The invention relates to the field of fuels, used in heat-engines, in particular, in internal combustion engines (ICE).

Most of fuel compositions are emulsions.

There has been known an emulsion based on hydrocarbon fuel, which, for improving the fuel quality includes the additive to the fuel (petrol) as water and emulsifier, containing amines substituted by hydrocarbon radicals C, 8-C6o, by 30 % neutralized by nitrobenzoic acid (the USSR Author's Certificate No. 1773933, cl. CIOL1/32, 1992). The use of this emulsion reduces specific fuel consumption, its corrosion activity and toxicity. However the increase of water concentration in fuel leads to the increase of emulsion viscosity, that hinders heat supply and emulsion dispersion.

There has also been known aqueous-fuel emulsion (the USSR Author's Certificate No. 930933, cl. C10 Ll/320, 1980), taken as a prototype, which contains hydrocarbon fuel, for example, petrol, with the addition of water and surface-active substance (SAS).

Preparation of emulsion is carried out by mixing its components in special plants.

The application of said emulsion allows to improve the fuel combustion, to extend the limits of the engine stable operation on poor composite fuels, to reduce a specific outflow of NO, and COx.

However plants for preparing emulsion, including vibro-cavitation and static powder dispensers with pressure system, are complicated and their use is power-intensive. Besides, here the rise of water contents leads to the increase of viscosity, causes coagulation and coalescence of the fuel composition and failures in the work of fuel system.

The object of the invention is the development of the compound and the way of preparing a fuel composition, based on hydrocarbon fuel, being characterized by the ability to keep the structure produced while preparing a composition before its compression in the combustion chamber, and the improvement of power parameters of fuel application.

The technical result of the invention is the producing of a homogeneous structure of the fuel composition as foam according to a simplified technology.

It is achieved by the fact that in the fuel composition for a heat- engine, containing hydrocarbon fuel, an oxidizer, for example, air and fuel additive including water and surface-active substance, they use a foam forming fuel additive in addition including active inhibitors, for example, combinations of alkaline metals, the ratio of hydrocarbon fuel and oxidizer coming to 0.65-1. 5, and the amount of the fuel additive coming to 1-98 % from the total amount of the fuel composition.

It is also achieved by the fact that in the method of preparing a fuel composition, including mixing of fuel composition components, by the first variant of preparation, first they produce a primary fuel mix including hydrocarbon fuel and an oxidizer, at the same time they carry

out a preliminary foaming of the fuel additive by the air, then introduce the foamed fuel additive into the primary fuel mix by a simultaneous additional foaming of the produced fuel composition, and then carry out final foaming of the produced fuel composition in the presence of the catalyst, all said operations being carried out outside of the combustion chamber of the heat-engine.

Or, by the second variant of preparing a fuel composition, it is achieved by mixing its components in the combustion chamber of the heat-engine, the fuel additive before the introduction to the combustion chamber being preliminarily foamed by the air, then in a step of suction they introduce separately hydrocarbon fuel and oxidizer to the combustion chamber with the preliminarily foamed fuel additive for mixing and final foaming of components, each component being introduced in an amount providing production of an efficient charge of the fuel composition.

The use of the foam forming fuel additive allows producing a fuel composition like a homogeneous foam containing particles of hydrocarbon fuel, oxidizer and a fuel additive. Such a structure of composition considerably increases the jet surface of the charge getting into the combustion chamber. Therefore the process of fuel combustion is intensified and stabilized, the possibility of formation of harmful by- products of combustion decreases. Water, being a part of the fuel additive, while foam is formed from a free drop-shaped state shall be transformed to a water skim, that increases dispersion and homogeneity

of the fuel composition, shall liquidate the possibility of its coagulation and coalescence.

At the same time the availability of a water film provides the absorption of heat of fuel burning reaction, extends the process of combustion, thus eliminating the possibility of fuel charge detonation with any octane number. Besides, intensively evaporating under fuel burning, water turns into working medium, creates additional pressure in the combustion chamber and increases tractive effort of the engine and reduces calorific intensity of the engine.

The method for producing the claimed fuel composition is offered in two variants: outside the combustion chamber of the engine, when the fuel composition is supplied to the combustion chamber after preparation, and directly in the combustion chamber where the composition components are supplied separately, and where they mix up, forming a fuel charge. Both variants are based on the use of standard equipment with minor supplements, which are much easier than the equipment used in the prior art.

The method is carried out as follows. At first by a known way, for example, using of the ICE carburetor, they produce a primary mixture of hydrocarbon fuel with an oxidizer, in particular, the air at the ratio of fuel and oxidizer 0. 65 1, 5. Simultaneously they carry out primary processing of the fuel additive by the air flow, having the aim of preliminary foaming. For this purpose simple mixer devices are used.

Then the fuel additive is supplied to the primary fuel mixture, for example, introducing it into the carburetor chamber, the produced fuel composition being foamed at the account of discharge occurring in the carburetor. Foaming of the produced fuel composition is carried further on, passing it, for example, through a grid with catalytic coating (metal compounds, nickel, platinum + palladium). After that the fuel composition in a finished condition is supplied to the engine combustion chambers.

There, under the action of high pressure and temperature the foam collapses and is transformed to the association of cluster groups of fuel, oxidizer, water and fuel additive having an enlarged jet surface for efficient combustion.

By applying non-carburetor ICE, in particular, injector ones, the second variant of the method of fuel composition preparation can be used-directly in the ICE combustion chamber. In this variant the fuel is supplied to the combustion chamber separately from oxidizer and fuel additive, for example, with the help of the injector, and mix up with them already in the combustion chamber. The ratio of fuel and oxidizer is the same, as in the first variant-0. 65-1. 5. Fuel additive, preliminarily foamed with the air flow, is separately supplied here. The components of the fuel composition are supplied to the combustion chamber in the amount providing the producing of fuel charge and depending on the ICE combustion chamber parameters, in the suction stroke under the influence of discharge in the engine cylinder, the process of foaming of

the fuel additive together with other components of the fuel composition proceeds up to the compression stroke. Further conversion of the fuel composition and its action is similar to that of described above, in the first variant.

The offered invention was tested on the engine of the automobile VAZ-2106 at a distance of 560 km with the steep lengthy ascents.

In the first stage of tests petrol A-72-76 with a fuel additive was used, and in the second stage-petrol A-91-93 with a fuel additive. As a fuel additive there was used a composition including mass %: -compounds, for example, chloride, 0.0008-0. 01 nitrate, hydroxide, chromate, dichromate, bromate, bromide, carbonate and their mixtures - SAS, for example, non-ionic 0.003-4. 1 - Water 95.89-99. 69 which was injected in the amount of 10-30% of the mass of the supplied fuel, depending on the engine capacity. In both stages there were similar results-increase of the engine capacity that allowed to pass complicated areas using the 4-th gear, temperature of the engine not exceeding 80°C at the temperature of the outside air +30°C, decrease of consumption of petrol component of the fuel composition by 8-12 of % in comparison with the use of pure petrol.

The tests have confirmed, that the offered fuel composition allows to provide efficient operation of the engine on petrol with any octane number, that makes it possible to use cheaper low-octane fuel with achievement of high operational parameters.