Write the properties of diesel as a fuel in CI engine.
1) Volatility: - The fuel should be sufficiently volatile in the operating range of temperature to produce good mixing and combustion.
2) Viscosity: Viscosity of a fuel is a measure of its resistance to flow.
3) Flash point: Flash point is the temperature at which a flammable liquid will produce, with a standardized apparatus and procedure, a mixture of its vapour and air which will ignite to give a visible flash by contact with an open flame.
4) Fire point: Fire point is the temperature at which the flash will sustain itself as a steady flame for at least five seconds.
5) Cetane number: The Cetane rating of a diesel fuel is measure of its ability to auto-ignite quickly when it is injected into the compressed and heated air in the engine.
6) Calorific value: It is about 50 MJ/Kg
7) Sulphur High sulphur content in diesel fuel causes corrosion, wear of engine parts, especially the cylinder walls, and tends to increase the rate of sticky and sludge - like deposits.
8) Contamination: The contents of sand and rust particles can clog small openings and abrasive particles can damage injector surface piston rings and cylinder walls.
9) Cloud point: The temperature below which the wax content of the petroleum oil separates out in the form of a solid is called cloud point. Such waxy solid can clog fuel lines and fuel filters.
10. Pour point: pour point is the temperature below which the entire mass of fuel, solid or liquid together, freeze and thus cause flow of fuel impossible. Pour point is usually 5 to 10°c below the cloud point.
11. Specific Heat: It is the amount of heat required to raise the temperature of unit mass of a diesel through 1°c. It is about 1.9 KJ/Kg°c.