Combustion of Organic Compounds

CO2 is essentially an inert gas. If you have enough O2 to keep your combustion, it should just go on... and release more CO2, of course. At least if combustion is complete. And would give you some more stuff like NOx, sulphur, ..., if you're considering mixing with fuel, residues, impurities... Some processes like welding, due to its nature, provoque some cracking of the CO2 releasing O2 that reacts with the metals. But most of the time and situations, CO2 behaves just like an inert gas. Unless someone else has detailed information about this burn under high pressure, temperature, etc... sorry, I'm not a specialist, just an observer.

It will depend on the concentration of O2 and CO2; the CO2 will not burn and as such will absorb energy from the reaction in the form of heat, which will be expelled in the exiting gasses.

Crank up the Bunsen and find out.

Report back.

Thanks.

Methane + pure oxygen is a potentially explosive mixture. Adding carbon dioxide to it, or any other inert gas (nitrogen?) for that matter, simply reduces the effects of any explosion until increasing levels snub the explosion.

Proceed with utmost caution.

CH4 + 4 O2 + CO2 = (BOOM)exp2 + xCO2 + yH2O

(sorry about that...NOT)

If you have commercial methane that has the 'odor' added, you have Sulphur present and will get a bit of sulphuric smell left over after the explosion.

The CO2 just slows down the reaction...except when a bit of free C with your CO2 gets cracked into 2CO like the syngas reaction, but that should be limited.

Since you've already eliminated the Nitrous Oxides and Halogens by using "pure" Oxygen, you'll get a violent combustion leaving water vapor and more CO2.

There is the limited potential for some transient localized CH4 + H2O by steam reforming into CO + 3H2, but any free H2 in the presence of additional pure 02 and the heat from the methane explosion will likely combust into further H2O.
As a result, however, and since CO is also stable, I think you may find some small volume of toxic Carbon Monoxide left over.

Assuming.....CO2 replaces N2 in the same molar ratio

I would expect that if the CO2 were in the same volume % or molar % (not weight percent) the combustion would be almost identical to burning in air. (Molecular wt of CO2=44, N2=28) So it is a denser. the heat capacity of CO2 (8.86 cal/deg-m) is greater than CO2 (6.79 cal/deg-m).

The only differences I would expect are:

1. The adiabatic flame temperature may be cooler.

2. The propagation of the flame front (and length of the flame) may be different because sonic velocity of CO2 may be different than N2. predict slower because of higher MW.

If you want the flame temperature or flame speed sonic velocity for the new gas you have most the information above.

whose heat capacity is more co2 or N2....

I don't know what you are asking. I stated in the last post:

the heat capacity of CO2 (8.86 cal/deg-m) is greater than CO2 (6.79 cal/deg-m).

This is at 30 deg C. The heat capacity will change with temperature but not that much.

What are you trying to understand or do?

Paddler

Actually I jus Want to eliminate nitrogen frm inlet air(in ic engines) and ve to add that much carbodioxide to it.And want to know How combustion charecteristics changes.Can u help me.This is my final project

I see my error. Both heat capacities were of CO2, my bad.

It should have read

(Molecular wt of CO2=44, N2=28) So it is a denser. the heat capacity of CO2 (8.86 cal/deg-m) is greater than N2 (6.79 cal/deg-m).

That was from Perry's.

In an IC engine the theoretical efficiency is (T hot- T cold) / T cold. Because the new T hot will be cooler, I expect the efficient to decrease. by the ratio from the formula.

If you assume T cold in all cases is 20 Dec C (290 K) than all you need is (T hot) for both cases. You can then state what the difference in the theoretical efficiency would be.

T hot = the adiabatic flame temperature for both cases.

Calculate by

1. Take the stoichiometric amount required to burn at 100% combustion and 0% excess O2 of air and fuel

2. Find the heat of combustion for that amount of gas

3. Calculate how much that heat will raise the final gas temperature. (CO2 and N2 for case 1 and CO2 only for case 2).

4. Plug in the numbers and go.

For my curiosity,

Where are you? What year? What school? Chem Eng?

Thanks for ur reply. I am Vinoth from India. I am doin mechanical engg (pre-final year).Actually m thinking of doin this as my final year project.May I know abt you. I want lot more information from you.Shall we chat over Yahoo messenger.