WO2016026583A1

WO2016026583A1 - Enhanced fuel and method of producing enhanced fuel for operating internal combustion engine

Info

Publication number: WO2016026583A1
Application number: PCT/EP2015/025059
Authority: WO
Inventors: James Robert Jennings; Glyn David Short
Original assignee: Avocet Fuel Solutions Inc.; Afs Avocet Plc.
Priority date: 2014-08-17
Filing date: 2015-08-16
Publication date: 2016-02-25
Also published as: EP3189121A1; US20170260466A1

Abstract

Disclosed is an enhanced fuel, a method of producing such enhanced fuel, and method of using such enhanced fuel for operating internal combustion engine. The fuel includes a mixture of at least one alcohol, water and ammonium nitrate (AN) as a cetane enhancer. The water is included in a quantity which renders the ammonium nitrate dissolved in the at least one alcohol. The fuel further contains dimethylether as an ignition-improver additive, at least one lubricity agent and at least one anti-corrosion agent.

Description

ENHANCED FUEL AND METHOD OF PRODUCING ENHANCED FUEL FOR OPERATING INTERNAL COMBUSTION ENGINE

Technical Field

The present disclosure relates to enhanced fuels suitable for use in internal combustion engines. Moreover, the present disclosure is also concerned with methods of producing such enhanced fuels. Furthermore, the present disclosure is also concerned with a method of using such fuel for operating an internal combustion engine.

Background

The use of combustible hydrocarbon fuels in combustion systems, such as internal combustion engines, is well known. Typically, combustible hydrocarbon fuels includes, petrol fuel (gasoline) or diesel fuel, which are oxidized by air to generate hot gases that are used to generate mechanical power, for example for vehicles powered by spark-ignition engines or compression-ignition engines. However, such combustion in air generates as by-products carbonaceous soot particles and Nitrogen oxides (NOx). Several innovations have been devised in recent years to reduce and/or filter such soot particles and Nitrogen oxides (NOx) in exhaust gases generated in operation from combustion systems.

Generally, such combustion fuels are derived, namely manufactured, from geological fossil reserves. Further, such fossil reserves are of finite capacity and are being gradually exhausted, as the present World consumption of oil and gas is in an order of 100 millions barrels of oil equivalent per annum. More recently, there is a growing interest in biofuels derived from contemporary biota, and therefore potentially more sustainable. The use of biofuel as a motor fuel has been already studied in detail since the 20th Century. Biofuels, in contradistinction to conventional fossil-reserve-derived fuels, are used as a motor fuel, or an addition to basic fossil- reserve-derived fuel, in many countries, such as Brazil, Germany, Sweden and USA [1 ]. Technologies have been developed for producing motor fuels including plain ethanol, as well as its blends with regular gasoline and diesel fuel to be used in internal combustion engines. Significant innovations relating to alternative fuels are described in published patent documents WO2009/106647, US5,628,805 and DE10339355. Further, in a European patent document EP01 1 6197B1 (proprietor: AECI Ltd. ; inventor Stiff), there is described a fuel additive comprising a mixture of a first component A, and second component B, wherein the first component A is at least one alcohol with a molecular weight of less than 1 60, and wherein the second component B is at least one organic compound of the formula:

N02-0-(CH2CH2-0-)x-N02 Eq. 1 wherein x is an integer greater than 3, and wherein the average molecular weight of at least one compound of the formula described in Equation 1 (Eq. 1 ) is in a range of 260 to about 390, with a proviso that no other compounds of formula described in Equation 1 are present.

Optionally, the fuel additive is added to a fuel such as ethanol and/or methanol to provide a mixture which can be combusted in combustion engines, for example in cylinder-based internal combustion engines. The additive is capable of improving fuel ignition in cylinder-based internal combustion engines, for example at lower temperatures when such engines are started and their respective engine blocks are cold. Over recent years, many different fuel additives have been developed. An example of a contemporary fuel additive is known as "Avocet", "Avocef is a trademark.

In the mid-1980's, a South African chemicals group, AECI, introduced a "green innovation" in the area of fuels, namely "Encetal"; "Enceta\" is a trademark. Encetal was developed for purposes of seeking to increase a local consumption of methanol produced from local coal feedstock, which could be used as an alternative to imported oil for fuels. "Encetal, the name of the fuel mixture of Methanol and Avocet, burns cleanly, producing low amounts of pollutant gases (Nitrous Oxide and Carbon Monoxide) and particulates in a vehicle's exhaust. Moreover, Avocet is an ignition improver to allow methanol fuel to be used in diesel engines, requiring a minimum of engine modifications to accommodate its use.

Avocet has been employed in several tests using alcohols as biofuels, to substitute for fossil-reserve-derived diesel fuel in private and public transportation vehicles. In the mid-1 990s, ethanol containing Avocet at a concentration in a range of 2% to 10% by volume as an ignition enhancer was tested in a small controlled group of public transport vehicles [1 ]. Theory predicts a significantly higher volume consumption of ethanol, in comparison to diesel fuel, but the exact higher volume has to be calculated for each case, since it depends on the specific characteristics of the vehicle (e.g. operating temperature) and the detailed composition of the fuel itself. It was found from the tests that the use of ethanol-Avocet fuel consumed 84% more per volume, which both negatively compensated for an initial economic argument as well as presented a new significant logistic challenge of transporting 84% more fuel by volume.

