Note: Descriptions are shown in the official language in which they were submitted.
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Diesel fuel compositions
The present invention relates to diesel fuel
compositions, their preparation and their use in diesel
engines, and to the use of additives in diesel fuel
compositions.
Some compression-ignition (diesel) engines appear to
suffer power loss after a period of use. The phenomenon
is to date poorly understood, but seems particularly to
affect direct injection (DI) diesel engines.
The problem may also be more marked when using fuels
with a low volumetric~energy content, for example low or
ultra low sulphur fuels or fuels with a relatively low
density (such as those containing Fischer-Tropsch methane
condensation products). Such fuels are often used where
lower vehicle emissions are a priority, or where there
are constraints on the nature or level of undesirable
fuel components.
It has now surprisingly been found that the use of
certain additives in a diesel fuel can reduce and in some
cases reverse power loss. A suitably additivated fuel
can therefore be used to help maintain and/or improve
engine performance. The additives may in particular be
used to enhance performance of an otherwise relatively
low energy fuel.
The use of such additives has moreover been found to
give other benefits, including reduced smoke and
particulate emissions.
According to a first aspect of the present invention
there is provided the use of a detergent-containing fuel
additive in a diesel fuel composition, for the purpose of
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reducing subsequent power loss in a diesel engine into
which the fuel composition is introduced.
According to a second aspect of the present
invention there is provided the use of a detergent-
s containing fuel additive in a diesel fuel composition,
for the purpose of reversing a previously incurred power
loss in a diesel engine into which the fuel composition
is introduced.
In this context, "reducing" includes complete
l0 prevention, and "reversing" embraces both complete and
partial reversal. "Use" of the additive in a fuel
composition means incorporating the additive into the
fuel composition, conveniently before the composition is
introduced into the engine.
15 Power loss in the engine may be manifested by, for
example, a reduction in tractive effort and/or
acceleration rate in a vehicle being driven by the
engine. Conversely, reversal of a previously incurred
power loss will mean an increase in engine power output,
20 which may be manifested by an increase in vehicle
tractive effort and/or a reduction in acceleration times.
A reduction in subsequent power loss will inhibit the
reduction in tractive effort and/or acceleration rate
which would otherwise have been expected, for instance
25 extrapolating from previous performance, in particular
compared to that which would have occurred had the engine
been run on an unadditivated fuel or a fuel containing
less, or no, detergent. In accordance with the present
invention, therefore, a detergent-containing additive may
30 be incorporated into a fuel composition with the aim of
achieving these indirect effects.
The present invention is particularly applicable
where the fuel composition is used or intended to be used
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in a direct injection diesel engine, for example of the
rotary pump, electronic unit injector or common rail
type. It may be of particular value for rotary pump
engines, in which power loss can be especially marked,
and in other diesel engines which rely on mechanical
actuation of the fuel injectors and/or a low pressure
pilot injection system.
The diesel fuel composition may be of an otherwise
conventional type, typically comprising liquid
hydrocarbon middle distillate fuel oils. However it may
in particular comprise a low or ultra low sulphur content
fuel, for instance containing at most 500 ppmw.(parts per
million by weight) sulphur, preferably less than 300
ppmw, more preferably less than 250 ppmw, still more
preferably no more than 100 ppmw, most preferably no more
than 60 or 50 or even 10 ppmw. It may be, or contain a
proportion (for instance, 10 o v/v or more) of, reaction
products of a Fischer-Tropsch methane condensation
process such as the. process known as. Shell Middle
Distillate Synthesis (SMDS) - such reaction products
suitably have boiling points within the typical diesel
fuel range (between about 150 and 370 °C), a density of
between about 0.76 and 0.79 g/cm3 at 15°C, a cetane
number greater than 72.7 (typically between about 75 and
82), a sulphur content of less than 5 ppmw, a viscosity
between about 2.9 and 3.7 centistokes (mm2/s) at 40 °C
and an aromatics content of no greater than 1 % w/w.
The diesel fuel composition may comprise a
relatively low density fuel, such as a fuel having a
density of less than 0.840 g/cm3, preferably less than
0.835 g/cm3, at 15°C. In fuels of these types, the
detergent-containing additive may be used for the purpose
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of compensating for the fuel.'s inherently lower energy
content. In other words, the additive may be used
generally to increase the power provided by a fuel
composition during subsequent use.
The additive must contain a detergent, by which is
meant an agent (suitably a surfactant) which can act to
remove, and/or to prevent the build up of, combustion
related deposits within the engine, in particular in the
fuel injection system such as~in the injector nozzles.
Such materials are sometimes referred to as dispersant
additives. Although we do not wish to be bound by this
theory,° the build up of combustion related deposits is
now believed to be at least partially responsible for
power loss in direct injection diesel engines.
The detergent is preferably included in the fuel
composition at a concentration sufficient to recover, at
least partially, power lost in the engine during a period
of running using another fuel (typically unadditivated,
or containing only low levels of, if any, detergent).
This is generally a concentration sufficient to remove,
at least partially, combustion related deposits which
have built up in the engine's fuel injection system, in
particular in the injector nozzles. It will depend on
the nature of the detergent, but preferred values lie in
the range 100 to 500 ppmw active matter detergent based
on the overall additivated fuel composition, more
preferably 150 to 300 ppmw. In the case of most
commercially available detergent-containing diesel fuel
additives, this will mean incorporating the additive at
levels higher than the standard recommended single treat
rate, for example between 1.2 and 3 times, preferably
between 1.5 and 2.5 times, such as about twice the
standard single treat rate.
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Lower detergent levels (for example, corresponding
to between 0.5 and 1.2 times, preferably the same as, the
standard single treat rate) may be used to reduce,
ideally tb prevent, further power losses as opposed to
reversing previously incurred losses.
Preferably the quantity of detergent-containing
additive used is sufficient to recover at least 25 0,
more preferably at least 50 % or 75 % or 90 % or 95 0,
most preferably 100 0, of power lost in the engine during
a previous period of use with a different fuel
composition, when the engine is subsequently run on the
detergent-containing fuel composition for a comparable
number of miles and under comparable driving conditions.
