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<p class="MsoNormal">Hi Phil,<o:p></o:p></p>
<p class="MsoNormal">Good question! When a performance curve uses Raw Data Points (INPUT-TYPE = DATA), the coefficients for the curve are generated based on the data points and can be seen in the eQUEST Basic Specifications tab for the Performance Curve Properties.
(You can generate the coefficients yourself mathematically, by using the LINEST Excel function for example.) Outputs for the curve will be determined even if the inputs (independent variable values) are outside the range of the raw data points. For example,
a PLR of 0.2 and dT of 25F gives an EIR multiplier of 0.14 in the example curve below. The outputs could even be nonsensical if the simulation used garbage inputs. (An output of -0.2 using inputs of -1,-1.) I don’t think there is a keyword that restricts the
input variable values, but the OUTPUT-MIN and OUTPUT-MAX fix the output at those values rather than letting it go outside of those boundaries. Additionally, chillers have the MIN-RATIO keyword which defines the load for which the chiller will cycle on and
off.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Regards,<o:p></o:p></p>
<p class="MsoNormal">~Bill<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Franklin Gothic Medium",sans-serif;color:black">William Bishop, PE, BEMP, BEAP, CEM, LEED AP<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black">Senior Energy Engineer<o:p></o:p></span></b></p>
<p class="MsoNormal"><b><span style="font-size:3.0pt;font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></b></p>
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</v:shapetype><v:shape id="Picture_x0020_4" o:spid="_x0000_s1026" type="#_x0000_t75" alt="Pathfinder-EA-logo-2" style='position:absolute;margin-left:0;margin-top:63.6pt;width:68.45pt;height:43.9pt;z-index:-251658752;visibility:visible;mso-wrap-style:square;mso-width-percent:0;mso-height-percent:0;mso-wrap-distance-left:9pt;mso-wrap-distance-top:0;mso-wrap-distance-right:9pt;mso-wrap-distance-bottom:0;mso-position-horizontal:left;mso-position-horizontal-relative:text;mso-position-vertical:absolute;mso-position-vertical-relative:text;mso-width-percent:0;mso-height-percent:0;mso-width-relative:page;mso-height-relative:page'>
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</v:shape><![endif]--><![if !vml]><img width="91" height="59" style="width:.9479in;height:.6145in" src="cid:image003.jpg@01D50CA4.977450D0" align="left" hspace="12" alt="Pathfinder-EA-logo-2" v:shapes="Picture_x0020_4"><![endif]><b><i><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#002060">T:
(585) 698-1956</span><span style="color:#002060"> </span></i></b><span style="color:#1F497D"> </span><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D">F: (585) 325-6005<o:p></o:p></span></p>
<p class="MsoNormal"><a href="mailto:wbishop@pathfinder-ea.com"><span style="font-size:9.0pt;font-family:"Arial",sans-serif">bbishop@pathfinder-ea.com</span></a><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black"> </span><a href="http://www.pathfinder-ea.com/"><span style="font-size:9.0pt;font-family:"Arial",sans-serif">www.pathfinder-ea.com</span></a><span style="color:#1F497D"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D">134 South Fitzhugh Street<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:#1F497D">Rochester, NY 14608
<img border="0" width="26" height="23" style="width:.2708in;height:.2395in" id="Picture_x0020_1" src="cid:image004.png@01D50CA4.977450D0"> </span><i><span style="font-size:7.0pt;font-family:"Verdana",sans-serif;color:#00B0F0">Act on the climate crisis - the
Energy Innovation and Carbon Dividend Act</span></i><span style="color:#1F497D"><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<div style="border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b>From:</b> Equest-users <<a href="mailto:equest-users-bounces@lists.onebuilding.org">equest-users-bounces@lists.onebuilding.org</a>>
<b>On Behalf Of </b>Phil Jordan via Equest-users<br>
<b>Sent:</b> Thursday, May 16, 2019 7:54 PM<br>
<b>To:</b> <a href="mailto:equest-users@lists.onebuilding.org">equest-users@lists.onebuilding.org</a><br>
<b>Subject:</b> [Equest-users] Performance Curves - independent variable boundaries<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When a curve output exceeds the limits (min/max output, OUTPUT-MIN and OUTPUT-MAX keywords), eQUEST throws a CAUTION message in the SIM file, something like this:<o:p></o:p></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New"">**CAUTION**********************************************************************<o:p></o:p></span></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New""> In curve: Variable Speed Drive FPLR the dependent value<o:p></o:p></span></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New""> is exceeding the limits.<o:p></o:p></span></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New""> Value/Min/Max/First time: 1.004 0.100 1.000 7/21/ 8<o:p></o:p></span></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="Normal"><span style="font-size:8.0pt;font-family:"Courier New""><o:p> </o:p></span></p>
<p class="MsoNormal">I’m curious, what happens when the input type for a performance curve is “Raw Data Points” and during the course of the simulation one of the independent variables is outside the range of the raw data points? For example, here’s a curve
from the library (BDLLIB.DAT) that’s defined via data points:<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New"">$LIBRARY-ENTRY SmFricW3VSD-EIR-fPLR&dT CURVE-FIT Sml Fric 3App -044d2 35<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New"">$ 70/140 ton, 3F approach evap & cond; R134a extended 460V 10F superheat -044d2 36<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New"">$ EIR = 0.182, 0.64 kW/ton, COP 5.5 -044d2 37<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> TYPE = BI-QUADRATIC-RATIO&DT INPUT-TYPE = DATA -044d2 38<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> IN-RATIO = ( 1.00, 0.75, 0.50, 0.25, $ PLR -044d2 39<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.75, 0.50, 0.25, -044d2 40<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.75, 0.50, 0.25, -044d2 41<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.75, 0.50, 0.28 ) -044d2 42<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> IN-DT = ( 41.0, 41.0, 41.0, 41.0, $ ECT-CHW DT -044d2 43<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 31.0, 31.0, 31.0, 31.0, -044d2 44<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 26.0, 26.0, 26.0, 26.0, -044d2 45<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 46.0, 46.0, 46.0, 46.0 ) -044d2 46<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> OUTPUT = ( 1.00, 0.70, 0.46, 0.27, $ EIR ratio -044d2 47<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.66, 0.39, 0.22, -044d2 48<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.65, 0.38, 0.19, -044d2 49<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:8.0pt;font-family:"Courier New""> 1.00, 0.72, 0.50, 0.32 ) .. -044d2 50<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In the data points, the minimum PLR boundary for the curve is 0.25 – what happens if during the simulation the PLR is 0.20? Does eQUEST use the curve output regardless (and is a CAUTION generated), or is the output at the minimum independent
variable used?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><span style="font-size:10.5pt;font-family:"Arial",sans-serif;color:#005E68">Phil Jordan</span></b><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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