Calculated Ignition Index
Encyclopedia
The Calculated Ignition Index (CII) is an index of the ignition quality of residual fuel oil.
The running of all internal combustion engines is dependent on the ignition quality of the fuel. For spark-ignition engines the fuel has an octane rating. For diesel engines it depends on the type of fuel, for distillate fuels the cetane number
s are used. Cetane numbers are tested using a special test engine and the existing engine was not made for residual fuels. For residual fuel oil two other empirical indexes are used CII and Calculated Carbon Aromaticity Index
(CCAI). Both CII and CCAI are calculated from the density
and kinematic viscosity
of the fuel.
Where:
D = density at 15°C (kg/m³)
V = viscosity (cST)
T = viscosity temperature (°C)
The running of all internal combustion engines is dependent on the ignition quality of the fuel. For spark-ignition engines the fuel has an octane rating. For diesel engines it depends on the type of fuel, for distillate fuels the cetane number
Cetane number
Cetane number or CN is a measurement of the combustion quality of diesel fuel during compression ignition. It is a significant expression of diesel fuel quality among a number of other measurements that determine overall diesel fuel quality.- Definition :...
s are used. Cetane numbers are tested using a special test engine and the existing engine was not made for residual fuels. For residual fuel oil two other empirical indexes are used CII and Calculated Carbon Aromaticity Index
Calculated Carbon Aromaticity Index
The calculated carbon aromaticity index is an index of the ignition quality of residual fuel oil.The running of all internal combustion engines is dependent on the ignition quality of the fuel. For spark-ignition engines the fuel has an octane rating. For diesel engines it depends on the type of...
(CCAI). Both CII and CCAI are calculated from the density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
and kinematic viscosity
Viscosity
Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...
of the fuel.
Definition
Formula for CII:Where:
D = density at 15°C (kg/m³)
V = viscosity (cST)
T = viscosity temperature (°C)