Even more preferably, the amount of detergent present is
sufficient to provide the stated recovery of power (which
may equate to a corresponding reduction in combustion
related deposits) when the engine is subsequently run on
the detergent-containing fuel composition for 75 %, yet
more preferably 50 0 or even 40 0 or 30 %, of the number
of miles covered on the previous fuel, again under
comparable driving conditions. The previous fuel may for
instance be an unadditivated diesel fuel composition,.or
one containing no, or no more than 50 or even 20 ppmw,
active matter detergent. _
Alternatively, the detergent-containing additive may
be used in a quantity sufficient to reduce by at least 25
o, preferably at least 50 a, more preferably at least 75
%, most preferably at least 90 0, such as by 100 0, the
amount of power loss incurred (which may equate to a
corresponding increase in combustion related deposits) .
when running the engine on the fuel composition, as
compared to that incurred when running the engine, under
comparable driving conditions, on an unadditivated fuel
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composition or one containing no, or no more than 50 or
20 ppmw, active matter detergent.
As explained above, engine power may be assessed
with reference to, for example, vehicle tractive effort
and/or acceleration times.
The degree of power recovery achievable by using, in
accordance with the invention, a detergent-containing
additive may conveniently be assessed using a method
according to the seventh aspect of the invention,
described below.
Detergent-containing diesel fuel additives are known
and commercially available, for instance from Infineum
(eg, F7661 and F7685) and Octel (eg, OMA 4130D). In the
past such additives have been added to diesel fuels at
relatively low levels (their "standard" treat rates
providing typically less than 100 ppmw active matter
detergent in the overall additivated fuel composition)
intended merely to reduce or slow the build up of engine
deposits. The additives have not to our knowledge been
used for the purpose of increasing engine power, and in
particular not at levels high enough to reverse
previously incurred power loss. That they are capable.of
achieving this is especially surprising.
Examples of detergents suitable f or use in fuel
additives for the present purpose include polyolefin
substituted succinimides or succinamides of polyamines,
for instance polyisobutylene succinimides or
polyisobutylene amine succinamides, aliphatic amines,
Mannish bases or amines and polyolefin (eg,
polyisobutylene) malefic anhydrides. Succinimide
dispersant additives are described for example in
GB-A-960493, EP-A-0147240, EP-A-0482253, EP-A-0613938,
EP-A-0557561 and WO-A-98/42808. Particularly preferred
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are polyolefin substituted succinimides such as
polyisobutylene succinimides.
The additive may contain other components in
addition to the detergent. Examples are lubricity
enhancers; dehazers, eg, alkoxylated phenol formaldehyde
polymers such as those commercially available as NALCOT""
EC5462A (formerly 7D07) (ex Nalco) , and TOLADT"' 2683 (ex
Petrolite); anti-foaming agents (eg, the polyether-
modified polysiloxanes commercially available as
TEGOPRENT"" 5851 and Q 25907 (ex Dow Corning) , SAGT"' TP-325
(ex OSi), or RHODORSILT"' (ex Rhone Poulenc));~ignition
improvers (cetane improvers) (eg, 2-ethylhexyl nitrate
(EHN), cyclohexyl nitrate, di-tert-butyl peroxide and
those disclosed in US-A-4208190 at column 2, line 27 to
column 3, line 21); anti-rust agents (eg, that sold
commercially by Rhein Chemie, Mannheim, Germany as "RC
4801", a propane-1, 2-diol semi-ester of tetrapropenyl
succinic acid, or polyhydric alcohol_esters of a succinic
acid derivative, the succinic acid derivative having on
at least one of its alpha-carbon atoms an unsubstituted
or substituted aliphatic hydrocarbon group containing
from 20 to 500 carbon atoms, eg, the pentaerythritol
diester of polyisobutylene-substituted succinic acid);
corrosion inhibitors; reodorants; anti-wear additives;
anti-oxidants (eg, phenolics such as 2,6-di-tert-
butylphenol, or phenylenediamines such as N,N'-di-sec-
butyl-p-phenylenediamine); and metal deactivators.
It is particularly preferred that the additive
include a lubricity enhancer, especially when the fuel
composition has a low (eg, 500 ppmw or less) sulphur
content. In the additivated fuel composition, the
lubricity enhancer is conveniently present at a
concentration between 50 and 1000 ppmw, preferably
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between 100 and 1000 ppmw. Suitable commercially
available lubricity enhancers include EC 832 and
PARADYNET"' 655 (ex ~Infineum) , HITECT"" E580 (ex Ethyl
Corporation) , VEKTRONT"' 6010 (ex Infineum) and amide-based
additives such as those available from the Lubrizol
Chemical Company, for instance LZ 539 C. Other lubricity
enhancers are described in the patent literature, in
particular in connection with their use in low sulphur
content diesel fuels, for example in:
- the paper by Danping Wei and H.A. Spikes, "The,
Lubricity of Diesel Fuels°', Wear, III (1986) 217-235;
- WO-A-95/33805 (Exxon) - cold flow improvers to
enhance lubricity of low sulphur fuels;
- WO-A-94/17160 (Exxon) - certain esters of a
carboxylic acid and an alcohol wherein the acid has from
2 to 50 carbon atoms and the alcohol has 1 or more carbon
atoms, particularly glycerol monooleate and di-isodecyl
adipate, as fuel additives for wear reduction in a diesel
engine injection system;
- US-A-5484462 (Texaco) - mentions dimerized
linoleic acid as a commercially available lubricity agent
for low sulphur diesel fuel (column l, line 38),,and
itself provides aminoalkylmorpholines as fuel lubricity
improvers;
- US-A-5490864 (Texaco) - certain dithiophosphoric
diester-dialcohols as anti-wear lubricity additives for
low sulphur diesel fuels; and
- WO-A-98/01516 - certain alkyl aromatic compounds
having at least one carboxyl group attached to their
aromatic nuclei, to confer anti-wear lubricity effects
particularly in low sulphur diesel fuels.
It is also preferred that the additive contain an
anti-foaming agent, more preferably in combination with
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an anti-rust agent and/or a corrosion inhibitor and/or a
lubricity additive.
Unless otherwise stated, the (active matter)
concentration of each such additional component in the
additivated fuel composition is preferably up to 1 o w/w,
more preferably in the range from 5 to 1000 ppmw, w
advantageously from 75 to 300 ppmw, such as from 95 to
150 ppmw.
