**4. Results**

**FAME Biodiesel fuels**

as used in our models [27].

64 Advances in Biofuels and Bioenergy

**TME LME BME CME PMK PME SFE PTE CSE CNE SNE**

**Table 2.** The groups of gasoline fuel molecules, their molar fractions, and the numbers of components within each group,

C8:0 — — 5.2 6.0 2.6 — — — — — — C10:0 — — 2.8 8.0 4.0 — — — — — — C12:0 0.2 — 3.4 50.0 50.0 0.3 — — — — — C14:0 2.5 1.0 11.0 15.0 17.0 1.3 — 0.5 2.0 1.0 — C15:0 — — — — — — — — — — — C16:0 27.9 26.0 31.7 9.0 8.0 45.1 5.2 8.0 19.0 9.0 5.9 C17:0 — — — — — — — — — — — C18:0 23.0 14.0 10.8 3.0 1.7 4.5 2.2 4.0 2.0 2.5 4.2 C20:0 0.4 — 0.4 — 1.5 0.4 — 7.0 — — 1.4 C22:0 0.4 — 0.4 — 1.5 0.2 — 7.0 — — 1.4 C24:0 — — — — — — — — — — — C16:1 2.5 2.8 2.4 — 0.4 0.2 — 1.5 — 1.5 — C17:1 — — — — — — — — — — — C18:1 40.0 44.0 26.3 7.0 12.0 38.4 76.4 49.0 31.0 40.0 18.5 C20:1 0.3 2.0 1.0 — — — — — 2.5 1.0 — C22:1 0.3 2.0 1.0 — — — — — 2.5 1.0 — C24:1 — — — — — — — — — — — C18:2 2.0 8.0 3.0 2.0 1.3 9.2 16.2 23.0 41.0 44.0 68.3 C20:2 — — — — — — — — — — — C18:3 — — 0.6 — — 0.2 — — — — 0.3 C20:3 — — — — — — — — — — — C18:4 — — — — — — — — — — — Others 0.5 0.2 — — — 0.2 — — — — —

*m* **Group Molar fractions (%) Number of components**

 N-Alkanes 28.50 5 Iso-alkanes 65.18 8 Aromatics 4.40 4 Indanes/naphthalenes 0.10 1 Cycloalkanes 0.33 1 Olefins 1.49 1

#### **4.1. Atomization**

The importance of spray breakup associated phenomena for various applications is well recognized and has been extensively investigated experimentally and numerically by engineers, environmentalists, automotive industrialists, pharmaceutics, and agriculturists [21, 37–41]. A rigorous representation of spray breakup is very complicated procedure as it would involve accurate estimation of nozzle flow, initial formation of ligaments, instabilities, cavitation, and droplets associated physics and their subsequent breakup, heating, evaporation, the entrainment of air and the effects of turbulence [21, 40]. The efficiency of the combustion process and emission reduction in internal combustion engines depends on the atomization characteristics; the most important characteristics of which are droplet Sauter mean diameter (SMD), cone angle, droplet size distributions. The SMD of biodiesel and diesel fuel droplets at temperature 80°C, as reported in [34], are shown in **Table 4**.

**4.3. Blended diesel-biodiesel fuel droplets**

some limited engineering applications.

**Figure 2.** Droplet surface temperatures *Ts*

B20, B50 and B100.

and radii *Rd*

ing at *Ud* <sup>=</sup> 10 ms−<sup>1</sup>

and *<sup>T</sup> <sup>s</sup>*

of *<sup>R</sup> <sup>d</sup>*

The DC model is facilitated for the analysis of heating and evaporation of diesel-biodiesel fuel droplets of initial radius *R*d0 <sup>=</sup> 12.66 μm and temperature *T*<sup>0</sup> <sup>=</sup> 360 K. The droplets are mov-

tures of diesel-biodiesel fuels (B5, B20, B50) and pure biodiesel fuel (B100) of 22 types of biodiesel fuels are analyzed. Typical examples of these results are presented in **Figures 2**–**7**. In **Figures 2**–**7** (some examples of the analyzed blends of diesel-biodiesel fuels), one can see that increasing the concentration of biodiesel from B5 to B100 has a noticeable effect on the evolution

that of B5 during the initial heating period. According to [22], the droplet break-up process can be enhanced as a result of the increase in droplet surface temperature. This can be attributed to the decrease in droplet surface tension. A full illustration of the results provided in **Figures 2**–**7** are shown in **Table 5**. The droplet lifetimes of 22 types of biodiesel fuel mixtures with PD fuel and their differences from the one predicted for PD fuel (2.25 ms) are presented in this table.

