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<DIV>Folks,</DIV>
<DIV>Don't be alarmed. The two curves in Xu's .pdf do not represent the same dependent value on the y-axis. The DOE-2 EIR f(PLR)curves essentially output kW (EIR(f)PLR x design kW) not kW/ton. The conversion to kW/ton has been discussed in previous posts, but, essentially, the "EIR"(kW) needs to be divided by the PLR (load, tons) to get kW/ton. The Trane curves probably include some condenser water reset, so a combination of DOE-2 curves would be needed to produce comparable outputs. </DIV>
<DIV> </DIV>
<DIV>Fred Porter</DIV>
<DIV>AEC<BR><BR>>>> "W. Peter Anderson" <panderson@jpengineer.com> 5/23/2008 3:25 PM >>><BR></DIV>
<DIV><FONT face=Arial size=2>I have not spent much time researching the eQuest EIR curve origins, but I have spent years performing chiller ratings and analyzing centrifgual chiller part load curves under many circumstances.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>In my opinion, the CVHE curve is much more representative of what the energy use will be for (1) chiller operating, than the eQuest curve. The nature of centrifugal chiller is, below 25% loading the kW/ton increases. Basically, system inefficiencies, which are relatively minor compared to power of compression at higher loads, are a bigger percentage of work input (kW) at low loads.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If you have mulitple chillers, more information is needed to make a determination of what your part load efficiency would be.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>It would be good to get feedback from someone more familiar with eQuest EIR.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>SEER is calculated differently than water cooled chiller performance, so that could be a source for differences as well.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I hope this helps,</FONT></DIV>
<DIV><FONT face=Arial size=2>Regards,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B> <A title=xiaowei.xu@ny.fk.com href="mailto:xiaowei.xu@ny.fk.com">Xu, Xiaowei</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=bldg-sim@lists.onebuilding.org href="mailto:bldg-sim@lists.onebuilding.org">bldg-sim@lists.onebuilding.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, May 23, 2008 4:06 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [Bldg-sim] chiller EIR curve</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt">Hi, <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt">I have a question about the chiller EIR curve in eQUEST. In the attachment, there are two curves of chiller EIR. One is the kWH/Ton curve from chiller manufacture. One the normalized EIR curve from eQUEST default. These two curves showed quite big difference when the chiller PLR drops to 30% or lower. <o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt">In my simulation, I used manufacturer data and this equation to calculate the EIR, and then normalized the EIR to get the curve. <o:p></o:p></SPAN></FONT></P><PRE><FONT face="Courier New" size=2><SPAN style="FONT-SIZE: 10pt">Cooling EIR = 0.941 * (1/(SEER/3.413))<o:p></o:p></SPAN></FONT></PRE>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt">Because about 20% of the chiller hours ran at less 20% of PLR, using two different curves (calculated manufacturer curve and eQUEST default curve) caused huge difference of chiller electricity consumption. So my question is which curve is right for the chiller performance? Thank you very much.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt"><o:p> </o:p></SPAN></FONT></P>
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