The (active matter) concentration of any dehazer in
the fuel composition will preferably be in the range from
1 to 20 ppmw, more preferably from 1 to 15 ppmw, still
more preferably from 1 to 10 ppmw and advantageously from
1 to 5 ppmw. The (active matter) concentrations of other
components (with the exception of the ignition improver)
will each preferably be in the range from 0 to 20 ppmw,
more preferably from 0 to 10 ppmw. The (active matter)
concentration of any ignition improver present will
preferably be between 0 and 600 ppmw and more preferably
between 0 and 500 ppmw, conveniently between 300 and 500
ppmw .
The additive will. typically contain the detergent,
optionally together with other components as described
above, and a diesel fuel-compatible diluent, which may be
a carrier oil (eg, a mineral oil), a polyether, which may
be capped or uncapped, a non-polar solvent such as .
toluene, xylene, white spirits and those sold by member
companies of the Royal Dutch/Shell Group under the trade
mark "SHELLSOL", and/or a polar solvent such as an ester
and, in particulars an alcohol, eg, hexanol, 2-
ethylhexanol, decanol, isotridecanol and alcohol mixtures
such as those sold by member companies of the~Royal
Dutch/Shell Group under the trade mark "LINEVOL",
especially LINEVOLT"" '79 alcohol which is a mixture of
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C~_9 primary alcohols, or the C12-14 alcohol mixture
commercially available from Sidobre Sinnova, France under
the trade mark "SIPOL"
The additive may be suitable for use in heavy and/or
light duty diesel engines.
Use of a detergent-containing additive, in
accordance with the present invention, may give rise to
additional benefits associated with engine emissions, in
particular lower smoke levels and lower particulate mass.
Previously in diesel fuels a reduction in emissions has
typically been accompanied by a reduction in power. It
has, however, surprisingly been found that a detergent-
containing additive may be used both to reduce smoke
and/or particulate emissions, whilst at the same time
(despite the fact that the additive will generally lower
the density of the fuel composition) increasing or at
least maintaining power levels. This dual action is a
further feature of the present invention. It may be put
to particular use in higher density fuel compositions
(which have previously been associated with higher smoke
and particulate emissions), to improve their
environmental performance but without a compromise in
power output.
The present invention thus also provides, according
25_ to a third aspect, the use of a detergent-containing fuel
additive in a diesel fuel composition, for the purpose of
reducing smoke and/or particulate emissions in a diesel
engine into which the fuel composition is introduced.
More preferably, the use has the purpose of achieving the
concurrent effects of (a) a reduction and/or reversal of
power loss (as defined above), and/or an increase in
power output, and (b) reduced smoke and/or particulate
emissions. Reduced emissions may conveniently be
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identified with reference to the unadditivated diesel
fuel composition.
When the present invention is applied in this
manner, it may be desirable for the unadditivated fuel
composition to be of a relatively high density, for
example greater than 0.845 g/cm3 at 15°C.
A fourth aspect of the present invention provides a
method of operating a diesel engine, and/or a vehicle
which is driven by a diesel engine, which method involves
introducing into the combustion chambers of the engine a
diesel fuel composition incorporating a detergent-
containing fuel additive, for one or more of the -
following purposes:
a) reducing subsequent power loss in the engine;
b) reversing a previously incurred power loss in the
engine; or .
,c) reducing smoke and/or.particulate emissions from the
engine.
The engine type, the nature of the diesel fuel
composition, the nature and concentration of the
detergent in the fuel composition as well as of other
components. in the additive, and the ways in which power
and emission levels may be assessed, may all be as
described above in connection with the first aspect of
the present invention.
According to a fifth aspect of the present
invention, there is provided a diesel fuel composition
which includes a major proportion of a fuel for an
internal combustion engine of the compression ignition
type, and a minor proportion of a detergent-containing
additive, wherein the active matter detergent
concentration in the composition is between 100 and 500
ppmw.
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By "minor proportion" is meant preferably less than
1 % w/w of the fuel composition, more preferably less
than 0.5 % w/w (5000 ppmw) and most preferably less than
0.2 % w/w (2000 ppmw); references to "major proportion"
may be construed accordingly. Preferred detergent
- concentrations and types are as described in connection
with the first aspect of the present invention, as are
other features of the fuel and the detergent-containing
additive. In particular, the diesel fuel composition
preferably contains between 150 and 300 ppmw active
matter detergent.
The fuel may be any fuel suitable for use.in a
diesel engine. It will typically have. an initial
distillation temperature of about 160 °C and a final
distillation temperature of between 290 and 360 °C,
depending on its grade and use. Vegetable oils may also
be used as diesel fuels per se or in blends with
hydrocarbon fuels.
The fuel may in particular be a low or ultra low
sulphur content fuel, or contain a proportion (for
instance, 10 % v/v or more) of, reaction products of a
Fischer-Tropsch methane condensation process such as the
process known as Shell Middle Distillate Synthesis
(SMDS), as described in connection with the first aspect
of the present .invention.
The fuel may itself be additivated (additive-
containing) or unadditivated (additive-free). If
additivated, it will contain minor amounts of one or more
additives selected for example from anti-static agents,
pipeline drag reducers, flow improvers (eg,
ethylene/vinyl acetate copolymers or acrylate/maleic
anhydride copolymers) and wax anti-settling agents (eg,
those commercially available under the Trade Marks
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"PARAFLOW" (eg, PARAFLOWT"" 450, ex Infineum), "OCTEL" (eg,
OCTELT"' W 5000, ex Octel) and "DODIFLOW" (eg, DODIFLOWT"" v
3958, ex Hoechst).
In accordance with a sixth aspect of the present
invention, there is provided a method of operating a
diesel engine, and/or a vehicle which is driven by a
diesel engine, which method involves introducing into the
combustion chambers of the engine a diesel fuel
composition according to the fifth aspect.
A seventh aspect of the present invention provides a
process for the preparation of a diesel fuel composition
according to the fifth aspect, which process involves
admixing a major proportion of a diesel engine fuel, as
described above, with a minor proportion of a detergent-
containing additive, also as described above. Said minor
proportion is sufficient to give an active matter
detergent concentration in the fuel composition of
between 100 and 500.ppmw.
