Class 2 (2nd Engineer) MEKG 📅 Apr 2024

Exam Question

With respect to the properties of fuel oil, explain the significance of the following terms

(a) Calculated Carbon Aromaticity index (CCAI). (4)

(b) Open flash point and Closed flash point. (4)

(d) Octane Number. (4)

Reference Answer

### (a) Calculated Carbon Aromaticity Index (CCAI)
CCAI is an empirical index used to estimate the ignition quality of residual marine fuel oils. It is particularly important because traditional indicators like Cetane Number are not suitable for heavy, viscous fuels. The CCAI is calculated based on the fuel's density and viscosity.
**Significance:**
1. **Ignition Delay:** A higher CCAI indicates a higher aromatic content in the fuel. Aromatic compounds are more stable and require more energy and time to break down and ignite. Therefore, a high CCAI corresponds to a longer ignition delay period.

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