Oilers/Plant Tenders (HHC) Civil Service Practice Exam

The cetane number is associated with which type of engine fuel?

1. Gasoline engine

2. Diesel engine

3. Jet engine

4. Biofuel engine

The correct answer is: Diesel engine

The cetane number is a critical parameter specifically associated with diesel engine fuels. It measures the ignition quality of diesel fuel, indicating how easily and quickly the fuel will ignite when injected into the combustion chamber. A higher cetane number signifies a better-quality fuel that ignites more swiftly, leading to more efficient combustion and less engine noise. For diesel engines, which rely on compression ignition, the cetane number is vital for ensuring that combustion occurs at the right moment during the engine cycle. If the cetane number is too low, it can lead to issues such as rough engine operation, increased exhaust emissions, and difficulty starting the engine. In contrast, gasoline engines use an octane rating, which measures a fuel's resistance to knocking during combustion, while jet engines utilize fuels designed for different properties entirely. Biofuels may have various characteristics, but their effectiveness in diesel engines is evaluated based on their cetane number, making it a key factor for diesel fuel specifically. Thus, associating the cetane number with diesel engine fuel is accurate and reflects its importance in engine performance and operation.