I checked the value, you are completely right. 400Bar is one order of magnitude too big.gruntguru wrote:400 Bar is peak combustion pressure - usually about 15* ATDC but probably a bit earlier in these "rapid combustion" engines.basti313 wrote:Sure. But according to the numbers of Merc there are 400Bar in the combustion chamber after compressing the air. So we surely need quite a lot of heat to vaporize the fuel and I guess the margins to knocking are really small.gruntguru wrote: 3. Vaporisation occurs after the injector nozzle when the pressure is much lower than 500 bar. Vaporisation before the nozzle is extremely undesirable.
Presumably all (certainly most) of the fuel is injected much earlier than that.
Are you mixing up spraying into small drops with atomizing? Atomizing means that you no longer have fuel, but C, O and H atoms.Jef Patat wrote: When I was at university this was physics and not chemistry. I don't see where PlatinumZealot is incorrect. Instead of spreading nonsense: here are facts:
https://en.wikipedia.org/wiki/Spray_(liquid_drop)If you master your first class chemistry that well, I hope you remember some physics and it should make perfect sense. Atomize first to have a bigger surface and with that bigger surface comes easier vaporization.Wikipedia wrote: Drop size is critical because the large surface area of a finely atomized spray enhances fuel evaporation rate. Dispersion of the fuel into the combustion air is critical to maximize the efficiency of these systems
Spraying into small drops changes how fast everything evaporates, but it does not change the physics, e.g. when it starts to vaporize.