According to an eighth aspect, the present invention
provides a method for assessing the performance of a
candidate diesel fuel composition, comprising the steps
of
1) measuring power output for a (preferably direct
injection) diesel engine running on a "standard"-diesel
fuel composition, which "standard" fuel composition is
either unadditivated or, if additivated, contains less
than 50 or preferably less than 20 ppmw active matter
detergent;
2) subjecting the engine to a first driving cycle by
running it for a first number of miles on the standard
fuel composition;
3) measuring engine power after the first driving
cycle;
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4) calculating the reduction in engine power during the
first driving cycle;
5) provided that significant power loss is observed
during the first driving cycle, subjecting the engine to
a second driving cycle by running it for a second number
of miles on the candidate diesel fuel composition;
6) measuring engine power after the second driving
cycle;
7) calculating the reduction in engine power (if any)
during the second driving cycle; and
8) if applicable, calculating the extent of engine
power recovery during the second driving cycle.
The test should proceed only if significant power
loss is observed during the first driving cycle. By
"significant" power loss is meant at least a 2
reduction in power, preferably at least 4 0, more
preferably at least 5 a or 7 0. In case of a lower or no
observed power loss, it may be appropriate to repeat the
test using a different fuel injector system in the
engine, and/or a different vehicle, since power losses
have in cases been found to be sensitive to such
variables. Higher power losses, for instance 10 % or
more, may be observed when testing indirect injection
diesel engines. _
The "standard" fuel composition is suitably a low or
ultra low sulphur diesel fuel, as described above, and is
preferably unadditivated.
The driving cycles involve accumulation of engine
miles, which may be under simulated conditions (such as
using a chassis dynamometer) but preferably involve
regular road driving, more preferably a mixture of
driving conditions including both urban and motorway
mileage.
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The first number of miles should be sufficient to
cause a significant loss in power compared to that
measured in step 1 of the test. A typical first driving
cycle might involve between 1000 and 4000 miles (1600 and
6400 km), preferably 1500 miles (2400 km) or more, more
preferably 2000 (3200 km) or 3000 miles (4800 km) or
more.
An appropriate number of miles for the second
driving cycle is typically between 10 and 100 %,
preferably between 10 and 80 %, more preferably between
10 and 60 %, such as around 50 0, of the first number of
miles.
The engine used for the test is preferably of, the
rotary pump or common rail type, more preferably rotary
pump. It is suitably a light duty diesel engine.
Particularly preferred is a Ford EnduraT"' engine, as used
in the Ford FocusT"" vehicle, such as the 1753 ~cc Ford
EnduraT"" Di C9DC engine which has a BoschT"" VP-30 rotary
distributor type fuel pump. Engines having mechanically
actuated injectors are preferred.
Engine power may suitably be measured in the ways
mentioned above in connection with the first aspect of
the present invention. In particular, it may be assessed
by measuring vehicle tractive effort (VTE) and/or
acceleration times for the engine. A reduction in power
corresponds to a reduction in VTE and/or an increase in
acceleration times; power recovery corresponds to a
recovery of (ie, increase in) VTE and acceleration rate,
and therefore a reduction in acceleration times.
Such power measurements may be conducted using the
standard fuel composition; conventional measurement.
procedures may be used. Ideally, acceleration times are
measured under two or more, preferably three, different
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driving conditions (for instance, in 3rd, 4th and 5th
gears) and the results averaged. Similarly, VTE
measurements are preferably averaged over two or more,
preferably three, different driving speeds, for instance
at 50, 85 and 100 kilometres per hour (kph) in 4th gear.
Acceleration time and VTE results may be combined and
averaged to give an overall power rating.
Engine emissions (in particular smoke and
particulate mass) may also be measured and compared
before and after the first and second driving cycles.
Again, conventional measurement procedures may be used,
and run on the standard fuel composition. Smoke
measurements are preferably averaged over two or more,
preferably three, engine speeds, for example 70, 85 and
100 kph in 4th gear.
The assessment method of the present invention is
particularly applicable to a candidate fuel composition
which incorporates a detergent-containing additive, more
particularly to an additivated low or ultra low sulphur
fuel and/or to an additivated fuel containing a
proportion (for instance, 10 o v/v or more) of, reaction
products of a Fischer-Tropsch methane condensation
process such as the process. known as Shell Middle
Distillate Synthesis (SMDS). The method may therefore be
used to identify and/or evaluate fuel compositions
according to the fourth aspect of the present invention.
The method may also be used to assess the
performance of a diesel engine, in particular a direct
injection diesel engine, more particularly of the rotary
30, pump type, and/or to assess the performance of a fuel
injection system for use in a~diesel engine, and/or to
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assess the performance of a vehicle driven by a diesel
engine.
An ninth aspect of the present invention provides a
diesel fuel composition which, when used as the candidate
fuel composition in the assessment method of the seventh
aspect of the present invention, causes at least a 25
recovery of the power lost during the first driving
cycle, preferably a 50 %, a 75 %, a.90 % or a 100
recovery, when the second number of miles is the same as
or more preferably 75 0 or even 50 0 of the first number
of miles, and the first number of miles is preferably at
least 1500 (2400 km), more preferably 3000 (4800 km) or
more.
Such a fuel composition ideally contains, in
accordance with the present invention, a detergent-
containing additive.
The present invention will be further understood
from the following illustrative examples, which
investigated the effects of using detergent-containing
additives in diesel fuel compositions, on the performance
of rotary pump direct injection diesel engines.
Particular attention was paid to the fuel injectors,
following a finding that power loss could be linked to
injector fouling.
References to "dirty-up" vehicle tests are generally
to the running of a vehicle using a typical unadditivated
diesel fuel, expected to result in power loss. Such .
tests, unless otherwise stated, used mixed driving
cycles, ie, road driving including both urban and
motorway mileage, typically for 3000 miles (4800 km).
References to "clean-up" vehicle tests are to the running
of a vehicle, again typically using a mixed driving
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cycle, on a fuel in accordance with the present
invention, expected to reduce and/or reverse power loss.
