It is an engine in which combustion of fuel take place outside of the engine. In this type of engine heat, which is generated by burning of fuel is use to convert the water or other low boiling temperature fluid into steam. This high pressure steam used to rotate a turbine.
This method is referred to as SPARK IGNITION. On the other hand, the compression temperature in a diesel engine is far above the ignition point of the fuel oil. Therefore, ignition of the fuel takes place as a result of heat generated by compression of the air within the cylinder, an action referred to as COMPRESSION IGNITION.
A pistonless rotary engine is an internal combustion engine that does not use pistons in the way a reciprocating engine does, but instead uses one or more rotors, sometimes called rotary pistons. An example of a pistonless rotary engine is the Wankel engine.
Characteristics. Single-cylinder engines are simple and compact, and will often deliver the maximum power possible within a given envelope. Cooling is simpler than with multiple cylinders, potentially saving further weight, especially if air cooling is used.