Moreover, the use of alcohols in existing diesel engines also requires some modifications to be made to engine components to prevent chemical degradation due to exposure to alcohols. Further improvements in engine operation, temperature and catalysts are needed in preparation for the use of ethanol and other alcohols as a replacement for diesel fuel. As far as economic arguments are concerned, a reduction in the use of Avocet, which represents a significant proportion of the costs, potentially makes combustion systems cheaper, namely potentially sufficiently cheaper to compensate for the comparative ratio Alcohol/diesel; as above, ethanol is taken as the reference, ethanol/diesel = 1 .84.

An initial economic argument for using the Avocet-enhanced methanol fuel as a diesel replacement was based on an average 25% cost savings when comparing the same volume of methanol to diesel fuel. Meanwhile, environmental arguments pointed out less particulate emissions and less smokiness of such Avocet-enhanced methanol fuel. However, in the early 1990's, the use of Avocet as an ignition improver or as a fuel enhancer was been deemed impracticable and/or too expensive for regular automobiles and other road vehicles by the parent company ICI-UK (Imperial Chemical Industries UK was the holding company of the group that owned AECI). This conclusion was reached, in part, due to the lack of commercial drive for environmentally friendly fuels, when the additive has been introduced in the early 1980s.

Although the composition of Avocet is proprietary, and may have varied over time, the composition of the original Avocet additive includes following components as provided in Table 1 :

Table 1 : Original Avocet composition

However, as aforementioned, Avocet is prohibitively expensive for use in many contemporary combustion systems, which has unfortunately limited its general use.

Further, additives are also employed in exhaust systems of vehicles, for example for reducing emissions of NOx components in exhaust gases emitted from exhaust systems associated with internal combustion engines. A well known contemporary additive for this purpose of reducing NOx emissions is "AdBlue", which is the registered trademark for AUS32, or Aqueous Urea Solution 32.5% that is used with the Selective Catalytic Reduction system (SCR) to reduce emissions of oxides of Nitrogen from the exhaust of UK diesel vehicles. AdBlue is a 32.5% solution of high- purity urea in de-mineralized water that is clear, non-toxic and safe to handle. It is non-explosive, non-flammable, nor harmful to the environment. AdBlue is classified under a minimum risk category of transportable fluids. However, Adblue is not a fuel, nor a fuel additive, and needs to be supplied from a dedicated tank in heavy-duty vehicles, for example trucks and buses. The dedicated tank is replenished with AdBlue in a similar manner to refuelling diesel into heavy-duty vehicles.

However, as aforementioned, Avocet is a fuel additive and is prohibitively expensive for use in many contemporary combustion systems, which has unfortunately limited its general use. Therefore, there is a need for alternative additives which, when added to fuel, are able to enhance combustion properties of the fuel.

In an example, a patent document WO2012021 64A1 discloses use additives in conjunction with diesel fuel. The document mentions Ammonium Nitrate (AN) as an example of compounds to be potentially used as an additive to diesel. In this case, AN is described as being emulsified in diesel. However, such emulsified fuels may be unstable in a range of temperature conditions in which the engine may need to operate, and hence such a fuel may be considered to be unreliable in particular operating conditions. Further, there is no mention of its use as a cetane enhancement of employed AN in methanol.

Further, currently accepted knowledge is that an additive based in PEG dinitrate is the only proven ignition improver for alcohols. In such instance, an alcohol based fuel may possibly use PEG dinitrate as the ignition improver. Accordingly, there arises a need to appropriately use such alcohol based fuel (having PEG dinitrate as ignition improver), and any improvement in combustion engines which are operable to burn such alcohol based fuel.

Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks of conventional fuels (particularly alcohol based fuels) and their use.

Summary

The present disclosure seeks to provide an enhanced fuel for use in internal combustion engines, for example the enhanced fuel which is based upon methanol.

Also, the present disclosure seeks to provide additives for fuels, which, when added to the fuels, is capable of enhancing the fuels. Further, the present disclosure also seeks to provide a method of producing such enhanced fuel. Moreover, the present disclosure also seeks to provide a method of using such enhanced fuel for operating internal combustion engine.

According to an aspect, there is provided a fuel for use in internal combustion engines, wherein the fuel includes a mixture of at least one alcohol, water and ammonium nitrate (AN) as a cetane enhancer. The water is included in a quantity which renders the ammonium nitrate dissolved in the at least one alcohol.

Optionally, the AN and water solution is mixed in alcohol to allow the AN/alcohol ratio in be in a range of 0.5% to 20% by weight with respect to the alcohol.

Optionally, the at least one alcohol includes methanol.

Optionally, the AN is included in a concentration having a range of 0.5% to 10% by weight with respect to the alcohol.

More optionally, the AN is included in a concentration having a range of 1 % to 5% by weight with respect to the alcohol.

Optionally, the fuel further contains polyethylene glycol dinitrate (PEGDN).

Optionally, the PEGDN is included in a concentration in a range of 5% to 10% by weight with respect to alcohol.

Optionally, the fuel further contains at least one ignition-improver additive, at least one lubricity agent and at least one anti-corrosion agent.

Optionally, the ignition-improver additive is at least one of dimethylether (DME), diethyl ether or methyl ethyl ether. Optionally, the DME is included in a concentration in a range of 0.1 % to 5% by weight with respect to the alcohol. More optionally, the DME is included in a concentration in a range of 0.1 % to 3% by weight with respect to the alcohol.

