What is cetane number

What is cetane number

In the field of fuel chemistry, the cetane number (CN) is an important indicator for measuring the self-ignition performance of diesel fuel. It directly affects the starting performance, combustion efficiency and emission levels of diesel engines. This article will introduce in detail the definition of cetane number, test methods, influencing factors and its practical applications.

1. Definition of cetane number

The cetane number is used to characterize the self-ignition characteristics of diesel fuel in compression ignition engines. The higher the value, the better the self-ignition performance of the fuel and the smoother the combustion. The standard test method is to use a standard single-cylinder engine and determine it by comparing the ignition delay time of the tested fuel with a mixture of n-cetane (CN=100) and α-methylnaphthalene (CN=0).

2. Testing method of cetane number

There are currently two main testing standards commonly used internationally:

3. Factors affecting cetane number

Several factors can affect the cetane number of diesel fuel:

4. The practical significance of cetane number

Proper cetane number is critical to engine operation:

1.Startup performance: High cetane number fuels are easier to start at low temperatures

2.Combustion characteristics: Affects combustion noise and vibration levels

3.Emission control: Directly related to particulate matter and NOx emissions

Modern diesel engines typically require fuel with a cetane number of no less than 51, while high-performance engines may require higher numbers.

5. Methods to increase cetane number

Refiners and fuel suppliers use a variety of methods to optimize cetane number:

6. Comparison of global cetane number standards

Different countries and regions have different requirements for diesel cetane number:

7. Future development trends

As emissions regulations become increasingly stringent, cetane number requirements are on the rise:

1. New generation engine designs require fuel with higher cetane number

2. Increasing the addition ratio of biodiesel will affect the overall cetane number

3. New fuels such as synthetic fuels and hydrogenated vegetable oils bring new challenges

The importance of cetane number as a key quality indicator for diesel fuel will continue to increase. Fuel producers and engine manufacturers need to work closely together to optimize fuel performance and meet increasingly stringent environmental requirements.