GB2521169A

GB2521169A - Compositions and methods for treating fuel systems

Info

Publication number: GB2521169A
Application number: GB1321895.3A
Authority: GB
Inventors: Stephen Grieve; Douglas Greenhalgh
Original assignee: ENGYM SERVICES Ltd
Current assignee: ENGYM SERVICES Ltd
Priority date: 2013-12-11
Filing date: 2013-12-11
Publication date: 2015-06-17
Also published as: GB201321895D0

Abstract

The present invention relates to an engine cleaning composition for cleaning the fuel system of an internal combustion engine, the composition comprising the following ingredients (% by volume): 15 to 99.5% of a C6 to C16 petroleum distillate; and optionally 0.5 to 80% of a C7 to C12 petroleum distillate; and at least one of 0.5 to 3% of tetrachloroethylene or 0.5 to 3% of a cetane or octane-raising additive. The invention also relates to a fuel comprising such a composition, and to methods of cleaning the fuel system of an engine.

Description

Compositions and Methods for Treating Fuel Systems The present invention relates to composition and methods for treating fuel systems.

Particularly, but not exclusively, the present invention relates to compositions which are adapted for use as additives for a fuel, and to compositions which are adapted for use in essentially neat (undiluted) form to clean the fuel system of a vehicle.

Background of the Invention

During the operation of any internal combustion engine deposits and contamination build up on all the major engine components. This is particularly noticeable within the fuel management systems, with harmful deposits building up on the fuel injectors and other critical components. If left untreated these contaminants can seriously impede engine performance and reduce the effective working life of an engine. They can also have a detrimental impact on the fuel combustion making it less economical to run the engine.

Over time the fuel system can also become contaminated with water, microbes biofilms and the like. It is advisable to remove these from the fuel system to improve the overall fuel performance as well as reduce contamination of the fuel management system.

In normal operation any internal combustion engine is prone to certain problems arising from the burning of fossil fuels as a power source, including: -Components directly involved in combustion, such as fuel flow lines, intake valves, spray injectors and combustion chambers see the build up of deposits such as carbon, tar and varnishes under normal running conditions.

-This is expected over the lifetime of a vehicle or plant equipment but can seriously impact engine performance and cause engine breakdown.

-The impact of this build up is to reduce performance and efficiency whereby more fuel is needed to develop the power needed -i.e. a loss of fuel economy.

-Emissions levels increase due to less efficient engine performance and incomplete combustion.

-Fuel can become contaminated, especially when bulk storage is utilised. This increase the risk of partial or complete clogging of the fuel system and filters, thereby reducing performance, creating significant wear on engine components and increasing fuel consumption.

-Contamination has a significant impact on emission levels. This type of problem is expected to become more prevalent as the levels of biodiesel in pump fuel increases to levels of over 20%. Biodiesel has the added complication of introducing feedstock waste and micro-organisms in to the engine.

-Biodiesel causes specific problems including; increased deposits on the injectors resulting in misfiring or difficult starting, deposit build up in the injector pump causing a reduction in power and misfiring, lubrication of oil becomes diluted resulting in a loss of oil pressure and worn bearings, poor starting in cold weather due to filter clogging.

Whilst engine technology has advanced over recent years improving fuel economy and emissions there is still a need to burn fossil fuel to power engines. This is unlikely to change for the foreseeable future with only electric powered vehicles offering an alternate option.

These engines have significant limitations, especially with range, and are unlikely to become a credible alternate.

There remains a need for improved system and compositions to permit the cleaning and maintenance of engine fuel systems.

Statements of the Invention

According to the present invention there is provided an engine cleaning composition for cleaning the fuel system of an internal combustion engine, the composition comprising the following ingredients (% by volume): -15 to 99.5% of a CS to C16 petroleum distillate; and optionally -0.5 to 80% of a C7 to C12 petroleum distillate; and at least one of: -0.5 to 3% of tetrachloroethylene; and -0.5 to 3% of a cetane or octane-raising additive.

It goes without saying that the relative amounts of the ingredients within the recited ranges can be determined by the skilled person, and that the sum of all ingredients and any additional components in the composition must equal 100%.

In some embodiments of the invention the composition consists of the abovementioned ingredients, i.e. there are no additional ingredients. In other embodiments additional ingredients can be added, e.g. where such ingredients can provide performance or safety benefits.

A CS to C16 petroleum distillate comprises a mixture of hydrocarbons, with the hydrocarbon molecules predominantly being in the range of from 6 to 16 carbon atoms per molecule (e.g. wherein at least 95% of the hydrocarbon molecules contain between 6 and 16 carbon atoms per molecule). A C7 to C12 petroleum distillate comprises a mixture of hydrocarbons, with the hydrocarbon molecules predominantly being in the range of from 7 and 12 carbon atoms per molecule (e.g. at least 95% of the hydrocarbon molecules contain between 7 and 12 carbon atoms per molecule).

Preferably the C6 to C16 petroleum distillate is kerosene, more preferably technical grade kerosene.

Preferably the C7 to C12 petroleum distillate is white spirit, more preferably technical grade white spirit.

Kerosene' (also known as paraffin) is a thin, clear liquid formed from hydrocarbons, with a density of 0.78-0.81 g/cm3, is obtained from the fractional distillation of petroleum between 150 °C and 275 °C, resulting in a mixture of carbon chains that typically contain between 6 and 16 carbon atoms per molecule. For example, the kerosene may be classed as BS 2869 Class Cl (also known as paraffin) or C2. An exemplary kerosene is listed under CAS No 8008-20-6, and is available from Sigma Aldrich under product code 101183759.

White spirit' is a mixture of aliphatic and alicyclic 07 to 012 hydrocarbons with a maximum content of 25% of 07 to 012 aromatic hydrocarbons. A typical composition for white spirit is >65% 010 or higher hydrocarbons, aliphatic solvent hexane, and a maximum benzene content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of 65°C, a dry point of approximately 69 °C, and a density of 0.7 g/ml. White spirit is also known as mineral spirits in the US and some other countries. An exemplary white spirit is listed under CAS No 64742-88-7 and is available commercially from VWR under product code 28963.368.

Preferably the white spirit is technical grade white spirit Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene ("perc" or "PERC"), and several other names, is a chlorocarbon with the formula CI2C=CCI2. It is a colourless liquid widely used for dry cleaning of fabrics, hence it is sometimes called "dry-cleaning fluid." Tetrachloroethylene is listed under CAS No 127-18-4 and is available from Sigma Aldrich under product code 371696.

The composition set out above is particularly well suited to use in a method of directly cleaning the fuel system of an internal combustion engine, e.g. by delivering the composition in a substantially undiluted form to the fuel system of the engine.

For compositions intended for directly cleaning the fuel system (i.e. application in substantially undiluted form) the presence of tetrachloroethylene is usually desirable. It is typically present at from 0.5 to 3% by volume, with about 1% being typical.

Accordingly, a composition comprising the following is typically preferred: -20 to 99.5% of a Ca to 016 petroleum distillate; -0 to 80% of a 07 to 012 petroleum distillate; and -0.5 to 3% of tetrachloroethylene.

For direct cleaning compositions it is desirable that the flashpoint is higher than 60 °C for safety reasons. Increasing the flash point can be achieved by using a comparatively high proportion of CO to 016 petroleum distillate (e.g. kerosene).

