A diesel engine is an internal combustion engine that uses diesel fuel, commonly found in applications such as automobiles, ships, and industrial machinery. The engine operates by compressing air to a high temperature, then injecting diesel fuel into the hot, pressurized air, causing the diesel to ignite and produce power. Compared to gasoline engines, diesel engines offer higher thermal efficiency and greater torque, making them particularly suited for heavy-duty machinery and vehicles that operate over long periods. Due to the higher energy density of diesel fuel, diesel engines often have a significant advantage in fuel efficiency. However, noise and emissions are challenges that still need to be addressed.