Which type of ignition system is used in diesel engines to initiate combustion?

In diesel engines, combustion is initiated through a process known as compression ignition. This method relies on the high temperature created by compressing air in the engine cylinder to ignite the fuel. Unlike gasoline engines, which use spark plugs and an electric ignition system to ignite a mixture of air and fuel, diesel engines compress air to a much higher pressure and temperature.

When diesel fuel is injected into the highly compressed and heated air, it spontaneously ignites due to the elevated temperature. This process is fundamental to the operation of diesel engines and distinguishes them from other ignition methods, such as high voltage, battery, or magneto ignition systems, which are typical in gasoline engines.

By understanding this principle, students can appreciate the unique characteristics and operating mechanisms of diesel engines compared to other internal combustion engines.