Accordingly, preferred compositions for direct cleaning comprise: -75 to 99.5% of a 06 to 016 petroleum distillate; -0 to 25% of a 07 to 012 petroleum distillate; and -0.5 to 3% of tetrachloroethylene.

More preferably -85 to 99.5% of a 06 to 016 petroleum distillate; -0 to 15% of a 07 to 012 petroleum distillate; and -0.5 to 2% of tetrachloroethylene.

A specific composition which is highly suitable for direct cleaning applications comprises: -95% to 99.5% by volume 06 to 016 petroleum distillate, for example de-aromatised kerosene (e.g. product no BAS 0220-235, Banner Chemicals Ltd, UK) -0.5 to 1.5% by volume tetrachloroethylene (e.g. product name Perklone Ext, Banner Chemicals Ltd, UK).

It is a preferred feature of the present invention that the composition is adapted such that the engine is able to run using the cleaning composition in substantially pure form. That is to say, that the engine is not run on a conventional fuel which has an additive added thereto, but rather where the cleaning composition is the sole (or at least major) fuel source. Thus the composition can be used in a method which comprises running the engine for at least a portion of the cleaning cycle using the cleaning composition as the sole fuel source. It will be apparent that there will be traces of normal fuel left in the fuel system which will be mixed with the cleaning composition to some extent, but this will only be relatively small amounts, and will be massively diluted in the total volume of the cleaning composition -where fuel is mixed with the cleaning composition in this way it is only considered a minor fraction, and the cleaning composition is still considered substantially pure.

The composition is suitably adapted such that the engine is able to run for a suitable period of time on a fuel source comprising at least 90%, more preferably 95%, most preferably 99% or higher of cleaning composition; correspondingly there is less than 10%, 5% or 1% of the engine's normal fuel present for the relevant period.

In order for this to occur, it will be apparent that the cleaning composition must be combustible (it will therefore typically be hydrocarbon-based), and have generally comparable combustion characteristics to the normal fuel of the vehicle.

In the case of a diesel engine, the cleaning composition preferably has a cetane number of or higher, preferably from about 51 to about 60 as measured in accordance with EN ISO 5165. Various cetane number modifying additives are known in the art which can be used to modify the cetane number of a cleaning composition, e.g. alkyl nitrates (principally 2-ethylhexyl nitrate) and di-tert-butyl peroxide (DTBP).

For petrol engines a cleaning composition preferably has an octane rating of 90 or higher (RON), more preferably from about 92 to about 102 RON. Various octane number modifying additives are known in the art which can be used to modify the octane number of a cleaning composition, e.g. methyl tert-butyl ether (also known as methyl tertiary butyl ether, MTBE), ethyl tert-butyl ether (ETBE), isooctane (2,2,4-trimethylpentane) and toluene (methylbenzene).

According to a second aspect of the present invention, there is provided a fuel additive composition suitable for addition to the fuel supply of an internal combustion engine, the composition comprising the ingredients set out above and, in addition, from 0.5 to 3% (by volume) of a cetane or octane number-raising additive.

Such a composition has been found to be surprisingly effective in improving fuel consumption and emissions when added to the fuel of a vehicle. This indicates that the additive of the present invention can clean or maintain the cleanliness of the fuel system of an engine when added to the fuel.

Suitably the fuel additive composition is an additive for diesel fuel. However, the additive could be for petrol (gasoline).

A preferred fuel additive composition comprises: -15 to 99.5% of a Ca to 016 petroleum distillate; -0 to 80% of a 07 to 012 petroleum distillate; and -0.5 to 3% of a cetane or octane number-raising additive.

In the case of a fuel additive, the flash point is not of such concern, and as such it is perfectly possible to have a comparatively high proportion of C7 to 012 petroleum distillate. Thus an exemplary fuel additive composition can suitably comprise: -60 to 80% of a 07 to 012 petroleum distillate; -10 to 39.5% of a 06 to 016 petroleum distillate; and -0.5 to 3% of a cetane or octane-raising additive.

A preferred composition comprises: -70-80% of a 07 to 012 petroleum distillate; -20-29.5% of a 06 to 016 petroleum distillate; and -0.5 to 3% of a cetane or octane-raising additive.

A more preferred composition comprises: -70-80% of white spirit; -20-29.5% of a kerosene; and -0.5 to 3% of 2-ethylhexyl nitrate.

A specific exemplary composition comprises: -73.5% by volume white spirit; -24.5 % by volume kerosene; and -2 % by volume 2-ethyihexyl nitrate.

The invention also contemplates a fuel (e.g. petrol or diesel) which comprises an additive according to the second aspect of the present invention. Suitably the fuel comprising a concentration of at least at least 0.01 % by volume, preferably from 0.05 to 5 %, more preferably from 0.1 to 1 %, and most preferably from 0.1 to 0.5 % by volume of the fuel additive composition.

A cetane number raising additive' is a composition which can be added to a hydrocarbon fuel to raise its cetane number. Cetane number (CN) is a measure of a fuel's ignition delay, the time period between the start of injection and the first identifiable pressure increase during combustion of the fuel. In a particular diesel engine, higher cetane fuels will have shorter ignition delay periods than lower cetane fuels. In short, the higher the cetane number the more easily the fuel will combust in a compression setting (such as a diesel engine). The characteristic diesel "knock" occurs when the first portion of fuel that has been injected into the cylinder suddenly ignites after an initial delay (once ignition occurs, all the remaining fuel burns smoothly as it leaves the injector nozzle). Minimizing this delay results in less unburned fuel in the cylinder at the beginning and less intense knock. Therefore higher-cetane fuel usually causes an engine to run more smoothly and quietly. There are a number of cetane improvers known, but the most common are alkyl nitrates (principally 2-ethylhexyl nitrate) and di-tert-butyl peroxide. 2-ethylhexyl nitrate is listed under CAS No 27247-96-7 and is available from Sigma Aldrich under product code 293784.

Suitably the composition of the present invention comprises a cetane number-raising additive which is an alkyl nitrate or di-tert-butyl peroxide. More preferably the cetane number raising additive is 2-ethyl hexyl nitrate.

Likewise, an octane number-raising additive' is a composition which can be added to a hydrocarbon fuel such as gasoline to raise its octane number. Octane rating or octane number is a standard measure of the performance of a motor or aviation fuel. The higher the octane number, the more compression the fuel can withstand before detonating.

Suitably the composition of the present invention comprises an octane number raising additive which is methyl tert-butyl ether (also known as methyl tertiary butyl ether, MTBE), ethyl tert-butyl ether (ETBE), isooctane (2,2,4-trimethylpentane) and toluene (methylbenzene).

An exemplary fuel additive composition for addition to diesel fuel comprises: -70-80% by volume white spirit, typically 73-76%; -20-30 % by volume kerosene, typically 22-26%; and -1-3 % by volume of an alkyl nitrate (preferably 2-ethylhexyl nitrate), and typically about 2%.

According to a third aspect of the present invention, there is provided a method of cleaning the fuel system of an engine, the method comprising running the engine using a fuel which comprises at least 50% by volume of a cleaning composition (and preferably higher, e.g. 90% or higher) according to the first aspect of the present invention for a suitable time period for cleaning to occur. The fuel in this case can be considered a surrogate fuel' as it replaces the conventional fuel for the duration of the cleaning process.