As can be seen from **Table 5**, the droplet lifetime for B100 of RME fuel is 6% less than that of PD. This reduction does not exceed 0.4% for the B5 fuel blend for the same fuel. Also, droplet lifetime of TGE biodiesel fuel droplet is noticeably close to that of PD droplet; it is less than 8 and 0.5% for B100 and B5 mixtures, respectively. The maximum difference in droplet lifetimes for these fuels is up to 21.6% (B100 CME), which cannot be sacrificed in any engineering application, and it is always higher than 5.29% (RME) compared to PD, which may be tolerated in

. In addition, the predicted surface temperature of the droplet for B100 is higher than

= 30 bar and *Tg* <sup>=</sup> 800 K,

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

) for three mix-

67

) and radii (*Rd*

versus time for four fractions of diesel-RME biodiesel fuels: B5,

in still air of pressure and temperature equal to *pg*

respectively. The evolutions of droplet surface temperatures (*Ts*


**Table 4.** The SMDs (in μm) of typical biodiesel and diesel fuel droplets at 80°C.

The average value of biodiesel fuel droplet SMDs (25.32 μm) is larger than those of diesel fuel droplets, which can be attributed to the higher viscosity of biodiesel fuels [34].

#### **4.2. Probability density function for biodiesel spray**

It is very important to know how biofuel droplets distribute/spread by size after the atomization. **Figure 1** shows the drop-size probability density for diesel and biodiesel fuels when experimental data [42] are fitted by maximum entropy method [43].

**Figure 1.** Probability density functions of the droplet diameters at distance of 15 mm from nozzle exit [43]; 1- for diesel fuel, 2 - for biodiesel fuel. Experimental data for diesel (•) and biodiesel (×) fuels are inferred from [43, 44].

The case shown in **Figure 1** is close to realistic diesel engine conditions with an injection pressure of 100 MPa. In this case, diesel fuel has emerged from the nozzle orifice with a velocity of about 100 m/s as ultra-high-speed videos shown in [40]. We assumed that biodiesel has a lower mean injection velocity than diesel, but this difference is compensated by the higher value of middle droplet diameters for biodiesel.

#### **4.3. Blended diesel-biodiesel fuel droplets**

the most important characteristics of which are droplet Sauter mean diameter (SMD), cone angle, droplet size distributions. The SMD of biodiesel and diesel fuel droplets at temperature

**Reference PME HME1 HME2 RME SME Diesel** Eq. (3) 25.1 — — 28.8 25.7 17.7 Eq. (4) — 23.55 23.55 26.69 23.87 18.3

The average value of biodiesel fuel droplet SMDs (25.32 μm) is larger than those of diesel fuel

It is very important to know how biofuel droplets distribute/spread by size after the atomization. **Figure 1** shows the drop-size probability density for diesel and biodiesel fuels when

The case shown in **Figure 1** is close to realistic diesel engine conditions with an injection pressure of 100 MPa. In this case, diesel fuel has emerged from the nozzle orifice with a velocity of about 100 m/s as ultra-high-speed videos shown in [40]. We assumed that biodiesel has a lower mean injection velocity than diesel, but this difference is compensated by the higher

**Figure 1.** Probability density functions of the droplet diameters at distance of 15 mm from nozzle exit [43]; 1- for diesel

fuel, 2 - for biodiesel fuel. Experimental data for diesel (•) and biodiesel (×) fuels are inferred from [43, 44].

droplets, which can be attributed to the higher viscosity of biodiesel fuels [34].

experimental data [42] are fitted by maximum entropy method [43].

80°C, as reported in [34], are shown in **Table 4**.

66 Advances in Biofuels and Bioenergy

**4.2. Probability density function for biodiesel spray**

**Table 4.** The SMDs (in μm) of typical biodiesel and diesel fuel droplets at 80°C.

value of middle droplet diameters for biodiesel.

