Rudolf Christian Karl Diesel was a German inventor and mechanical engineer. He was born on March 18, 1858, and died on September 29, 1913. He is most famous for creating the diesel engine, which uses diesel fuel. Both the engine and the fuel are named after him.

Early life and education

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

After Rudolf was born, he was sent to live with a farmer family in Vincennes for the first nine months of his life. When he returned to his family, they moved to a flat at 49 Rue de la Fontaine-au-Roi. At that time, the Diesel family faced financial difficulties. Because of this, young Rudolf had to help his father by working in his workshop and delivering leather goods to customers using a small cart. He attended a Protestant-French school and became interested in social issues and technology. As a top student, Rudolf received a bronze medal from the Société pour l'Instruction Elémentaire and planned to enter the Ecole Primaire Supérieure in 1870.

In 1870, when the Franco-Prussian War began, the Diesel family was forced to move to England and settled in London. There, Rudolf attended an English-speaking school. However, before the war ended, his mother sent 12-year-old Rudolf to live with his aunt and uncle, Barbara and Christoph Barnickel, in Augsburg, Germany. She wanted him to learn German and study at the Königliche Kreis-Gewerbeschule (Royal County Vocational College), where his uncle taught mathematics. Rudolf was enrolled at the Technische Hochschule (Technical High School).

At age 14, Rudolf wrote a letter to his parents saying 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. He accepted the scholarship, even though his parents wanted him to start working instead.

Career

In 1879, one of Rudolf Diesel’s professors in Munich was Carl von Linde. Diesel could not graduate with his class in July 1879 because he became very sick with typhoid fever. While waiting for the next exam, he worked as an engineer at the Sulzer Brothers Machine Works in Winterthur, Switzerland. Diesel graduated in January 1880 with the highest academic honors and returned to Paris, where he helped Linde design and build a modern refrigeration and ice plant. A year later, Diesel became the director of the plant.

In 1883, Diesel married Martha Flasche and continued working for Linde, earning many patents in Germany and France.

In early 1890, Diesel moved to Berlin with his wife and children—Rudolf Jr., Heddy, and Eugen—to manage Linde’s corporate research and development department and join other corporate boards. Because he could not use his patents for personal purposes while working for Linde, he expanded his work beyond refrigeration. He first studied steam engines, researching how to improve thermal and fuel efficiency. He built a steam engine using ammonia vapor, but during testing, the engine exploded and nearly killed him. His experiments with high-compression cylinder pressures tested the strength of iron and steel cylinder heads. One of these heads exploded during a test, and Diesel spent many months in the hospital, followed by health and eyesight problems. During this time, he began developing the idea for a diesel engine.

Since attending Carl von Linde’s lectures, Diesel had worked to design an internal combustion engine that could reach the maximum theoretical thermal efficiency of the Carnot cycle. In 1892, after years of study, he completed his theory and received the German patent DRP 67207. In 1893, he published a treatise titled Theory and Construction of a Rational Heat-Engine to Replace the Steam Engine and the Combustion Engines Known Today, which described his ideas. By summer 1893, he realized his initial theory had errors and filed a new patent application for the corrected version.

Diesel understood thermodynamics and the limits of fuel efficiency. He knew that steam engines waste about 90% of the energy in fuel. His work aimed to create engines with much higher efficiency.

Unlike engines that use external ignition to spark fuel and air mixtures, Diesel’s engine compressed air inside the cylinder, heating it until the fuel could ignite on its own just before the compression ended. This design made the engine smaller and lighter than most steam engines and eliminated the need for additional fuel sources. Fuel efficiency in Diesel’s engine reached 75% above the 10% theoretical efficiency of steam engines.

In his engine, fuel was injected at the end of the compression stroke and ignited by the high temperature from compression. From 1893 to 1897, Heinrich von Buz, director of Maschinenfabrik Augsburg, supported Diesel’s testing and development of his ideas. The Krupp firm also provided assistance.

Diesel’s design used compression ignition instead of spark plugs, like those in gas engines. It could run on biodiesel or other fuels besides petroleum-based ones. Compression engines are about 30% more efficient than conventional gas engines because compressed air in the combustion chamber creates higher temperatures, leading to faster expansion and greater pressure on the pistons, which rotate the crankshaft more quickly.

Biodiesel is often made from synthesis gas produced by gasifying waste cellulose or extracting lipids from algae. It is commonly made by combining vegetable oils and algae with methanol through a process called transesterification. Many companies have developed different methods to produce biodiesel.

In 1897, the first successful diesel engine, Motor 250/400, was tested. It had a 25-horsepower, four-stroke, single vertical cylinder compression design. This engine revolutionized the engine manufacturing industry and brought Diesel great wealth through royalties. The engine is now on display at the German Technical Museum in Munich.