The method thus comprises using the cleaning composition as a fuel source to run the engine. This allows the cleaning composition to pass completely through the fuel system of the engine to the combustion chamber(s). This means that the cleaning composition in concentrated or substantially pure form is able to enter into, and pass through, for example, the fuel rail and injectors and the like, which are parts of the fuel system and often at least partially occluded by contaminants.

Preferably the fuel is entirely or substantially comprised of the cleaning composition of the present invention. For example the fuel comprises at least 90%, more preferably 95%, most preferably 99% or higher of the cleaning composition; correspondingly there is less than 10%, 5% or 1% of the engine's normal fuel (e.g. petrol or diesel) present for the relevant period.

Obviously the amount of time required will depend on the amount of cleaning to be performed, the level of contamination present, the type of contamination present, the type of engine, etc. Thus one cannot define specific time periods for all situations. However, experimental work suggests that time period of from 20 minutes to 1 hour results in a suitable level of cleaning for most engines, including diesel engines in commercial vehicles.

The level of cleaning which has been achieved can be quantified by comparing fuel efficiency and pollutant levels in exhaust gases before and after cleaning. Techniques to do this are well known in the art.

Additionally, by monitoring changes of flow rate of the cleaning composition as cleaning progresses, or by measuring fuel flow rates before and after cleaning, an indication of the amount of cleaning which has occurred can be determined.

The method preferably comprises matching the delivery pressure of the cleaning composition to the native pressure of the engine fuel system. Suitably this can be achieved by measuring the native pressure of the fuel system of the engine and matching the delivery pressure of the cleaning composition to this. However, this can also be achieved by setting the delivery pressure to an appropriate level for the engine type without performing the measuring step, e.g. using a database of pressures for various engines. Exact numerical correspondence of pressures is not required, but the match should be close enough to allow the ECU to permit the engine to run.

The pressure of the cleaning composition can conveniently be set to a desired level using a pump with a variable output pressure to control the pressure in the delivery line.

A suitable apparatus for use in the method is described below.

In a fourth aspect of the present invention, there is provided a method comprising adding a fuel additive composition according to the second aspect of the present invention to the fuel supply of an engine. The method preferable comprises running the engine using the fuel supply.

Preferably the fuel is diesel.

Preferably the fuel is added to the fuel tank of a vehicle.

Suitably the additive is added to form a fuel comprising a concentration of at least 0.01 % by volume, preferably from 0.05 to 5 %, more preferably from 0.1 to 1 %, and most preferably from 0.1 to 0.5% by volume of the fuel additive composition.

According to another aspect of the invention, there is provided a method of niaking a modified fuel comprising adding a fuel additive as set out above to a fuel, e.g. diesel or petrol.

Specific Description of Embodiments of the Invention The present invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: -Fig 1 shows typical variability of speed in the steady state runs, test run at 50 mile/h, standard fuel; -Fig 2 shows typical variability of speed in the steady state runs test run at 50 mile/h, modified fuel; -Fig 3 shows fuel consumption of standard and modified fuel; -Fig 4 shows carbon dioxide levels of standard and modified fuel; -Fig 5 shows oxygen levels of standard and modified fuel; -Fig 6 shows nitrogen oxide levels of standard and modified fuel; -Fig 7 shows sulphur dioxide levels of standard and modified fuel; -Fig 8 shows CO levels with standard and modified fuel; -Fig 9 shows uHC levels with standard and modified fuel; -Fig 10 shows smoke levels with standard and modified fuel; -Fig 11 shows an apparatus adapted for use in the third aspect if the invention, i.e. delivery of a composition of the present invention to a fuel system of an engine in substantially pure form; -Fig 12 shows a modified apparatus adapted for use in the third aspect if the invention; -Fig 13 shows a further modified apparatus adapted for use in the third aspect if the invention; and -Fig 14 shows a conventional common rail injection system.

Method of Treating and Engine Using Cleaning Composition In normal operation any internal combustion engine is prone to certain problems arising from the burning of fossil fuels as a power source, as discussed above.

Whilst engine technology has advanced over recent years, improving fuel economy and emissions, and alternative fuel sources are slowly emerging, there is still a need to burn fossil fuel to power engines. This is unlikely to change for the foreseeable future, with only electric powered vehicles offering an alternate option; these electric vehicles have significant limitations, especially with range, and are unlikely to become a credible alternate for quite some time.

The present invention is aimed at reducing fuel consumption and reducing pollutants to improve our environment, also and has specific benefits within the biodiesel uptake.

A suitable apparatus can be used in conjunction with the compositions of the present invention to remove deposits that have built up on the fuel system components using a chemical cleaning solution. The apparatus is connected to an engine's fuel system flow (i.e. from the fuel tank to the engine) and return (i.e. from the engine back to the tank) lines and a cleaning chemical is pumped through the system under nominal operating pressure. The chemicals clean the fuel system components, in many cases returning them to nearly new condition. The apparatus is then disconnected so no permanent modification is made to the engine.

The impact of this cleaning process is immediate and significant: -Fuel flows more efficiently, the spray injectors fully atomise the fuel which is crucial in ensuring complete combustion of fuel in the chamber. This results in maximum power from the fuel.

-Since a very high proportion of the fuel is completely burnt during combustion the effect on emissions is significant with lower levels of un-burnt hydrocarbons being found and a reduction in undesirable pollutant gas output -A significant reduction in particulate emissions.

-Regular treatment of engines has the impact of prolonging the life of key components such as the injector spray arms which, when blocked, is often the cause of engine breakdown.

The apparatus has the secondary functionality of fuel conditioning. Fuel can be removed from a tank or storage vessel, passed through a centrifugal and filtration mechanism which acts to remove microbial, water and other contamination types.

Contamination of fuel has serious impacts including; reduced filter life, coalescer malfunction, engine wear due to variations in fuel flow, corrosion of the fuel system, corrosion of injectors, high fuel consumption and increased emissions.

A flow meter can be incorporated into the apparatus to allow for accurate assessment of the treatment composition flow rate. This flow rate can give an indication of the degree of fouling and contamination within the fuel management system. Once the cleaning process has been run an improvement in the fuel flow rate should be observed. It can also show how much fuel is wasted in engine idling and warm up when flow rate is compared between a cold start and fully warmed up.

A preferred alternative to the use of a flow meter is that changes in the level of cleaning composition can be measured by a fuel level measurement device in the fuel reservoir. This can then be compared against elapsed time to measure consumption and thus engine efficiency. Suitable level measure sensors are available commercially from IFM Electronics Ltd, UK, for example.

The treatment of an engines fuel system (and optionally its fuel tank) can conveniently take place during normal vehicle or plant servicing. An added feature of the apparatus can be an engine diagnostic capability provided by diagnostic software applied via a laptop interface.

This will allow operators to effectively manage the entire servicing and cleaning procedures.

An exemplary apparatus is shown in Fig 11. The apparatus comprises a reservoir 2, in the form of a tank, with an opening at the top ito allow the reservoir to be filled with a cleaning composition. The reservoir has a drain 3, which allows for emptying of the reservoir to remove waste composition, e.g. after a cleaning operation has been concluded.

