All you chemistry types out there

[ManDownUnder]

I was wondering...

I put 17 litres of fuel into my bike, and my engine lovingly converts it to a number of things - the part I'm interested in is the pollution.

What weight and volume of Gas (STP) does a litre of fuel turn into (assuming all gets burned, well tuned engine etc etc etc)...

What are the expected proportions of CO and CO2 that are being spat out

?

[Motu]

It's 10 yrs since I was using a 4 gas analyser everyday,so don't remember what the numbers were - but it was kinda irrelevent as it's a balance and you just achieve the best you can and look for something out of whack.We just tried to get as high a CO2 reading as we could,and look for free oxy,that means it's running pretty good.HCs and CO were indicators of something wrong - HCs means a miss fire,so ign miss,high CO is incomplete combustion,so a mixture or timing issue.The catch 22 was as HC and CO went down and the motor was running efficiently,then the NOX went up.We ignored NOX back then,but it's a problem these day.If I find out something I might get back - but today has just gone to shit in a big way....

[bugjuice]

doesn't a lot of it depend on things like engine and air temp, humidity, air density, how efficiently the bike is running etc etc etc.. No idea on even a rough number, but there's a heap to consider, I would have thought..

[ducatilover]

What weight and volume of Gas (STP) does a litre of fuel turn into (assuming all gets burned, well tuned engine etc etc etc)...

What are the expected proportions of CO and CO2 that are being spat out

?

that depends on the engine.....it'll never be zero but newer engines are managing to make less and less emisions....it all depends on the eficiency of the engine cycle etc....

[Bartman10]

My instant estimate (which is an over estimate) says you will get about 20,000 litre of carbon oxides and about 24,000 liter of water gas.

assume 1 mole = 22.4 litre at stp (ideal gas) and petrol is mostly C8H18 and you get complete combustion - which is the least valid assumption.

17 l of petrol = 13.651 kg.
C8H18 = 114 g/mol
~ 120 mol.
120 * 8 = moles of CO + CO2 ~ 960 * 22.4 ~ 20,000 litres (1 sf).

No idea on proportions. The proportion of CO/CO2/unburnt hydrocarbons etc would depent on pressure, temperature and engine operating conditions, spark quality, humiditiy etc....

Do a search on the web and you might find some more info.

[ManDownUnder]

My instant estimate (which is an over estimate) says you will get about 20,000 litre of carbon oxides and about 24,000 liter of water gas.

assume 1 mole = 22.4 litre at stp (ideal gas) and petrol is mostly C8H18 and you get complete combustion - which is the least valid assumption.

17 l of petrol = 13.651 kg.
C8H18 = 114 g/mol
~ 120 mol.
120 * 8 = moles of CO + CO2 ~ 960 * 22.4 ~ 20,000 litres (1 sf).

No idea on proportions. The proportion of CO/CO2/unburnt hydrocarbons etc would depent on pressure, temperature and engine operating conditions, spark quality, humiditiy etc....

Do a search on the web and you might find some more info.

Cheers all - Bartman, those were the answers I was after. I expect there are a lot of variables which need understanding before an exact answer can be derived - and to be honest, I have no idea what variables to think about , let alone what their values are.

So a tank full of fuel creates about 20 cubic meters of gas (for me anyway). What is the weight of that?

Cheers
MDU

[Bartman10]

Cheers all - Bartman, those were the answers I was after. I expect there are a lot of variables which need understanding before an exact answer can be derived - and to be honest, I have no idea what variables to think about , let alone what their values are.

So a tank full of fuel creates about 20 cubic meters of gas (for me anyway). What is the weight of that?

Cheers
MDU

20 cubic meters of carbon containing gas, and another 20 cubic meters of water gas.

Weight is imposible to calculate without knowledge of composition, but it would be in the range 20 - 40 kg of carbon containting molecules and less than ~20 kg of water.

(for those of you who are wondering how I got upto ~60 kg out of 13 kg, the extra comes from adding oxygen, and a whole lot of it!)

[ManDownUnder]

20 cubic meters of carbon containing gas, and another 20 cubic meters of water gas.

Weight is imposible to calculate without knowledge of composition, but it would be in the range 20 - 40 kg of carbon containting molecules and less than ~20 kg of water.

(for those of you who are wondering how I got upto ~60 kg out of 13 kg, the extra comes from adding oxygen, and a whole lot of it!)

Cheers dude...
MDU

[TwoSeven]

The amount of emmissions basically refers to the length of burn and temp of burn. On a road bike you'll note that the reflection wave from the megaphone is timed to hold exhaust gases in the cylinder longer - on a race bike its designed to scavange the cylinder.

Apart from that, if you dont have the mix right, or the ignition temp hot enough you wont get a clean burn and will get crap out the back. What crap comes out, depends on what fuel you use and what crap they put in it.

Dont forget to also calculate heat as a by-product (emission) as well

[thealmightytaco]

I found this:

http://www.greenhouse.gov.au/fuellabel/environment.html

Is done by greenies so I wouldn't take it too exactly but they gotta be near. Apparently about 2.5kg of CO2 per litre of petrol, so 42.5kg's of CO2 from your 17L of gas. And it'd also be about 2/3's that weight in water vapour (double the no' of CO2 molecules, but H2O molecules weigh about a third of a CO2 molecule).

Might do my own calc later if I can be bothered lookin' for molecular weights and densities anywhere.

[thealmightytaco]

Dont forget to also calculate heat as a by-product (emission) as well

And the energy turned to kinetic energy, also a by product. And the heat in bearings, chain and your tyres. Can work that out from how much your original tank of gas plus the air you've used weighs vs how much your gases weigh in the end actually, whatever's left over you can put through the good ol' E=mc2 action. Need other tables with weight/energy associated with moleular bonds though, long time since I done it.

I'm all curious now though...

[thealmightytaco]

Here ya go:

http://www.cem.msu.edu/~reusch/VirtualText/react2.htm

Ya work out energy in the bonds of stuff for before and after, the difference is the energy you've got out of it all and is what has pushed your bike and burnt ya leg. And if ya want to you can figure out what the weight difference between before and after is by the E=mc2. Energy has weight. Useful huh.

[TwoSeven]

I found this:

http://www.greenhouse.gov.au/fuellabel/environment.html

Is done by greenies so I wouldn't take it too exactly but they gotta be near. Apparently about 2.5kg of CO2 per litre of petrol, so 42.5kg's of CO2 from your 17L of gas. And it'd also be about 2/3's that weight in water vapour (double the no' of CO2 molecules, but H2O molecules weigh about a third of a CO2 molecule).

Might do my own calc later if I can be bothered lookin' for molecular weights and densities anywhere.

The 2.5kg out had be flumoxed for a bit as a litre of fuel going in only weighs approx 1kg and I was wondering how you get something heavier coming out than what went in.

Then I realised that in a 1000cc inline-4 you'll probably only have a head area of about 20cc per cylinder. And only part of that will be filled by fuel maybe 2cc - the rest will be compressed air.