radiation in fire tube furnace

[omarali]

in fire tube boiler furnace on oil fuel calculation
we want to calculate emissivity of gases as
emissivity=B(1-e^kps)
k is attenuation factor
can i write
k=k1+k2
k1 is for luminous flame oil and gas
k2 is for nonluminous flame or is thing wrong imust write only
k= k1
and how ican calculate it for gases fuel

 

[chicopee]

Mechanical and Chemical engineering handbooks such as Kent and Perry have sections dealing with this subject extensively. However, what are your reasons of figuring out the emissivities of combustion gases? If you are trying to figure out the radiation heat transfer in fire tube boilers, whatever answers you develop, you will be in all likely hood way off on the values. Your best bet would be to adjust your theoretical values with empirical data, otherwise use the time tested value ranging from 3.5 to 5 lbs/hr per square foot of heating surface if you want to determine the steam generating capacity; in some firetube boilers this range can go up to 7 lbs/hr of steam per square foot of heating surface.