The apparatus comprises an outlet to a delivery line 20, which allows the cleaning fluid to leave the reservoir towards the engine. A filter 5 is provided in the delivery line immediately downstream of the reservoir to filter the cleaning composition.

A pump 8 is provided in the delivery line downstream of the filter 5. The pump is a conventional fuel pump, e.g. a Walbro GSL 392. The pump should be a low spark transfer pump, ideally able to run from of domestic electric supply. It should be chemical resistant and capable of variable speed control, ideally resistive to bio diesel up to B30. The pump acts to pressurise the cleaning composition. The pump is controlled by the programmable logic circuit (PLC) 18 in order to provide the correct pressure and/or flow rate of the cleaning composition, as will be described in more detail below.

Frist and second pressure sensors 9 are provided downstream of the pump 8. These can be any suitable pressure sensors for use in fuel systems, e.g. IFM PT9554 pressure sensors are suitable. Between the pressure sensors is a dump valve 10 (e.g. a Murphy Pry 50 valve) located in the delivery line and connected to a pressure release line 22 which leads to the reservoir 2. The dump valve 10 is operable to release the pressure in the delivery line, e.g. after a cleaning operation is complete. The dump valve is operated by the PLC 18. The pressure sensors 9 measure the pressure both upstream and downstream from the shuttle valve. This allows the PLC to monitor pressure in the delivery line and thereby adjust the operation of the pump 8 to control the pressure and monitor operation of the shuttle valve 10 to dissipate system pressure.

Below the second pressure sensor 9 is a second filterS. This filter has a principle role in ensuring that there is no possibility of debris from the pump, which can be released as a result of wear or malfunction, reaching the fuel system of the engine.

The filters 5 are capable of filtering bio diesel and are capable of sustaining a pressure of 3.5 bar. There are many filters on the market that may be adopted to suit end user preferences.

Downstream of second filter there can be provided a flow meter 11, which is able to monitor the flow through the delivery line 20. This allows the PLC to monitor consumption of the cleaning composition provided in the reservoir 2, and also to monitor for changes in flow as the cleaning process proceeds. This latter observation is a useful indicator of successful treatment of the fuel system. An alternative, and preferred method can adopted, as described previously. This involves using a measuring device in the reservoir to monitor the level of the cleaning composition, and the consumption of cleaning composition against time can be used to determine consumption of the cleaning composition.

The delivery line then comprises suitable interface means to allow connection of the delivery line to the fuel system of a vehicle. Suitable interlace means comprise push fit fuel line connectors, optionally with step-up or step-down adaptors, if required to accommodate different fuel line diameters.

An exemplary common rail diesel fuel injection system 30 is illustrated in Fig 14. The delivery line suitably connects at a point 32 after the primary fuel pump 36, but before the high pressure (HP) fuel pump 38. A return line is connected via a suitable interface means at a point 34 after the injection rail 40, typically before or at the point the fuel line reaches the fuel tank 42.

Suitable interface means for various engine/fuel systems will be stored on a database to allow a user to determine the appropriate connector for a particular vehicle or engine type.

The return line 24 of the apparatus discharges into the reservoir 24, returning any unused cleaning solution (and fuel from the engine fuel system lines, at the beginning of the cleaning process) to the reseivoir. The returning cleaning solution is the recycled through the system.

A flow meter can be provided in the return line 24 to allow the POT to monitor the amount of cleaning composition returned to the reservoir and thus monitor consumption of the composition; this is useful to monitor for efficiency of the engine and to monitor the amount of cleaning solution left in the system.

In the delivery line 20 there is preferably provided a third pressure sensor 26, immediately upstream of the interface. Preferably this is associated with a non-return valve upstream (not shown) which prevents the flow of fluid back up the delivery line. This pressure sensor 26 is used to measure the native pressure of the fuel system, i.e., the pressure exerted by the primary fuel pump 36 in operation. To achieve this, the interface is connected to the fuel system. The ignition system of the engine is then turned on so as to power up the primary fuel pump. This will apply the native pressure to the pressure sensor 26. This is recorded by the PLC and will later be used to set the appropriate pressure applied by the pump 8.

In use the apparatus is connected to the fuel system 30 as discussed above. The relevant pressure is taken. The vehicle fuel pump is then preferably deactivated, e.g. by removing the relevant fuse, relay or by providing a loop of fuel line to return pumped fuel to tank.

The connection is then modified (if necessary) to permit the delivery line to deliver the cleaning composition into the fuel system 30, flowing towards the injection system. The pump 8 is activated by the PLC 18 to apply the appropriate pressure to the fuel line. The engine ignition is then activated and the engine is started. Because the pressure exerted by pump 8 mirrors the native pressure of the fuel system, the engine control unit (ECU) of the engine does not detect any error and allows the engine to start and run as normal.

It is preferred that vehicle fuel filters are replaced to ensure a clean free supply of cleaning composition to the fuel system. If the pipe connection is before filter assembly of the engine fuel system, this will prevent any residual contamination being washed through the filter into the injection system.

The cleaning composition then flows into the engine fuel system 30 and cleans the various deposits and contamination therefrom. The cleaning solution is able to dissolve deposits that would not be dissolved by fuel, even fuel which has a cleaning additive provided. By providing a neat' cleaning composition, the present invention thus provides for a level of cleaning rigour which is far better than any known system.

The cleaning composition acts a replacement surrogate fuel' for the engine. It is thus important that the composition is able to be burned by the engine, and has appropriate combustion properties. Most diesel engines can successfully burn fuels with a cetane number of 40 or higher, with cetane numbers of 51 to 60 being typically preferred (see EN ISO 5165 for calculation methodology). For petrol engines a cleaning composition preferably has an octane no of 90 or higher (RON), more preferably from 92 to 102 RON.

A suitable cleaning composition for a diesel engine comprises: -70 to 75% by volume of a C7 to C12 petroleum distillate (e.g. white spirit); -20 to 25% by volume of a C6 to C16 petroleum distillate (e.g. kerosene); and -0.5 to 1% by volume of tetrachloroethylene.

This composition has been demonstrated to allow effective cleaning when used in the manner described in the present application.

It is, however, preferred that the cleaning composition has a flash point of 60 °C or higher.

A more preferred cleaning composition comprises: -95% to 99% by volume 06 to 016 petroleum distillate, for example de-aromatised kerosene (e.g. Product no BAS D220-235, Banner Chemicals Ltd, UK) -1% by volume tetrachloroethylene (e.g. Product name Perklone Ext, Banner Chemicals Ltd, UK) This cleaning composition has a flashpoint of over 60 °C and a high level of cleaning efficacy.

