**3. Result and discussion**

**5.** The flow of fuel vapor into the exhaust system during valve overlap in gasoline engines. The first two mechanisms and in particular the crevice formation are considered to be the most important and need to be accounted for in a thermodynamic model. Partial burn and quench layer effect cannot be physically described in a quasi-dimensional approach, but may

The formation of unburned HC in the crevices is described by assuming that the pressure in the cylinder and in the crevices is the same and that the temperature of the mass in the crevice

*RTpiston*

In Eq. (7), *mcrevice* represents the mass of unburned charge in the crevice, *p* denotes cylinder pressure, *Vcrevice* stands for total crevice volume, *M* represents unburned molecular weight, *Tpiston* is the

The second important source of HC is the presence of lubricating oil in the fuel or on the walls of the combustion chamber. During the compression stroke, the fuel vapor pressure increases so, by Henry's law, absorption occurs even if the oil was saturated during the intake. During combustion the concentration of fuel vapor in the burned gases goes to zero so the absorbed fuel vapor will desorb from the liquid oil into the burned gases. Fuel solubility is a positive function of the molecular weight, so the oil layer contributed to HC emissions depending on

The assumptions made in the development of the HC absorption/desorption are the following: **1.** Fuel is constituted by a single hydrocarbon species, completely vaporized in the fresh mixture.

**4.** Oil is represented by squalane (C30H62), whose characteristics resemble those of the

**5.** Diffusion of the fuel in the oil film is the limiting factor, for the diffusion constant in the liquid phase which is 104 times smaller than the corresponding value in the gas phase.

The radial distribution of the fuel mass fraction in the oil film can be determined by solving

position in the oil film (distance from the wall), and *D* is relative (fuel-oil) diffusion coefficient.

represents fuel's mass fraction in the oil film, *t* is the time, *r* stands for radial

<sup>∂</sup> *<sup>r</sup>* <sup>2</sup> <sup>=</sup> <sup>0</sup> (8)

∂ *wF* <sup>∂</sup>*<sup>t</sup>* <sup>−</sup> *<sup>D</sup>* ∂ \_\_\_\_ <sup>2</sup> *wF* (7)

be included by adopting tunable semiempirical correlations.

The mass in the crevices at any time is described by Eq. (7):

*mcrevice* <sup>=</sup> *pV*\_\_\_\_\_\_\_\_ *crevice <sup>M</sup>*

temperature of the piston, and *R* denotes gas constant.

the different solubility of individual hydrocarbons in the lubricating oil.

**2.** The oil film temperature is at the same as the cylinder wall.

**3.** Traverse flow across the oil film is negligible.

\_\_\_\_

SAE5W20 lubricant.

the diffusion Eq. (8):

In Eq. (8), *wF*

volumes is equal to the piston temperature.

146 Biofuels - Challenges and opportunities

The present research focused on the performance and emission characteristics of the methanol and ethanol-gasoline blends. Various concentrations of the blends 0% methanol (ethanol) M0 (E0), 5% methanol (ethanol) M5 (E5), 10% methanol (ethanol) M10 (E10), 20% methanol (ethanol) M20 (E20), 30% methanol (ethanol) M30 (E30), 50% methanol (ethanol) M50 (E50), and 85% methanol (ethanol) M85 (E85) by volume were analyzed.

#### **3.1. Engine performance characteristics**

The results of the brake power and specific fuel consumption for ethanol-gasoline blended fuels at different engine speeds are shown on **Figures 2** and **3**.

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, E10, E20, E30, E50, and pure gasoline E0. The ethanol content in the blended fuel increased, and the brake power decreased for all engine speeds. The gasoline brake power was higher than E5–E50 for all engine speeds. The ethanol's heat of evaporation is higher in comparison to gasoline fuel, providing air-fuel charge cooling and increasing the density of the charge. The blended fuel causes the equivalence ratio of blend approaches to stoichiometric condition which can lead to a better combustion. However, the ethanol heating value is lower compared to gasoline, and it can neutralize the previous positive effects. Consequently, a lower power output is obtained.

**Figure 3** shows the changes of the BSFC for ethanol-gasoline blends under various engine speeds. The figure shows that the BSFC increased as the ethanol percentage increased. Heating value and stoichiometric air-fuel ratio are the smallest for these two fuels, which means that for specific air-fuel equivalence ratio, more fuel is needed. The highest specific fuel consumption is obtained at E50 ethanol-gasoline blend.

