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Alcohols and Ethers
Alcohols as engine fuel have been of interest for a long time. In the hydrocarbons when a hydrogen atom is substituted with hydroxyl radical (OH), alcohols are formed. Among the alcohols, methyl alcohol (CH3OH) and ethyl alcohol (C2H5OH) are considered as alternative fuels. Ethers, such as di-methyl ether (DME) has been investigated as diesel engine fuel and methyl teriary butyl ether (MTBE) is being used as a high octane blending component in gasoline.
General Fuel Quality Requirements
Many properties of the fuels influence engine performance and emissions. The most important properties of liquid fuels, gasoline and diesel most of which are specified in the fuel quality standards are given in Table 8.1
| Table 8.1 |
| Important Characteristics of Liquid Petroleum Fuels |
| Gasoline |
Diesel |
| Distillation |
Ignition quality (Cetane index, Cetane number) |
| Reid vapour pressure |
Distillation (volatility), 90% boiling point |
| Heat of combustion* |
Heat of combustion* |
| Density |
Density |
| Antiknock quality (Research and Motor octane number) |
Viscosity |
| Oxidation stability |
Aromatic content |
| Gum content, mg/100ml |
Sulphur content |
| Lead content |
Storage stability |
| Sulphur |
Injection system cleanliness |
| Benzene |
|
| Sediments |
Sediments |
| * Heat of combustion is not specified in the fuel quality standards |
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