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class=812411722-11032008>Assuming this is a fixed-speed centrifugal chiller,
a reasonable first cut is that the power is proportional to the lift
(compressor pressure out- pressure in). Look at the refrigerant pressures
at the expected condensing and evaporating temperatures, and ratio the lift at
the new condensing temp to the lift at the old condensing
temp.</SPAN></FONT></DIV>
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<DIV dir=ltr align=left><FONT face=Arial><FONT color=#0000ff><FONT size=2><SPAN
class=812411722-11032008>This approach neglects the change in compressor
efficiency that probably occurs, but </SPAN>I've done this in the past prior to
getting a complete chiller map, and the approach works out pretty well. It
also matches with the com<SPAN class=812411722-11032008>m</SPAN>on rule of thumb
that the power changes 1 to 2% per deg F change in condensing
temp.</FONT></FONT></FONT></DIV>
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<DIV dir=ltr align=left></SPAN></FONT><SPAN class=812411722-11032008><FONT
face=Arial color=#0000ff size=2>With nagging, it may be possible to get a
complete chiller map from the manufacturer. You can almost certainly get
it in a competitive procurement situation.</FONT></SPAN></DIV>
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color=#0000ff size=2></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=812411722-11032008><FONT face=Arial
color=#0000ff size=2>William E. Koran, P.E.<BR>Senior Engineer<BR>Q u E S
T<BR>Quantum Energy Services and Technologies<BR><A
href="http://www.quest-world.com">www.quest-world.com</A></FONT></SPAN></DIV></DIV>
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class=812411722-11032008></SPAN></FONT> </DIV>
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<FONT face=Tahoma size=2><B>From:</B> bldg-sim-bounces@lists.onebuilding.org
[mailto:bldg-sim-bounces@lists.onebuilding.org] <B>On Behalf Of </B>Wyman, Kevin
L UTPWR<BR><B>Sent:</B> Tuesday, March 11, 2008 9:41 AM<BR><B>To:</B>
bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> [Bldg-sim] Chiller
Loads<BR></FONT><BR></DIV>
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<P><FONT size=2>I am trying to determine chiller power draw at reduced
condensing temperatures. The load is constant (100%) for all condensing temps. I
have manufacturer data for 100% 90% 80% ... 20% at both constant condensing
temperature (85F) and with ARI relief (but a partial loads).<BR><BR>Any
suggestions to get full load kW/ton at different condensing
temperatures?<BR><BR>Thanks.<BR><BR><BR><BR>Kevin L. Wyman, P.E.<BR>LEED
AP<BR>On-Site Power Product Management<BR>UTC Power<BR>195 Governor's
Highway<BR>South Windsor, CT 06074<BR>(860) 727-7020 (V)<BR>(860) 660-0723
(F)<BR>(860) 882-9595 (M)<BR>Kevin.wyman@utcpower.com</FONT> </P></BODY></HTML>