Optionally, the lubricity agent is at least one of polyethylene glycol, synthetic esters, and fatty acids.

Optionally, the anti-corrosion agent contains organic amines.

According to another aspect, there is provided a method of producing a fuel, wherein the method includes:

(i) Mixing at least one alcohol, dimethylether (DME) and Ammonium Nitrate

(AN); and

(ii) During mixing in (i), adding water in a quantity which renders the AN dissolved in the at least one alcohol. Optionally, the method further includes adding at least one lubricity agent and at least one anti-corrosion agent.

Optionally, the method further includes adding polyethylene glycol dinitrate (PEGDN).

According to yet another aspect, there is provided a method of using a fuel for operating an internal combustion engine, wherein the combustion engine including one or more combustion chambers having reciprocating and/or rotating elements therein which are operable to generate mechanical work from the engine, and an injection arrangement for injecting fuel into the one or more combustion chambers, wherein the method includes: (a) operating the injection arrangement to inject an alcohol -based fuel into the one or more combustion chambers, and wherein there is injected in combination with the alcohol-based fuel at least one ignition-improver. Optionally, the method further includes pre-mixing the alcohol-based fuel and the at least one ignition-improver using a pre-mixing arrangement.

Optionally, the method further includes injecting the pre-mixed alcohol-based fuel and at least one ignition-improver as aqueous solution into one or more engine cylinders by a common injector.

Optionally, the method further includes injecting the alcohol-based fuel and the at least one ignition-improver into one or more engine cylinders by separate injectors. Optionally, the method further includes controlling an amount of the at least one ignition-improver injected into the one or more combustion chambers relative to an amount of alcohol-based fuel injected therein by using a control arrangement.

More optionally, the controlling of the amount of the at least one ignition-improver is based on one or more measured parameters associated with the combustion engine.

Optionally, the alcohol-based fuel contains at least one alcohol, water, at least one lubricity agent and at least one anti-corrosion agent.

Optionally, the ignition-improver is at least one of: Dimethylether (DME), diethyl ether, methyl ethyl ether, Ammonium Nitrate (AN), PEG-nitrate, octyl nitrate, hydrazine, and hydroxylamine nitrate. The present disclosure relates to an enhanced fuel, a method of producing such enhanced fuel, and method of using such enhanced fuel for operating internal combustion engine. Specifically, the present disclosure relates to fuels, for example to hydrocarbon fuels which are useable as a replacement for conventional diesel fuel and petrol fuels. The fuel is of advantage is that an addition of water renders Ammonium Nitrate co-soluble in at least one alcohol, for example methanol, thereby providing a solution which is stable in storage, and also useable directly as a substitute for fuels such as diesel, petrol, kerosene and other heavy fuel oils. Further, addition of water keeps the engine cool, on account of the high latent heat of evaporation of water, thereby decreasing the need for cooling systems. Furthermore, the fuel of the present disclosure is economical to manufacture and results in a clean burn reaction within combustion engines. For example, all fuel components are inexpensive and widely available, which enables large scale production for allowing easy adaptation in the market and efficient distribution. Moreover, the fuel is capable of being employed as a substitute fuel in various types of engine systems, although ratios of its constituent components are optionally varied depending upon intended uses. It will be appreciated that features of the disclosure are susceptible to being combined in various combinations without departing from the scope of the disclosure as defined by the appended claims.

Description of the diagrams

Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:

FIG. 1 is a graphical illustration of an enhanced fuel, in accordance with an embodiment of the present disclosure;

FIG. 2 is a graphical illustration of an enhanced fuel, in accordance with another embodiment of the present disclosure;

FIG. 3 is an illustration of a method of producing an enhanced fuel, in accordance with an embodiment of the present disclosure;

FIG. 4 is an illustration of components of a enhanced fuel applied to a spark-ignited engine, in accordance with an embodiment of the present disclosure; and

FIG. 5 is an illustration of components of a enhanced fuel applied to a compression- ignition engine, in accordance with an embodiment of the present disclosure. In the accompanying diagrams, when a number is non-underlined and accompanied by an associated arrow or lead line, the non-underlined number is used to identify a general item at which the arrow or lead line is pointing. Description of embodiments of the disclosure

In overview, the present disclosure is concerned with an enhanced fuel which is based upon an alcohol, for example ethanol and/or methanol, which is economical in use, and which can be used as a diesel fuel substitute, with only minor changes being necessary to an internal combustion engine which is configured to operate from conventional diesel fuel.

The environmental benefits of using an alcohol, as a replacement for diesel fuel, have been well established in prior-art, since a combustion system employing such alcohol as a fuel produces lower amounts of pollutant gases and particulates in a vehicle's exhaust in comparison to fuels such as petrol and diesel fuel. Moreover, in recent years, governments and society in general have been increasingly applying pressure on companies to adopt more environmentally friendly alternatives. Therefore, as the intrinsic environmental benefits of using alcohols as a running fuel of contemporary vehicles are well-accepted and understood, it is clear from the foregoing that improving the economic efficiency of the use of alcohols as alternative fuels is a key problem to be resolved.

In the present disclosure, there is proposed an alternative additive as a substitute for Avocet additive that allows alcohols to be used in existing compression ignition engines.

