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.

McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
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 ( South China Morning Post reported that the nation is looking to make huge strides into space over the next three decades, with the country's biggest rocket developer announcing its plan to create a fleet of space shuttles that run on nuclear energy, rather than chemical fuel, by 2040 and then use that technology to harvest space resources.
No one is to be blamed for this as they use a chemical fuel in Europe and many teams had issues with it.
The Lithuanian satellite stands out for being fuelled by chemical fuel, which is tested for the first time on the tiny satellite.
Shijian 13 will use electric propulsion after it enters orbit, which will extensively reduce the chemical fuel the satellite carries.
"Artificial leaf" is like living leaves; this device can turn the sunlight directly into a chemical fuel that can be stored and used later as an energy source.
It was a declaration that Obama has at last given in to the warmongers who have been leading a media blitz that has been beating the drums of war on Syria for two and a half years now; Kerry only added "chemical fuel" to it.
Different human cell types can contain from one up to 10,000 mitochondria, which power the cells by generating the chemical fuel called adenosine triphosphate (ATP) needed to drive most biochemical processes.
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.
"The AFRL role is focused on the early test stages Acting as a gatekeeper for basic property data for further testing by the likes of GE, Pratt & Whitney, Rolls-Royce, or the Alternative Fuels Certification Office for the US Air Force, to support the technology readiness of the fuel: says Tim Edwards, leader of the Chemical Fuel Branch of AFRL.