Effect of Gasoline Fuel Additives on Combustion and Engine Performance

Particle/Droplet Image Analysis 
PFI
Port Fuel Injection 

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17 
PM
Particulate Matter 
PMT
Photomultiplier Tube 
PN 
Particulate Number 
PPM
parts per million, mg/L 
PT 
Pressure Transducer 
RCM
Rapid Compression Machine 
SG 
Shadowgraph(y) 
SI 
Spark Ignition 
SMD
Sauter Mean Diameter 
SOI
Start of Injection 
Symbols
 
A 
Area
(m
2
) 
A
Constant. 25.1 for pintle nozzles, 23.9 for hole
nozzles, 22.4 for throttling pintle nozzles. 
B, C
Constant determined by nozzle geometry 
f 
focal length 
ν
Kinematic viscosity of fuel
(m
2
/s) 
σ
Surface tension 
(N/m) 
ρ
Density 
(kg/m
3
) 
µ 
Viscosity of fuel 
(Pa*s) 
θ 
Half cone angle of spray/ Contact angle 
(°) 
ΔP
Mean pressure drop across the nozzle 
(MPa) 
Q 
Injection quantity 
(m
3
/stroke) 
Q’ 
Injection quantity 
(kg/s) 
t 
Liquid film thickness at plane of discharge from nozzle 
(m) 
V
Volume of fuel per cycle per cylinder 
(m
3
/stroke)
 
Subscripts and Superscripts 
a 
Air 
c 
Critical 
eff 
Total effective for all nozzle holes at ΔP 
f 
Fuel 

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18 
fc 
Fuel per cycle per cylinder 
g 
Gas 
l 
Liquid 
orf 
Total for all nozzle holes 

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1.1 Background on Additives 
19 
 
 
Chapter 1 
1
 
Introduction 
The discovery of crude oil in the middle of 19
th
century and the subsequent 
development of the internal combustion engine have led the use of fossil fuels to 
increase exponentially. Figure 1.1 displays the increase in the number of cars and fuel 
usage throughout the last century in USA. Similar trends can be seen throughout the
Figure 1.1: Fuel Usage and Number of Cars in the USA throughout 20th century [1, 2] 
-
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
-
50,000
100,000
150,000
200,000
1890
1910
1930
1950
1970
1990
2010
Gas
oli
n
e 
D
ai
ly
 S
u
p
p
ly
, t
h
ou
sa
n
d
 b
ar
rel
s
N
u
m
b
e
r 
o
f R
e
gi
ste
re
d
 Car
s,
 t
h
o
u
san
d
s
Year
Number of Cars
Gasoline Supply

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1.1 Background on Additives 
20 
developed world. It has been widely accepted that the emissions from burning fossil 
fuels contribute towards climate change and air pollution. As a result increasingly 
stringent regulations, for instance the EURO 1-6 emission standards shown in Table 
1.1, concerning fuel efficiency and emissions are imposed on new vehicles. The need 
for compliance with the regulations has been among driving forces behind advances 
in engine and fuel technologies. Among techniques employed to improve the fuel’s 
performance is the use of fuel additives. They are a chemical tool used to improve fuel 
properties and offer great advantages from environmental and economic point of view.