 Difficult birth
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From what has already been said, you might conclude that the diesel engine originated more from theory. And rightly so. Daimler and Maybach built an engine that supposedly also worked with auto- ignition.
As difficult as the definition is, they subjected the engine to long series of tests until it satisfied all the parameters and was content to continue running on its own.
It was repeatedly set back because the fuel-air mixture ignited too early. The question was whether to use a glow tube or highly heated air to heat the mixture to ignition temperature. But Rudolf Diesel was far
from that during his time in Paris. He still dreamed of a process similar to that of the steam engine, or perhaps comparable to today's air conditioning system.
The big difference between the steam engine and the internal combustion engine wasn't even the latter's long warm-up phase, but rather the external combustion. The location of the heating wasn't the plsce
where the resulting pressure was converted into kinetic energy. Only the internal combustion engine had managed to combine the two into one, even though both engine types already had a crank mechanism.
As mentioned, Rudolf Diesel was still experimenting with the refrigeration principle. Ammonia was compressed at one point, releasing heat, and extended at another, absorbing a corresponding amount of heat.
And that's how it still works with our car air conditioning systems.
To avoid very high pressures and thus losses, substances with low boiling points are used as refrigerants. This is because the heat transfer effect is many times greater when the boiling or dew point is
exceeded each time during compression or expansion. Today, this point is so low that refrigerant escapes from an open line as a gas. Ammonia is also a gas with an even lower boiling point. We will not
discuss its harmful effects here.
Throughout his time in Paris as director of an ice cream factory and while starting a family, Diesel researched not only the ammonia cycle but also the chemical composition of potential fuels for his engine. No,
coal dust doesn't seem to have been his first priority, but rather a liquid, for example, based on petroleum.
So ungefähr mit der erzwungenen Übersiedlung seiner inzwischen auf fünf Köpfe angewachsenen Familie 1990 nach Berlin dreht sich sein Focus und er wendet sich der internen Verbrennung und der
reinen Luft als mögliches Treibmittel für hohe Temperaturen zu. Es soll schon öfter vorgekommen sein, dass jemand vor lauter Bäumen den Wald nicht gesehen hat. Seine Forderung nach einer hohen,
den Wirkungsgrad erhöhenden Verdichtung aber bleibt.
Around the time of his forced relocation of his family, which had now grown to five members, to Berlin in 1890, his focus shifted, and he turned to internal combustion and pure air as a potential propellant for
high temperatures. It's said that someone has often missed the forest for the trees. His demand for high compression, which would increase efficiency, remained.
So he turned to Otto's four-stroke engine, but under a completely different premise. First, the danger of self-ignition during compression was averted, because the necessary fuel was missing. This only entered the cylinder
when the air was heated enough and for this reason self-ignition could take place without any further aids.
Diesel's consideration of efficiency even went so far as to assume an isothermal change of state. The fuel should therefore provide exactly enough heat to compensate for the reduction in heat caused by the expansion of
the volume during the power stroke. This is where his inner theoretician came through. Only much later, during his experiments on the real engine, did he have to abandon this requirement. It hasn't been met to this day.
However, in his 1893 publication "Theory and Construction of a Rational Heat Engine to Replace Steam Engines and Today's Common Combustion Engines," he adhered to the principle, as well as in his patent
specifications. Competitors and envious people later found plenty of potential for challenge here, causing Rudolf Diesel much grief. But we're not there yet.
How, despite the fierce criticism of his work, Krupp and Maschinenfabrik Augsburg (before the merger with Nuremberg) came to participate financially is something we'll leave open for discussion. The latter company still
did not believe that it could technically realize the high pressures demanded by Diesel, even after the provision of an operating site, although the latter had already withdrawn his demands in applications to General Director
Heinrich Buz. Buz, however, seems to have proven a strong supporter on the arduous path to the diesel engine.
What a gap between expectation and reality. Diesel thought he'll be able to bring the nearly three-meter-tall monster in the separate workshop to life relatively soon. Yes, the first test engine exploded after the first self-
ignition. Significantly modified, it gave off a manageable sign of life, but it was far from running smoothly. Direct injection of kerosene or gasoline proved impossible, so it was injected together with air.
After countless defeats and a dreaded abandonment of the entire project, an engine was finally presented in mid-1895 that could accept all possible crude oil products, including the crude oil itself, and that consumed half
as much fuel as a gasoline engine. Two more engines, considered reasonably reliable, were built by 1896. The world watched in amazement.
With this we say goodbye to Rudolf Diesel and his worldwide success. For him, a difficult period of apparent wealth began, but also illness and an early death, or rather, suicide. After further periods of catastrophe, his
engine experienced a golden age, but primarily as a large unit, e.g., in power plants, ships, and railways. Further patents were required for use in motor vehicles.
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