Diesel spent his early childhood in France, but as a result of the outbreak of the Franco-Prussian War in 1870, the family was forced to leave and immigrated to London. Before the end of the war, however, Diesel's mother sent 12-year-old Rudolf to Augsburg to live with his aunt and uncle, Barbara and Christoph Barnickel, so that he might learn to speak German and visit the Königliche Kreis-Gewerbsschule or Royal County Trade School, where his uncle taught mathematics.
At age 14, Rudolf wrote to his parents that he wanted to become an engineer, and after finishing his basic education at the top of his class in 1873, he enrolled at the newly-founded Industrial School of Augsburg. Later, in 1875, he received a merit scholarship from the Royal Bavarian Polytechnic in Munich which he accepted against the will of his perennially cash-strapped parents who would rather have seen him begin earning money.
In Munich, one of his professors was Carl von Linde. Diesel was unable to graduate with his class in July 1879 because of a bout with typhoid. While he waited for the next exam date, he gathered practical engineering experience at the Gebrüder Sulzer Maschinenfabrik in Winterthur, Switzerland. Diesel graduated with highest academic honors from his Munich alma mater in January 1880 and returned to Paris, where he assisted his former Munich professor Carl von Linde with the design and construction of a modern refrigeration and ice plant. Diesel became the director of the plant a scant year later.
In 1883, Diesel married Martha Flasche, and continued to work for Linde, garnering numerous patents in both Germany and France.
In early 1890, Diesel moved his wife and their now three children Rudolf junior, Heddy and Eugen, to Berlin to assume management of Linde's corporate research and development department and to join several other corporate boards there. Because he was not allowed to use the patents he developed while an employee of Linde's for his own purposes, Diesel sought to expand into an area outside of refrigeration. He first toyed with steam, his research into fuel efficiency leading him to build a steam engine using ammonia vapor. During tests, this machine exploded with almost fatal consequences and resulted in many months in the hospital and a great deal of ill health and eyesight problems. He also began designing an engine based on the Carnot cycle, and in 1893, soon after Gottlieb Daimler and Karl Benz had invented the automobile in 1887, Diesel published a treatise entitled Theorie und Construktion eines rationellen Wärmemotors zum Ersatz der Dampfmaschine und der heute bekannten Verbrennungsmotoren or Theory and Construction of a Rational Heat-engine to Replace the Steam Engine and Combustion Engines Known Today and formed the basis for his work on and invention of the Diesel engine.
After Diesel's death, the diesel engine underwent much development, and became a very important replacement for the steam piston engine in many applications. Because the diesel engine required a heavier, more robust construction than a gasoline engine, it was not widely used in aviation (but see aircraft diesel engine). However, the diesel engine became widespread in many other applications, such as stationary engines, submarines, ships, and much later, locomotives, trucks, and in modern automobiles. Diesel engines are most often found in applications where a high torque requirement and low RPM requirement exist. Because of their generally more robust construction and high torque, Diesel engines have also become the workhorses of the trucking industry. Recently, diesel engines that have overcome this weight penalty have been designed, certified and flown in light aircraft. These engines are designed to run on either Diesel fuel or more commonly jet fuel.
The diesel engine has the benefit of running more fuel-efficiently than gasoline engines. Diesel was especially interested in using coal dust or vegetable oil as fuel, and his engine in fact ran on peanut oil. Although these fuels were not immediately popular, recent rises in fuel prices coupled with concerns about oil reserves have led to more widespread use of vegetable oil and biodiesel. The primary source of fuel remains what became known as Diesel fuel, an oil byproduct derived from refinement of petroleum.
Details of the claim that a patent submitted by Herbert Akroyd Stuart has pre-dated that of Rudolf Diesel can be found under the name of that inventor.