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

Disappearance and death

On the evening of September 29, 1913, Rudolf Diesel boarded the Great Eastern Railway ship SS Dresden in Antwerp on his way to a meeting with the Consolidated Diesel Manufacturing company in London. He had dinner on the ship and then went to his cabin around 10 p.m. He left a message to be called at 6:15 a.m. the next day, but he was never seen again. The next morning, his cabin was empty, and his bed had not been slept in. His nightshirt was neatly placed, and his watch was visible from the bed. His hat and folded overcoat were found under the afterdeck railing.

Soon after Diesel disappeared, his wife, Martha, opened a bag he had given her before his trip, as instructed not to open it until the following week. Inside, she found 20,000 German marks in cash (about $120,000 in today’s money) and papers showing their bank accounts were nearly empty. In a diary he carried, a cross was drawn for September 29, 1913, which might have indicated death.

Ten days after his disappearance, the crew of the Dutch pilot boat Coertsen found a man’s body floating in the Eastern Scheldt. The body was so decomposed that it could not be recognized. Because of heavy weather, the crew did not bring the body aboard. Instead, they took personal items (a pill case, wallet, ID card, pocketknife, and eyeglass case) from the man’s clothing and returned the body to the sea. On October 13, these items were identified by Rudolf’s son, Eugen Diesel, as belonging to his father. Five months later, in March 1914, Martha Diesel seemed to disappear in Germany. She later died in Brandenburg on April 16, 1944, at age 85.

Several theories explain Diesel’s death. Some biographers, such as Grosser (1978) and Sittauer (1978), believe he died by suicide. Others suggest he was murdered because he refused to give German forces exclusive rights to his invention. Diesel had boarded the Dresden to meet with Royal Navy representatives about using diesel engines to power British submarines. Another theory claims his death was a cover-up to hide his defection to the British cause. It is said he later worked in Canada for the Vickers shipyard in Montreal and helped improve submarine diesel engine production. However, due to limited evidence, his disappearance and death remain unsolved.

In 1950, Magokichi Yamaoka, founder of Yanmar, a Japanese diesel engine company, visited West Germany and learned that no tomb or monument honored Diesel. Yamaoka and others began planning to honor him. In 1957, on the 100th anniversary of Diesel’s birth and the 60th anniversary of the diesel engine’s development, Yamaoka dedicated the Rudolf Diesel Memorial Garden (Rudolf-Diesel-Gedächtnishain) in Wittelsbacher Park, Augsburg, Bavaria. This was where Diesel received his early technical education and developed his original engine.

Legacy

He was inducted into the Automotive Hall of Fame in 1978.

After Diesel's death, his engine continued to be developed and became an important replacement for the steam piston engine in many uses. Because the Diesel engine required stronger construction than a gasoline engine, it was used less in aviation. However, the Diesel engine became widely used in other areas, such as stationary engines, agricultural machines, off-road equipment, submarines, ships, and later, locomotives, trucks, and modern cars.

Diesel engines use fuel more efficiently than other internal combustion engines used in vehicles, turning more heat into mechanical energy.

Diesel was interested in using coal dust or vegetable oil as fuel. His engine was even run on peanut oil. Although these fuels were not better replacements at the time, in 2008, higher fuel prices and concerns about petroleum supplies led to increased use of vegetable oil and biodiesel.

The main fuel used in Diesel engines is diesel fuel, which comes from refining crude oil. Diesel is safer to store than gasoline because its flash point is about 81°C (145°F) higher, and it will not explode.

The asteroid 10093 Diesel, found in the main asteroid belt in 1990 by Eric Walter Elst at the European Southern Observatory, was named in his honor.

In a book titled Diesel Engines for Land and Marine Work, Diesel wrote, "In 1900, a small Diesel engine was shown by the Otto company. As suggested by the French government, it was run on arachide [peanut] oil and worked so well that few noticed. The engine was built for ordinary oils and could run on vegetable oil without changes. I recently repeated these experiments on a large scale with full success and confirmation of earlier results."

Works

• Rudolf Diesel: The Theory and Design of an Efficient Heat Engine to Replace Steam Engines and Modern Combustion Engines. Springer, Berlin, 1893, ISBN 978-3-642-64949-3 (The Theory and Design of an Efficient Heat Engine at Google Books)
• Rudolf Diesel: The Development of the Diesel Engine. Springer, Berlin, 1913. ISBN 978-3-642-64940-0
• Rudolf Diesel: Solidarismus: Natural Economic Freedom for People. Oldenbourg, Berlin/Munich, 1903. (PDF Archived 10 May 2021 at the Wayback Machine)