The DC model is facilitated for the analysis of heating and evaporation of diesel-biodiesel fuel droplets of initial radius *R*d0 <sup>=</sup> 12.66 μm and temperature *T*<sup>0</sup> <sup>=</sup> 360 K. The droplets are moving at *Ud* <sup>=</sup> 10 ms−<sup>1</sup> in still air of pressure and temperature equal to *pg* = 30 bar and *Tg* <sup>=</sup> 800 K, respectively. The evolutions of droplet surface temperatures (*Ts* ) and radii (*Rd* ) for three mixtures of diesel-biodiesel fuels (B5, B20, B50) and pure biodiesel fuel (B100) of 22 types of biodiesel fuels are analyzed. Typical examples of these results are presented in **Figures 2**–**7**.

In **Figures 2**–**7** (some examples of the analyzed blends of diesel-biodiesel fuels), one can see that increasing the concentration of biodiesel from B5 to B100 has a noticeable effect on the evolution of *<sup>R</sup> <sup>d</sup>* and *<sup>T</sup> <sup>s</sup>* . In addition, the predicted surface temperature of the droplet for B100 is higher than that of B5 during the initial heating period. According to [22], the droplet break-up process can be enhanced as a result of the increase in droplet surface temperature. This can be attributed to the decrease in droplet surface tension. A full illustration of the results provided in **Figures 2**–**7** are shown in **Table 5**. The droplet lifetimes of 22 types of biodiesel fuel mixtures with PD fuel and their differences from the one predicted for PD fuel (2.25 ms) are presented in this table.

As can be seen from **Table 5**, the droplet lifetime for B100 of RME fuel is 6% less than that of PD. This reduction does not exceed 0.4% for the B5 fuel blend for the same fuel. Also, droplet lifetime of TGE biodiesel fuel droplet is noticeably close to that of PD droplet; it is less than 8 and 0.5% for B100 and B5 mixtures, respectively. The maximum difference in droplet lifetimes for these fuels is up to 21.6% (B100 CME), which cannot be sacrificed in any engineering application, and it is always higher than 5.29% (RME) compared to PD, which may be tolerated in some limited engineering applications.

**Figure 2.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-RME biodiesel fuels: B5, B20, B50 and B100.

**Figure 3.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-CME biodiesel fuels: B5, B20, B50 and B100.

**Figure 4.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-LME biodiesel fuels: B5, B20, B50 and B100.

In some previous studies (for example, see [22, 23]) the heating and evaporation of PD fuel droplets and their comparison to the results of diesel-biodiesel blends were analyzed. For instance, in [23] the droplet lifetime for B100 of WCO was shown to be 11% less than that of PD. While in [22], the droplet lifetime for B100 of SME fuel was shown to be 6% less than that for PD. In this study, similar trends were predicted for the same fuels. This prediction, however, was different for the other types of biodiesel fuel presented in this work. For example, the B100 droplet lifetimes for CME and PMK biodiesel fuels showed deviations of 21.6 and

versus time for four fractions of diesel-HME1 biodiesel fuels: B5,

versus time for four fractions of diesel-SME biodiesel fuels: B5,

Atomization of Bio-Fossil Fuel Blends http://dx.doi.org/10.5772/intechopen.73180 69

and radii *Rd*

and radii *Rd*

18%, respectively, from that of PD fuel.

**Figure 6.** Droplet surface temperatures *Ts*

**Figure 5.** Droplet surface temperatures *Ts*

B20, B50 and B100.

B20, B50 and B100.

**Figure 5.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-SME biodiesel fuels: B5, B20, B50 and B100.

**Figure 6.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-HME1 biodiesel fuels: B5, B20, B50 and B100.

for PD. In this study, similar trends were predicted for the same fuels. This prediction, however, was different for the other types of biodiesel fuel presented in this work. For example, the B100 droplet lifetimes for CME and PMK biodiesel fuels showed deviations of 21.6 and 18%, respectively, from that of PD fuel.

In some previous studies (for example, see [22, 23]) the heating and evaporation of PD fuel droplets and their comparison to the results of diesel-biodiesel blends were analyzed. For instance, in [23] the droplet lifetime for B100 of WCO was shown to be 11% less than that of PD. While in [22], the droplet lifetime for B100 of SME fuel was shown to be 6% less than that

versus time for four fractions of diesel-LME biodiesel fuels: B5,

versus time for four fractions of diesel-CME biodiesel fuels: B5,

and radii *Rd*

and radii *Rd*

**Figure 4.** Droplet surface temperatures *Ts*

**Figure 3.** Droplet surface temperatures *Ts*

68 Advances in Biofuels and Bioenergy

B20, B50 and B100.

B20, B50 and B100.

