Who invented the diesel engine?

Rudolf Diesel invented the diesel engine.

Diesel was a German inventor and mechanical engineer who pursued an engine far more efficient than contemporary steam engines. His thinking was influenced by thermodynamics and by lectures from Carl von Linde, whom Diesel encountered as a student at the Polytechnic School in Munich. Diesel aimed to develop an engine approaching the efficiency of the Carnot cycle.

He published his ideas in 1893 in a treatise describing a “rational heat engine.” Unlike a conventional spark-ignition engine, his design compressed air until it became hot enough to ignite injected fuel. This compression-ignition principle is the defining feature of a diesel engine.

The first prototypes were difficult to develop, and Diesel worked with Maschinenfabrik Augsburg, later associated with MAN, as well as Krupp. A successful engine was tested publicly in 1897. Diesel received patents in several countries, including Germany and the United States. The engine and diesel fuel were subsequently named after him, although early engines could operate on fuels such as kerosene, vegetable oil, and even peanut oil.