Hi Brad.
I'm having a little trouble with the above statement. Surely there must be a " pressure " value?
A fixed quantity of gas, air in our case, when rapidly compressed WILL increase its temperature to a point where the fuel carried with it auto ignites.
I spent yesterday, off and on, trying to find a definitive reference but it seems the mathematics are rather complex with many variables to consider. Things like the cylinders ability to remove the heat generated etc.
Over to the mathematicians.
Cheers Graham.
Ok,i will try and explain a little better.
As stated,it is the temperature that auto ignites the air/fuel mix-not the pressure
This temperature is created by compressing gas at speed. If we compress the gas slowly,so as no heat is generated(dissipated as fast as it builds),then you can compress all you like,and the gas will not ignite.
So, what pressure do we need to achieve a temperature of 570 degrees Celsius?
There is no clear answer to this question,as there are to many variables that need to be considered.
1-how fast will the gas be compressed ?
2-what is the compression ratio?
3-Is the engine cold or hot-what is it's running temperature?.
The 3rd question might sound silly,but ask your self-->why do we need more fuel to start an engine when it's cold?,even though the compression ratio remains the same as that when it's hot.
An example is-if we have an engine with a compression ratio of say 10:1,and we spin that engine at say 1000rpm,then the temperature of the compressed gas may reach say 180*C at 6*BTDC. If we spin that engine at 2000rpm,then the temperature of the compressed gas may reach 200*C at 6*BTDC. This is the reason that compression ignition gasoline engines are so very hard to control. You might get it to run right at say 1500rpm,and then trouble starts at 2000rpm,as the gas heats up to auto ignition temperature well before it did at 1500rpm,and so you get engine knock. This is where my design come into play. As the RPM increases,the compression ratio decreases,which keeps the gas temperature a constant in relation to piston position within the bore.
As with other auto ignition engines,the ignition point advances with RPM--which you do not want. With my system,the ignition point remains the same throughout the rev range.
Then there are a whole lot of other things to look at,where the measured compression ratio is not the be all-end all. We then need to know the effective compression ratio. This takes into account valve overlap,valve timing etc.
It is extremely hard to control a true compression ignition gasoline engine,and so it's just easier to use a spark plug. Even Mazda's new skyactiv X engine has spark plugs to ignite the fuel,but they call it a compression ignition engine. They cheated a little,and stretched the term !compression ignition! to fit there claim. But in reality,it is not a true compression ignition gasoline engine.
Sometimes i wonder just what kind of !engineers! these companies employ.
These guys have millions of dollars at there disposal,and this is the best they can come up with.
I have a few bucks and a scrap pile,and i can achieve what they cannot.
The sad thing is,my design will probably never see the light of day.
Anyway,for now lets answer the old HHO question
I've been at this for 9 days and nights straight,so im taking tonight off to kick back and relax.
Brad
With pure HHO,we could raise the compression ratio to 25:1,and still need to ignite it with a spark plug.
Never let your schooling get in the way of your education.
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Topic: The Engine,and then the gas (Read 49067 times)