Power levels were.assessed on the basis of (i)
vehicle tractive effort (VTE), measured in 4th gear at
50, 85 and 100 kph and (ii) gated acceleration times in
3rd (30-80 kph), 4th (40-100 kph) and 5th (60-120 kph)
gears. Where indicated, results were averaged over the
three driving speeds.
All acceleration and power measurements, unless
otherwise stated, were taken using a purpose built
performance measurement chassis dynamometer, using the
test protocol described below. Temperature, pressure and
humidity were recorded at each measurement. All VTE
measurements were NTP corrected (DIN 70020), ie,
corrected to take account of variations in temperature
and pressure. Acceleration time correction factors were
not applied.
Where new injectors were fitted, 200 miles of
conditioning were, run prior to taking power measurements.
In some experiments, smoke and particulate emissions
were also measured, using standard procedures as recorded
in the relevant examples.
The type of engine used in all of the tests was a
1753 cc Ford EnduraT"" Di C9DC engine, which is a direct
injection engine having a BoschT"' VP-30 rotary distributor
type fuel pump chain driven from the crankshaft. It is a
four cylinder (in-line configuration) engine which
features turbo-charging and after-cooling. The fuel
injectors are of the slim five-hole type (pencil fuel
injectors) located centrally over the piston recess. The
injectors are mechanically actuated and operate at a fuel
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injection pressure of approximately 1100 bar (110 MPa).
Fuel injection is electronically controlled.
The exhaust gas recirculation (EGR) system of the
EnduraT"" engine recycles measured quantities of exhaust
gas back through the engine where they mix with the
incoming air charge, and incorporates an EGR cooler to
cool the recirculated exhaust gas therefore lowering the
combustion temperature and reducing the formation of
nitrogen oxides.
Acceleration and power measurement test protocol
The vehicle is either mounted on a chassis
dynamometer or driven under test track conditions. The
vehicle and/or chassis dynamometer are initially warmed
up over a suitable period of time in order to stabilise
oil and coolant temperatures.
At each fuel change, the engine is flushed with an
ULSD base fuel to ensure there is no cross-contamination
between fuels. Also at each change, the vehicle is pre-
conditioned with five consecutive accelerations (4th gear
full throttle from 30 mph (48 kph) to 60 mph (96 kph)).
Eight further consecutive accelerations are then carried
out to allow the engine management system to adapt to the
fuel and test conditions.
Vehicle acceleration times are measured between two
chosen speeds. Data logging commences 2 kph below the
chosen start point and ffinishes 2 kph above the end
point. The engine is driven with a clean and progressive
full throttle movement, keeping below 4500 rpm at all
times, and full throttle is held until the end point has
been exceeded. The vehicle is allowed to decelerate at
the same rate that it accelerated, which is achieved
using the foot brake, although normal unaided
deceleration is allowed for the ffinal 200 rpm. Three
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acceleration measurements are carried out for each test
condition, and the results averaged.
Vehicle tractive effort (VTE) measurements are taken
from the dynamometer, which measures power at the driven
wheels, again using ful'1 throttle.
Acceleration times are reported to the nearest 0.01
second and constant speed VTE measurements to the nearest
0.01 kW.
Example 1
This demonstrates the ability of a detergent-
containing additive to arrest, and also to reverse, power
loss in a light duty direct injection diesel engine
running on an ultra low sulphur diesel (ULSD) fuel.
The vehicle used was a Ford FocusT"' equipped with an
EnduraT"" engine, as described above. Its fuel injectors
were new at the start of the experiment and were
subjected to 3000 miles of "dirty-up" on an ULSD base
fuel during step 1.
The base fuel, which contained no additives, had the
following specification (Table A):
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Table A
Property Test method
Density @ 15 C (g/cm3 IP 365 / ASTM D4052 0.8301
)
Distillation: IP 123 / ASTM D86
IBP (C) 169.5
l00 204.0
200 225.0
300 244.0
400 260.0
50% 273.5
600 285.0
700 297.0
800 310.0
900 328.0
950 345.0
FBp . 356.0
Cetane number ASTM D613 54.5
Sulphur (ppmw) ASTM D2622 54.5
Step 2 of the experiment involved a 1500 mile
"clean-up", for which a detergent-containing additive A
was added to the base fuel in accordance with the present
invention. Additive A is a top-tier detergency additive
available from Infineum (F7661) containing a
polyisobutylene substituted succinimide detergent, an
anti-foam agent, an anti-rust agent, a dehazer, EHN as an
'ignition improver, and a lubricity enhancer. It was
added at a concentration of 1870 ppmw (double its
standard treat rate); this results in an active matter
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detergent concentration of 162 ppmw in the additivated
fuel.
Acceleration times and vTE were measured, using the
base fuel, on the new injectors and at the end of each
subsequent step. The results are shown in Table 1.
Table 1
Test condition Average NTP Average
corrected VTE acceleration time
(kW) (s)
Injectors as new 38.13 15.73
After 3000 mile (4800 36.42 17.20
km) dirty-up (step 1)
After 1500 mile (2400 38.74 15.68
km) clean-up (step 2)
A significant loss of power (as manifested by a
reduction in vTE and a corresponding increase in
acceleration times) was observed after running the engine
on the base fuel alone. Following 1500 miles on the
additivated fuel however, the lost power had been fully
recovered. This demonstrates the ability of additive A
to reverse the adverse effects of running on an
unadditivated ULSD fuel.
The experiment then investigated the effect of using
additive A at a lower concentration (935 ppmw, its
"standard" treat rate ) . A dif f erent Ford FocusT"" was
used, but having the same type of engine and in
particular injection system as the vehicle used for the
first part of the test. The procedure was as follows,
acceleration and VTE measurements again being taken,
using the base fuel, after each step:
Step 3 3000 mile (4800 km) dirty-up on the base fuel.
Step 4 1500 mile (2400 km) clean-up (base fuel +
additive A (935 ppmw)).
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Step 5 Further 1500 mile (2400 km) dirty-up (base
fuel) .
The results are shown in Table 2.
