Is a spark required to ignite fuel in a diesel engine?

In a diesel engine, the combustion process relies on the principle of compression ignition, which means that fuel is ignited by the heat generated from compressing air within the cylinder, rather than through a spark.

During operation, the air in the combustion chamber is compressed to a very high pressure, resulting in a significant rise in temperature. When the fuel is injected into this high-temperature, high-pressure environment, it ignites almost immediately due to the heat from the compressed air. This is different from a gasoline engine, which typically uses spark plugs to ignite a fuel-air mixture.

Understanding this distinction is crucial for comprehending how different types of internal combustion engines operate. The principles of thermodynamics that govern diesel engines are specific to their design and fuel characteristics, which emphasize the importance of compression over ignition sources like sparks.