Effect of Gasoline Fuel Additives on Combustion and Engine Performance

Figure 4.17: Heat release and pressure rise traces for spray combustion under ambient 
temperature and 5 bar (gauge) air pressure conditions 
Figure 4.18: Gasoline spray combustion under ambient temperature and 5 bar (gauge) air 
pressure. Images taken at 9,000 fps with Nikon 60 mm f/1.8 lens 
Although successful combustion could be reached at low temperatures, high 
soot content and low experimental repeatability was seen. As such, further studies 
under heated air and pre-combustion environments were conducted. Figure 4.19 
displays a spray combustion using the pre-combustion method described in Chapter 3 
with hydrogen as the fuel. Hydrogen pre-combustion prior to the spray caused the 
spray combustion duration to decrease by around 10-15 ms although peak pressure 
change due to the combustion event remained below 0.1 bar. Spray combustion with
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0
20
40
60
80
100
H
R
R
, kJ
/s
Pr
e
ssur
e
, b
ar
Time, ms
Pressure
HRR

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4.2 Combustion Investigations 
108 
Figure 4.19: Gasoline spray combustion using hydrogen pre-combustion (hydrogen-air 
mixture φ = 0.3) (Not same as Figure 4.17) Images taken at 6,000 fps with Nikon 50 mm 
f/1.2 lens 
heated air produced similar results. As previously mentioned, the full range of the 
pressure transducers used in the study was 0-100 bar and 0-250 bar raising concerns 
over the accuracy of readings at such low pressure change levels. Although the 
dynamic sensor could support low pressure changes, the second 0-100 bar transducer 
could only offer accuracies of 0.25 % or 0.25 bar which was up to 5 times higher than 
the measured pressure rise as a result of a combustion event.