Effect of Gasoline Fuel Additives on Combustion and Engine Performance

3.2.1.3
 
Emissions Analysis 
Emissions were analysed using a Horiba MEXA 9100 HEGR gas analyser. 
The analyser measures NO
x
emissions through chemiluminescence. CO and CO
2
230
232
234
236
238
240
242
244
246
248
250
0
5
10
15
20
Sp
a
rk
 Sig
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l 
to
 Sta
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 o
f 
Sp
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, 
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Spark Event, No

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3.2 Combustion Experiments 
88 
content is established using non-dispersive infrared analyser. The analyser can further 
measure unburnt hydrocarbon content using the flame ionisation method. Due to the 
distance of the gas analyser from the combustion vessel, fuel condensation in gas lines 
was likely, resulting in false hydrocarbon readings. Furthermore, the GDI combustion 
method means misfires can occur as a result of spray variability and any hydrocarbons 
detected might not represent additive effects. Therefore, no hydrocarbon emissions 
were measured for any set of combustion experiments.
The combustion efficiency could additionally be evaluated by analysing the 
soot contents with a Cambustion DMS500 particulate spectrometer. The device 
produces output in terms of particle size, number and mass. 
3.2.1.4
 
Combustion Apparatus Overview 
Schematics of the experimental rig for the combustion experiments can be seen 
in Figure 3.13. Main changes included an ignition and pre-heating systems. High 
speed imaging was used with spray combustion as a means of qualitative analysis. 
Quantitative analysis is carried out based on methods describe in Section 2.4.1 using 
pressure data.