Ammonium Nitrate is known to be an explosive material. Moreover, Ammonium Nitrate has been hitherto perceived to be unsuitable for use as an additive, because it is not soluble in alcohols, for example methanol. However, pursuant to embodiments of the present disclosure, Ammonium nitrate (AN) has a significant potential as a cetane enhancer for alcohols, such as methanol. The cetane enhancement capability effectively allows AN to be used as an ignition improver for such alcohol fuels. Ammonium Nitrate is, for example, manufactured in large quantities, for example for use in agriculture to replenish soil after crops have been grown which have a high fixed nitrogen requirement, for example grain crops, beans and so forth. In respect of the use of ammonium nitrate (AN) as additive for methanol, Ammonium nitrate (AN) has a significant potential as a cetane enhancer for alcohols such as methanol, as aforementioned. The cetane enhancement capability effectively allows AN to be used as an ignition improver for such alcohol fuels, which allows these fuels to be used as direct replacement for known convention combustible fuels.

Disclosed an embodiment of the present disclosure in which AN is employed as an ignition improver/cetane enhancement for methanol, or another alcohol. AN is not very soluble in methanol for example, but both methanol and AN are soluble in water. Therefore, there is disclosed a fuel including a mixture of an alcohol, for example ethanol and/or methanol, AN and water, as shown in FIG. 1 . Such a fuel is beneficially manufactured from a method including:

(i) Mixing methanol and AN to the desired concentration, for example in a range of 0.5% to 10% AN relative to methanol; and

(ii) During mixing in (i), adding enough water so that AN becomes dissolvable in the methanol water mix.

In step (i) of the method, the range in which AN needs to be added is defined by a ratio N/C (namely, Nitrogen to Carbon), wherein Nitrogen atoms come from the AN additive and Carbon atoms, mostly, comes from the fuel, for example methanol.

In an example, the AN is included in a concentration having a range of 1 % to 5% by weight with respect to the alcohol. Further, the AN and water solution is mixed in alcohol to allow the AN/alcohol ratio in be in a range of 0.5% to 20% by weight with respect to the alcohol.

In step (ii) of the method, water needs to be added to an extent that solubilises the required amount of AN, namely: Enhanced fuel = Methanol + water + AN

The enhanced fuel (or mixture) of water, AN and methanol is of advantage in that it can be easily stored over a long-term period without separating out into individual components parts, and does not form an emulsion and does not need to be emulsified. The enhance fuel pursuant to Equation 2 (Eq. 2) only contains fully soluble compounds and, thus, is considered to be more stable and more reliable in operating conditions. The enhanced fuel pursuant to Equation 2 (Eq. 2) is considerably cheaper than known diesel fuel substitutes based on methanol, for example employing Avocet, and also is very clean when burnt in an internal combustion engine, for example very low soot production and low NOx production. Moreover, the enhanced fuel pursuant to Equation 2 (Eq. 2) potentially avoids a need to employ Adblue in the exhaust systems of vehicles. Methanol can be generated from a variety of sources, for example fermenting biological waste, biota material, algea culture, processing wood by-products, fossil fuel reserves, coal, coal liquefaction, hydrates and so forth; mutatis mutandis ethanol is similarly derivable. Embodiments of the present disclosure are concerned with an introduction of a new additive which increases the efficiency of a given fuel, for example methanol-based fuel, by acting as a cetane enhancer. The new additive provides at least one of following benefits:

(a) the new additive allows methanol to act a direct replacement for diesel fuel; (b) the new additive in solution is non-explosive, and thus less hazardous in than, for example, octyl nitrate; and

(c) the new additive has a potential for application in petrol engines.

"Cetane" is a measure of an ignition quality of a diesel fuel. The higher the cetane measure of a given diesel fuel, the easier it is to start a standard (direct injection) diesel engine using the given diesel fuel. The cetane measure is defined by a percentage, by volume, of cetane, with a chemical name " hexadecane" ^', in a combustion mixture, containing cetane and 1 -methylnaphthalene, whose ignition characteristics match those of a given diesel fuel being tested. Comparisons with other additives and fuels can be made by way of "equivalent cetane measure", for example as employed when describing embodiments of the present disclosure. Benefits of the enhanced fuel in Equation 2 (Eq. 2) include:

(a) The method allows Ammonium Nitrate to be used as an ignition improver to methanol or similar alcohols, in turn allowing the fuel to be used in existing diesel engines with minimum modifications;

(b) The addition of water keeps an engine burning the fuel of Equation 2 (Eq. 2) cool (due to a high latent heat of water), thereby decreasing a need for cooling systems, thus making the vehicle more energy efficient;

(c) Lower particulate emission from engines burning the enhanced fuel of Equation 2, namely lower particulate emission than achievable by employing other methods, for example sing exhaust filters, using Adblue spraying in exhaust systems and so forth; (d) Environmentally friendly, since the N-groups in AN are released as N2 gas at the end of a burn cycle in a combustion engine;

(e) The enhanced fuel of Equation 2 (Eq. 2) results in a significant reduction in cost in comparison to PEG-dinitrate-based additives, namely AN cost approximately less than 1 /10th of Avocet additives; and

(f) Cooler engine operation consequent upon the introduction of water results in lower NOx formation. Since NOx is the precursor of tropospheric ozone pollution, the reduction in NOx constitutes a significant environmental benefit.