**Figure 2.** Influence of ethanol-gasoline blended fuels on brake power.

**Figure 5** shows the variations of the BSFC for methanol-gasoline blended fuels under various engine speeds. As shown in this figure, the BSFC increased as the methanol percentage increased. This can be described with heating value, and stoichiometric air-fuel ratio is the smallest for these two fuels, which means that for specific air-fuel equivalence ratio, more fuel is needed. The specific fuel consumption of M50 methanol-gasoline blend was highest compared to those of

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation

http://dx.doi.org/10.5772/intechopen.81776

149

Furthermore, there is a small difference between the BSFC when using gasoline and when using methanol-gasoline blended fuels (M5–M30). As engine speed increased reaching

The results of the brake power and specific fuel consumption for ethanol- and methanol-

When there was an increase in the ethanol content in the blended fuel, the brake power decreased for all engine speeds. The brake power of gasoline fuel was higher than those of E5–E50. The heating value of ethanol is lower than pure gasoline fuel, and the heating value of the blends decreases with the increase of the ethanol percentage. Consequently, a lower

By increasing the percentage of methanol in the blends (M5 and M10), the brake power slightly increased, which can be explained by better combustion efficiency of oxygenated fuels. By increasing the methanol content in the blends (M30 and M50), the engine brake power decreased for all engine speeds. The blended fuel heating value decreases with the increase of the percentage of methanol. This results in a lower power output. The gasoline

**Figure 7** shows the changes of the BSFC for blended fuels under different engine speeds. The BSFC increased as the ethanol and methanol percentage increased. The reason has been known—the heating value and stoichiometric air-fuel ratio are the smallest for this fuel, which

gasoline blended fuels at different engine speeds are presented in **Figures 6** and **7**.

gasoline for all engine speeds.

power output is obtained [22, 23].

brake power was higher compared to blend M50.

**Figure 5.** Influence of methanol-gasoline blended fuels on engine brake power.

2000 rpm, the BSFC decreased reaching its minimum value.

**Figure 3.** Influence of ethanol-gasoline blended fuels on brake-specific fuel consumption.

Moreover, there is a slight difference between the BSFC when using pure gasoline and when using blends (E5, E10, and E20). The lower energy content of blended fuels causes some increment in BSFC of the engine.

**Figure 4** shows the influence of methanol-gasoline blended fuels on engine brake power. The variation of brake power with speed was obtained at full load conditions for M5, M10, M20, M30, M50, and pure gasoline M0. When the methanol content in the blended fuel was increased (M10, M20, and M30), there was not a significant increase in engine brake power.

The engine brake power may be due to the increase of the indicated mean effective pressure for higher methanol content blends. The methanol's heat of evaporation is higher compared to that of gasoline, thus providing air-fuel charge cooling and increasing the density of the charge. Therefore, a higher power output is obtained. The engine brake power was higher in operation with gasoline in comparison to M50 for all engine speeds.

**Figure 4.** Influence of methanol-gasoline blended fuels on brake power.

**Figure 5** shows the variations of the BSFC for methanol-gasoline blended fuels under various engine speeds. As shown in this figure, the BSFC increased as the methanol percentage increased. This can be described with heating value, and stoichiometric air-fuel ratio is the smallest for these two fuels, which means that for specific air-fuel equivalence ratio, more fuel is needed. The specific fuel consumption of M50 methanol-gasoline blend was highest compared to those of gasoline for all engine speeds.

Furthermore, there is a small difference between the BSFC when using gasoline and when using methanol-gasoline blended fuels (M5–M30). As engine speed increased reaching 2000 rpm, the BSFC decreased reaching its minimum value.

The results of the brake power and specific fuel consumption for ethanol- and methanolgasoline blended fuels at different engine speeds are presented in **Figures 6** and **7**.

When there was an increase in the ethanol content in the blended fuel, the brake power decreased for all engine speeds. The brake power of gasoline fuel was higher than those of E5–E50. The heating value of ethanol is lower than pure gasoline fuel, and the heating value of the blends decreases with the increase of the ethanol percentage. Consequently, a lower power output is obtained [22, 23].

