Effect of Gasoline Fuel Additives on Combustion and Engine Performance

6.2
 
Gasoline Vapour Combustion 
Figure 6.1 displays sample images of the flames captured with high speed 
imaging. The flames for CI-A at 1X and 10X concentration produced similar if not 
slightly brighter luminosity compared to the base fuel. CI-I flame burned at much 
lower brightness with the flame for 10X fuel being while CI-Additional seemed to be 
affected the most by the additive. As described by ATC [255], organometallic anti-
knock additives are utilised as catalysts for the burn-out of soot particles. This was 
represented by localised bright spots throughout the combustion event. 
The main outcomes of combustion vessel investigations are presented in 
Figures 6.2 – 6.7. Figure 6.2 displays the relationship between the peak pressure and 
peak heat release rates. It can be seen that a positive correlation exists. This is due to 
factors described in Section 2.4.1. A positive relationship was also experienced 
between NO
x
emissions and peak pressures, as presented in Figure 6.3. This was 
expected, as higher pressure results from higher temperature which is a precursor for

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6.2 Gasoline Vapour Combustion 
140 
Figure 6.1: Sample flames of additive combustion at t = 29 ms after ignition 
Figure 6.2: Relationship between peak heat release rate and peak pressure reached within 
the combustion chamber 
NO
x
formation during combustion. Although it has been suggested by some 
researchers [48, 49] that additive bound nitrogen compounds can increase NO
x
emissions, the results of current study have not provided evidence to support the 
claims.
1,000
1,050
1,100
1,150
1,200
1,250
1,300
1,350
1,400
1,450
7.1
7.3
7.5
7.7
7.9
8.1