Basic Considerations of the Choice of  Fuels

 The choice of fuel depends on the purpose of the combustion process and several other factors

1.          Energy content per volume or per mass
2.          Safety
3.          Combustion and  fuel properties
4.          Cost of fuel

 Classification of  Fuels by Phase at Ambient Conditions

Distribution methods and combustion processes vary based on a fuel’s state of matter, making the phase of  fuel at standard conditions a logical basis for classification

   a) Solid  Fuel

1. Solid fuel consists of moisture, volatile matter, fixed carbon, and ash. The ultimate analysis of solid fuels defines the relative amounts of these constituents on a mass basis. The ultimate analysis may be given on the dry basis
2. Hydrocarbon solid fuel: C_aH_bO_g with a > b – produce more CO₂ when burned
3. Examples: wood, coal, biomass

   b) Liquid Fuel

1. Most liquid fuels are mixtures of many different Hydrocarbons.  Commonly a liquid fuel is treated as a single hydrocarbon with a common formula C_xH_y� but it can be a mixture of several hydrocarbons
2.  liquid  hydrocarbon fuels : C_aH_bO_g with a < b 
3. Examples: Gasoline, oil, diesel etc.

c) Gaseous Fuel

1. Coal gas (a mixture of methane and Hydrogen) etc.
2. For gaseous fuel:  C_aH_bO_g with na <b – have the lowest C/H ratio that results in the least greenhouse gas (CO₂) per unit energy output
3. Examples: LPG gas, Syngas, CNG, NG gas, Biogas etc.