Table 2
Test condition Average NTP Average
corrected VTE acceleration time
(kW) (s)
After 3000 mile (4800 36.75 16.38
km) dirty-up (step 3)
After 1500 mile (2400 36.81 16.26
km) clean-up with
lower additive dose
(step 4)
After 1500 mile (2400 36.06 16.82
km) dirty-up (step 5)
Again, dirty-up using the unadditivated fuel caused
significant loss of power. Incorporation of additive A
into the fuel, even at this lower dose, prevented further
power loss. The inclusion of step 5 (further dirty-up)
verifies that this effect is due to the presence of the
additive rather than a peak in power loss having been
attained - it can be seen that the further dirty-up
results in yet further power losses..
Overall, the experiment revealed a power loss of
approximately 5 o after 3000 miles (4800 km) of dirty-up,
with approximately 100 o recovery following 1500 miles
(2400 km) on the additivated fuel (higher dose). The
further 3000 mile (4800 km) dirty-up resulted in another
5 o power loss; to which there was no change during the
1500 miles (2400 km) on the lower dose additivated fuel.
The final dirty-up resulted in approximately 6.9 o total
power loss.
Thus, the inclusion of additive A in the fuel can be
seen to be of use in both maintaining engine power and,
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at higher concentrations, reversing previously incurred
power losses.
Example 2
This also demonstrates power loss and recovery in a
direct injection diesel engine.
A second hand Endura~" engined Ford FocusT'" (different
to that used in Example 1), which had run around 11,000
miles (17600 km), was fuelled with an unadditivated ULSD
base fuel having the following properties (Table B):
Table B
Property Test method
Density ~ 15 C (g/cm3) IP 365 / ASTM D4052 0.834
Distillation: IP 123 / ASTM D86
IBP ( C) 166 . 0
100 ~ 209.5
200 231.5
300 253.5
40a 269.5
500 ~ 281.5
600 292.0
700 302.0
800 314.5
900 331.5
950 ~ 347.0
FBP 355.5
Cetane number ASTM D613 54.6
Sulphur (ppmw) ASTM D2622 45
The vehicle was serviced prior to starting the
experiment. A new set of injectors was then fitted and
conditioned and power measurements (acceleration times
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and VTE) recorded using the ULSD base fuel. A 1500 mile
(2400 km) dirty-up was then carried out using the base
fuel, followed by further power measurements.
The remaining procedure was as follows, each step
being followed by acceleration and VTE measurements on
the base fuel:
Step 1 Further 1500 mile (2400 km) dirty-up (base
fuel) .
Step 2 Fit and condition a new injector set.
Step 3 Replace old injector set; 1500 mile- (2400 km)
clean-up on (base~fuel + 1870 ppmw of additive
A) .
Step 4 1500 mile (2400 km) dirty-up (base fuel).
Step 5 Further 1500 mile (2400 km) dirty-up (base
fuel ) .
Step 6 1500 (2400 km) mile clean-up (base fuel + 1920
ppmw of additive A).
Steps 4 to 6 were included to demonstrate the
repeatability of steps 1 to 3.
Miles were accumulated by normal evening and weekend
driving, no journey involving exclusively motorway
driving and the accumulation rate being no greater than
750 miles (1200 km) per week.
The VTE results are shown in Table 3 and the
acceleration times in Table 4.
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Table 3
Test NTP Average
condition corrected power loss
VTE (kg) 85 kph 100 kph (~) relative
at - to new
50 kph injectors
After initial 131.835 187.571 170.960 5.34
1500 mile
(2400 km)
dirty-up
After further 122.609 185.956 169.609 7.69
1500 mile
(2400 km)
dirty-up
( step 1 )
New injectors 138.411 196.422 183.192 0
(step 2)
Old injectors 140.824 195.533 176.283 1.04
after 1500
mile (2400
km) clean-up
(step 3)
After 1500 126.500 190.800 175.500 4.87
mile (2400
km) dirty-up
(step 4)
After further 124.767 187.817 171.359 6.58
1500 mile
(2400 km)
dirty-up
(step 5)
After 1500 134.179 201.268 183.448 0.17
mile (2400
km) clean-up _
( step 6 )
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Table 4
Test Acceleration Average
condition time (s) in increase in
4th gear 5th gear acceleration
3rd gear (40-100 (60-120 time (%)
(30-80 kph) kph) kph) relative to
new
injectors
After initial 9.13 18.23 24.40 10.77
1500 mile
(2400 km)
dirty-up
After further 9.91 19.76 26.58 20.41
1500 mile
(2400 km)
dirty-up
(step 1)
New injectors 8.53 16.23 21.97 0
(step 2)
Old injectors 8.72 16.7 9 22.48 2.71
after 1500
mile (2400
km) clean-up
(step 3)
After 1500 9.13 17.65 23.62 7.88
mile (2400
km) dirty-up
(step 4)
After further 8.93 18.43 25.24 12.61
1500 mile
(2400 km)
dirty-up
(step 5)
After 1500 9.12 17.08 23.18 5.70,
mile (2400
km) clean-up
(step 6)
The base measurement for these results was taken as
the value recorded after fitting the new injectors.
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Both sets of results indicate a significant decrease
in power (around 5 o reduction in VTE and 8-10 % increase
in acceleration times) after 1500 miles (2400 km) on the
ULSD base fuel, with a further increase on accumulating
another 1500 miles (2400 km) (around 8 % cumulative VTE
loss and 11-20 a cumulative increase in acceleration
times). Following the 1500 mile (2400 km) clean-up (step
3), using an additivated fuel in accordance.with the
present invention, power appeared to have been recovered
and VTE was no longer significantly different to that
recorded for the clean injectors. Acceleration times
returned to levels approaching (higher by between 2 and 6
o) those achieved with the new injectors.
During steps 4 and 5 the earlier power losses were
more or less repeated, the VTE losses being 5 o after
step 4 and 7 o after step 5 (not significantly different
to the results from steps 1 and 2). Again the
additivated fuel yielded a full power recovery, VTE
returning to a level comparable with that achieved using
the new injectors.
Example 3
This demonstrates the use of alternative additivated
fuel compositions in accordance with the present
invention.
Two detergent-containing additives, B and C, were
used. Additive B is an additive available from Infineum
(F7685) which passes the Cummins L10 heavy duty
detergency test and contains inter alia a detergent, an
anti-foam agent and a corrosion inhibitor. Additive C is
an additive available from Octel (OMA 4130D) of use for
low sulphur fuels and contains a,detergent, an anti-foam
agent, an anti-rust agent and a dehazer.