**Figure 7.** Droplet surface temperatures *Ts* and radii *Rd* versus time for four fractions of diesel-WCO biodiesel fuels: B5, B20, B50 and B100.

A general trend shows that droplets' lifetimes of all 22 types of B5 diesel-biodiesel blends that are used in this study deviate with less than 1% from the one predicated for PD droplets. This concludes the possibility of labeling diesel-biodiesel blends, with up to about 5% biodiesel concentration, without modifying the automotive system is achievable. For some fuel blends (for example B20 RME, TGE, LNE, and HME1), this deviation (up to 2%) is still relatively negligible to mix higher biodiesel concentrations (for example, 20% biodiesel and 80% diesel fuels) without losing the main feature of these processes (i.e. droplet lifetime).

The difference in thermodynamic and transport properties between hydrocarbons and methyl esters is the main reason for the influence of biodiesel fuel fractions on the heating and evaporation of diesel fuel droplets. For instance, when increasing the biodiesel fractions, the droplet surface temperature tends to reach a plateau during the evaporation process, which is similar to the case of single component model (see [20, 28]). Also, the significance of such behavior can change depending on the input parameters and ambient conditions.

expense of the lighter ones leading to different properties of duel near the evaporation time. The impacts of ambient pressure on the estimated droplet lifetimes of various LME biodiesel-

**Table 5.** Estimation of biodiesel fuel droplets lifetimes and their differences compared with those of PD fuel (2.25 ms),

**B100 B50 B20 B5**

TME 1.967 12.6 2.102 6.6 2.184 2.9 2.232 0.80 LME 1.995 11.3 2.114 6.0 2.190 2.7 2.234 0.71 BME 1.943 13.6 2.089 7.2 2.180 3.1 2.232 0.80 CME 1.765 21.6 2.036 9.5 2.166 3.7 2.229 0.93 PMK 1.846 18.0 2.050 8.9 2.169 3.6 2.230 0.89 PME 1.944 13.6 2.097 6.8 2.183 3.0 2.232 0.80 SFE 1.980 12.0 2.122 5.7 2.195 2.4 2.235 0.67 PTE 2.052 8.8 2.138 5.0 2.199 2.3 2.236 0.62 CSE 2.014 10.5 2.128 5.4 2.197 2.4 2.236 0.62 CNE 2.002 11.0 2.128 5.4 2.197 2.4 2.236 0.62 SNE 2.011 10.6 2.132 5.2 2.200 2.2 2.237 0.58 SME 1.981 12.0 2.127 5.5 2.198 2.3 2.236 0.62 RME 2.131 5.3 2.188 2.8 2.222 1.2 2.242 0.36 LNE 1.991 11.5 2.141 4.8 2.206 2.0 2.239 0.49 TGE 2.085 7.3 2.160 4.0 2.211 1.7 2.240 0.44 HME1 2.022 10.1 2.138 5.0 2.203 2.1 2.237 0.58 HME2 1.994 11.4 2.135 5.1 2.202 2.1 2.238 0.53 CAN 2.014 10.5 2.130 5.3 2.199 2.3 2.236 0.62 WCO 2.002 11.0 2.121 5.7 2.194 2.5 2.235 0.67 CML 2.064 8.3 2.153 4.3 2.209 1.8 2.239 0.49 JTR 2.047 9.0 2.133 5.2 2.198 2.3 2.236 0.62 YGR 2.077 7.7 2.149 4.5 2.203 2.1 2.237 0.58

**Diff. (%)**

**Lifetime (ms)**

**Diff. (%)**

**Lifetime (ms)**

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

> **Diff. (%)**

71

**Lifetime (ms)**

It can be seen from **Figure 9** that the impacts of increasing ambient pressure (20–60 bar) at a relatively high ambient temperature (800 K) on reducing the estimated droplet lifetimes are proportional with almost the same effect for all mixtures (B5 – B100), but with lower droplet lifetimes for B100 and higher ones for B5. One can see that the difference in droplet lifetimes for different blends increase with increasing ambient pressure. Typical ambient pressure at diesel injection time is about 32 bar, however, it can be concluded that minimizing the pressure to 32 bar is better for high blend ratios, as the less the pressure the less the expected deviation in droplet lifetimes.

diesel mixtures are shown in **Figure 9**.

under the same conditions shown in **Figures 2**–**7**.

