Fuels, Part 2

Liquid Fuels

Liquid fuels, as the name implies, are combustible materials that are in liquid form.

Liquids, in general, have the following characteristics:

  • assumes the shape of its container

  • has a definite volume, but no definite shape

  • are slightly compressible because their molecules are more loosely-packed compared to that of liquids

Liquid fuels also share the aforementioned characteristics. Additionally, just as the case for solids, sufficient heat must be available to turn liquid fuels into gas for combustion to occur.

Types of Liquid Fuels

A table of the different types and classes of flammable liquids

Gaseous Fuels

Finally, we have gaseous fuels, or those fuels that exist in gaseous form.

Molecules of gases are in relative free motion. Just like liquids, gases have no definite shape. Unlike liquids that have a definite volume, however, gases have no definite volume. They can expand to fill the room or container.

Since this type of fuel is already in gas form, heat is no longer required to transform it. Gaseous fuels can readily ignite under the proper conditions,

Note, however, that not all gases burn. Some of them, like carbon dioxide, are even used to extinguish fires.

Classifications of Gaseous Fuels

According to Source

  1. Natural Gas is used to heat buildings, cook food, and provide energy. Methane, the chief component of natural gas, is a colorless and odorless gas. Hence, foul-smelling substances, like sulfur, are usually added to them to help detect leaks. Common examples are butane and propane. They are easily contained and distributed when pressurized into liquid form. They change back into gas when pressure is removed.

  2. Manufactured Gas is used when other types are scarce. Coal, petroleum, and biomass can be converted to gas through various chemical processes.

According to Physical Properties

Compressed Gas

Exist as a gas in its container even under normal temperatures

Image shown is the international symbol used for compressed gases


By Unknown author - EPS file bottle.eps from UNECE web site converted with ImageMagick convert and with potrace, edited in inkscape, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4984049

Liquified Gas

Partly liquid and partly gaseous in its container

Cryogenic Gas

Liquified gas which exist in its container at a temperature far below normal atmospheric temperature, usually slightly above its boiling point, and low to moderate pressure.

Pictured above is liquid nitrogen.


By Cory Doctorow aka gruntzoki on Flickr - https://www.flickr.com/photos/doctorow/2288526230/, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=8848989

According to Usage

Fuel

For use in generating heat, power, light, and comfort

Industrial

For use in processes as welding and cutting, refrigeration, water treatment, etc.

Medical

For use in treatments such as anesthesia and respiratory therapy

The following are special classifications of fuels.

"Skeletal formula of hydrazine with all explicit hydrogens added"

Chemical Fuels

Used chiefly in rocket engines, chemical fuels, which can be in solid or liquid form, produce great amounts of heat a power. They are made up of a fuel and an oxidizer, such as nitrogen tetroxide. Hydrazine is common rocket fuel. (The skeletal formula of this substance is shown here.) Chemical fuels are also used in racing cars.


By NEUROtiker - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3465595

Nuclear Fuels

These provide energy through the fission or fusion of atoms. The most commonly used nuclear fuel is uranium, but plutonium may also be used. They are mainly used to generate electricity, but they can also be used to power some submarines and ships.