Diesel was born in Paris, France in 1858, 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 home town 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.
Rudolf Diesel spent his early childhood in France, but as a result of the outbreak of the Franco-Prussian War in 1870, his family (as were many other Germans) was forced to leave. They settled in London. Before the war's end
in 1871, 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-Gewerbsschule (Royal County Trade School), where his uncle
At age 14, Rudolf wrote a letter to his parents stating that he wanted 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 would rather have seen him start
One of his professors in Munich was Carl von Linde. Diesel was unable to be graduated with his class in July 1879 because he fell ill with typhoid. While waiting
for the next examination date, he gained practical engineering experience at the Gebrüder Sulzer Maschinenfabrik (Sulzer Brothers Machine Works) in Winterthur, Switzerland. Diesel was graduated in January 1880 with highest academic honours 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 one year later.
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 there. As he was not allowed to use the patents he developed
while an employee of Linde's for his own purposes, 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 vapour. During tests, however,
the engine exploded and almost killed him. He spent many months in a hospital, followed by health and eyesight problems. He then began designing an engine based on the Carnot cycle, and in 1893, soon after Karl Benz was granted a patent for his invention of
the motor car in 1886, Diesel published a treatise entitled Theorie und Konstruktion eines rationellen Wärmemotors zum Ersatz der Dampfmaschine und der heute bekannten Verbrennungsmotoren [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.
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. After experimenting with a Carnot
Cycle engine, he developed his own approach. Eventually he obtained a patent for his design for a compression-ignition engine. In his engine, fuel was injected at the end of compression and the fuel was ignited by the high temperature resulting from compression.
From 1893 to 1897, Heinrich von Buz, director of MAN AG in Augsburg, gave Rudolf Diesel the opportunity to test and develop his ideas. Rudolf Diesel obtained patents for his design in Germany and other countries, including the USA