**Biodiesel fuels**

**Lifetime (ms)**

**Diff. (%)**

A typical example of time evolutions of mass fractions at the surface of droplets (*Ylis*) of selected nine species of B50 fuel mixture of diesel with RME is shown in **Figure 8**; in which, the curves 1, 2 and 3, refer to alkane hydrocarbons of C27H56, C25H52 and C23H48, respectively; and the curves 4, 5 and 6, refer to cycloalkane hydrocarbons of C27H54, *C*25H50 and C23H46, respectively; and the curves, 7 and 8, refer to rapeseed methyl esters of C19H36O2 and C19H34O2 , respectively, under the same conditions used in **Figures 2**–**7**.

As can be seen from **Figure 8**, the diffusion of mass fractions of components at the surface of droplets is typical and similar to those presented in previous studies. The mass fractions of the heavy components, for example C27H56 (1) and C27H54 (4), increase with time at the


A general trend shows that droplets' lifetimes of all 22 types of B5 diesel-biodiesel blends that are used in this study deviate with less than 1% from the one predicated for PD droplets. This concludes the possibility of labeling diesel-biodiesel blends, with up to about 5% biodiesel concentration, without modifying the automotive system is achievable. For some fuel blends (for example B20 RME, TGE, LNE, and HME1), this deviation (up to 2%) is still relatively negligible to mix higher biodiesel concentrations (for example, 20% biodiesel and 80% diesel

The difference in thermodynamic and transport properties between hydrocarbons and methyl esters is the main reason for the influence of biodiesel fuel fractions on the heating and evaporation of diesel fuel droplets. For instance, when increasing the biodiesel fractions, the droplet surface temperature tends to reach a plateau during the evaporation process, which is similar to the case of single component model (see [20, 28]). Also, the significance of such behavior

A typical example of time evolutions of mass fractions at the surface of droplets (*Ylis*) of selected nine species of B50 fuel mixture of diesel with RME is shown in **Figure 8**; in which, the curves 1, 2 and 3, refer to alkane hydrocarbons of C27H56, C25H52 and C23H48, respectively; and the curves 4, 5 and 6, refer to cycloalkane hydrocarbons of C27H54, *C*25H50 and C23H46, respectively;

As can be seen from **Figure 8**, the diffusion of mass fractions of components at the surface of droplets is typical and similar to those presented in previous studies. The mass fractions of the heavy components, for example C27H56 (1) and C27H54 (4), increase with time at the

and C19H34O2

versus time for four fractions of diesel-WCO biodiesel fuels: B5,

, respectively,

fuels) without losing the main feature of these processes (i.e. droplet lifetime).

and radii *Rd*

can change depending on the input parameters and ambient conditions.

and the curves, 7 and 8, refer to rapeseed methyl esters of C19H36O2

under the same conditions used in **Figures 2**–**7**.

**Figure 7.** Droplet surface temperatures *Ts*

70 Advances in Biofuels and Bioenergy

B20, B50 and B100.

**Table 5.** Estimation of biodiesel fuel droplets lifetimes and their differences compared with those of PD fuel (2.25 ms), under the same conditions shown in **Figures 2**–**7**.

expense of the lighter ones leading to different properties of duel near the evaporation time. The impacts of ambient pressure on the estimated droplet lifetimes of various LME biodieseldiesel mixtures are shown in **Figure 9**.

It can be seen from **Figure 9** that the impacts of increasing ambient pressure (20–60 bar) at a relatively high ambient temperature (800 K) on reducing the estimated droplet lifetimes are proportional with almost the same effect for all mixtures (B5 – B100), but with lower droplet lifetimes for B100 and higher ones for B5. One can see that the difference in droplet lifetimes for different blends increase with increasing ambient pressure. Typical ambient pressure at diesel injection time is about 32 bar, however, it can be concluded that minimizing the pressure to 32 bar is better for high blend ratios, as the less the pressure the less the expected deviation in droplet lifetimes.

In **Figures 10**–**11**, the plots for droplet radii and transient surface temperatures are shown,

Atomization of Bio-Fossil Fuel Blends http://dx.doi.org/10.5772/intechopen.73180 73

In **Figure 10**, the droplet lifetime for pure gasoline fuel (E0) is the smallest. This increases with the increase of ethanol fraction from E0 to E100. The error in predicted droplet lifetime of E100 is

versus time for six fractions of ethanol-gasoline fuels: E0, E5, E20, E50, E85 and E100.

versus time for six fractions of ethanol-gasoline fuels: E0, E5, E20, E50, E85

respectively, for six mixing ratios of ethanol-gasoline fuel blends (E0 – E100).

