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flame radiant energy
2

flame radiant energy

flame radiant energy

(OP)
I am trying to determine the quantity of thermal radiation from a flame.  Also, more importantly, I'm trying to determine the radiant load as a function of distance from an object (i.e. don't want to burn up something near the flame).  Does anyone know the relationship between thermal radiation and distance to the source?  Obviously the closer to the source, the hotter it feels...

Thanks!

RE: flame radiant energy

any beginning heat transfer text will cover that.  perhaps an internet search would help.

RE: flame radiant energy

(OP)
Found it.  Relation between intensity and distance is the inverse of the distance squared.

Any clues for the emisivity factor for a flame?  Would it depend on the fuel?

Thanks.

RE: flame radiant energy

The emissivity will depend on the gaseous products of combustion.  If you are close enough to the flame you will also have to account for conduction effects.

I2I

RE: flame radiant energy

(OP)
Ok, I'm no chemist, but I'm burning natural gas and fuel oil.  Any ideas?

RE: flame radiant energy

Any thermo or combustion book should cover the stoichiometry.  The products of combustion will be a function of your A/F ratio and whether you're completely burning the fuel. Typically, you will have a mixture of carbon dioxide, water vapor and nitrogen for sure, but depending on your specific operating conditions, you may have oxygen, carbon monoxide, NOX, any trace elements/impurities in gas/fuel supply, as well as unburnt hydrocarbons.  You will need to run through the calculations for your operating conditions.  Incidentally, this is also how you will find the adiabatic flame temp.

I2I

RE: flame radiant energy

see thread610-140748

Note that the emissivity is highly dependent on the depth of the flame itself as well.  A small flame has effectively low emissivity, while a thicker flame has a higher effective emissivity.

TTFN



RE: flame radiant energy

Review API_RP_521  In the fourth edition the section of interest should be, 4.4.2.3  

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