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4 Jan 2005, 21:11 (Ref:1193217) | #1 | ||
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Expansion of combustion
Im working on an idea at the moment and I cant seem to find anywhere the delta(volume) of fuel-air (95 octane) mixture after combustion.
Anyone who has an appropriate book or just happens to know can you please give me an average ratio. Thanks in advance. |
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4 Jan 2005, 22:53 (Ref:1193281) | #2 | ||
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Maybe page 359 of the Bosch Automotive Handbook 4th Edition?
It's a tough one to answer as it depends on a couple of key influences (lambda, vol eff, etc) that make it hard to generalise. |
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5 Jan 2005, 06:02 (Ref:1193386) | #3 | ||
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so many factors its useless to generalize when considering unconstrained reactions in an engine however it is limited by the BDC clinder volume, and the rest is wasted expansion unless the engine is turbocharged in which case the valve timing can use this excess to spin up the turbo
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5 Jan 2005, 11:00 (Ref:1193519) | #4 | ||
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To combust petrol you dont need an engine. What I need to know is how much a complete combustion of petrol will expand at constant pressure. The volume will increase by a certain ration which is not going to change if the reaction is complete.
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A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel." |
5 Jan 2005, 19:13 (Ref:1193875) | #5 | ||
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as a guide, I was told a while back that Propane expands 9 times each way. ie a volume of 9^3 of its original
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7 Jan 2005, 05:11 (Ref:1194952) | #6 | ||
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OK, so maybe PV=nRT answers the question. P (pressure) is constant, n (mass of air in cylinder) you'll have to look up, R (real gas constant for air) and T which is your combustion temp. Do the sum at intake charge temp and then with combustion temp and it'll be somewhere near right. The transposed equation would be V=nRT/P.
Or something like that. |
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7 Jan 2005, 10:13 (Ref:1195099) | #7 | ||
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Is it as simple as that one though? Is it an ideal gas expansion? Your changing the fuel air mixture into Carbon Dioxide and water and the expansion of Nitrogen would act ideally.
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A Saudi saying, "My father rode a camel. I drive a car. My son flies a jet-plane. His son will ride a camel." |
14 Jan 2005, 20:31 (Ref:1201162) | #8 | ||
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The expansion due to the combustion reaction is negligible. It almost all comes from the temperature rise.
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Geoff Butcher |
14 Jan 2005, 22:55 (Ref:1201265) | #9 | ||
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Which is directly proportional to both pressure and volume. The math of it is that simple. If you have constant volume and a rise in temperature then pressure has to rise according to that equation.
Of course, making it all work in real life is a bit tougher........ |
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7 Feb 2005, 03:06 (Ref:1219117) | #10 | ||
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Wow,seeing some bright sparks on here lately! (sorry,bad unintended pun)
Good to see there are people out there that are good at these things |
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