Rudolf Christian Karl Diesel (English: /ˈd iː z əl ˌ – s əl /, German: [ˈʁuːdɔlf ˈkʀɪsti̯an kaʁl ˈdiːzl̩]) was a German inventor and mechanical engineer. He is 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 born to Elise (née Strobel) and Theodor Diesel. His parents were immigrants from Bavaria, a region in Germany, who lived in Paris. Theodor Diesel worked as a bookbinder, a person who binds books together. He 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. Theodor later became a manufacturer of leather goods, which are products made from leather.

After Rudolf was born, he was given to a farmer family in Vincennes and lived with them 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 work in his father’s workshop and deliver leather goods to customers using a barrow, which is a small cart pulled by hand. He attended a school that taught both Protestant and French subjects. He became interested in social issues and technology. Rudolf was a very good student. At age 12, he received a bronze medal from the Société pour l'Instruction Elémentaire, an organization that supports education. He planned to attend the Ecole Primaire Supérieure in 1870.

In 1870, the Franco-Prussian War began. Because of the war, Rudolf’s family was sent to England and settled in London. There, Rudolf attended a school that taught in English. 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. He went there to learn German and visit the Königliche Kreis-Gewerbeschule, a school that teaches vocational skills. His uncle taught mathematics there. Rudolf was enrolled at the Technische Hochschule, a 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 in 1873, he joined the newly founded Industrial School of Augsburg. He graduated at the top of his class. 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

Rudolf Diesel studied under Professor Carl von Linde in Munich. In July 1879, Diesel could not graduate with his class because he became very sick with typhoid fever. While waiting for the next exam, he worked at the Sulzer Brothers Machine Works in Winterthur, Switzerland, gaining hands-on engineering experience. He graduated in January 1880 with top 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. He took charge of Linde’s research and development department and joined other corporate boards. Because he could not use his patents for personal purposes while working for Linde, Diesel 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 head exploded during a test, and Diesel spent months in the hospital. He later faced health and eyesight problems. It was during this time that Diesel began imagining the idea of a diesel engine.

Since attending von Linde’s lectures, Diesel had worked on designing 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 a German patent (DRP 67207). In 1893, he published a book 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 was incorrect 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 ignite fuel mixtures, Diesel’s engine compressed air inside the cylinder. The fuel was introduced just before the compression ended, causing it to ignite on its own. 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 was 75% higher than 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. The Krupp firm also provided assistance.

Diesel’s design used compression ignition instead of spark plugs, like in gas engines. His engine could run on biodiesel or petroleum-based fuels. Compression engines are about 30% more efficient than conventional gas engines because compressed air raises the temperature inside the combustion chamber, causing faster expansion and greater pressure on the pistons, which turn 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.

The first successful diesel engine, Motor 250/400, was tested in 1897. It had a 25-horsepower four-stroke, single vertical cylinder compression design. After revolutionizing the engine manufacturing industry, it became an immediate success, earning Diesel significant income through royalties. The engine is now displayed at the German Technical Museum in Munich.

In addition to Germany, Diesel 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 ship SS Dresden in Antwerp, Belgium, 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 told the crew to wake him 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 near the ship’s railing.

After Diesel disappeared, his wife, Martha, opened a bag he had given her before his trip. He had told her not to open it until the following week. Inside, she found 20,000 German marks in cash (about $120,000 today) and papers showing their bank accounts were almost empty. In a diary he carried, a cross was drawn next to the date September 29, 1913, which might mean he was dead.

Ten days after his disappearance, the crew of a Dutch boat named Coertsen found a man’s body floating in the Eastern Scheldt. The body was very decomposed and could not be recognized. Because of bad weather, the crew did not take the body aboard. Instead, they collected personal items from the man’s clothing, including a pill case, wallet, ID card, pocketknife, and eyeglass case, 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 died in Brandenburg on April 16, 1944, at the age of 85.

There are many theories about Diesel’s death. Some historians, like Grosser (1978) and Sittauer (1978), believe he died by suicide. Others think he was murdered, possibly because he refused to let German forces use his invention exclusively. Diesel had traveled to Dresden to meet with Royal Navy representatives to discuss using diesel engines to power British submarines. Another theory suggests that his death was a trick to hide his escape to Britain. It is claimed he later worked in Canada for the Vickers shipyard in Montreal and helped improve submarine engine production. However, because of limited evidence, Diesel’s 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, to celebrate the 100th anniversary of Diesel’s birth and the 60th anniversary of the diesel engine’s invention, Yamaoka dedicated the Rudolf Diesel Memorial Garden (Rudolf-Diesel-Gedächtnishain) in Wittelsbacher Park, Augsburg, Bavaria. This was where Diesel studied and first developed his engine.

Legacy

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

After Diesel's death, his engine had many improvements and became a key replacement for the steam piston engine in many uses. Because the Diesel engine needed a stronger design than a gasoline engine, it was not widely used in airplanes. However, it became common in other areas, such as stationary engines, farming equipment, off-road machinery, submarines, ships, and later, trains, trucks, and modern cars.

Diesel engines are more fuel-efficient than other types of internal combustion engines used in vehicles. This means they can turn more heat into useful work.

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 alternatives at the time, rising fuel prices and worries about limited oil supplies in 2008 led to more use of vegetable oil and biodiesel.

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

The asteroid 10093 Diesel, found 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. At the suggestion of the French Government, it was run on arachide [peanut] oil and worked very well. Few people knew this. The engine was built for regular oils and could run on vegetable oil without changes. I recently repeated these tests on a large scale with full success and confirmed the earlier results."

Works

• Rudolf Diesel: Theory and Design of a Rational Heat Engine to Replace the Steam Engine and Today’s Known Combustion Engines. Springer, Berlin, 1893. ISBN 978-3-642-64949-3 (Theory and Design of a Rational Heat Engine available on Google Books).
• Rudolf Diesel: The Origin of the Diesel Engine. Springer, Berlin, 1913. ISBN 978-3-642-64940-0.
• Rudolf Diesel: Solidarismus: Natural Economic Liberation of Humanity. Oldenbourg, Berlin/Munich, 1903. (PDF archived on May 10, 2021, at the Wayback Machine).