Power required to raise air temperature
Power required to raise air temperature
(OP)
thread391-260422: Watts required to raise air temp
Starting with 500lb/min of dry air at 400F moving through a pipe at 84fps (appr. 11,000ACFM) what is the wattage required to raise the temperature 100F?
CP 1.026
Density .046 lb/ft3
It's a real life problem, not homework so any help will be much appreciated.
Starting with 500lb/min of dry air at 400F moving through a pipe at 84fps (appr. 11,000ACFM) what is the wattage required to raise the temperature 100F?
CP 1.026
Density .046 lb/ft3
It's a real life problem, not homework so any help will be much appreciated.





RE: Power required to raise air temperature
Ballpark at least. The 1.1 factor is likely a bit off for your elevated temperatures.
RE: Power required to raise air temperature
Can you tell me where you get 1.1 and 0.3 in your formula?
Is your 1.1 the Cp and then the 0.3 is a conversion of the air to mass?
Thanks,
Rich
RE: Power required to raise air temperature
-What diameter pipe?
-What 'efficiency" are you going to assume for the wall-to-gas heat transfer?
-How long a heater are going to wrap around the pipe? (That question works frmo the above efficiency assumption?
-How are you going to insulate the outside of that heat exchanger so "all" of your heat from electricity is going to go "into" the pipe wall then through the pipe wall then into the air inside the pipe?
By the way, the 1.206 cp is for degrees C = 200 C, NOT for a Fahrenheit unit of measurement (400 F) like your density of lbs/ft^3
RE: Power required to raise air temperature
The heat will not be applied externally so the wall to gas transfer is immaterial.
The question is how much power will it take to raise the temperature of 500lb/min of dry air at 400F moving through a pipe at 84fps which equals approximately 11,000ACFM.
Intuitively, I don't buy the 300 kW either, about half that seems more reasonable based on field experience with smaller systems. Not having experience with this volume of flow I thought I would throw it out to the thermo gurus.
RE: Power required to raise air temperature
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RE: Power required to raise air temperature
RE: Power required to raise air temperature
RE: Power required to raise air temperature
Energy input is w*change in stagnation enthalpy.
Regards
RE: Power required to raise air temperature