Moreover, there is a slight difference between the BSFC when using pure gasoline and when using blends (E5, E10, and E20). The lower energy content of blended fuels causes some incre-

**Figure 4** shows the influence of methanol-gasoline blended fuels on engine brake power. The variation of brake power with speed was obtained at full load conditions for M5, M10, M20, M30, M50, and pure gasoline M0. When the methanol content in the blended fuel was increased

The engine brake power may be due to the increase of the indicated mean effective pressure for higher methanol content blends. The methanol's heat of evaporation is higher compared to that of gasoline, thus providing air-fuel charge cooling and increasing the density of the charge. Therefore, a higher power output is obtained. The engine brake power was higher in

(M10, M20, and M30), there was not a significant increase in engine brake power.

operation with gasoline in comparison to M50 for all engine speeds.

**Figure 3.** Influence of ethanol-gasoline blended fuels on brake-specific fuel consumption.

**Figure 4.** Influence of methanol-gasoline blended fuels on brake power.

ment in BSFC of the engine.

148 Biofuels - Challenges and opportunities

By increasing the percentage of methanol in the blends (M5 and M10), the brake power slightly increased, which can be explained by better combustion efficiency of oxygenated fuels. By increasing the methanol content in the blends (M30 and M50), the engine brake power decreased for all engine speeds. The blended fuel heating value decreases with the increase of the percentage of methanol. This results in a lower power output. The gasoline brake power was higher compared to blend M50.

**Figure 7** shows the changes of the BSFC for blended fuels under different engine speeds. The BSFC increased as the ethanol and methanol percentage increased. The reason has been known—the heating value and stoichiometric air-fuel ratio are the smallest for this fuel, which

**Figure 5.** Influence of methanol-gasoline blended fuels on engine brake power.

**Figure 6.** Effect of blended fuels on engine brake power.

means that more fuel is needed for specific air-fuel equivalence ratio. The highest specific fuel consumption is obtained at E50 (M50) blended fuel.

**Figure 7.** Influence of blended fuels on engine fuel consumption.

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation

http://dx.doi.org/10.5772/intechopen.81776

151

**Figure 8.** Influence of ethanol-gasoline blended fuels on CO emissions.

What is more, there is small difference between the BSFC when using pure gasoline and blended fuels (E5 (M5), E10 (M10), and E20 (M20)). The lower energy content of ethanol blended fuels makes some increment in BSFC.

#### **3.2. Emission characteristics**

The result of the ethanol-blended fuels on CO emissions is shown in **Figure 8**.

A conclusion, which can be made by **Figure 8**, is that when ethanol content increases, the CO emission decreases. The reason for this could be explained with the enrichment of oxygen owing to the ethanol, in which an increase in the proportion of oxygen will promote the further oxidation of CO during the engine exhaust process. One of the other significant reasons for this reduction is that ethanol (C<sup>2</sup> H5 OH) has less carbon than gasoline (C<sup>8</sup> H18).

**Figure 7.** Influence of blended fuels on engine fuel consumption.

means that more fuel is needed for specific air-fuel equivalence ratio. The highest specific fuel

What is more, there is small difference between the BSFC when using pure gasoline and blended fuels (E5 (M5), E10 (M10), and E20 (M20)). The lower energy content of ethanol blended fuels

A conclusion, which can be made by **Figure 8**, is that when ethanol content increases, the CO emission decreases. The reason for this could be explained with the enrichment of oxygen owing to the ethanol, in which an increase in the proportion of oxygen will promote the further oxidation of CO during the engine exhaust process. One of the other significant reasons for this reduc-

H18).

The result of the ethanol-blended fuels on CO emissions is shown in **Figure 8**.

OH) has less carbon than gasoline (C<sup>8</sup>

consumption is obtained at E50 (M50) blended fuel.

**Figure 6.** Effect of blended fuels on engine brake power.

H5

makes some increment in BSFC.

**3.2. Emission characteristics**

150 Biofuels - Challenges and opportunities

tion is that ethanol (C<sup>2</sup>

**Figure 8.** Influence of ethanol-gasoline blended fuels on CO emissions.

The result of the ethanol gasoline blends on HC emissions is shown in **Figure 9.** The figure shows that when ethanol percentage increases, the HC concentration decreases. The HC emission decreases with the increase of the relative air-fuel ratio. The decrease of HC can be explained similarly to that of CO concentration described above.

