How Does Gas Volume Change After Combustion in an Engine?

[CHICAGO]

Hi you all

Seaching in internet, I have not found an answer to this:

In a air-gasoline stechiometric mixture, what can be the volumen relationship between the unburned (intake gas) and final exhaust gases?.

I guess temperature is important, but let's consider a normal working temperature for that engine. And let's also consider the cylinder is filled at 1 bar.

I just only want to have an idea of how much the gas is expanded after combustion.

Thanks in advance.

 

[Ranger Mike]

may i ask why this is important?

 

[brewnog]

Under quasi-static conditions, the ratio of volumes before and after combustion is approximately the compression ratio of the engine (since the volume is dictated by the geometry of the swept combustion chamber, not by the gases!). This is pretty meaningless. For an approximate "final" exhaust gas volume, just assume it's air at whatever temperature you're interested in. For an accurate "final" exhaust gas volume, you need to know the exact temperature, fuel type, and air-fuel ratio.

 

[Ranger Mike]

Brewnog ..you are good!
wish i said that...

 

[CHICAGO]

I know what you mean, but I assume a volumen of air-gasoline stechiometric mixture at 1 bar pressure.What is the volumen at 1 bar pressure of the ignited result gases?.

We better forget this gas in a engine, and let's do the test in a lab. We have 1 cubic inch of that stech. mixture and we flame it. How many cubic inches of gas (whatever gases are those) do we get out of that combustion?

I do not know if I exposed the question properly. Sorry if it is not.

.

 

[Ranger Mike]

see Post titled gas pressure in internal combustion gasoline engine
in this forum a few days ago

 

[brewnog]

I know what you mean, but I assume a volumen of air-gasoline stechiometric mixture at 1 bar pressure.What is the volumen at 1 bar pressure of the ignited result gases?.

We better forget this gas in a engine, and let's do the test in a lab. We have 1 cubic inch of that stech. mixture and we flame it. How many cubic inches of gas (whatever gases are those) do we get out of that combustion?

I do not know if I exposed the question properly. Sorry if it is not.

.

It depends. Do a mass balance and then convert to volume at whatever temperature you're in. Just think back to the gas laws.