The specifications of BAS D220-235 is set out in Table 1

Table 1

PROPERTY QUALITY TEST METHOD TYPICAL

REQUIREMENT REFERENCE LEVELS

MIN MAX

DENSITY at 15°C (g/ml) 0.800 0.820 ASTM D1298 0.810 COLOUR (Saybolt) +30 ASTM D 156 +30 BOILING RANGE: °C ASTM D 86 INITIAL POINT 218 222 DRY POINT _______ 240 ___________ 232 FLASH POINT: °C 1P 170 93 AROMATICS %wt 0.1 max UV ANILINE POINT °C ASTM D 611 80 VAPOUR PRESSURE @20°C hPa 0.1 BENZENECONTENTppm CC -<100 SULPHUR CONTENT-ppm --ASTM D 3120 <1 VISCOSITY @20 °C mm2/s 2.7 2.7 DOCTOR TEST IP 30 Negative As the cleaning composition passes through the fuel system it removes deposits of carbon, tar, biofilms and varnishes within the fuel system. These are generally dissolved and then are burnt as they are carried into the combustion chamber. It has been found that a critical area of cleaning is in the injector body itself. It has been found that the nozzle of the injector is not generally prone to blocking as the high pressures and the very narrow diameters involved tend to keep the nozzle clear. However, within the body of the injector deposits can accumulate which leads to poor fuel delivery to the nozzle and consequently poor fuel delivery and atomisation. This in turn leads to poor combustion, lack of power and an increase in particulate (soot) emissions.

Cleaning composition which is not used for combustion is returned to the reservoir via the return line 24.

The delivery and return lines are suitably conventional 8mm internal diametel fuel hoses.

Such lines allow sufficient flow and are compatible with the cleaning composition. They also allow for easy interconnection to engine fuel systems, using step-up or step-down adaptors if required.

The cleaning process is continued for as long as is required to clean the engine fuel system to a suitable level. It has been found that cleaning times of from 20 minutes to 1 hour are typically adequate for commercial vehicle diesel engines.

Suitable electronic control systems for the device comprise a motherboard (e.g. a Gigabyte B85M-HD3) to which is connected: -A CPU (e.g. Intel Pentium G2020) -Disk drive (e.g. Crucial V4 64GB SSD) -Ram (e.g. Crucial 2GB DDR3) -I/O Card (e.g. National Instruments PCIe 6320) -Touch screen display (e.g. Microtouch C1700SS) The various pressure sensors, pumps etc. are connected to the motherboard to allow them to report or be controlled, as appropriate. Suitable software/firmware is provided for the device to be operated.

The device of the present invention may also comprise other features such as a pressure trip (e.g. IFM PK5524), temperature trip, and/or level sensor for safety and/or operational considerations.

Shutoff valves for use in the present invention are suitably pilot operated 2-port solenoid valves, e.g. those available from SMC Pneumatics Ltd (Milton Keynes, UK) under part number VXD214OA-04F-5D01. Other valves could of course be used.

The dump valve is suitably a Murphy PRV 50 valve although, again, other dump valves could of course be used.

This summarises the core functionality of the apparatus of the present invention. However, the apparatus can have additional functionality, as discussed below.

In one preferred embodiment the apparatus comprises a fuel cleaning device, also known as a fuel polishing device or fuel conditioning unit. This device comprises an inlet to receive fuel from a storage tank (e.g. a vehicle fuel tank), a filter system to remove contaminants and an outlet to return the cleaned fuel to the tank, optionally via a temporary store. Preferably the fuel cleaning device comprises a pump to circulate the fuel through the filter system, e.g. a Marco 164-003-10 pump. The filter system is intended to remove particulates and water contamination in particular. Fuel polishing kits are available for cleaning fuel supplies, e.g. IPU mobile fuel polishing kits (e.g. product FB500 from Industrial Power Units Ltd., Churchbridge, UK) or the 1000FH turbine diesel cleaning unit from Racor. Such commercially available kits can be readily incorporated into the apparatus of the present invention.

In another preferred embodiment the apparatus comprises agitation means to agitate the contents of the storage tank. Suitably this comprises an air compressor (e.g. Gast 71R142-POOl B-D3O1X) to provide a source of pressurised air, and a suitable applicator with a nozzle to deliver a stream of compressed air to the tank, and an air line connecting the compresso to the nozzle. In a simple embodiment the applicator can be a simple flexible hose. This has the effect of agitating the contents of the tank to bring settled contaminants into suspension, and also allows the surfaces of the tank to be scoured to remove adherent deposits, such as biofilms or the like. Other agitations systems can be used, but are typically less preferred. For example, the agitator can extract fuel from the tank, pressurise it, and direct it back into the tank under pressure to agitate the contents of the tank and scour its surfaces. Mechanical agitators such as rotating pad or the like could also be used.

Figure 12 shows an exemplary schematic of a modified apparatus.

Notable in the embodiment shown in Figure 3 is the addition, relative to the embodiment shown in Fig 1, of further safety features in the form of an emergency stop system 50, two safety valves 52 and 54, which stop flow of fuel/cleaning composition when activated, and a dump valve 56 which dumps pressurised cleaning composition back to the reservoir 58, e.g. at normal shutdown or in an emergency stop. This dump valve is a very significant safety feature as it means that the system is depressurised at the end of the process and/or if a problem is encountered. If the pressure was not released then there could be safety issues with pressurised cleaning composition being ejected when connectors are de-coupled. The embodiment in Fig 3 automates the depressurising system which reduces the risk of human error.

The emergency stop system can be activated automatically where the control systems detect a problem and/or manually where a user has need to activate it.

As can be seen, the apparatus comprises a power and control enclosure which houses the various electronic systems 80, and which is connected to an external AC supply.

The agitator system 70 comprises an agitator pump 72 (air compressor) and a compressed air line 74 leading to a nozzle (not shown).

A fuel cleaning device 60 comprises a fuel polishing unit 62 and a fuel pump 64 and a safety shutoff valve 54. The safety shutoff valve 54 is connected to the emergency stop system, which allows operation of the fuel cleaning system to be halted if required by tripping the emergency stop system. In normal running, the fuel is pumped from the tank through the polishing unit and then back to the tank. If the emergency stop is pressed, the fuel pump will stop and also safety valve 54 would close meaning that no fuel could leave the system; this also occurs if power was cut or removed from the apparatus.

The dump valve 52 in the cleaning composition supply line is a 3-way valve which has a default position to direct flow to the reservoir, i.e. absent a control signal which causes the valve to direct flow to the outlet. This is a significant safety feature as it means that the apparatus is adapted to safely recycle cleaning composition or release stored pressure in the cleaning composition to the reservoir when required. When a suitable control signal is applied, i.e. when the cleaning process is in correct operation, the dump valve directs flow to the outlet and thus to the engine fuel system.

Fig 13 shows another embodiment of an appalatus for delivering the cleaning composition.

This embodiment is even more preferred than the two previous versions discussed, and includes additional refinements and safety features.

The agitator system 70 is provided in a compressor enclosure within the apparatus. This is an additional safety feature and mechanically isolates the compressor and associated systems from the fuel/cleaning composition systems. An air safety valve 76 is provided in line with the output of the compressor, which is set to 2 bar. If the pressure between the pump and the air outlet connection builds and exceeds the set pressure, the air safety valve will open and the pressure shall be safely vented through a silencer (not shown).

An additional feature in the fuel cleaning system of this embodiment has been added to further improve safety. If there is no connection made to the tank and the system is set to run, a pressure would build up against the output connector which could become problematic. An overpressure valve 64 has been fitted, which is a mechanical valve (i.e. with no electrical control). This is designed to open at 5 bar of pressure, which releases excessive built up pressure back into the polishing unit, and would continually loop until the pressure falls below 5 bar or the pump is halted.

