Do bituminous coal flames emit more radiant heat than natural gas flames?

[Green Xenon]

Hi:

 

Does a bituminous coal flame emit more thermal radiation than a methane flame of the same size?

 

 

Thanks,

 

GX

[Essay]

Hi:

 

Does a bituminous coal flame emit more thermal radiation than a methane flame of the same size?

 

 

Thanks,

 

GX

 

I know you get twice as much carbon emission from coal, as compared with natural gas, per Watt of power.

 

But, whatever that might mean, I'd expect coal to burn hotter since there are lots of double-bonds in the carbonaceous structure of coal. Coal has a lot of graphene, with a benzene-like structure, and I assume benzene burns hotter than methane. Methane has a higher ratio of H/C, compared with coal... carbon burning hotter than hydrogen also, I think; so coal would burn hotter than methane... I'm speculating.

 

~

[Hal.]

It is unusual to try to compare heating values of fuels based on the size of flame that they produce being constant . Usually , people compare heating values according to the mass or volume of fuel burned or the cost of fuel burned . I remember reading of scientists who had gas calorimeters in the 1940's , the coal mining laboratory types , who tried to reproduce the same measurements in their equipment by calibrating with a flame of the same size and the same fuel each time . If the same calorimeter could be calibrated using your two chosen fuels , each time using the same size of flame , then maybe your two fuels could be compared . It would only be approximate and there is the added problem that bituminous coal is a solid . This morphs your problem into another problem which you could consider .

Edited June 26, 2011 by Hal.

[Green Xenon]

Usually , people compare heating values according to the mass or volume of fuel burned or the cost of fuel burned .

 

Lets say's it is measured this way. Would the bituminous coal flame emit more radiant heat than the methane flame?

[swansont]

I suspect you would need to look at the color profile of the flame. The blackbody distribution will tell you the amount of emitted power.

[John Cuthber]

The coal flame will be sooty and the hot soot will emit lots of IR. The methane flame will only emit IR from the CO2 and H2O which might not be so effective so it's certainly possible that the coal flame will give out more IR.

"thermal radiation" isn't a really well defined term so it was hard to answer the original question but, for radiant heat I think the coal flame will produce more.

 

Why do you ask?

[Green Xenon]

The coal flame will be sooty and the hot soot will emit lots of IR. The methane flame will only emit IR from the CO2 and H2O which might not be so effective so it's certainly possible that the coal flame will give out more IR.

"thermal radiation" isn't a really well defined term so it was hard to answer the original question but, for radiant heat I think the coal flame will produce more.

 

Why do you ask?

 

 

The possibility that a lower temperature flame will emit more intense radiant heat than a higher temperature flame is one of the many things that I find interesting.

[Hal.]

From one source .......... ,

 

The Higher Calorific Value of Bituminous Coal is 17,000 - 23,250 KJ/Kg

The Higher Calorific Value of Methane is 55,530 KJ/Kg

 

If I was determining whether a piece of bread near to a flame of these fuels will toast quicker based on the same rate of combustion of fuel gravimetrically , I would suppose methane as being a better bet .

 

You are also supposing that natural gas is methane but it can be a mixture of a lot of things . Here are a few Higher Heating Values for some different Natural Gas mixtures .

 

From another source .......... ,

 

Algeria: 42,000 kJ/m³ , Bangladesh: 36,000 kJ/m³ , Canada: 38,200 kJ/m³ , Indonesia: 40,600 kJ/m³ ,

Netherlands: 33,320 kJ/m³ , Norway: 39,877 kJ/m³ , Pakistan: 34,900 kJ/m³ , Russia: 38,231 kJ/m³ ,

Saudi Arabia: 38,000 kJ/m³ , United Kingdom: 39,710 kJ/m³ , United States: 38,416 kJ/m³ , Uzbekistan: 37,889 kJ/m³

 

These values are Volumetric values at standard temperature and pressure . Maybe some Algerian Natural gas might toast the bread quickest .

 

 

[John Cuthber]

The gas flame will give more heat ( per Kg of fuel) but the heat will largely be carried away by convection. Also, the calculated adiabatic flame temperature is higher for the coal than for the gas.

It's possible that the soot in the coal flame will make it so much more effective as an emitter that it will give out more radiant heat than the gas flame.

On the other hand, it might not. There are lot's of other parameters.

 

You would need to do the experiment to be certain.

[Hal.]

If two independent flames can be made , a simple piece of metal could be placed near to each flame . If this piece of metal is connected in a simple electric circuit where the current flowing depends in part on the temperature of the metal , then the current can be used as a measure of the temperature that the flame has brought the metal to . It is difficult to know which will be warmer , I have often stood at a bonfire and still been cold .

[Green Xenon]

The gas flame will give more heat ( per Kg of fuel) but the heat will largely be carried away by convection. Also, the calculated adiabatic flame temperature is higher for the coal than for the gas.

It's possible that the soot in the coal flame will make it so much more effective as an emitter that it will give out more radiant heat than the gas flame.

On the other hand, it might not. There are lot's of other parameters.

 

You would need to do the experiment to be certain.

 

 

Has bituminous coal ever been used to directly fuel radiant heaters? If so, was the burning bituminous coal the direct emitter of the IR?

[John Cuthber]

Have you heard of a coal fire?

[Green Xenon]

Have you heard of a coal fire?

 

Yes

[Hal.]

Here is one of my favourites ! , Methane Exhaust Flame , Best listened to with a high volume !

 

And another , with no slippers ,

Best looked at with a nice cup of tea ! Edited June 29, 2011 by Hal.