Flame radiation in fire tube
Flame radiation in fire tube
(OP)
I would like to calculate the heattransfer in a firetube of a boiler. I know how to calculate the H20/CO2 gas radiation to the wall in an ideal stirred vessel.
I assume that the area of the firetube in which the flame is present should be calculated otherwise. As far as I know should direct flame radiation be calculated as cylindrical gaseous body surrounded by a concentric tube. I got stuck when calculation the emmisivity of the flame (gaseous body).
It concerns a natural gas flame.
I am not sure if I am on the right track.
- Who can tell me more about this subject.
- Are there example calculations to be found on the internet?
- What literature is best to read about this subject?
>>> Any help is welcome <<<
JeKo
I assume that the area of the firetube in which the flame is present should be calculated otherwise. As far as I know should direct flame radiation be calculated as cylindrical gaseous body surrounded by a concentric tube. I got stuck when calculation the emmisivity of the flame (gaseous body).
It concerns a natural gas flame.
I am not sure if I am on the right track.
- Who can tell me more about this subject.
- Are there example calculations to be found on the internet?
- What literature is best to read about this subject?
>>> Any help is welcome <<<
JeKo





RE: Flame radiation in fire tube
The main form of heat transfer from the flame is luminous radiation and consequently radiation from CO2 and H2O tends to be ignored.
Furnace temperature calculations are based on empirical/test data and a simple heat balance around the furnace as follows:
Heat in fuel and air to furnace = Heat in flue gas leaving the furnace + Heat transfered to furnace walls.
Heat in fuel and air to furnace = (Fuel flow rate kg/s * NCV kJ/kg ) + Air flow rate kg/s * Enthalpy kJ/kg
Heat in flue gas leaving the furnace = Flue gas flow kg/s * Enthalpy kJ/kg
Heat transfered to furnace walls
=5.673/100000000*Em*((Tf+273.15)^4-(Ts+273.15)^4)*Furnace area m^2
Tf = furnace gas temperature C
Ts = temperature of furnace walls C
Em = emissivity of flame based on test data and fuel fired
typically 0.85-0.90 for oil
Hope this helps
Regards,
athomas236
RE: Flame radiation in fire tube
You may find material that you will find useful at http://www.wargaboiler.com/extras.html, which is a firetube boiler site. Also, design formulas and helpful material can be found at http://www.HRSGdesign.com, even though this is a water tube boiler design site versus a firetube design.
Jack Hardie
RE: Flame radiation in fire tube
A good text book on the subject is as follows
'Process Heat Transfer' by D Q Kern isbn 0-07-085353-3
RE: Flame radiation in fire tube