In normal running, the cleaning composition (and residual fuel) is pumped from the engine fuel system into the reservoir 58, out of the reservoir through the filters and pressure sensors and back to the engine fuel system. If the emergency stop is pressed, the fuel pump will stop and also safety shutoff valve 52 would close meaning no fuel would pass out of the apparatus. At the same time the dump valve 56 shall open directing any pressurised cleaning composition back into the reservoir 58. An overpressure valve 57 is provided and operates in an analogous way to the overpressure valve 64 in the fuel cleaning device, directing flow into the return line from the engine fuel system and back into the reservoir.

In Fig 13 a tank level sensor 59 is shown associated with the reservoir 58, which monitors the level of cleaning composition in the reservoir.

S Real-World Examples of Treating a Vehicle Engine Using the Apparatus and Composition of the Invention.

Test 1

Summary

Testing was carried out at the Intertek Tickford Ltd Vehicle Emission Test Laboratory in Milton Keynes, on behalf of Engym Services Ltd. The purpose of the tests was to quantify any improvements that may occur, following a process carried out on a diesel fuelled vehicle. A used Ford Transit 85 T260 van was tested, using the EC169212008 test standard, in an as received condition, immediately after the process and then again after 270 miles of mixed use. The tests showed: -The average fuel consumption improvement on the combined drive cycle was 7.2% (change from 35.00mpg to 37.52mpg achieved after mileage accumulation.

-The best fuel consumption improvement on the combined drive cycle is 8.01% (change from a low of 34.84mpg to a high of 37.63mpg achieved after mileage accumulation).

-The highest overall improvement was seen in the urban drive cycle; 9.09% (change from 29.81mpg to 32.52mpg achieved after mileage accumulation).

-The average CO2 was reduced by 6.8%.

-The exhaust particulates were reduced by 86.0%.

1. Introduction

Intertek Tickford were requested by Engym Services Ltd to quote for chassis dyno-based vehicle emission and fuel consumption testing to determine the effect of a fuel treatment process they are developing. This report outlines the test procedure and summarises the results of a series of tests run on a used Ford Transit.

2. Emission Test Laboratory The Intertek Tickford Emission Test Laboratory is equipped with a MRW twin roll chassis dynamometer and Horiba 9000 emission bench, with Constant Volume Sampling (CVS) system. The system retains dilute exhaust gas in sample bags for post-test analysis. The chassis dynamometer is designed to simulate the on road behaviour of the test vehicle, 21.

using a combination of inertia weights and an electrical absorber. A windscreen mounted monitor displays the drive trace to be followed by the driver. This also indicates the points at which gear changes should be performed and is controlled by a test control computer that also records data from the emission bench and chassis dynamometer.

S

3. Test Method The test vehicle was installed into the test laboratory with the driven wheels on the chassis dynamometer rollers. The dynamometer control system was set to the appropriate road load model (RLM) and the exhaust tailpipe was connected to the CVS system. The vehicle was tested as received, using forecourt grade diesel fuel, with a preconditioning run followed by a test on three subsequent days as outlined in the European test procedure EC/69212008 (Euro 5). On completion of the initial batch of tests, representatives of Engym Services Ltd attended Intertek Tickford, and carried out, under confidence, a cleaning process on the vehicle as set out above.

This cleaning process was the direct cleaning method described above, run for 30 mins and used a cleaning composition comprising: -74.5% by volume white spirit; -24.5 by volume e.g. kerosene; and -1% by volume of tetrachloroethylene.

The test sequence was then repeated on each vehicle. Following this the vehicle was driven for 27Omiles on a varied route of motoiways, A roads and urban routes. The vehicle was then retested. A preconditioning run and two tests, on subsequent days, were completed.

The average of the baseline, post process tests and post mileage accumulation tests were used to make comparisons.

Each test was run using the Euro drive cycle to establish the Urban, Extra Urban and overall Fuel Consumption and Regulated Exhaust Emissions (CO, C02, THC, NOx) including particulate mass. During the test the exhaust gases were collected and analysed using the dilute gas bag methods and carbon balance fuel consumption calculated.

4. Test Results UMTS CO C02 I F4C NOx ParticWaes 1'PG 5. Th Li çjcn C20 2136 £C3l 027 C 1910 3500 Post Procns ________________ L.'m O CtTh T.*40 NOx Partkadats rIPG Cbrsd -G97 C C6F _____________________ 1St -21 306 3.22 i,445 205 _______________________ 826 -5 20 -75.8 50 Post I'rocess + ViM 270 mfl ___________________________________________ _______ WcTS CO t02___ T iC NO Pflctdds MPG 033 82 kO.3 4 ".5-Ji cm -iCC 30i3' 1214_________ 1% tBbO -SB -ISY 1.S -SC 72

5. Conclusions

With regard to fuel consumption: -The average fuel consumption improvement on the combined drive cycle was 7.2% (change from 35.00mpg to 37.52mpg achieved after mileage accumulation.

-The best fuel consumption improvement on the combined drive cycle is 8.01% (change from a low of 34.48mpg to a high of 37.63mpg achieved after mileage accumulation).

With regard to regulated exhaust emissions: -The average CO2 was reduced by 6.8%.

-The exhaust particulates were reduced by 86.0%.

Test 2

Summary

Testing was carried out at the Intertek Tickford Ltd Vehicle Emission Test Laboratory in Milton Keynes, on behalf of Engym Services Ltd. The purpose of the tests was to quantify any improvements that may occur, following a process carried out on a diesel fuelled vehicle. A used Ford Transit 100 T280 van was tested, using the EC/69212008 test standard, in an as received condition, immediately after the process and then again after 265 miles of mixed use. The tests showed: -The average fuel consumption improvement on the combined drive cycle was 4.0% change from 35.47mpg to 36.91mpg achieved after mileage accumulation.

-The best fuel consumption improvement on the combined drive cycle is 4.76% (change from a low of 35.27mpg to a high of 36.95mpg achieved after mileage accumulation).

-The highest overall improvement was seen in the urban drive cycle; 8.03% (change from 29.40mpg to 31.76mpg achieved after mileage accumulation).

-The average C02 was reduced by 3.7%.

-The exhaust particulates were reduced by 75.3%.

1. Introduction

Intertek Tickford were requested by Engym Services Ltd to quote for chassis dyno based vehicle emission and fuel consumption testing to determine the effect of a fuel treatment process they are developing. This report outlines the test procedure and summarises the results of a series of tests run on a used Ford Transit.

2. Emission Test Laboratory The Intertek Tickford Emission Test Laboratory is equipped with a MRW twin roll chassis dynamometer and Horiba 9000 emission bench, with Constant Volume Sampling (CVS) system. The system retains dilute exhaust gas in sample bags for post-test analysis. The chassis dynamometer is designed to simulate the on road behaviour of the test vehicle, using a combination of inertia weights and an electrical absorber. A windscreen mounted monitor displays the drive trace to be followed by the driver. This also indicates the points at which gear changes should be performed and is controlled by a test control computer that also records data from the emission bench and chassis dynamometer.

