Why Can't Diesel Ignite Even Though Its Flash Point Is Lower Than Gasoline?

[VanPenelope]

Diesel is more prone to spontaneous combustion than gasoline but harder to ignite because of its poor volatility. Below are some key points about diesel: 1. Properties: A light petroleum product, diesel is a complex mixture of hydrocarbons with carbon atoms ranging from 10 to 22. It serves as fuel for compression-ignition engines (i.e., diesel engines). Diesel is primarily produced by blending fractions obtained from crude oil distillation, catalytic cracking, thermal cracking, hydrocracking, and petroleum coking (followed by refining and additive incorporation). It can also be derived from crude oil or shale oil through direct distillation or cracking processes. Depending on the crude oil source, diesel can be paraffinic, naphthenic, or naphthenic-aromatic. 2. Applications: Due to its lower fuel consumption (50–75g/MJ) compared to gasoline engines (75–100g/MJ), diesel engines are increasingly used in large transport vehicles. Diesel is widely employed in heavy-duty vehicles, railway locomotives, and marine vessels. As a liquid fuel for diesel engines, it offers low energy consumption and reduced pollution, making it an eco-friendly choice. Consequently, some small cars and even high-performance vehicles have switched to diesel.