Rudolf Diesel
Rudolf Christian Karl Diesel (1858 – 1913) was an inventor and mechanical engineer who knew that steam engines are only between 10-15% thermodynamically efficient, meaning that up to 90% of the energy available in the fuel is wasted. His work in engine design was driven by the goal of achieving a much higher efficiency ratio, and this ultimately led to the invention of the engine that still bears his name today.
Rudolf developed an engine that relied on a high compression of the fuel to ignite it, rather than the spark plug used in the Otto internal combustion engine. He received a patent for this in 1892 and in 1894 was able to run a single piston engine fueled by powdered coal injected with compressed air for one minute. He built an improved prototype in early 1897, but because his engine had similarities with one invented in 1890, he was embroiled for some years in various patent disputes. However, in the end he prevailed with his more efficient engine, and his invention came to be called the diesel engine.
The Diesel Engine
A diesel engine is an internal combustion engine that uses the heat of compression to initiate ignition to burn the fuel, unlike a petrol engine where a fuel and air mixture is ignited by a spark from a plug. Diesel engines have the highest thermal efficiency of any combustion engine because of their relatively high compression ratio. Diesel was interested in using coal dust or vegetable oil as the fuel for his engine, and although it is often reported that he designed it to run on peanut oil at the Paris Exhibition in 1900, he was in fact impressed by an engine that did just that and later conducted related tests and appeared supportive of the idea.
Diesel's Legacy
Unfortunately Rudolf died in unusal circumatances. In September 1913, he boarded a steamer in Antwerp enroute to a meeting of the Consolidated Diesel Manufacturing company in London. After retiring to his cabin after dinner and leaving word to be called early the next morning, he was never seen alive again. Ten days later, a Dutch crew found the corpse of a man floating in the English Channel. As the body was badly decomposed they did not bring it aboard but instead retrieved somepersonal items and returned the body to the sea. Rudolf's son later identified these items as belonging to his father. There are various theories regarding his death, from suicide due to depression and large debts to being murdered, either by German agents to stop his engine falling into British hands on the eve of World War One, or by hitmen hired by the petroleum industry. Or perhaps it was a simple but unfortunate accident? The truth is, we will probably never know. One thing though is for certain: he invented an environmentally friendly engine before such a phrase was even coined that has continued to improve and become popular.
After Diesel's death, his engine underwent much development and became an important replacement for the steam piston engine in many applications, including stationary engines, submarines, ships, and later, locomotives, and trucks. Because it required a more robust construction than a petrol engine, and was therefore heavier, it was not widely used in aviation at first. However, these days the weight issue has been resolved and they are used in light aircraft, whose engines are designed to run on either diesel fuel or jet fuel. Diesel engines are most often found in applications where a high torque requirement and low RPM requirement exist. One thing is for sure: Rudolf Diesel invented a remarkable engine.