The external combustion engine means that its fuel is burned outside the engine. It was invented by R. Stirling of Scotland in 1816, so it is also called the Stirling engine. The engine converts the heat generated by this combustion into kinetic energy. Watt’s modified steam engine is a typical external combustion engine. When a large amount of coal is burned to produce heat and heat water into a large amount of water vapor, high pressure is generated. The high pressure pushes the machine to do work, thus completing the transformation from thermal energy to kinetic energy.
internal combustion engine
If you understand what an external combustion engine is, you also know what an internal combustion engine
is. The internal combustion engine is a reciprocating piston engine. The biggest difference between this type of engine and an external combustion engine is that its fuel is burned inside. There are many types of internal combustion engines. Common gasoline engines and diesel engines are typical internal combustion engines.