In an example, systems and methods may be disclosed for the use of an aqueous solution of ammonium nitrate (AN) as an ignition improver directly injected into the engine cylinder, which will be explained in greater detail herein later. For example, the systems and methods may include tanks fitted to contain an aqueous solution of urea as the tanks to contain the AN solution prior to injection. According to another aspect, the enhanced fuel, as disclosed above with the help of the FIG. 1 and Equation 2 (Eq. 2), can also include other components that collectively form additive for the fuel. In an example, the fuel further includes an ignition-improver additive, preferably, dimethylether (DME). Specifically, the fuel includes DME in addition to the components of the fuel disclosed in FIG. 1 . In such instance, ammonium nitrate (AN) acts cetane enhancer additive, which is an alternative additive as a substitute for Avocet additives that allows alcohols to be used as an improved fuel in existing compression-ignition engines. Optionally, the fuel can further include other cetane enhancer, such as hydrazine, hydroxylamine nitrates, octyl nitrate having similar technical benefits, although their cost is greater than that of AN Dimethylether (DME) and other compounds with relatively high vapour pressures, including low-boiling point ethers, namely diethyl ether or methyl ethyl ether are suitable compounds to be employed as ignition-improver additive, particularly to enhance the cold-start of spark-ignited engines. Dimethylether (DME) is produced by dehydration of methanol over a preferred catalyst, and is an additive independent of petroleum. For example, DME is soluble in methanol and water, and thus preferably mixed directly into the fuel without the need of emulsification. The chemical formula of DME does not contain Carbon-Carbon bonds, which significantly reduces the possibility of formation of particulate impurities when compared to other commonly used additives, for example Avocet. Further advantages include the possibility of using DME in any engine tuned to be run with methanol as a fuel, wherein no extra modifications in this type of engine are needed.

Dimethylether (DME) additive is inexpensive and readily available in large-scale. It provides several benefits to the engine operation, which includes enhancing the cold- start of spark-ignited engines. The DME additive can be utilised in range of 0.1 -5% by weight with respect to the alcohol. For example, the DME additive is to be utilised range of 0.1 -3% by weight with respect to the alcohol. For its utilisation as an additive to a methanol-based fuel, DME has the following favourable characteristics:

a) It is inexpensive, widely available and in large scale production

b) It is miscible with methanol

c) It is derived efficiently from methanol by dehydration over an alumina catalyst, and, as such, is independent of petroleum. d) It is a chemical with no C-C bonds, thus significantly decreasing the chance of formation of particulate impurities.

e) Engines tuned to be run with methanol-based fuels are also capable of running with DME as an additive without extra modifications.

f) It has a high vapour pressure at ambient temperatures, so enabling facile starting of alcohol fuelled SI engines.

Methanol modified in the way proposed in the present disclosure enables the full benefits of dedicated methanol SI engines to be realised. These benefits include low emissions coupled with the high fuel efficiency and high power output resulting from increased compression ratios made possible by methanol's high octane value.

There is therefore disclosed an embodiment of the present disclosure, wherein DEM and/or AN are/is employed as ignition improver for methanol and/or another alcohol. AN is not directly soluble in methanol, for example, but both methanol and AN are soluble in water. Therefore, there is disclosed a fuel including a mixture of an alcohol, for example ethanol and/or methanol, water, DME (as ignition-improver additive) and AN (as cetane enhancer), as shown in FIG. 2. It is to be understood that AN may be optionally added as cetane enhancer. Such a fuel is beneficially optionally manufactured using a method (300 shown in FIG. 3). Specifically, the method 300 of producing a fuel includes:

(i) Mixing methanol, DME and AN to a desired concentration, for example in a range of 1 % to 5% AN relative to methanol; and 0.1 to 3% DME relative to methanol, at step 302;

(ii) During mixing in (i), adding enough water so that AN becomes dissolvable in the methanol-water-DME mix, at step 304.

In step (i) of the method, the range in which AN needs to be added is defined by a ratio N/C (namely, Nitrogen to Carbon), wherein Nitrogen atoms come from the AN additive and Carbon atoms, mostly, comes from the fuel, for example methanol. In contradistinction, in a case of PEG dinitrate, there is a Nitrogen to Carbon N:C = 20:1 is a typically required ratio. However, the values may vary depending on requirements of engine design and operating temperature. In step (ii) of the method, water needs to be added to an extent that renders the required amount of AN soluble in the mixture, namely: Enhanced fuel = Methanol + water + DME + AN Eq. 3

Such a mixture of water, AN and methanol is of advantage in that it can be easily stored over a long-term period without separating out into individual component parts, and does not form an emulsion and does not need to be emulsified.

The enhanced fuel pursuant to Equation 3 is considerably cheaper than known fuel substitutes based upon methanol, for example employing Avocet, and also is very clean when burnt in an internal combustion engine, for example results in very low soot production and low NOx production. Moreover, the enhanced fuel pursuant to Equation 3 potentially avoids a need to employ Adblue in exhaust systems of vehicles.

Additionally, the fuel (or the method 300) also includes addition of at least one lubricity agent and at least one anti-corrosion agent, so providing a "universal fuel" (which is alcohol based). Therefore, fuel of the present disclosure, proposes an alcohol-based fuel which can be used in vehicles powered by compression-ignition (diesel family), spark-ignition engines, or other suitable hybrid engines.