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Both additives were incorporated into the ULSD base
fuel used in Example 1, at a concentration of 1042 ppmw
for additive B and 500 ppmw for additive C. In both
cases this represents double the "standard" treatment
. 5 dose for the additive in question, and yields an active
matter detergent concentration of greater than 100 ppmw
in the additivated fuel.
The procedure was analogous to steps 1 and 2 of
Example 1, although only VTE measurements were taken.
New or cleaned injector sets were used at the start of
each test. All tests were run on Ford FocusT"" vehicles
with EnduraT"" engines, as described above.
In the test using additive B, mileage accumulation
was carried out using a mileage accumulation chassis
dynamometer (MACD) (rolling road). Dirty-up mileage
accumulation consisted of 72 hours on a light duty test
cycle (representing approximately 3000 road miles (4800
km)); clean-up consisted of 36 hours (approximately 1500
road miles (2400 km)) on the same cycle. Each test cycle
involved 300 seconds' steady running at an effective road
speed of 37 mph (59 kph), followed by about 10 seconds'
acceleration between 37 (59 kph) and 50 mph (80 kph),
followed by about 50 seconds' steady running at 50 mph
(80 kph) and then 90 seconds' idle.
In the test using additive C, miles were accumulated
using a mixed driving cycle as in. Example 1. Here,
dirty-up and clean-up were run using two different
vehicles, the second (clean-up) being that used in
Example 1. Thus, in assessing the results, percentage
changes in VTE from the beginning of each test point must
be considered, rather than absolute values.
The results are shown in Tables 5 (additive B) and 6
(additive C).
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Table 5
Test condition NTP corrected VTE
(kW) at - 85 kph 100 kph
50 kph
Pre dirty-up 18.53 43.95 48.18
Post dirty-up 15.51 41.67 45.66
Post clean-up 16.73 44.07 48.11
Table 6
Test condition NTP corrected
VTE (kW) at -
50 kph 85 kph 100 kph
Pre dirty-up 19.18 . 47.47 51.04
(vehicle 1)
Post dirty-up 16.63 44.43 47.22
(vehicle 1)
Pre clean-up 14.99 42.45 46.35
(vehicle 2)
Post clean-up 17.19 43.48 46.85
(vehicle 2) .
Averaged over the three test speeds, additive B gave
approximately 80 o power recovery, and additive C
approximately 50 %.
Example 4
This demonstrates how power recovery progresses
during use of an additivated fuel in accordance with the
present invention.
Using the Ford FocusT"" used in Example 1,
acceleration and VTE measurements were taken at the
start, middle (after 750 miles (1200 km)) and end of a
1500 mile (2400 km) clean-up cycle using the Example 1
base fuel to which 1870 ppmw of additive A had been
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added. Having undergone the Example 1 procedure, the
vehicle had already been subjected to 3000 miles (4800
km) of dirty-up on the base fuel, 1500 miles (2400 km) on
(base fuel + 935 ppmw additive A) and a further 1500
miles (2400 km) on the base fuel alone.
The power levels were compared with those for the
new injectors, ie, prior to any dirty-up.
The VTE results are shown in Table 7.
Table 7
Test point NTP corrected
VTE (kW) at -
50 kph 85 kph 100 kph
Start of test 15.19 42.10 45.85
Middle of test 15.66 43.69 48.12
(750 miles (1200 km)
)
End of test 16.33 44.62 48.33
(1500 miles (2400 km))
The relative percentage gains in power, comparing
the start and end of test results, were 7.5 o at 50 kph,
6.0 o at 85 kph and 5.4 o at 100 kph. This averages to a
6.3 % power recovery over the three test conditions.
Power had not, however, been fully recovered after only
750 miles (1200 km).
The acceleration time results are shown in Table 8.
Table 8
Test point Acceleration
time (s) in - 4th gear 5th gear
3rd gear (30-80 (40-100 (60-120
kph ) kph ) kph )
Start of test 9.95 19.40 26.41
Middle of test 9.40 18.33 25.30
(750 miles)
End of test 9.16 17.97 24.38
(1500 miles)
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Consistent with the increase in VTE during clean-up,
the acceleration times in all gears were reduced.
Comparing the start and end of test results, in 3rd gear
an overall 8.0 o reduction was observed, in 4th gear a
7.4 a reduction and in 5th gear a 7.7 % reduction. The
average across the three test conditions was therefore a
7.7 o reduction.
Example 5
This demonstrates an additional benefit of using an
additivated fuel in accordance with the present
invention.
Measurements of black smoke opacity, using a
CelescoT"" C107 opacimeter, were taken at the start and end
of the Example 4 test. From the start of each VTE speed
set point, 5 seconds of stabilisation were followed by
logging of the opacimeter output for 10 seconds (output
averaged). Measurements were recorded at 70, 85 and 100
kph, then the vehicle deccelerated back to idle for 5
minutes with a fan speed at 50 kph. This procedure was
repeated twice more, giving three measurements at each of
the test speeds. The fuel used for the smoke
measurements was the Example 1 base fuel.
The results are shown in Table 9.
Table 9
Test point Smoke opacity (%) at
-
70 kph
(90 % confidence 85 kph 100 kph
limits)
Start of test 4.292 (0.457) 5.201 7.976
(0.347) (0.457)
End of test 3.724 (0.187) 5.027 6.659
(0.160) (0.326)
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The average reduction in smoke opacity over the
three vehicle speeds was 15 0, which is significant at a
90 o confidence level. The reduction was particularly
marked at 100 kph. This demonstrates that an additivated
fuel composition in accordance with the present invention
may yield environmental benefits, as well as the
previously observed power recovery effect.
Example 6
This demonstrates the use of detergent-containing
additives in alternative fuel compositions in accordance
with the present invention.
The "base" fuel composition for these experiments..
had the following properties (Table C):
Table C
Property Test method
Density @ 15 C (g/cm3) IP 365 / 0.8377
ASTM D4052
C (o m/m) 86.3
- . 13_.7
H (% m/m) .
