When you compress a gas, it gets hot and gives off that heat, when you decompress it, it reabsorbs that heat (feels cold). It would absorb the same amount of heat htat it gave off when it was compressed.

 

Well based on more of the information. Let's rough out what you have.

So let's say you have 1 CI of gas at 100F and it's ignited to 1000F, how much would it expand?

Again, PV=mRT Pressure*Volume=mass*(constant)*Temp
Pressue stays the same - because the volume will change and since we don't know enough about the situation
m stays the same
So basically all we can say is that delta V is proportional to delta T. It isn't EQUAL to delta T, but proportional. We just don't have sufficient information here. Mainly how much air will expand after being heated up by 900 F.

The final pressure doesn't matter, the final volume doesn't matter - they're just variable with unspecified values.

Here's a link that defines this stuff better than I can, it's just been far too long for me

http://www.heliosat3.de/e-learning/A...ection3_02.pdf

 

Why in the world would anyone want to know the answer to a question like that? With all these terrorist running around and stuff some things need to be kept a secret.......Gezzzzzz next thing people will want to know is "how many grams of TNT does it take to blow the tires off a 727" gez

 

How does that have anything to do with terrorist acts? Its a honest question, give him a break.

 

I was never so great in Thermo, but I'd question the assumption being made that a fuel-air mixture is an ideal gas (applying the ideal gas law, PV=nRT).

-Jim

 

Why not? It's a subject that is directly related to engine operation.

'Secret'??? Oh God! You're killing me.

Hmmmmm. You have the answer to that? Maybe Homeland Security should be checking you out.

 

The best I could do given all the other assumptions that were being made. We don't know anything else about the conditions, all are assumptions - but you're more than welcome to offer up a helpful suggestion.

 

A stoichiometric fuel ratio means that there are 14.7 parts of air for every part of fuel. At this ratio, fuel in a perfect combustion chamber would burn off completely. The products of stoichiometric combustion are water (H<SUB>2</SUB>O), carbon dioxide (CO<SUB>2</SUB>) and oxides of nitrogen (NOx). Note that NOx is a pollutant.

I think, forces that are more or less negligable, can be ignored, at least until someone fugures out the explosive force of the fuel charge.

Wouldn't it be based on the calorie or joule content of the particular fuel. That would equate to the fuel's ability to do 'work' more than anything else.

 

Ok when some terrorist figures out all this how to blow up gasoline stuff it will be too late,,,

 

Homeland security is about as effective as our border patrol........As much good as ******* on a bore hog!

 

Here's the formula: glass coke bottle + gas + rag + match

Woops!

 

Only in the ideal case. You'll also have some unburned HC, CO, and a bit of leftover O2 as is the case in an engine. To burn most of the HC, one would need a slightly lean mixture.

In any case, I was thhinking a bit more about the original question, and as it was asked, it's exceedingly difficult, or nearly impossible to answer it precisely without actually doing an experiment and measuring the pressure and temperature.

The main problem is that gasoline is a mixture of hundreds, or maybe even more various hydrocarbons and a few other compounds, and so one would need to know the exact composition of a given gasoline sample and figure out how much heat each compound would produce, and then sum them up. It's not that difficult for mixtures that contain a few compounds (i.e. propane and butane) but with few hundred compunds, that's a bit too much. The problem is that one can't simply go on H and C content as the heat given up is different for single, double and triple bonds between C atoms.

IMHO, the simplest thing would be to rig up an engine with a pressure and temperature sensor somehow, or do a search and try to find out if a similar question had already been answered. An approximate answer can be obtained if one assumes gasoline to be a straight chained C8H18, however.

 

my brain hurts

 

This goes to show that mechanics. Have to "WALK THE WALK AND NOT JUST TALK THE TALK" Plenty of people can read and understand what they are reading, but when it comes to getting a wrench and doing it they find they are all thumbs and cant,

 

How does that have anything at all to do with this?