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The mysterious Cetane number: How to calculate it to make your diesel engine perform well?
The performance of a diesel engine depends to a considerable extent on the properties of its fuel, and the Cetane number (CN) is a key indicator of the quality of diesel fuel. The Cetane number refers to the burning speed of diesel fuel and the degree of compression required for ignition. For diesel, its importance is comparable to the octane number of gasoline.
"Cetane number can be regarded as an indicator of diesel quality. It is not only the burning speed of fuel, but also the key to engine efficiency."
What are Cetane numbers?
According to the standard definition, the Cetane number is measured by finding a fuel that is a mixture of cetane and isocetane. The Cetane number of Cetane is defined as 100, while the Cetane number of isocetane is 15. This standard replaces the previous reference fuel alpha-methylnaphthalene, which had a Cetane number of 0.
The Cetane number for this fuel mixture is calculated based on the actual volume weighted average. Simply put, the higher the Cetane number, the shorter the ignition delay time of the fuel in the diesel engine, making the combustion process more efficient.
The influence of Cetane number
Generally speaking, diesel engines run best in the Cetane number range of 48 to 50. A lower Cetane number usually results in a longer ignition delay, which affects the fuel combustion process, especially in high-revving diesel engines. To this end, many European countries have successively formulated corresponding standards to increase the Cetane number of diesel fuel.
"Since 2001, the European Union standard EN 590 requires a minimum Cetane number of 51, which is crucial for improving diesel performance."
Measure the Cetane number
Accurately measuring the Cetane number is not simple and often requires specialized equipment such as the Cooperative Fuels Research (CFR) engine. During this process, the operator adjusts the compression ratio to ensure the specified ignition delay time is met. On the other hand, reliable Cetane number measurements can also be obtained using tools such as the Ignition Quality Tester (IQT) or the Fuel Ignition Tester (FIT), but the principles are different from CFR.
The role of additives
In order to increase the Cetane number of fuel, some additives are usually introduced, such as alkyl nitrates and di-tert-butyl peroxide. This not only improves the combustion characteristics of the fuel, but also improves its lubricity, allowing the engine to run more smoothly.
The potential of alternative fuels
With the increasing awareness of environmental protection, biodiesel is gradually gaining popularity. Biodiesel from vegetable oils has a Cetane number between 46 and 52, while animal fat-based biodiesel has a Cetane number ranging from 56 to 60. These alternative fuels have the potential to not only improve the performance of diesel engines but also reduce their environmental impact.
"The fuel selection of diesel engines is likely to undergo revolutionary changes in the future, which makes the research of alternative fuels a focus."
Industry standards and trends
There are also clear standards for the measurement of Cetane number in the industry, such as ASTM D613 (ISO 5165) for CFR engine testing, and D6890 for IQT testing standards. These standards ensure the quality of diesel fuel and build confidence for consumers and manufacturers.
With the advancement of diesel technology and the increasing emphasis on environmental protection, the study of Cetane number and the quality of diesel fuel will undoubtedly be important issues in the future.
In this competition of fuel quality, how to correctly calculate the Cetane number and select suitable diesel fuel will become a major challenge for all diesel car owners. Are you ready to meet the challenge?