N (% m/m) < 0.1
Calorific value (gross heat 1_0945
of combustion) (cal (IT) /g)
Calorific value (net heat of 10251
combustion) (cal(IT)/g)
It was used with a single dose (100 ppmw) of a
commercially available lubricity additive PARADYNET"" 655
( ex Inf ineum) .
A blend of this base fuel was also prepared with 15
o v/v of a mixture of Shell Middle Distillate Synthesis
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(Fischer-Tropsch) reaction products having the following
properties (Table D):
Table D
Property Test method
Density C 15 C (g/cm~ IP 365 / 0.776
ASTM D4052
Distillation: IP 123 / ASTM D86
IBP (C) 183.5
l00 214.1
200 228.4
30% 243.6
40a 259.5
500 275.4
600 291.2
700 306.9
800 322.9
900 340
950 351.3
FBp 359
Cetane number ASTM D613 81
Sulphur (ppmw) IP 373 0
It was to the blended fuel (overall density 0.830
g/cm3) that additives A and B were added for subsequent
testing.
The experimental procedure was as follows:
Step 1 Using the base fuel alone, record start-of-test
(SOT) acceleration, VTE and smoke measurements,
followed by particulate emission levels.
Step 2 Using the blended fuel, together with 1042 ppmw
of additive B, record start-of-test
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acceleration, VTE and smoke measurements,
followed by particulate emission levels..
Step 3 Using the blended fuel together with 1870 ppmw
of additive A, record start-of-test
acceleration, VTE and smoke measurements,
followed by particulate emission levels.
Step 4 Remove the fuel lines and change to the ULSD
base fuel of Example l, but containing 1042
ppmw of additive B.
Step 5 "Clean-up" cycle - 1500 miles (2400 km) of
mixed driving using the fuel referred to in
step 4.
Step 6 Refit auxiliary fuel lines and record
acceleration and VTE measurements using the
ULSD base fuel alone.
Step 7 Using the blended fuel together with 1042 ppmw
of additive B, record end-of-test (ie, post
clean-up, EOT) acceleration, VTE and smoke
measurements, followed by particulate emission
levels .
Step 8 Using the blended fuel together with 1870 ppmw
of additive A, record end-of-test acceleration,
VTE and smoke measurements, followed by
particulate emission levels.
The same chassis dynamometer was used for the smoke
as for the acceleration and VTE measurements. The
procedure for the smoke measurements was as in Example 5.
Particulate emissions were tested using a chassis
dynamometer. Testing used the standard ECE 1505(m) 11s
221 cycle, with sampling including cranking and start up
emissions. A 40 second idle~(Euro 2) was run prior to
sampling. The cycle comprises four ECE cycles and one
EUDC cycle with the results presented in a three phase
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format which includes the combined the first and second
ECE cycles (cold engine), the combined third and fourth
ECE cycles (hot engine) and the EUDC cycle. Particulate
measurements were made for each phase. Results quoted
below are for the full cycle.
The VTE results are shown in Table 10.
m~,.~, P., , ~
Fuel composition Average NTP
corrected VTE End of test
(kW) -
Start of test
ULSD base fuel 33.49 36.99
Example 6 base fuel 37.13 Not measured
Blended fuel + additive 36.77 37.73
A
Blended fuel + additive 36.67 37.59
C
Comparisons for the ULSD base fuel at the start and
end of the tests appeared to indicate complete power
recovery. Changing to the higher density Example 6 base
fuel led to a significant, but predictable, increase in
power compared to the ULSD base fuel (density of the ULSD
base fuel = 0.8301 g/cm3, whereas that of the Example 6
base fuel = 0.8377 g/cm3).
The fuels containing additives A and B were of lower
density than the Example 6 base fuel and as such'
predicted to cause reductions in power. Previous tests
have indicated that a reduction in density of 3 0 leads
to a lowering in VTE of between 5 and 8 %. In contrast,
the incorporation of additives A and B in this
experiment, although it caused a density reduction of 0.9
o, led to an average power reduction of only around 1 0.
Both additivated fuels showed consistent trends
between the start and end of test power measurements, VTE
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being increased in both cases by around 2.5 o relative to
the start of test measurements.
The acceleration time results showed directionally
similar trends to those recorded for the vTE. Additive B
gave an average reduction in acceleration times of 3 0
following clean-up, whilst additive A gave an average
11 % reduction.
The Celesco black smoke measurements are shown in
Table 11.
Table 11
Fuel Smoke
composition opacity
(%) 85 kph 100 kph
at
-
70 kph
(90
% confidence
limits)
Example 6 basefuel 5.120 (0.194) 4.972 6.289
(SOT) (0.223) (0.726)
Blended fuel additive 3.922 (0.716) 3.774 5.061
+
A (SOT) (0.223) (0.303)
Blended fuel additive 3.611 (0.797) 4.380 5.239
+
A (EOT) (0.621) (0.223)
Blended fuel additive 3.330 (0.254) 3.463 4.780
+
C (SOT) (0.438) (0.129)
Blended fuel additive 2.575 (0.084) 2.975 4.143
+
C (EOT) ~ ~ (0.223) (0.702)
These results demonstrate that the increase in power
associated with incorporation of additive A or B is
accompanied~by a reduction in smoke. The inclusion of
additive A gave a significant (> 90 % confidence)
reduction in smoke over the test period, at all three
vehicle speeds.
The lower density blended fuel generally gave
significantly lower (on average 20 % across the three
test phases) smoke levels, compared to the Example 6 base
fuel.
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The results of the particulate level measurements
are shown in Table 12.
Fuel Particulate
composition
matter (g/km)
Example 7 base fuel 0.0464
Blended fuel additive (SOT) 0.046
+ A
Blended fuel additive (EOT) 0.043
+ A
Blended fuel additive (SOT) 0.043
+ B
Blended fuel additive (EOT) 0.041
+ B
A reduction in particulate mass was observed after
the clean-up cycle. The Example 6 base fuel, as expected
for a higher density fuel, produced higher particulate
levels than the lower density blended fuels. However
both additives A and B gave a consistent additional
reduction in particulate levels of 6-7 % after clean-up.
These results indicate that the reductions in smoke and
increases in power observed when using the detergent-
containing additives A and B are the genuine results of
engine clean-up rather than some form of artefact derived
from the test conditions.