3. Test Method The test vehicle was installed into the test laboratory with the driven wheels on the chassis dynamometer rollers. The dynamometer control system was set to the appropriate road load model (RLM) and the exhaust tailpipe was connected to the CVS system. The vehicle was tested as received, using forecourt grade diesel fuel, with a preconditioning run followed by a test on three subsequent days as outlined in the European test procedure EC/69212008 (Euro 5). On completion of the initial batch of tests, representatives of Engym Services Ltd attended Intertek Tickford, and carried out, under confidence, a cleaning process on the vehicle as set out above (this was identical to the direct cleaning process carried out in Test 1). The test sequence was then repeated on each vehicle. Following this the vehicle was driven for 265 miles on a varied route of motorways, A roads and urban routes. The vehicle was then retested. A preconditioning run and two tests, on subsequent days, were completed.

4. Test Results Pre Process _______ _______ _______ _______ _______ ___________ Cans UNTS CO C02 J T HG I NOx j Parvcuates MPG raa J F J J I result] D$a J 2C _______] C45 __________ 3341

FL I

Post Ptocess _______________ _______ _______ _______ ___________ _______ _______________ i. I GO G02 7 HG NOx PartcuWs MPG Mean CLrbreo * Uff'er%ea *I 1 -T20 aQia E&2 1:31 c, I.34 -673 3' Post Ptcess + 2& ______________________________________________ ________ ____ UNiTS CO C02 T HG NOx Pnvci$ates MPG Mean C)rb red g?4n 314E 2Q24 r1& _______ D4n'oe _____ JJC3 768__3oaHc2ia 04 I -37..395 477 75a

5. Conclusions

With regard to fuel consumption: -The average fuel consumption improvement on the combined drive cycle was 4.0% (change from 35.47mpg to 36.91 mpg achieved after mileage accumulation).

-The best fuel consumption improvement on the combined drive cycle is 4.76% (change from a low of 35.27mpg to a high of 36.95mpg achieved post process).

With regard to regulated exhaust emissions: -The average CO2 was reduced by 3.7% -The exhaust particulates were reduced by 75.3%.

Overall Conclusions

The two real world tests described above demonstrate the potential of the present invention to improve the performance of engines. A clear improvement in fuel economy was demonstrated after the test had been performed, and a very large improvement in particulate emissions was shown. Such a reduction of particulate emissions is particularly important in view of the health impact of such emissions, especially in an urban environment.

Further Testing, Including the Use of a Fuel Additive Composition

1 INTRODUCTION

Engym Services Ltd has developed an engine treatment procedure incorporating a fuel additive which is believed to reduce both fuel consumption and exhaust gas emissions. The company commissioned NEL to perform industry-standard vehicle tests to establish evidence of any improvements.

2 OBJECTIVE The objective of the project was to determine whether there was any significant reduction in fuel consumption and exhaust gas emissions due to the vehicle preparation and fuel treatment procedure adopted by Engym.

3 APPROACH The tests were undertaken in two stages: 1. Standard vehicle operating on standard fuel.

2. Modified vehicle operating on treated fuel.

At each stage the vehicle was operated at three steady state speed conditions and at two loads for each speed. Engym staff undertook the vehicle modification and the treatment of the fuel. Details of these tasks were not disclosed to NEL.

The test vehicle remained at the ETC building in a secure environment from delivery to the rolling road test cell throughout the complete test programme. It was not removed from the test site, except for being driven on the open road for a short period after the engine modification had been undertaken. A member of NEL staff was a passenger in the vehicle during this short drive.

4 TEST EQUIPMENT The vehicle used for the tests was a 2005 model year diesel Ford Transit 85T280, 1998cc, utilising a standard distributor pump type mechanical fuel injection system. The tests were carried out on a Consine Dynamics twin-drum chassis dynamometer operating in performance mode. For this mode of operation, loading is provided by an eddy current retarder. This retarder was operated in constant torque mode during the tests. A PC-controlled driver's aid unit was used to provide a visual reference of the target speed to the driver. The tests carried out were conducted at a series of steady speeds of 30, 40 and 50 mile/h. Fuel was supplied via a closed loop circulation system external to the vehicle. Fuel consumption was measured by a modified Hird-Brown gravimetric system which monitored the make-up flow to the closed loop. Exhaust emissions were measured using a Beckman CVS emissions system operating in raw gas mode. Non dispersive infra-red analysers were used to evaluate CC, CC2 and SO2 emissions. uHC emissions were measured by an FID device, NO emissions were measured by a chemiluminescent detector and 0 was measured by a paramagnetic detector. Raw gas tailpipe emissions were sampled from a location upstream of the CVS dilution point. An AVL 415 variable sampling smoke meter was used to determine variation in exhaust smoke concentration.

Thermocouples were fitted to record air inlet temperature, coolant temperature and fuel temperature.

TEST PROCEDURE

Prior to executing the tests the dynamometer was motored for a period of 30 minutes to stabilise bearing friction. The vehicle was then driven for sufficient time to enable the coolant temperature to stabilise. Steady-state measurements were initially recorded at a light road-load at 40 mile/h. This process was repeated at 50 mile/h and then at 30 mile/h with the same level of brake load. The test sequence was then repeated at a second, higher, road-load condition. This programme of six test points was then repeated in its entirety to provide two sets of baseline data. After the baseline tests were completed, Engym staff undertook two tasks: 1. A batch of diesel fuel was treated in preparation for further tests.

2. Modification was undertaken on the vehicle.

These tasks were undertaken at NEL premises and took approximately 90 minutes to complete. Details of these tasks were not disclosed to NEL. The standard fuel was then drained from the system and it was then flushed with the treated fuel. The system was drained again and refilled with the treated fuel. Following completion of the service procedures, the test vehicle was driven on the open road for approx 30 minutes prior to re-testing. A member of NEL staff was a passenger during the open road drive to verify no further work was undertaken. On completion of the fuel treatment process, the vehicle modification and the 30 minute drive, the tests carried out for the baseline measurements were repeated in their entirety with the modified vehicle and treated fuel.

The treated fuel was a conventional diesel containing 5 ppt (0.5 % by volume) of a diesel fuel additive comprising: -73.5% by volume white spirit; -24.5 % by volume kerosene; and -2 % by volume 2-ethylhexyl nitrate.

The vehicle treatment was the same method as used in the Intertek Tickford tests 1 and 2 discussed above, i.e. the direct cleaning method, run for 30 mins and used a cleaning composition comprising: -74.5% by volume white spirit; -24.5 by volume e.g. kerosene; and -1% by volume of tetrachloroethylene.

6 TEST RESULTS The test conditions used in the project are summarised in Table 2.

Table 2

Test parnt Road speed mile/ti Torque at rofls Mm 1 40 75 2.50 75 3 30 75 4 40 13 50 139 13 30: ______________________ The load figures represent the torque set and measured at rolls. This value was adjusted in each run to allow for the necessary corrections due to changes in ambient pressure and temperature. Typical variability of speed in the steady state runs is shown in Figures 1 and 2 for the 50 mile/h, 75 Nm torque condition. Some speed variability can be observed and a larger number of repeat runs would be required to ensure that the effect of this would be eliminated from the results. The vehicle service procedure and the fuel treatment were both undertaken at the same time, so it is not possible to separate the effects of these in the tests undertaken.