For example, the method 300 (or the fuel) further includes adding an ignition-improver additive, preferably dimethylether (DME), adding at least one lubricity agent and at least one anti-corrosion agent. The at least one lubricity agent is selected from additives based on mono-acids and/or fatty-acids such as HiTec and BioTec products from Afton (HiTec, BioTec and Afton are trademarks). Further, the lubricity agents are preferably selected from compositions including polyethylene glycol, synthetic esters or hydroxyesters, fatty acids. The at least one anti-corrosion agent is selected from corrosion inhibitor additives including additives based on zinc dithiophosphates and/or calcium nitrates. Further, the anti-corrosion agent can be selected from at least one of DCI-4A, DCI-6A, DCI-1 1 , DCI-28, DCI-30 (DCI is a trade mark). Moreover, at least one anti-corrosion agent is selected from corrosion inhibitors including organic amines, for example ethanolamine or morpholine or similar basic heterocyclic compounds. The fuel can also include other cetane enhancer (other than AN, hydrazine, hydroxylamine nitrates and octyl nitrate) such as, polyethylene glycol dinitrate (PEGDN). Further, in the fuel the PEGDN can be included in a concentration in a range 5% to 10% by weight with respect to alcohol. The present embodiment of the present disclosure (similar to embodiment disclosed in FIG. 1 ) is concerned with an introduction of a new additive which increases the efficiency of a given fuel, for example a methanol-based fuel, having an cetane enhancer and an ignition-improver additive. The new additive provides at least one of following benefits:

(a) the new additive allows methanol to act a direct replacement for many types of conventional fossil-reserve-derived fuel;

(b) the new additive Is non-explosive, and this less hazardous in use; and

(c) the new additive has a potential for application in a wide range of combustion engines.

Further, similarly the benefits of the enhanced fuel in Equation 3 include:

(a) The method allows Ammonium Nitrate to be used as cetane enhancer for methanol or similar alcohols, in turn allowing the fuel to be used in existing compression-ignition engines with minimal modifications;

(b) The addition of water keeps an engine burning the fuel of Equation 3 cool (due to a high latent heat of evaporation of water), thereby decreasing a need for cooling systems, thus making the vehicle more energy efficient;

(c) Lower particulate emission from engines burning the enhanced fuel of Equation 3, namely lower particulate emission than achievable by employing other methods, for example using exhaust filters, using Adblue spraying in exhaust systems and so forth;

(d) Environmentally friendly, since the N-groups in AN are released as N2 gas at the end of a burn cycle in a combustion engine;

(e) The enhanced fuel of Equation 2 results in a significant reduction in cost in comparison to PEG-dinitrate-based additives, namely AN cost approximately 1/10th of Avocet additives.

Embodiments of the present disclosure provide benefits in direct injection combustion engines, and are also capable of providing cost reduction. Such cost reduction here is based on two factors:

(i) cost reduction due to the direct injection; and

(ii) cost reduction due to the use of AN instead of Avocet additives. With respect to diesel engines, the present disclosure provides a direct competitor to Octyl Nitrate, which is a currently favoured substance for improving the cetane number of lower grade diesel fuels. The addition of enough water to Ammonium Nitrate (AN) is capable of making this compound soluble in alcohol-based fuels, such as methanol. In turn, this potentially allows for the use of methanol, or another alcohol, in place of diesel fuel in current modern diesel engines. Moreover, modern diesel engines are required to be fitted with tanks containing an aqueous solution of urea, which in turn, are optionally used as a reservoir for the AN solution prior to injection. Current European diesel trucks are fitted with a small urea tank, which is beneficially optionally used as the reservoir for the Ammonium Nitrate (AN), while petrol engines do not need such an addition.

Ammonium Nitrate (AN) has a great potential to be used as an ignition improver - cetane enhancement for methanol (or another alcohol). This present disclosure relates to the use of an aqueous solution of ammonium nitrate as an ignition improver directly injected into the engine cylinder.

In the case of modern diesel engine, the AN solution is beneficially injected in concentrations which vary in a range of 5% to 20% by weight with respect to the alcohol. The composition of an alcohol-based fuel, preferably methanol, with the additions of the AN solution in the range specified and a lubricity agent could be potentially used without adjustment in combustion engines, leading to the concept of a versatile fuel.

If the AN is injected as described above, then the fuel can be any substance suitable for use, for example, as a diesel fuel. The fuel can be used directly in spark-ignited petrol engines. For economic, safety, transport and environmental reasons, methanol has a unique capacity to provide this capability.

The fuel is used by way of direct injection of additive into a given cylinder of a combustion engine. Modern diesel engines are required to be fitted with tanks containing an aqueous solution of urea; this same tank is beneficially made available to contain the AN solution prior to injection, provided that the injection line is modified to inject the additive solution directly into the engine cylinder. Modern engines with computer-based fuel injection management systems, under software control, are capable of using fuels pursuant to the present disclosure.

Embodiments of the present disclosure provide a versatile fuel, for example a mixture of methanol, a lubricity additive and at least one anti-corrosion agent. Such a versatile fuel is susceptible to being employed in spark-ignition engines. Injection of AN enables the versatile fuel to be employed in compression-ignition engines.

Optionally, the fuel is used by way of direct injection of additive into a given cylinder of a combustion engine. Modern diesel engines are required to be fitted with tanks containing an aqueous solution of urea; this same tank is beneficially made available to contain the AN solution prior to injection, provided that the injection line is modified to inject the additive solution directly into the engine cylinder. Modern engines with computer-based fuel injection management systems, under software control, are capable of using fuels pursuant to the present disclosure.

