Which fraction is commonly used as diesel fuel?

Which fraction is commonly used as diesel fuel?

• A. Petrol
• B. Kerosine
• C. Diesel
• D. Heavy fuel oil

Answer: (C)

The concept being tested is how the different fractions obtained from crude oil are suited for specific engine types. Diesel fuel comes from the middle distillate range in fractional distillation. This fraction has a balance of viscosity, boiling point, and energy content that makes it ideal for diesel engines, which rely on compression ignition. It is heavy enough to lubricate the engine and flow properly at typical temperatures, yet not so heavy or viscous that it won’t atomize and burn efficiently in the engine cylinders. Petrol is lighter and is designed for spark-ignition engines, so it would vaporize and ignite too readily in a diesel engine. Kerosene is lighter still and used for jet fuel or heating due to its properties, not for typical diesel engines. Heavy fuel oil is much more viscous and boils at a higher range, making it unsuitable for most road diesel engines. The diesel fraction sits in the right part of the distillation range to meet the needs of diesel engines, which is why it is the commonly used diesel fuel.

The concept being tested is how the different fractions obtained from crude oil are suited for specific engine types. Diesel fuel comes from the middle distillate range in fractional distillation. This fraction has a balance of viscosity, boiling point, and energy content that makes it ideal for diesel engines, which rely on compression ignition. It is heavy enough to lubricate the engine and flow properly at typical temperatures, yet not so heavy or viscous that it won’t atomize and burn efficiently in the engine cylinders.

Petrol is lighter and is designed for spark-ignition engines, so it would vaporize and ignite too readily in a diesel engine. Kerosene is lighter still and used for jet fuel or heating due to its properties, not for typical diesel engines. Heavy fuel oil is much more viscous and boils at a higher range, making it unsuitable for most road diesel engines. The diesel fraction sits in the right part of the distillation range to meet the needs of diesel engines, which is why it is the commonly used diesel fuel.