[BLDG-SIM] Question about Fan Power
David S Eldridge
DSE at grummanbutkus.com
Thu Jul 5 13:39:30 PDT 2007
Assuming an approximate conversion at 746 W per BHP - numerator, which is divided by some motor efficiency corrections (all the logarithmic stuff) to get your Pfan in Watts.
For instance with 50 BHP, your numbers might give you something similar to: 746 / 0.929 x 50 = Pfan = 40.2 kW
David
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Vikram Sami
Sent: Thursday, July 05, 2007 3:12 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Question about Fan Power
So I'm trying to calculate fan power, and came across this mindbender
Pfan = 746 / (1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ]) × bhp
Having done the hard part (I figured out how to automate the process in XL with just the CFM input using the natural log function ), I have only one question - does the bhp (highlighted at the end) go in the numerator or denominator of the equation?
i.e. - Should the equation read
Pfan = 746 / [(1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ]) × bhp]
Or
Pfan = [746 / (1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ])] × bhp
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