In recent years, current environmental laws and society pressure have placed less emphasis on economics of fuels, and more on environmental gains. Nevertheless, an additive that costs less, and makes an overall combustion process in internal combustion engines more efficient will increase economic benefits, which associated to intrinsic environmental gains, makes alcohol once more an attractive alternative to diesel fuel from a commercial perspective.

Therefore, in another aspect, the present disclosure relates to method of using a fuel for operating internal combustion engine. The combustion engine primarily includes one or more combustion chambers having reciprocating and/or rotating elements therein which are operable to generate mechanical work from the engine. The combustion engine also includes an injection arrangement for injecting fuel into the one or more combustion chambers. Therefore, the method pursuant to present aspect includes operating the injection arrangement to inject an alcohol-based fuel into the one or more combustion chambers, and wherein there is injected in combination with the alcohol-based fuel at least one ignition-improver.

The term "at least ignition-improver" broadly encompasses the cetane enhancers and the ignition-improver additives, disclosed herein above. Therefore, the ignition- improver is at least one of: Dimethylether (DME), diethyl ether, methyl ethyl ether, Ammonium Nitrate (AN), PEG-nitrate, octyl nitrate, hydrazine, and hydroxylamine nitrate.

Further, the term "alcohol-based fuel" used herein mainly includes components of the fuels disclosed herein above. For example, the alcohol-based fuel contains at least one alcohol, water, at least one lubricity agent and at least one anti-corrosion agent. Moreover, the lubricity agent is at least one of polyethylene glycol, synthetic esters, and fatty acids; and the anti-corrosion agent contains organic amines. In an embodiment, the method of using the fuel for operating internal combustion engine further includes pre-mixing the alcohol-based fuel and the at least one ignition-improver using a pre-mixing arrangement. Further, the pre-mixed alcohol- based fuel and at least one ignition-improver are injected as aqueous solution into one or more engine cylinders by a common injector. Alternatively, the method of using the fuel for operating internal combustion engine includes injecting the alcohol- based fuel and the at least one ignition-improver into one or more engine cylinders by separate injectors. The method also includes controlling an amount of the at least one ignition-improver injected into the one or more combustion chambers relative to an amount of alcohol-based fuel injected therein by using a control arrangement. The controlling of the amount of the at least one ignition-improver is based on one or more measured parameters associated with the combustion engine. In an example, the control arrangement includes a computing-device-based controller operable to execute computer program instructions, including one or more sensors for dynamically controlling the fluid pumps as a function of one or more engine parameters, for example as a function of at least one of engine temperature, engine load, ambient temperature, fuel-type, accelerator pedal position.

The nozzles for injectors in combustion engines pursuant to the present disclosure are beneficially manufactured from spark-eroded Hastelloy-N, sintered Silicon Carbide, sintered metals, sintered ceramic materials such as Carborundum, and similar. Sintered materials are of advantage in that they can be spatially formed by a moulding process prior to their sintering.

According to an embodiment of the present disclosure, there is provided a retrofit kit including nozzles, fluid pumps and piping for providing additive and fuel separately for injection into cylinders of a combustion engine. Otherwise, the retrofit kit can include a single nozzle (or the common injector) associated with the pre-mixing arrangement (such as a pre-mixing container).

In the present disclosure, Dimethylether and Ammonium nitrate (AN) are beneficially employed, for example with reference to FIG. 4 and FIG. 5, respectively as ignition- improver and as a directly-injected cetane improver. For example, as shown in FIG.

4, the alcohol-based fuel includes the alcohol (such as methanol), the ignition- improver additive (such as DME), water, the lubricity agent and the anti-corrosion which are premixed (for in the pre-mixing container) and injected in the spark ignition engine by the single nozzle (or the common injector). However, in the shown in FIG.

5, the alcohol-based fuel and an aqueous solution of AN is beneficially directly injected into a cylinder of a combustion engine to function as the cetane enhancer. Specifically, in such an engine (compression-ignition), two injectors are employed for each cylinder of the combustion engine. Thus, use of aqueous AN injection as a cetane enhancer enables fuel neutral operation to be achieved, namely applicable for both diesel fuel and alcohol-based fuels. The above embodiment relates to combustion engines which are operable to use an aqueous solution of Ammonium Nitrate as an ignition improver directly injected into the engine cylinder, for example via a dedicated nozzle for the ignition improver and/or when the ignition improver is pre-mixed into fuel which is injected into the engine cylinder. Further, the method allows Dimethylether and/or Ammonium Nitrate to be used as an ignition improver for methanol-based or similar alcohol-based fuels, in turn allowing the fuels to be used in existing compression ignition engines with minimum modifications; or by exchanging injector nozzles of cylinders of a compression ignition engine with an alternative type, which has multiple injection nozzles, namely one nozzle for the alcohol-based fuel and another nozzle for the Ammonium Nitrate.

Modifications to embodiments of the disclosure described in the foregoing are possible without departing from the scope of the disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "consisting of, "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. Numerals included within parentheses in the accompanying claims are intended to assist understanding of the claims and should not be construed in any way to limit subject matter claimed by these claims.

Reference literature [1 ] Gaouyer, J. P. : " What has happened in Europe in the Biofuels Domain over the last two years?" Proceedings 2nd European Motor Biofuels Forum, Graz, p. 37 - 41 , 1996.

