Quote:
Originally Posted by stovie
I understand that you need the 14.7-1 a/f ratio (or the stoichiometric ratio) to burn the fuel at atmospheric pressure to achieve a "2 C8H18 + 25 O2 → 16 CO2 + 18 H2O". However, once you get further away from that ratio the issue becomes weither or not the "reaction" will continue after exceeding that ratio is the distance of the fuel molecules. If there to far a part then some will "react", but others will not braking the reaction and stopping the burning of the fuel.
Now in a internal combustion engine where it compresses the a/f mixture it's a bit less of an issue. However the issue after that is the increased heat produced as you lean it out, because if the engine is running pretty rich then your already running at the other end of the stoichiometric ratio. Basically what i'm trying to say is that the only real way to get the a/f ratio to the lowest you can, you have to start with no fuel and slowly add it tell the engine starts to run properly, and with my experience with doing that so far it is far less then the 14.7-1 a/f ratio that the car manufacturers say they are using.
A car can handle the "instant explosion" caused by going so low because it's a very small explosion when you get it to the right amount. It's like lighting a small balloon of gas in a closed room, to big and it will blow the windows out. If it's just the right size though it will explode but just enough to raise the pressure in the room without blowing out the windows. In an engine if the "instant Explosion" is too high it just increases the RPM's.
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A method of extending flammability limits is to do away with the "flame front" and cause combustion throughout the combustion chamber all at once... one does this with a flood of free radicals to kick-start the reaction. That's why corona discharge ignition works so well to allow engines to run leaner.
Combustion is nothing more than a free radical cascade. Flood the combustion chamber with free radicals (electrons), and you'll get combustion everywhere all at once. The side benefit is that you do away with knocking because there is no collision of flame fronts.
Corona discharge works by cutting on and off the high voltage at such a frequency that while the electricity can start sending corona discharge phase streamers, it can't enter the higher-amperage arc phase. Thus, CD uses less current than traditional ignitions. It just uses it more efficiently. And those streamers can reach throughout the entirety of the combustion chamber volume, since the piston is near TDC and the volume is relatively small.
Since lean burns hot, the increased temperatures will create NOx. Knocking NOx creation down with water injection (which moderates the temperature spikes by absorbing the heat and evaporating the water) not only limits NOx creation, but the expanding steam adds to cylinder pressure, enhancing engine power output.
A side benefit that I'd briefly thought about then shelved before Peter Rotgans (Peterrr) revived my interest in it, is that the water preferentially condenses on the in-cylinder surfaces when pressure rises, before any fuel can likewise condense (and it definitely does condense despite the high temperatures and short amount of time... wedge shaped heads are specifically designed in part to mitigate this problem by reducing condensation area). Thus, the condensed fuel is sitting on a very thin layer of water. When the flame approaches those surfaces, the water flashes to steam, pushing that condensed fuel back into the flame and thereby increasing fuel efficiency and reducing UBHC by reducing partial burn.
Unfortunately, certain trolls who didn't understand Peter's point, since English is obviously a second language for him, chose to run Peter off the forum with insults rather than undertake to learn what Peter was trying to teach... despite Peter giving mathematical proof and third-party corroborated data, despite that certain troll understanding Peter's native tongue and not bothering to ask Peter to clarify in that native tongue. The guilty party shall remain unnamed, but I'm betting he'll be around shortly to bray further justifications for his inability to understand the in-depth fourth-grade mathematics of what Peter was saying, choosing instead to lash out and drive away an innovative thinker.