CHEE2325 – Lecture 10
Types of systems:
- Nonreacting systems are systems whose chemical composition remains
unchanged during a process.
- Reacting systems are systems whose chemical composition changes during a
process.
Fuel:
- A fuel is a material that can be burned to release thermal energy.
- Hydrocarbons are a common fuel type with general chemical formula C x H y.
- Distillation of crude oil produces liquid hydrocarbon fuels. The most volatile
hydrocarbons, such as gasoline, vapourise first, while the less volatile ones,
such as diesel, vapourise later.
- Natural gas is composed mainly of methane and is produced from gas wells
or oil wells rich in natural gas.
- CNG is natural gas stored in the gas phase at 150-250 atm.
- LNG is natural gas stored in the liquid phase at -162 oC.
- LPG is liquefied petroleum gas and is a by-product of natural gas or crude oil
refining. It is composed of propane.
- Ethanol is obtained from corn, grains, and natural gas.
- Methanol is mainly obtained from natural gas but can also be obtained from
coal or biomass.
- Alternative fuels are fuels that are friendlier to the environment than traditional
petroleum fuels.
Combustion:
- Combustion is a chemical reaction during which a fuel is oxidised and
releases a large quantity of energy.
- Air is a very common oxidiser. By volume, air is around 21% O2, and 79% N 2.
- Nitrogen and water are usually assumed to be inert.
- The air-fuel ratio is:
m air
AF=
m fuel
- The stoichiometric air-fuel ratio is:
mair , stoich
AF stoich =
m fuel
Types of systems:
- Nonreacting systems are systems whose chemical composition remains
unchanged during a process.
- Reacting systems are systems whose chemical composition changes during a
process.
Fuel:
- A fuel is a material that can be burned to release thermal energy.
- Hydrocarbons are a common fuel type with general chemical formula C x H y.
- Distillation of crude oil produces liquid hydrocarbon fuels. The most volatile
hydrocarbons, such as gasoline, vapourise first, while the less volatile ones,
such as diesel, vapourise later.
- Natural gas is composed mainly of methane and is produced from gas wells
or oil wells rich in natural gas.
- CNG is natural gas stored in the gas phase at 150-250 atm.
- LNG is natural gas stored in the liquid phase at -162 oC.
- LPG is liquefied petroleum gas and is a by-product of natural gas or crude oil
refining. It is composed of propane.
- Ethanol is obtained from corn, grains, and natural gas.
- Methanol is mainly obtained from natural gas but can also be obtained from
coal or biomass.
- Alternative fuels are fuels that are friendlier to the environment than traditional
petroleum fuels.
Combustion:
- Combustion is a chemical reaction during which a fuel is oxidised and
releases a large quantity of energy.
- Air is a very common oxidiser. By volume, air is around 21% O2, and 79% N 2.
- Nitrogen and water are usually assumed to be inert.
- The air-fuel ratio is:
m air
AF=
m fuel
- The stoichiometric air-fuel ratio is:
mair , stoich
AF stoich =
m fuel
