**5. Conclusion**

33.9% compared to the one predicted for E0. In **Figure 11**, the impact of increasing the ethanol/ gasoline fraction from E0 to E100 is seen to be significant. The deviation in the predicted droplet surface temperature for E100 is 24.3% compared to the one predicted for E0. The impacts of dif-

Diff % <sup>=</sup> |(*tim eEN* –*tim eE*0)| \_\_\_\_\_\_\_\_\_\_\_\_\_\_ *tim eE*<sup>0</sup>

The droplet lifetimes of ethanol-gasoline fuel mixtures (**Figures 10**–**11**) have been estimated under standard engine conditions. The impact of different ambient conditions on these pre-

As can be seen from **Figures 12** and **13**, increasing the ambient temperature (500 to 650 K), or pressure (3 to 20 bar), leads to a proportional reduction in estimated droplet lifetimes with

**Figure 12.** The impact of ambient temperatures on droplet lifetimes for E0, E50, E85 and E100 fuel blends, estimated at

ferent ethanol/gasoline fuel mixtures on droplet lifetimes are presented in **Table 6**.

dictions is presented in **Figures 12** and **13**.

**Blends Time (ms) Diff%** E0 1.988 —

74 Advances in Biofuels and Bioenergy

E50 2.093 5.282 E85 2.356 18.511

E100 2.662 33.903

E5 1.989 0.050 *Note:*

E20 1.994 0.302 × 100%

**Table 6.** The impact of ethanol/gasoline fuel blends on the estimated droplet lifetimes.

ambient pressures 3 and 20 bar.

almost the same effect for all ethanol-gasoline blends.

In this chapter, the maximum entropy method was applied for the droplet distribution of diesel and biodiesel fuel sprays in conditions relevant to diesel internal combustion engines. The droplet distribution for biodiesel was more skewed to the right compared to the predicted diesel spray. The theoretical distribution indicated that biodiesel fuel droplets are larger than those of diesel fuel. The model was validated against available experimental data to show a reasonable agreement between both results.

The discrete component model was used to analyze the heating and evaporation of blended diesel-biodiesel fuel sprays and droplets using 22 types of biodiesel, European standard diesel, gasoline FACE C, and ethanol-gasoline fuels. The full compositions of diesel, biodiesel and gasoline fuels were considered. The diesel and gasoline fuels consisted of 98 and 20 hydrocarbons respectively, while the 22 biodiesel fuels consisted of 4 to 18 components of methyl esters.

The effect of increasing biodiesel fuel concentration on the evolutions of droplet surface temperatures and evaporation times was clearly illustrated. The predicted B5 fuel droplet lifetimes for the 22 types of biodiesel fuel were only 1% less than that of pure diesel (PD) fuel. The RME biodiesel fuel droplets were observed to have lifetimes close to that of PD fuel, where their predicted lifetimes for B5 and B100 droplets were up to 0.4 and 0.6%, respectively, less than the one estimated for PD fuel droplet. However, for ethanol, the predicted E5 fuel droplet lifetimes were only 0.05% greater than that of pure gasoline (E0) and only 0.3% greater for E20.

To conclude, the B5 fuel droplet lifetimes for all 22 types of biodiesel fuels used in this study are almost identical to the one predicted for PD fuel; i.e. diesel fuel can be possibly blended with up to 5% biodiesel fuel without any noticeable effect on the evolutions of their droplet radii or surface temperatures. Similarly, the E5 and E20 fuel droplet lifetimes are almost identical to the one predicted for E0 fuel; i.e. gasoline fuel can be possibly blended with up to 20% ethanol fuel without/minimal modifications to the gasoline engine. Also, increasing the ambient pressure, or temperature, will lead to a faster evaporation of E0-E100 droplets regardless of their blending ratios.

LP length parameter PD pure diesel fuel E0 pure gasoline fuel PME palm methyl ester

PMK palm kernel methyl ester

Atomization of Bio-Fossil Fuel Blends http://dx.doi.org/10.5772/intechopen.73180 77

PTE peanut methyl ester RME rapeseed methyl ester SFE safflower methyl ester SMD Sauter mean diameter SME soybean methyl ester SNE sunflower methyl ester

TGE tung methyl ester TME tallow methyl ester WCO waste cooking oil

Symbols

YGR yellow grease methyl ester

*A* spray penetration coefficient

*D* diffusion coefficient [m<sup>2</sup> s−1]

*k* thermal conductivity [W m−1 K−1]

*d* nozzle diameter [m]

*p* pressure [Pa]

*R* radius [μm]

*U* velocity [ms−1] *Y* mass fraction

*κ* thermal diffusivity

*ρ* density [kg m−3]

*μ* dynamic viscosity [Pa s]

*t* time [ms]

*T* temperature [K]
