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<DIV dir=ltr align=left><SPAN class=937473320-05072007><FONT
face="Lucida Console" color=#0000ff size=2>BHP must be in the numerator else it
would take less power to run motors of increasing horsepower,
QED?</FONT></SPAN></DIV>
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<FONT face=Tahoma size=2><B>From:</B> BLDG-SIM@gard.com
[mailto:BLDG-SIM@gard.com] <B>On Behalf Of </B>Vikram Sami<BR><B>Sent:</B>
Thursday, July 05, 2007 1:12 PM<BR><B>To:</B>
BLDG-SIM@gard.com<BR><B>Subject:</B> [BLDG-SIM] Question about Fan
Power<BR></FONT><BR></DIV>
<DIV></DIV><!-- Converted from text/rtf format -->
<P><FONT face=Arial size=2>So I'm trying to calculate fan power, and came across
this mindbender</FONT> </P>
<P><I><FONT face="Times New Roman">Pfan</FONT></I> <FONT
face="Times New Roman">= 746 / (1 - e[ -0.2437839 × ln( bhp ) - 1.685541
])<U><B> </B></U></FONT><U><B><FONT face="Times New Roman" color=#ff0000>×
bhp</FONT></B></U><B></B> </P>
<P><FONT face=Arial size=2>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?</FONT></P>
<P><FONT face=Arial size=2>i.e. - Should the equation read</FONT> </P>
<P><I><FONT face="Times New Roman">Pfan</FONT></I> <FONT
face="Times New Roman">= 746 / [(1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ]) ×
bhp]</FONT> </P>
<P><FONT face="Times New Roman">Or</FONT> </P>
<P><I><FONT face="Times New Roman">Pfan</FONT></I> <FONT
face="Times New Roman">= [746 / (1 - e[ -0.2437839 × ln( bhp ) - 1.685541 ])] ×
bhp</FONT> </P>
<P><FONT face=Arial size=2>Any help is much appreciated.</FONT> </P>
<P><FONT face=Arial size=2>Thanks</FONT> </P>
<P><B><FONT face=Garamond color=#000000>Vikram Sami,</FONT></B> <FONT
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size=2>**************************************************************************</FONT>
<BR><FONT face=TT12B7o00 size=2>G3.1.2.9</FONT><B></B><B> <FONT
face="Times New Roman" size=2>Supply Fan Power.</FONT></B> <FONT
face="Times New Roman" size=2>System fan electrical power</FONT> <BR><FONT
face="Times New Roman" size=2>for supply, return, exhaust, and relief (excluding
power to fanpowered</FONT> <BR><FONT face="Times New Roman" size=2>VAV boxes)
shall be calculated using the following</FONT> <BR><FONT face="Times New Roman"
size=2>formulas:</FONT> <BR><I><FONT face="Times New Roman" size=2>P</FONT><FONT
face="Times New Roman" size=1>fan</FONT></I> <FONT face="Times New Roman"
size=2>= 746 / (1 - e</FONT><FONT face="Times New Roman" size=1>[ -0.2437839 ×
ln( bhp ) - 1.685541 ]</FONT><FONT face="Times New Roman" size=2>) × bhp</FONT>
<BR><FONT face="Times New Roman" size=2>where</FONT> <BR><I><FONT
face="Times New Roman" size=2>P</FONT><FONT face="Times New Roman"
size=1>fan</FONT></I> <FONT face="Times New Roman" size=2>= electric power to
fan motor (watts) and</FONT> <BR><FONT face="Times New Roman" size=2>bhp = brake
horsepower of</FONT><I> <FONT face="Times New Roman" size=2>baseline</FONT></I>
<FONT face="Times New Roman" size=2>fan motor from Table</FONT> <BR><FONT
face="Times New Roman" size=2>G3.1.2.9, where cfm represents design supply
flow</FONT> <BR><FONT face="Times New Roman" size=2>rate.</FONT> <BR><FONT
face=Arial
size=2>***************************************************************************</FONT>
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