The results are reviewed briefly in two sections: * Fuel consumption * Emissions 6.1 Fuel Consumption Measurements Figure 3 shows the comparison of the average measured fuel consumption at each test condition. Two test runs were undertaken at each speed/load condition and the average of these two runs is shown. The results for the modified condition were recorded using treated fuel and the vehicle modification. At first sight it would appear that the modified vehicle with treated fuel has resulted in a reduction in fuel consumption at each condition evaluated. In percentage terms the reduction appears large (up to 14%); however care is required in the interpretation of the results. The error bars shown in the figure illustrate that the measurements were highly variable and the measurement variability was considerably larger than the apparent reduction in fuel flow rate. A comparison of the range covered by the error bars does, however, suggest a reduction in fuel consumption in four out of six test conditions evaluated. The degree of variability in the measurements, however, precludes any accurate evaluation of the magnitude of any reduction in fuel consumption. The calibrated accuracy of the fuel measurement system was better than 1%, and therefore the variability in the measurements is likely to be due to small changes in speed and load over the test condition.

Since only two sets of test data were recorded at each test condition it was not possible to carry out a meaningful statistical analysis of the data. Further work would be required to gather more data points, to enable confidence limits to be determined.

6.2 Emissions Measurement Exhaust gas emissions measurements are less obviously affected by instability in operating conditions due to the sample transport times, mixing in the exhaust collection pipe work and analyser response times. Figure 4 shows the comparative levels of CO measured with standard vehicle set up and the modified vehicle with treated fuel.

Figure 5 shows the same plot for exhaust gas 0 levels. Although exhaust emissions are expressed as a volumetric fraction, if a significant reduction in fuel flow rate was achieved, it might be expected that a reduction in CO levels and an increase in residual oxygen would be apparent. No such changes are evident in figures 4 and 5. It should be noted that the CO figures are quoted as percentage concentration by volume, not as g/km.

Figure 7 suggests some reduction in SO2 levels with the modified vehicle and treated fuel.

Comparisons of CO emissions and uHC emissions with standard vehicle set up and modified vehicle with treated fuel are shown in Figures 8 and 9 and although these show reductions in emissions, all the values are at trace concentration levels, so no conclusion can be drawn.

Figure 10 shows that there was a significant improvement in exhaust smoke concentration with modified vehicle and treated fuel (as expressed in terms of Filter Smoke Number -FSN).

7 CONCLUSIONS

1. Steady state fuel consumption and exhaust emissions measurements were carried out on a Ford transit vehicle operating (1) in standard form with standard pump fuel and (2) after engine cleaning and with diesel fuel treated with a fuel additive.

2. Fuel flow rate measurements indicated a reduction in fuel consumption when operating with the modified vehicle and treated fuel.

3. The fuel flow rate measurements were subject to a degree of variability and more data would be required to perform meaningful statistical analysis. Nonetheless, the overall results are indicative of improved engine performance.

4. Measured data was recorded on the vehicle after both cleaning and fuel modification. It was not possible to determine the separate contribution of the vehicle modification or of the treated fuel to any changes in performance.

5. A more extensive test programme would be required to accurately quantify the magnitude of the benefits offered by the vehicle modification and treated fuel.

Claims

Claims 1. An engine cleaning composition for cleaning the fuel system of an internal combustion engine, the composition comprising the following ingredients (% by volume): -15 to 99.5% of a 06 to 016 petroleum distillate; and optionally -0.5 to 80% of a 07 to 012 petroleum distillate; and at least one of: -0.5 to 3% of tetrachloroethylene; and -0.5 to 3% of a cetane or octane-raising additive.
2. An engine cleaning composition according to claim 1 wherein the 06 to 016 petroleum distillate is kerosene.
3. An engine cleaning composition according to claim 1 or2 wherein the C7to 012 petroleum distillate is white spirit.
4. A composition according to any preceding claim for direct cleaning the fuel system of an internal combustion engine, in substantially undiluted form, comprising: -20 to 99.5% of aCe to 016 petroleum distillate; -0 to 80% of a 07 to 012 petroleum distillate; and -0.5 to 3% of tetrachloroethylene.
5. A composition according to claim 4 comprising: -75 to 99.5% of a 06 to 016 petroleum distillate; -0 to 25% of a 07 to 012 petroleum distillate; and -0.5 to 3% of tetrachloroethylene.
6. A composition according to claim 5 comprising: -85 to 99.5% of kerosene; -Oto 15% of white spirit; and -0.5 to 2% of tetrachloroethylene.
7. A composition according to claim 6 comprising: -95% to 99.5% de-aromatised kerosene; -0.5 to 1.5% by volume tetrachloroethylene.
8. A composition according to any preceding claim which is suitable such that the engine is able to run for a suitable period of time on a fuel source comprising at least 90%, more preferably 95%, most preferably 99% or higher of cleaning composition.
9. A composition according to any preceding claim 8 which has a cetane number of 40 or higher, preferably from about 51 to about 60, as measured in accordance with EN ISO 5165.
10. A composition according to any preceding claim 8 which has an octane rating of 90 or higher (RON), more preferably from about 92 to about 102 RON.
11. A composition according to any one of claims ito 3, which is a fuel additive composition suitable for addition to the fuel supply of an internal combustion engine, the composition comprising the composition of any one of claims ito 3 and, in addition, from 0.5 to 3% of a cetane or octane number-raising additive.
12. A fuel additive composition of claim 11 comprising: -60 to 80% of a 07 to 012 petroleum distillate; -10 to 39.5% of a CS to 016 petroleum distillate; and -0.5 to 3% of a cetane or octane-raising additive.
13. A fuel additive composition of claim 12 comprising: -70-80% white spirit; -20-29.5% kerosene; and -0.5 to 3% 2-ethylhexyl nitrate.
14. A fuel additive composition of claim 13 comprising: -73.5% white spirit; -24.5% kerosene; and -2% 2-ethylhexyl nitrate.
15. A fuel which comprises an additive according to any one of claims 11 to 14.
16. The fuel of claim 15 which is a diesel fuel.
17. The fuel of claim 15 or 16 which comprises a concentration of at least at least 0.01 % by volume, preferably from 0.05 to 5 %, more preferably from 0.1 to 1 %, and most preferably from 0.1 to 0.5 % by volume of the fuel additive composition.
18. A method of cleaning the fuel system of an engine, the method comprising running the engine using a surrogate fuel which comprises at least 50% by volume of a cleaning composition according to any one of claims 1 to 10 for a suitable time period for cleaning to occur.
19. Preferably the surrogate fuel is entirely or substantially comprised of the cleaning composition according to any one of claims 1 to 10.
20. The method of claim 18 or 19 wherein the time period for cleaning to occur is from 20 minutes to 1 hour.
21. The method of claim 20 which comprises matching the delivery pressure of the cleaning composition to the native pressure of the engine fuel system.
22. A method for operating an internal combustion engine which comprises adding a fuel additive composition according to any one of claims 11 to 14 to the fuel supply for an engine.
23. The method of claim 22 comprising running the engine using the fuel supply.
24. The method of claim 22 or 23 wherein the additive is added to form a fuel having a concentration of at least 0.01 % by volume, preferably from 0.05 to 5 %, more preferably from 0.1 to 1 %, and most preferably from 0.1 to 0.5 % by volume of the fuel additive composition.
25. A method of making a modified fuel comprising adding a fuel additive according to any one of claims 11 to 14 to a fuel.