Effect of Gasoline Fuel Additives on Combustion and Engine Performance

SM
D
, 
µm
Temperature, deg C
100% Dodecane
50/50 Mixture
100% Hexene

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5.2 Droplet Sizing with Alternative Fuels 
130 
diesel and gasoline fuels, diesel to be more affected by temperature changes. This was 
thought to be due to much higher initial viscosity of diesel compared to gasoline (also 
hexene and dodecane for current set of experiments) that for the same temperature 
range will decrease more rapidly. However, the SMD values measured for different 
temperatures exhibit very good agreement with the theory that fuel properties change 
proportionately to their constituent components. The SMD for the 50/50 mixture 
clearly lies in the middle of the two pure component fuels without any clear tendencies 
towards either. 
5.2.2.2
 
Toluene and Heptane Binary Mixtures 
Further experiments with toluene and n-heptane with an additional 50% binary 
mixture were carried out. Results are presented in Figure 5.15. Although similar in 
carbon molecule number and boiling point, toluene and n-heptane differ greatly in 
molecular structure. Hellier et al. [242] found a 75% n-heptane / 25% toluene binary 
mixture to cause two stage ignition and more than 50% toluene in the mixture to 
suppress ignition altogether.
Figure 5.15: Droplet size for of toluene, heptane and a 50% binary mixture at minimum 
transmission 
Measurements were carried out to look for any significant changes in binary 
mixture physical properties that would explain the combustion phenomena but similar 
proportional relationship of the components in the mixture to the pure fuels as 
previously was seen. As such, changes to ignition characteristics were attributed to 
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