oxygen than that of M5. It is commonly known that the higher oxygen concentration in the cylinder is a contributor to NOx formation. At 100 km/h, NOx emissions of E5, E10 and M5, decreased by 10.5%, 13.5%, and 5%, respectively, while NOx emission of the M10

200

200

Unburned HC emission (ppm)

Unburned HC emission (ppm)

80 km/h 180

160

140

120

100

80

Gasoline E5 E10 M5 M10

180

100 km/h

160

140

120

100

80 5

10

15

Wheel power (kW)

20

5

10

15

Wheel power (kW)

Fig. 4. Comparison of unburned HC emission for test fuels at vehicle speeds of 80 km/h and 100 km/h.

20

116

M. Canakci et al. / Renewable Energy 52 (2013) 111e117

2000

1750

NOx emission (ppm)

1750

NOx emission (ppm)

2000

Gasoline E5 E10 M5 M10

1500

1250

1000

1500

1250

1000

80 km/h

750 5

10

15

20

Wheel power (kW)

100 km/h

750 5

10

15

20

Wheel power (kW)

Fig. 5. Comparison of NOx emission for test fuels at vehicle speeds of 80 km/h and 100 km/h.

increased by 2.8%, on average, compared with those of pure gasoline. Although M10 has higher latent heat of vaporization, the maximum cylinder gas pressures were obtained for M10 fuel blend at the vehicle speed of 100 km/h and 10 kW, 15 kW wheel powers, as mentioned in our previous article [20]. The higher cylinder gas pressure and temperature cause to the increase in NOx emissions, especially if the fuel contains more oxygen in its structure which reacts with nitrogen easily and produces NOx emissions. 4. Conclusions The exhaust emissions of an SI engine fueled with the ethanolegasoline (E5, E10) and methanolegasoline (M5, M10) fuel blends were investigated and compared to those of pure gasoline. The test results showed that the use of ethanolegasoline and methanolegasoline fuel blends causes to decrease in CO and unburned HC emissions significantly at the vehicle speed of 80 km/h. This is due to improving combustion process as a result of oxygen content in ethanol and methanol. However, similar trend was not obtained for CO emissions at the vehicle speed of 100 km/h because of the different engine running condition. With the increase of ethanol and methanol fraction in the fuel blend, the airefuel equivalence ratio increased. In general, the airefuel equivalence ratio decreased with the increase of wheel power for the all test fuels. By using ethanol and methanol blended gasoline, CO2 and NOx emissions reduced at the vehicle speed of 80 km/h, while CO2 and NOx emissions of M10 increased slightly at the vehicle speed of 100 km/h depending on the engine running conditions. Acknowledgment This study was supported by the Scientific Research Foundation of Kocaeli University (Project No: 2006/25). The authors would like to thank the individuals at the engine test laboratory who were involved in making this work possible. References [1] Cheng WH, Kung HH. Methanol production and use. New York: Marcel Dekker; 1994. [2] Cardona CA, Sanchez OJ. Fuel ethanol production: process design trends and integration opportunities. Bioresour Technol 2007;98:2415e57. [3] Evrendilek F, Ertekin C. Assessing the potential of renewable energy sources in Turkey. Renew Energy 2003;28:2303e15. [4] Agarwal AK. Biofuels (alcohols and biodiesel) applications as fuels for internal combustion engines. Prog Energ Combust 2007;33:233e71. [5] Sward K. The legend of Henry Ford. 1st ed. New York: Rinehart; 1948.

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