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 On this day in engineering history, Germany's Imperial Patent Office granted Rudolph Diesel Patent No. 67207 for "a new efficient thermal engine". The pressure-ignited heat engine which bears Diesel's name required less fuel than Nikolaus Otto's compression-mixture engine and was more efficient than James Watt's steam engine. Unlike the Otto engine, which compressed a mixture of fuel and air during the intake stroke, the Diesel engine took in only pure air. This pure-air stream enabled a diesel cylinder to achieve a higher compression ratio, squeezing more mechanical energy from the heated, pressurized air. Fuel injection during a subsequent step produced a powerful but controlled explosion, proving that an air-fuel mixture could be ignited without a spark. Indeed, years later, Diesel was granted a separate patent for inventing an engine which compressed air to such a degree that the air's temperature far exceeded the fuel's ignition temperature.
Diesel's patent of February 23, 1893 was the first step on a long road to a working engine. With contracts from Frederick Krupp and other manufacturers, Rudolph Diesel experimented and tested multiple models. In August 1893, Diesel's prime model, a single 10-foot iron cylinder with a flywheel at its base, ran on its own power for the first time. Operating at 26% efficiency, the first diesel engine offered more than twice the efficiency of contemporary steam engines. Over the next two years, Diesel improved his design before unveiling a second engine with a theoretical efficiency of 75.6%. By 1898, Rudolph Diesel was ready to demonstrate his creation at Paris' Exhibition Fair. Powered by peanut oil, this diesel engine burned fuel only when necessary - a sharp contrast to fuel-hungry steam engines.
A respected thermal engineer, Rudolph Diesel was also a social theorist who sought to remake armies, industries, societies, and nations. According to its creator, the diesel engine would revolutionize naval warfare and maritime transportation, hasten the progress of developing nations, and provide power to independent craftsman who struggled to compete with large industries. Although Diesel did not live long enough to recognize his vision, the steps he took after receiving his first patent helped to shape the twentieth century and the world beyond.
Resources:
https://inventors.about.com/library/inventors/bldiesel.htm
https://links.jstor.org/sici?sici=0040-165X(196624)7%3A1%3C90%3ARDPOTA%3E2.0.CO%3B2-W
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Re: February 23, 1893 – Rudolph Diesel’s Patent
