Before Bill and Trevor Wrote:
> So, the chemical reaction is 2(CH2) + 3(O2) => 2(CO2) + 4(H2O) + heat.
Now
> assuming that the hydrocarbon in liquid coming in and the water is
gaseous
> going out due to the high temp, you ingest 3 oxygen gas molecules and put
> out 6 gas molecules including 2 carbon dioxide and 4 water. So
combustion
> puts out 50% more molecules that it brings in.
>
> So your engine has about 2.2 times the volume of
> gasses coming out than going in.
But remember, petrol goes in not as a gas but as a vapour, which
is technically particles of liquid suspended in air.
The liquid petrol is MUCH more dense than the gas exhaust. Much
like boiling water in a pressure cooker, you create a LOT of volume
when you convert a liquid to a gas.
The 2.2 might hold true if you were burning gas-state hydrocarbons
into gas-state exhaust, but you are actually burning liquid-state
hydrocarbons into gas-state exhaust.>>>>>>>
I am sorry, I made a mistake in the formula. It should be:
2(CH2) + 4(O2) => 2(CO2) + 4(H2O) + heat
So you have 4 oxygen molecules in and 6 CO2 / H2O molecules out for a 50%
increase which is correct originally. I corrected it in my head but not on
paper. I did not include the fuel going in as taking up volume because,
as Trevor correctly points out, its volume is negligible when compared to
the gasses. I beg everyone's forgiveness for the error in calculation but
I must point out that, as a proud MGA owner, the post was impeccably
spelled ;-)
Regards,
Bill Eastman
61 MGA
Lots of useless knowledge
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Date: Wed, 21 Jan 1998 14:59:47 -0600
From: Trevor Boicey <tboicey@brit.ca>
To: william.eastman@medtronic.com
Cc: mgs@autox.team.net
Subject: Re: Passing gas- an exhaustive study
Bill Eastman wrote:
> So, the chemical reaction is 2(CH2) + 3(O2) => 2(CO2) + 4(H2O) + heat.
Now
> assuming that the hydrocarbon in liquid coming in and the water is
gaseous
> going out due to the high temp, you ingest 3 oxygen gas molecules and put
> out 6 gas molecules including 2 carbon dioxide and 4 water. So
combustion
> puts out 50% more molecules that it brings in.
>
> So your engine has about 2.2 times the volume of
> gasses coming out than going in.
But remember, petrol goes in not as a gas but as a vapour, which
is technically particles of liquid suspended in air.
The liquid petrol is MUCH more dense than the gas exhaust. Much
like boiling water in a pressure cooker, you create a LOT of volume
when you convert a liquid to a gas.
The 2.2 might hold true if you were burning gas-state hydrocarbons
into gas-state exhaust, but you are actually burning liquid-state
hydrocarbons into gas-state exhaust.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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