The effect of the ethanol gasoline blends on NOx emissions for various engine speeds is shown in **Figure 10**. When the combustion process is closer to stoichiometric, flame temperature increases. As a result, the NOx emissions are increased.

The effect of the methanol-gasoline blends on CO emissions for various engine speeds can be seen in **Figure 11**. When methanol percentage increases, the CO concentration decreases. This can be explained with the enrichment of oxygen because of the methanol and less carbon of methanol than gasoline.

The effect of the methanol-gasoline blends on HC emissions is visible in **Figure 12**. When methanol 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 resembles that of ethanol.

**Figure 10.** Influence of ethanol-gasoline blended fuels on NOx emissions.

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation

http://dx.doi.org/10.5772/intechopen.81776

153

**Figure 11.** Influence of methanol-gasoline blended fuels on CO emissions.

**Figure 12.** Influence of methanol-gasoline blended fuels on HC emissions.

The effect of the methanol-gasoline blends on NOx emissions can be seen in **Figure 13**. When methanol percentage increases, the NOx concentration increases. When combustion process is closer to stoichiometric, flame temperature increases and the NOx emissions increase as well.

The effect of the ethanol- and methanol-gasoline blends on CO emissions can be viewed in **Figure 14**. By increasing the methanol and ethanol content in the blended fuel, the CO emission decreases. The reason can be the enrichment of oxygen because of the ethanol and methanol, in which an increase in the proportion of oxygen will promote the further oxidation of CO during the engine exhaust process. Another major reason for this reduction is that ethanol (C<sup>2</sup> H5 OH) and methanol (CH<sup>3</sup> OH) have less carbon than gasoline (C<sup>8</sup> H18). The lowest CO emissions are obtained with blended fuel containing methanol (M50).

**Figure 9.** Influence of ethanol-gasoline blended fuels on HC emissions.

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation http://dx.doi.org/10.5772/intechopen.81776 153

**Figure 10.** Influence of ethanol-gasoline blended fuels on NOx emissions.

**Figure 11.** Influence of methanol-gasoline blended fuels on CO emissions.

**Figure 12.** Influence of methanol-gasoline blended fuels on HC emissions.

**Figure 9.** Influence of ethanol-gasoline blended fuels on HC emissions.

The result of the ethanol gasoline blends on HC emissions is shown in **Figure 9.** The figure shows that when ethanol percentage increases, the HC concentration decreases. The HC emission decreases with the increase of the relative air-fuel ratio. The decrease of HC can be

The effect of the ethanol gasoline blends on NOx emissions for various engine speeds is shown in **Figure 10**. When the combustion process is closer to stoichiometric, flame temperature

The effect of the methanol-gasoline blends on CO emissions for various engine speeds can be seen in **Figure 11**. When methanol percentage increases, the CO concentration decreases. This can be explained with the enrichment of oxygen because of the methanol and less carbon of

The effect of the methanol-gasoline blends on HC emissions is visible in **Figure 12**. When methanol 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

The effect of the methanol-gasoline blends on NOx emissions can be seen in **Figure 13**. When methanol percentage increases, the NOx concentration increases. When combustion process is closer to stoichiometric, flame temperature increases and the NOx emissions increase as well. The effect of the ethanol- and methanol-gasoline blends on CO emissions can be viewed in **Figure 14**. By increasing the methanol and ethanol content in the blended fuel, the CO emission decreases. The reason can be the enrichment of oxygen because of the ethanol and methanol, in which an increase in the proportion of oxygen will promote the further oxidation of CO during the engine exhaust process. Another major reason for this reduction is that

OH) have less carbon than gasoline (C<sup>8</sup>

H18). The lowest

explained similarly to that of CO concentration described above.

increases. As a result, the NOx emissions are increased.

of HC concentration resembles that of ethanol.

OH) and methanol (CH<sup>3</sup>

CO emissions are obtained with blended fuel containing methanol (M50).

methanol than gasoline.

152 Biofuels - Challenges and opportunities

ethanol (C<sup>2</sup>

H5

The effect of the ethanol- and methanol-gasoline blends on HC emissions is visible in **Figure 15**. When there is an increase in the ethanol and methanol percentage, the HC concentration

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation

http://dx.doi.org/10.5772/intechopen.81776

155

decreases.