Claims

CLAIMS We claim:

1 . A fuel for use in internal combustion engines, wherein the fuel includes a mixture of at least one alcohol, water and ammonium nitrate (AN) as a cetane enhancer, wherein water is included in a quantity which renders the ammonium nitrate dissolved in the at least one alcohol.

2. The fuel as claimed in claim 1 , wherein the AN and water solution is mixed in alcohol to allow the AN/alcohol ratio in be in a range of 0.5% to 20% by weight with respect to the alcohol.

3. The fuel as claimed in claims 1 -2, wherein the at least one alcohol includes methanol.

4. The fuel as claimed in any preceding claim, wherein the AN is included in a concentration having a range of 0.5% to 10% by weight with respect to the alcohol.

5. The fuel as claimed in claims 1 -3, wherein the AN is included in a concentration having a range of 1 % to 5% by weight with respect to the alcohol.

6. The fuel as claimed in any preceding claim, further contains polyethylene glycol dinitrate (PEGDN).

7. The fuel as claimed in claim 6, wherein the PEGDN is included in a concentration in a range of 5% to 10% by weight with respect to alcohol.

8. The fuel as claimed in claims 1 -6, wherein the fuel further contains at least one ignition-improver additive, at least one lubricity agent and at least one anti-corrosion agent.

9. The fuel as claimed in claim 8, wherein the ignition-improver additive is at least one of dimethylether (DME), diethyl ether or methyl ethyl ether.

10. The fuel as claimed in claim 9, wherein the DME is included in a concentration in a range of 0.1 % to 5% by weight with respect to the alcohol.

1 1 . The fuel as claimed in claim 9, wherein the DME is included in a concentration in a range of 0.1 % to 3% by weight with respect to the alcohol.

12. The alcohol based fuel as claimed in claim 8, wherein the lubricity agent is at least one of polyethylene glycol, synthetic esters, and fatty acids.

13. The alcohol based fuel as claimed in claim 8, wherein the anti-corrosion agent contains organic amines.

14. A method of producing a fuel, wherein the method includes:

(i) Mixing at least one alcohol, dimethylether (DME) and Ammonium Nitrate (AN); and

(ii) During mixing in (i), adding water in a quantity which renders the AN dissolved in the at least one alcohol.

15. The method as claimed in claim 14, wherein the at least one alcohol includes methanol.

1 6. The method as claimed in claims 14-15, wherein the AN is included in a concentration having a range of 0.5% to 10% by weight with respect to the alcohol.

17. The method as claimed in claims 14-15, wherein the AN is included in a concentration having a range of 1 % to 5% by weight with respect to the alcohol.

18. The method as claimed in claim 14, wherein the DME is included in a concentration in a range of 0.1 % to 5% by weight with respect to the alcohol.

19. The method as claimed in claim 14, wherein the DME is included in a concentration in a range of 0.1 % to 3% by weight with respect to the alcohol.

20. The method as claimed in claims 14-19, further includes adding at least one lubricity agent and at least one anti-corrosion agent.

21 . The method as claimed in claim 20, wherein the lubricity agent is at least one of polyethylene glycol, synthetic esters, and fatty acids.

22. The method as claimed in claim 20, wherein the anti-corrosion agent includes organic amines.

23. The method as claimed in claim 14, further includes adding polyethylene glycol dinitrate (PEGDN).

24. The method as claimed in claim 23, wherein the PEGDN is included in a concentration in a range of 5% to 10% by weight with respect to alcohol.

25. A method of using a fuel for operating an internal combustion engine, wherein the combustion engine including one or more combustion chambers having reciprocating and/or rotating elements therein which are operable to generate mechanical work from the engine, and an injection arrangement for injecting fuel into the one or more combustion chambers, wherein the method includes:

(a) operating the injection arrangement to inject an alcohol-based fuel into the one or more combustion chambers, and wherein there is injected in combination with the alcohol-based fuel at least one ignition-improver.

26. The method as claimed in claim 25, further includes pre-mixing the alcohol- based fuel and the at least one ignition-improver using a pre-mixing arrangement.

27. The method as claimed in claims 25-26, further includes injecting the pre-mixed alcohol-based fuel and at least one ignition-improver as aqueous solution into one or more engine cylinders by a common injector.

28. The method as claimed in claim 25, further includes injecting the alcohol-based fuel and the at least one ignition-improver into one or more engine cylinders by separate injectors.

29. The method as claimed in claims 25-28, further includes controlling an amount of the at least one ignition-improver injected into the one or more combustion chambers relative to an amount of alcohol-based fuel injected therein by using a control arrangement.

30. The method as claimed in claim 29, wherein the controlling of the amount of the at least one ignition-improver is based on one or more measured parameters associated with the combustion engine.

31 . The method as claimed in claims 25-30, wherein the alcohol-based fuel contains at least one alcohol, water, at least one lubricity agent and at least one anti-corrosion agent.

32. The method as claimed in claim 31 , wherein the lubricity agent is at least one of polyethylene glycol, synthetic esters, and fatty acids.

33. The method as claimed in claim 31 , wherein the anti-corrosion agent contains organic amines.

34. The method as claimed in claims 25-30, wherein the ignition-improver is at least one of: Dimethylether (DME), diethyl ether, methyl ethyl ether, Ammonium Nitrate (AN), PEG-nitrate, octyl nitrate, hydrazine, and hydroxylamine nitrate.