|
| 
|
 Combustion 2
Visiting the glass extension in Bad Cannstatt near Stuttgart, the former workplace of Daimler and Maybach, one comes across a container labeled 'Petroleum' in the corner (see image below).
Now, kerosene is better known as a fuel for diesel engines than for gasoline engines. Diesel's experimental engines ran on it, and even the Mercedes 190D, built from 1961 onwards, allowed
the optional use of this fuel. Could it be that these two men were working on such an engine almost 15 years before Rudolf Diesel?
The fuel was already mixed with the intake air and was not injected separately or blown in together with air at the ignition point. The diesel engine therefore has a precisely definable ignition
point, just like the later gasoline engine. In the diesel engine, it coincides with the injection point, whereas in the gasoline engine, the electric ignition initiates the process. And the first engine
with hot-tube ignition lacked precisely that.
This brings us to the two characteristic features of the diesel engine: high compression, injection at the point of ignition, and self-ignition. However, since gasoline engines now also inject fuel directly into the
combustion chamber, the only remaining characteristic of the diesel engine is the lack of electric ignition. There are even (experimental) engines that can switch to self-ignition without electrical assistance
while driving, thus temporarily 'dieseling'.
Incidentally, 'dieseling' used to be a derogatory term for gasoline engines. If, for example, a gasoline engine 'dieseled (after being switched off), it would continue to run more or less roughly even after it had
been stopped already. This was because, for example, smoldering carbon deposits could repeatedly trigger new ignitions. If this happened, the engine actually had to be forcibly stalled. The fuel supply cut-off
in the carburetor via a solenoid valve dates back to this time.
| Liquefied petroleum gas (LPG) | below 30°C |
| (Special) light gasoline | 30 - 100°C |
| (Automotive) heavy gasoline | 100 - 150°C |
| Kerosene, petroleum | 150 - 250°C |
| Diesel, light heating oil | 250 - 300°C |
Heavy oil, heavy heating oil,
bitumen | more than 300°C |
Here you can see the different levels from which both substances emerge from the distillation tower, with correspondingly different temperatures.
|
|
