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<DIV>The way I "deal" with this is by using a spreadsheet I've built which evaluates groups of the DOE-2.2 chiller curves at any combination of temperatures and loads. In this situation I would evaluate a number of DOE2 chiller curves' output EIRs and CAPs at the IPLV or NPLV condensing and evaporating temperatures, delta Ts, and PLRs. Then compare these with the rated values at the four "EIRs" given by the IPLV/NPLV values. Then pick the curves with the best match (hopefully all in the same family!). If that fails, simply make an educated guess of the difference between reality and the model and correct the model result with that, or try to create some better curves. If the real chiller seems to have much better low-load performance, possibly model more chillers than the real proposed case, though I have seen that backfire.</DIV>
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<DIV>Having said that, I think USGBC should disallow any claims for improved chiller (or really any equipment) part load performance vs the baseline unless the manufacturer has supplied off-design performance data adequate to characterize the chiller and usable in the analyst's simulation program. For their part USGBC, ASHRAE, or the IRS need to define similar off-design performance data that correspond with the minimum performance IPLVs in Table 6.8. Maybe the USGBC could hire someone quickly to do this with some of the million bucks they have budgeted for "green bldg research." The ASHRAE App G text should probably stick to the big picture. In the ACM, the California Energy Commission has defined chiller curves for the T24 "standard" case model (these evaluate to better than the ASHRAE minimum IPLVs) and they also have some restrictions on claims of improved part load performance in the "design" model. </DIV>
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<DIV>Fred Porter</DIV>
<DIV>AEC</DIV>
<DIV><BR><BR>>>> "Aulbach, John" <jaulbach@nexant.com> 12/19/2007 6:02 PM >>><BR></DIV>
<DIV dir=ltr align=left><SPAN class=707430001-20122007><FONT face=Arial color=#0000ff size=2>So I cannot "reverse engineer" a part load curve that uses condenser water relief in calculating the points, knowing what condenser temps are used at what part load point (100%, 75%, 50%, etc) ???</FONT></SPAN></DIV><BR>
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<FONT face=Tahoma size=2><B>From:</B> Steven Gates [mailto:steve.gates@doe2.com] <BR><B>Sent:</B> Wednesday, December 19, 2007 4:57 PM<BR><B>To:</B> Aulbach, John; bldg-sim@lists.onebuilding.org<BR><B>Subject:</B> RE: [Bldg-sim] Chiller part load raw data points into eQuest<BR></FONT><BR></DIV>
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<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Unfortunately the IPLV is of little or no value when setting up chiller curves. To set up the EIR-fT and EIR-fPLR curves requires more data points than is available in the IPLV. IPLV basically describes a two-dimensional curve, whereas the actual chiller performance is 3-dimensional. The IPLV assumes that condenser temperature drops as chiller load drops, but this is not necessarily the case. Examples:<o:p></o:p></SPAN></FONT></P>
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<LI class=MsoNormal style="COLOR: navy; mso-list: l0 level1 lfo1"><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">A cooling tower has a fixed setpoint of 85°F. Or, the condenser water source is a lake or river. In this case condenser temperature does not drop as chiller load drops.<o:p></o:p></SPAN></FONT>
<LI class=MsoNormal style="COLOR: navy; mso-list: l0 level1 lfo1"><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">A large plant has 3 chillers utilizing a single cooling tower. The current load is 33% of design, so one chiller is running at full load. IPLV assumes an entering condenser temperature of 85°F (full load), whereas the cooling tower is actually lightly loaded and can achieve a smaller approach to wetbulb.<o:p></o:p></SPAN></FONT>
<LI class=MsoNormal style="COLOR: navy; mso-list: l0 level1 lfo1"><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">The building is on the West coast (low wetbulb) vs. Florida (high wetbulb). Tower performance and condenser temperature vs. load is entirely different in these two climates.<o:p></o:p></SPAN></FONT> </LI></OL>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">So while IPLV may be an interesting figure for rough comparisons, it is insufficient for an hourly simulation program. This is true for all energy simulation programs, not just eQUEST. Ultimately this issue will need to be addressed by standards organizations such as ARI, and/or equipment manufacturers.<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Steve Gates<BR>eQUEST development team<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><B><FONT face=Tahoma size=2><SPAN style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> bldg-sim-bounces@lists.onebuilding.org [mailto:bldg-sim-bounces@lists.onebuilding.org] <B><SPAN style="FONT-WEIGHT: bold">On Behalf Of </SPAN></B>Aulbach, John<BR><B><SPAN style="FONT-WEIGHT: bold">Sent:</SPAN></B> Wednesday, December 19, 2007 4:04 PM<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B> bldg-sim@lists.onebuilding.org<BR><B><SPAN style="FONT-WEIGHT: bold">Subject:</SPAN></B> [Bldg-sim] Chiller part load raw data points into eQuest</SPAN></FONT><o:p></o:p></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">Hi Gang:<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">I have a part load curve from a chiller manufacturer for input into eQuest. Unfortunately, it has condenser temperature relief (this is an evaporatively cooled chiller, so we are speaking of dry bulb outdoor temperatures.<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">Normally, I ask for a part load curve with a constant condenser temperature, and let eQuest modify this curve based on changing outdoor air conditions.<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">But now I have the IPLV data and it deals with condenser relief. I DO have at what part load a particular condenser temperature occurs (complimenting this IPLV data.<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">Can anyone help me?<o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Tahoma color=blue size=2><SPAN style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Tahoma">John R. Aulbach, PE, CEM</SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><EM><I><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Project Manager</SPAN></FONT></I></EM><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Arial color=blue size=2><SPAN style="FONT-SIZE: 10pt; COLOR: blue; FONT-FAMILY: Arial">Nexant, Inc</SPAN></FONT><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">.</SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">100 North Barranca, Suite 820</SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">West Covina, CA 91791 USA</SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Phone: 626-430-9054</SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
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<P class=MsoNormal style="MARGIN: 0in 0in 0pt"><FONT face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">email: <A title=mailto:jaulbach@nexant.com href="mailto:jaulbach@nexant.com">jaulbach@nexant.com</A></SPAN></FONT><FONT face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"><o:p></o:p></SPAN></FONT></P>
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