Chemical fuel

Chemical fuel

The principal fuels used in internal combustion engines (automobiles, diesel, and turbojet) and in the furnaces of stationary power plants are organic fossil fuels. These fuels, and others derived from them by various refining and separation processes, are found in the earth in the solid (coal), liquid (petroleum), and gas (natural gas) phases.

Special fuels to improve the performance of combustion engines are obtained by synthetic chemical procedures. These special fuels serve to increase the specific impulse of the engine or to increase the heat of combustion available to the engine per unit mass or per unit volume of the fuel. A special fuel which possesses a very high heat of combustion per unit mass is liquid hydrogen. It has been used along with liquid oxygen in rocket engines. Because of its low liquid density, liquid hydrogen is not too useful in systems requiring high heats of combustion per unit volume of fuel (“volume-limited” systems).

A special fuel which produces high flame temperatures of the order of 5000°F (2800°C) is gaseous cyanogen. This is used with gaseous oxygen as the oxidizer. The liquid fuel hydrazine, and other hydrazine-based fuels, with the liquid oxidizer nitrogen tetroxide are used in many space-oriented rocket engines. The boron hydrides, such as diborane and pentaborane, are high-energy fuels which are used in advanced rocket engines.

For air-breathing propulsion engines (turbojets and ramjets), hydrocarbon fuels are most often used. For some applications, metal alkyl fuels which are pyrophoric (that is, ignite spontaneously in the presence of air), and even liquid hydrogen, are being used.

Fuels which liberate heat in the absence of an oxidizer while decomposing either spontaneously or because of the presence of a catalyst are called monopropellants and have been used in rocket engines. Examples of these monopropellants are hydrogen peroxide and nitro-methane.

Liquid fuels and oxidizers are used in most large-thrust rocket engines. When thrust is not a consideration, solid-propellant fuels and oxidizers are frequently employed because of the lack of moving parts such as valves and pumps, and the consequent simplicity of this type of rocket engine. Solid fuels fall into two broad classes, double-base and composites. Double-base fuels are compounded of nitroglycerin (glycerol trinitrate) and nitrocellulose, with no separate oxidizer required. The double-base propellant is generally formed in a mold into the desired shape (called a grain) required for the rocket case. Composite propellants are made of a fuel and an oxidizer. The latter could be an inorganic perchlorate or a nitrate. Fuels for composite propellants are generally the asphalt-oil-type, thermosetting plastics or several types of synthetic rubber and gumlike substances. Metal particles such as boron, aluminum, and beryllium have been added to solid propellants to increase their heats of combustion and to eliminate certain types of combustion instability.

References in classic literature ?
It was also equally impossible to obtain the necessary ingredients for our chemical fuel, and, as we had very little left aboard, we determined to step our folding mast and proceed under sail, hoarding our fuel supply for use in emergencies.
As we sailed away, after procuring the necessary ingredients of our chemical fuel, the Grubittens lined the shore in silent wonder at the strange sight of our dainty craft dancing over the sparkling waters, and watched us until we were lost to their sight.
The demonstration system is approximately one square centimeter in area, converts 10 percent of the energy in sunlight into stored energy in the chemical fuel, and can operate for more than 40 hours continuously.
This strange energy conversion process works by using externally supplied energy to constantly pump a lot more protons onto one side of a biological membrane than the other and then having them flow back "downhill" immediately, but only through a turbine-like molecular engine which creates a chemical fuel called ATP; a fuel that cells "burn" in order to power vital cell processes.
Unlike batteries, fuel cells are "conversion" devices that change some kind of chemical fuel into electricity.
Naval fuel burning graphology (Ghia, 1991, 1995) is defined as the scientific discipline concerned with the graphic evolution transposition of intermediate fuel's burning processes, establishing the ignition-burning characteristics, including the governing laws for these changes, depending on the burning conditions and the chemical fuel structure.
If we used chemical fuel rockets like the Apollo mission to the moon, the journey to the nearest star would take 50,000 years.
Hawking said chemical fuel rockets would take too long, adding: "Science fiction has developed the idea of warp drive.
We are introducing this product to provide our customers with a cost-effective solution to ASTM D-975 compliance," said Afton Chemical fuel additives manager Tara Sharrer.
As a chemical fuel, hydrogen can be used in a much wider range of energy applications than electricity.
1 billion development program, probably would also be based there operationally because of the space required for its equipment and chemical fuel, Maj.
Specifications and chemical fuel delivered shall not be lower than specified in the Annexes of the said Regulation.