Class 4 (4th Engineer) MEP 📅 Apr 2025

Exam Question

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

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

(b) The importance of Sodium to Vanadium Ratio. (4)

(d) Pour point (4)

Reference Answer

### (a) Calculated Carbon Aromaticity Index (CCAI)
**1. Definition and Significance:**
The Calculated Carbon Aromaticity Index (CCAI) is an empirical value calculated from the density and viscosity of a residual fuel oil. It serves as a crucial indicator of the fuel's ignition quality. A lower CCAI value (typically below 850) indicates better ignition quality (a shorter ignition delay), whereas a higher CCAI (above 870) signifies poor ignition quality and a longer ignition delay.
**2. Underlying Principle:**

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