**Figure 15.** Influence of blended fuels on HC and NOx emissions.

**Figure 13.** Influence of methanol-gasoline blended fuels on NOx emissions.

**Figure 14.** Influence of ethanol- and methanol–gasoline blended fuels on CO emissions.

The effect of the ethanol- and methanol-gasoline blends on HC emissions is visible in **Figure 15**. When there is an increase in the ethanol and methanol percentage, the HC concentration decreases.

**Figure 15.** Influence of blended fuels on HC and NOx emissions.

**Figure 13.** Influence of methanol-gasoline blended fuels on NOx emissions.

154 Biofuels - Challenges and opportunities

**Figure 14.** Influence of ethanol- and methanol–gasoline blended fuels on CO emissions.

When the relative air-fuel ratio increases, the concentration of HC emissions decreases. The reason for the decrease in HC emissions is similar to that of CO described above. The comparison between the decrease in HC emissions and the blended fuels indicates that methanol is more effective than ethanol. The lowest HC emissions are obtained with methanol-blended fuel (M50). When more combustion is complete, it will result in lower HC emissions.

**Acknowledgements**

**Author details**

Simeon Iliev

**References**

2007. 2007-24-0035

2003;**10**:3-4

under the university partnership program.

Address all correspondence to: spi@uni-ruse.bg

Department of Engines and Vehicles, University of Ruse, Ruse, Bulgaria

The present chapter has been written with the Project No 2018-RU-07's financial assistance. We are also eternally grateful to AVL-AST, Graz, Austria, for granting the use of AVL BOOST

Comparison of Ethanol and Methanol Blending with Gasoline Using Engine Simulation

http://dx.doi.org/10.5772/intechopen.81776

157

[1] Iliev S. Investigation of N-butanol blending with gasoline using a 1-d engine model. In: Special Session on Sustainable Mobility Solutions: Vehicle and Traffic Simulation, On-Road Trials and EV Charging. 2017. pp. 385-391. DOI: 10.5220/0006284703850391 [2] Melo T, Machado G, Machado RT, Pereira Belchior CR Jr, Pereira PP. Thermodynamic modeling of compression, combustion and expansion processes of gasoline, ethanol and natural gas with experimental validation on a flexible fuel engine. In: SAE World Congress.

[3] Varol Y, Oner C, Oztop HF, Altun S. Comparison of methanol, ethanol, or n-butanol blending with unleaded gasoline on exhaust emissions of an SI engine. Energy Sources

[4] Pourkhesalian A, Shamekhi A, Salimi F. Alternative fuel and gasoline in an SI engine: A comparative study of performance and emissions characteristics. Fuel. 2010;**89**:1056-1063

[5] Chen C, Rao P, Delfino J. Oxygenated fuel induced to solvent effect on the dissolution of polynuclear aromatic hydrocarbons from contemned soil. Chemosphere. 2005;**60**:1572-1582

[6] Canaksi M, Ozsezen AN, Alptekin E. Impact of alcohol-gasoline fuel blends on exhaust

[7] Cavalcante Cordeiro de Melo T, Bastos Machado G, Machado RT, Pereira Belchior CR Jr, Pereira PP. Thermodynamic modeling of compression, combustion and expansion processes of gasoline, ethanol and natural gas with experimental validation on a flexible fuel

[8] Pikunas A, Pukalskas S, Grabys J. Influence of composition of gasoline-ethanol blends on parameters of internal combustion engines. Journal of KONES Internal Combustion Engines.

Part A Recovery Utilization and Environmental Effects. 2014;**36**:938-948

emission on an SI engine. Renewable Energy. 2013;**52**:111-117

engine. In: SAE World Congress. 2007. 2007-24-0035

**Figure 15** shows the influence of the blended fuels on NOx emissions. It is noticeable that when methanol and ethanol percentage increases up to 30% E30 (M30), the NOx emission increases, after which it decreases with increasing the percentage of the methanol (ethanol).

The reason is that the improved combustion results in increased temperature in combustion chamber. The higher methanol (ethanol) content in the blends lowers the temperature in combustion chamber. The lower temperature is due to:

