Cetaanilukema

Cetaanilukema, commonly called cetane number, is a measure used to describe how readily diesel fuel will ignite in a diesel engine under compression. It expresses ignition delay on a standardized scale: fuels with higher cetane numbers ignite more quickly, while those with lower numbers take longer to ignite. The value is a relative measurement, typically interpreted as an indicator of ignition quality rather than an absolute ignition time.

Determination of cetane number is carried out by standardized engine tests that compare the ignition delay of the test fuel with that of reference fuels. In practice, laboratories determine a single cetane number by either direct engine testing or by accepted correlation methods that estimate ignition quality from fuel properties. The scale generally ranges from 0 to 100, with higher numbers signaling shorter ignition delays.

Significance for engine performance is practical. Fuels with higher cetane numbers usually enable faster and more stable ignition, smoother starting, reduced cold-start problems, and often lower emissions of smoke and unburned hydrocarbons. Very low cetane fuels can result in rough operation and increased emissions. Cetane number can be influenced by refining processes, feedstock, and the use of cetane improvers or biodiesel blends, which may raise or modify ignition quality depending on composition.

In many regions, diesel fuel specifications include a minimum cetane number or cetane index as part of overall quality control. The cetane number is one aspect of combustion performance, alongside properties such as sulfur content, cold-flow characteristics, and lubricity, which together determine fuel suitability for modern diesel engines.