**Figure 10.** Droplet radii *Rd*

**Figure 11.** Droplet surface temperatures *Ts*

and E100.

**Figure 8.** The liquid mass fractions at the surface of droplet (*Ylis*) versus time for selected 8 components of 106 components of B50 (50% diesel hydrocarbons and 50% rapeseed methyl ester (RME)) fuel mixture.

**Figure 9.** The effect of ambient pressure on diesel-biodiesel (LME) droplet lifetimes.

#### **4.4. Blended ethanol-gasoline fuel droplets**

The DC model is facilitated for the analysis of heating and evaporation of ethanol-gasoline fuel droplets of initial radius *R*d0 <sup>=</sup> 12μm and temperature *T*<sup>0</sup> <sup>=</sup> 296 K. The droplets are assumed to be moving at *Ud* <sup>=</sup> 24 ms‐<sup>1</sup> in still air of pressure and temperature equal to *pg* <sup>=</sup> 9 bar and *Tg* <sup>=</sup> 545 K, respectively. The evolutions of droplet surface temperatures (*Ts* ) and radii (*Rd* ) for the ethanol-gasoline fuel mixtures are analyzed. The mixtures are: E0 (pure gasoline), E5 (5% ethanol, 95% gasoline), E20 (20% ethanol, 80% gasoline), E50 (50% ethanol, 50% gasoline), E85 (85% ethanol, 15% gasoline) and E100 (pure ethanol).

In **Figures 10**–**11**, the plots for droplet radii and transient surface temperatures are shown, respectively, for six mixing ratios of ethanol-gasoline fuel blends (E0 – E100).

In **Figure 10**, the droplet lifetime for pure gasoline fuel (E0) is the smallest. This increases with the increase of ethanol fraction from E0 to E100. The error in predicted droplet lifetime of E100 is

**Figure 10.** Droplet radii *Rd* versus time for six fractions of ethanol-gasoline fuels: E0, E5, E20, E50, E85 and E100.

**4.4. Blended ethanol-gasoline fuel droplets**

(85% ethanol, 15% gasoline) and E100 (pure ethanol).

to be moving at *Ud* <sup>=</sup> 24 ms‐<sup>1</sup>

72 Advances in Biofuels and Bioenergy

The DC model is facilitated for the analysis of heating and evaporation of ethanol-gasoline fuel droplets of initial radius *R*d0 <sup>=</sup> 12μm and temperature *T*<sup>0</sup> <sup>=</sup> 296 K. The droplets are assumed

**Figure 8.** The liquid mass fractions at the surface of droplet (*Ylis*) versus time for selected 8 components of 106 components

of B50 (50% diesel hydrocarbons and 50% rapeseed methyl ester (RME)) fuel mixture.

the ethanol-gasoline fuel mixtures are analyzed. The mixtures are: E0 (pure gasoline), E5 (5% ethanol, 95% gasoline), E20 (20% ethanol, 80% gasoline), E50 (50% ethanol, 50% gasoline), E85

*Tg* <sup>=</sup> 545 K, respectively. The evolutions of droplet surface temperatures (*Ts*

**Figure 9.** The effect of ambient pressure on diesel-biodiesel (LME) droplet lifetimes.

in still air of pressure and temperature equal to *pg* <sup>=</sup> 9 bar and

) and radii (*Rd*

) for

**Figure 11.** Droplet surface temperatures *Ts* versus time for six fractions of ethanol-gasoline fuels: E0, E5, E20, E50, E85 and E100.


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

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

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

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 almost the same effect for all ethanol-gasoline blends.

**5. Conclusion**

ambient temperature 650 K.

methyl esters.

greater for E20.

reasonable agreement between both results.

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

**Figure 13.** The impact of ambient pressures on droplet lifetimes for E0, E50, E85 and E100 fuel blends, estimated at

Atomization of Bio-Fossil Fuel Blends http://dx.doi.org/10.5772/intechopen.73180 75

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

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%

**Figure 12.** The impact of ambient temperatures on droplet lifetimes for E0, E50, E85 and E100 fuel blends, estimated at ambient pressures 3 and 20 bar.

**Figure 13.** The impact of ambient pressures on droplet lifetimes for E0, E50, E85 and E100 fuel blends, estimated at ambient temperature 650 K.
