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Old 04-13-2009, 08:18 AM   #1
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Heat transfer


I have a 4 in. duct moving air at 300 FPM. I know that this equals about 24 CFPM. I want to know how much energy(BTU's or watts) it takes to heat this air 10 degrees F. The air starts at 30 F, 50 Hum. and sea level.
+ or - 5% is good enough.
OR, how much energy does it take to heat X amount of air(CFPM), Y amount of degrees(F)?
Thanks,
Chuck

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Old 04-13-2009, 08:53 AM   #2
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Heat transfer


1.08 BTUs per CFM per 1 temp rise.

In the case of your 4" duct, at 24 CFM and 10 rise, 259.2BTU.

A 4" rouind at 300 FPM is 26CFM.
(10*1.08)*26=280.8 BTUs.

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Old 04-13-2009, 10:34 AM   #3
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Heat transfer


Quote:
Originally Posted by beenthere View Post
1.08 BTUs per CFM per 1 temp rise.

In the case of your 4" duct, at 24 CFM and 10 rise, 259.2BTU.

A 4" rouind at 300 FPM is 26CFM.
(10*1.08)*26=280.8 BTUs.
Thanks Beenthere, follow-on question- the literature says that it takes one BTU to heat 1 CF of water 1 degree C. What am I missing?
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Old 04-13-2009, 10:42 AM   #4
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Heat transfer


xxxxxx!

Last edited by Yoyizit; 04-13-2009 at 12:06 PM.
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Old 04-13-2009, 11:30 AM   #5
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Heat transfer


Its 1 BTU to heat 1 pound of water 1F.

A cubic foot of water, is 7.49 gallons, and weighs 62.39 pounds at 60F.
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Old 04-13-2009, 11:36 AM   #6
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Heat transfer


Quote:
Originally Posted by beenthere View Post
Its 1 BTU to heat 1 pound of water 1F.

A cubic foot of water, is 7.49 gallons, and weighs 62.39 pounds at 60F.
Damm, you the man.
Thanks,
Chuck
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Old 04-13-2009, 11:46 AM   #7
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Heat transfer


Your welcome.

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