Rudolf Diesel

Diesel was born on 18 March 1858 at 38 Rue Notre-Dame-de-Nazareth in Paris, France, the second of three children of Elise (née Strobel) and Theodor Diesel. His parents were Bavarian immigrants living in Paris. Theodor Diesel, a bookbinder by trade, left his hometown of Augsburg, Bavaria, in 1848. He met his wife, a daughter of a Nuremberg merchant, in Paris in 1855 and became a leather goods manufacturer there.

Shortly after his birth, Diesel was given away to a Vincennes farmer family, where he spent his first nine months. When he was returned to his family, they moved into a flat at 49 Rue de la Fontaine-au-Roi. At the time, the Diesel family suffered from financial difficulties, thus young Rudolf Diesel had to work in his father's workshop and deliver leather goods to customers using a barrow. He attended a Protestant-French school and soon became interested in social questions and technology. Being a very good student, 12-year-old Diesel received the Société pour l'Instruction Elémentaire bronze medal and had plans to enter Ecole Primaire Supérieure in 1870.

At the outbreak of the Franco-Prussian War the same year, his family were deported to England, settling in London, where Diesel attended an English-speaking school. Before the war's end, however, Diesel's mother sent 12-year-old Rudolf to Augsburg to live with his aunt and uncle, Barbara and Christoph Barnickel, to become fluent in German and to visit the Königliche Kreis-Gewerbeschule (Royal County Vocational College), where his uncle taught mathematics. He was enrolled at the Technische Hochschule (Technical High School).

At the age of 14, Diesel wrote a letter to his parents saying that he intended to become an engineer. After finishing his basic education at the top of his class in 1873, he enrolled at the newly founded Industrial School of Augsburg. Two years later, he received a merit scholarship from the Royal Bavarian Polytechnic of Munich, which he accepted against the wishes of his parents, who wanted him to begin working instead.

One of Diesel's professors in Munich was the engineer and businessman Carl von Linde. Diesel was unable to graduate with his class in July 1879 because he fell ill with typhoid fever. While waiting for the next examination date, he gained practical engineering experience at the Sulzer Brothers Machine Works in Winterthur, Switzerland. Diesel graduated in January 1880 with highest academic honours and returned to Paris, where he assisted Linde with the design and construction of a modern refrigeration and ice plant. Diesel became the director of the plant a year afterwards.

In 1883, Diesel married Martha Flasche and continued to work for Linde, gaining numerous patents in both Germany and France.

In early 1890, Diesel moved to Berlin with his wife and children, Rudolf Jr, Heddy, and Eugen, to assume management of Linde's corporate research and development department and to join several other corporate boards. Since he was not allowed to use for his own purposes the patents he developed while an employee of Linde's, he expanded beyond the field of refrigeration. He first worked with steam, his research into thermal efficiency and fuel efficiency leading him to build a steam engine using ammonia vapor. During tests, however, the engine exploded and almost killed him. His research into high-compression cylinder pressures tested the strength of iron and steel cylinder heads. One exploded during a test run. He spent many months in a hospital, followed by health and eyesight problems. It was during this year that Diesel began conceptualising the idea of a diesel engine.

Ever since attending lectures of von Linde, Diesel worked on designing an internal combustion engine that could approach the maximum theoretical thermal efficiency of the Carnot cycle. In 1892, after working on this idea for several years, he considered his theory to be completed. In the same year, Diesel was given the German patent DRP 67207. In 1893, he published a treatise entitled Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and The Combustion Engines Known Today, which he had been working on since early 1892. This treatise formed the basis for his work on and development of the diesel engine. By summer 1893, Diesel had realised that his initial theory was erroneous, leading him to file another patent application for the corrected theory in 1893.

Diesel understood thermodynamics and the theoretical and practical constraints on fuel efficiency. He knew that as much as 90% of the energy available in the fuel is wasted in a steam engine. His work in engine design was driven by the goal of much higher efficiency ratios.

As opposed to outside ignition applied against internal air and fuel mixture, air was compressed internally within the cylinder whilst heating. Fuel was injected at the end of the compression stroke and was ignited by the high temperature resulting from the compression, with no need for a spark plug. Therefore, the engine was smaller and weighed less than most contemporary steam engines, not to mention the fact that further fuel sources weren't required. Fuel efficiency was measured 75% above the 10% theoretical efficiency for steam engines.

From 1893 to 1897, Heinrich von Buz, director of Maschinenfabrik Augsburg in Augsburg, provided Rudolf Diesel the opportunity to test and develop his ideas. Diesel also received support from the Krupp firm.

The first successful diesel engine Motor 250/400 was officially tested in 1897, featuring a 25 horsepower four-stroke, single vertical cylinder compression. Having just revolutionised the engine manufacturing industry, it became an immediate success, with royalties amassing great wealth for Diesel. The engine is currently on display at the German Technical Museum in Munich.

Besides Germany, Diesel obtained patents for his design in other countries, including the United States (1895,1898).

The primary fuel used in Diesel engines today is the eponymous diesel fuel, derived from crude oil. While developing his engine, Diesel tested a wide range of liquid fuels, primarily coal distillates and petroleum products. Diesel also considered using coal dust, and he demonstrated vegetable oil as fuel. In a book titled Diesel Engines for Land and Marine Work, Diesel wrote: In 1900 a small Diesel engine was exhibited by the Otto company which, on the suggestion of the French Government, was run on arachide [peanut] oil, and operated so well that very few people were aware of the fact. The motor was built for ordinary oils, and without any modification was run on vegetable oil. I have recently repeated these experiments on a large scale with full success and entire confirmation of the results formerly obtained.