Fuels and Combustion (Theory and Elements) - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on fuels and combustion.

Hydrocarbon fuel

A fuel composed primarily of hydrogen and carbon; can be liquid, gaseous, or solid; examples include gasoline, diesel, kerosene.

Distillation

Process by which liquid hydrocarbon fuels are separated from crude oil based on boiling points.

Cracking

Process that breaks larger hydrocarbon molecules into smaller ones to increase fuel yields.

Octane (C8H18)

A simplified hydrocarbon model used in combustion calculations for gasoline.

Dodecane (C12H26)

A simplified hydrocarbon model used in combustion calculations for diesel fuel.

Natural gas

Gaseous hydrocarbon fuel produced from wells; major constituent is methane (CH4).

Methane (CH4)

Primary component of natural gas and the simplest alkane.

Mole fraction

Fraction of a gas mixture based on the number of moles of each component; used to specify gas compositions.

Ultimate analysis

Coal analysis showing the mass fractions of elemental constituents C, H, O, N, S, plus moisture (M) and ash (A), summing to 100%.

Moisture (M)

Water content in coal as determined in the ultimate analysis.

Ash (A)

Inert inorganic residue remaining after coal combustion.

Dry and ash free analysis

Combustible basis analysis obtained by dividing C, H, O, N, S by (1 − (M + A)/100).

Heating Value (HV) / Calorific Value

Heat released by complete combustion of a unit mass of fuel; for gases, often expressed per cubic meter.

Higher Heating Value (HHV)

Total heat released when combustion products are cooled to room temperature, including the latent heat of condensing water.

Lower Heating Value (LHV)

Net heat when combustion products leave as water vapor; excludes latent heat of vaporization.

Bomb calorimeter

Instrument used to determine HHV by burning a fuel sample in pure oxygen inside a sealed vessel and measuring temperature rise in water.

Pour point

Lowest temperature at which oil will flow under standard conditions.

Flash point

Minimum temperature at which oil may ignite under specified test conditions.

Crude oil fractions

Fractions distilled from crude oil; lighter fractions (gasoline, kerosene, light diesel) used as fuels, heavier fractions for boiler fuel and chemical production.

Liquefied Natural Gas (LNG)

Natural gas cooled to cryogenic temperatures to become a liquid for transport and storage.

Compressed Natural Gas (CNG)

Natural gas stored under high pressure for use as a vehicle fuel.

Liquefied Petroleum Gas (LPG)

Hydrocarbons such as propane and butane that are liquefied under moderate pressure for domestic and other uses.

Combustion

High-temperature oxidation of fuel leading to energy release and product formation.

Complete combustion

All carbon to CO2, all hydrogen to H2O, and all sulfur to SO2; other elements fully oxidized.

Incomplete combustion

Occurs when there is not enough oxygen, producing CO or other partially oxidized products.

MATT

M is for mixture (turbulence), A for air-fuel ratio, T for temperature, and the second T for time—four factors critical for complete combustion.

Excess air

More air than the stoichiometric requirement to ensure complete combustion; greater turbulence reduces the needed excess air.