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<p class=MsoNormal><span style='color:#1F497D'>Hi Jeremy,<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>I’m going to pose a few
suggestions in response – I’ll caution that for each question, I had to
question what exactly you were questioning… so you may need to paraphrase / simplify
your queries in a few cases:<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>1a. When
you specify a PLR for a data point in the EIR-fPLR (or EIR-fPLR&dT) curve,
it’s value is “capacity at this data point” divided by “capacity at the
reference point.” Whether that reference point capacity matches what your
manf. rep entered in their sizing software depends on your rep and how well you
explained your needs to them. Ultimately, whether that point represents your
design capacity or your maximum capacity, you can work with that data provided
you are consistent with using the same reference data point between all three
curves and in your specification of the chiller in eQuest. Note that if you
are creating only the PLR curve you need to have that reference point be at ARI
conditions as that’s what the other two curves are normalized to.<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>1b. “%
load(ing)” means the percentage of capacity from the maximum/design capacity (whatever
is in context). PLR means Part Load Ratio - you might also call it the “normalized
capacity.” “Part load capacity” is an unnecessary term you’re sprinkling in to
confuse yourself (wink wink ^_^), but I would interpret it as the capacity at a
given part load.<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>2. To
paraphrase the line in the EDR reference you brought up: The part load data
points used to make your EIR-f(PLR) or EIR-f(PLR,dT) curve need to be at
matching conditions as the point(s) at 100% loading.<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>3. You
should not be asking for part load points for your curves that are a function
of CWT and CHWT. They should be run at either design or maximum capacity,
depending on your chiller type.<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>4. When
developing a spreadsheet to do the math to come up with your data points for
eQuest to do the coefficient regressions, I’d suggest ignoring the equations in
the EDR guidelines and following the definitions for the variables in the DOE2
help entries – they make much more sense. PLR as eQuest interprets it is just
as I described under response 1a. The reference point is should not change
between the curves – review the help entry titled “Chiller Energy Consumption” carefully
if you are not perfectly sure why. Be consistent. <o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'>4b. If
your curve using the same reference point between all three curves (and in the
equest interface) is resulting in crazy chiller performance – have you checked
your work? Take the generated coefficients and plot them against each other as
in excel as I demonstrated. See if your curves make sense – can you use the
curves to work backwards and read off an EIR for a set of PLR, CWT, CHWT conditions
that matches manufacturer data?<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:.25in'><span style='color:#1F497D'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>There’s my end of the week
effort =). Hope this helps you and others!<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'>~Nick<o:p></o:p></span></p>
<div>
<p class=MsoNormal><span style='color:#1F497D'><img width=119 height=37
id="Picture_x0020_1" src="cid:image001.jpg@01CB7D0A.23A2D510"
alt="cid:489575314@22072009-0ABB"></span><b><span style='font-family:"Stylus BT","sans-serif";
color:#2D4D5E'><o:p></o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Stylus BT","sans-serif";
color:#2D4D5E'><o:p> </o:p></span></b></p>
<p class=MsoNormal><b><span style='font-family:"Stylus BT","sans-serif";
color:#2D4D5E'>NICK CATON, E.I.T.</span></b><b><span style='font-size:12.0pt;
font-family:"Stylus BT","sans-serif";color:#2D4D5E'><o:p></o:p></span></b></p>
<p class=MsoNormal><span style='font-size:7.5pt;color:#CC9900'>PROJECT ENGINEER</span><span
style='font-size:7.5pt;font-family:"Times New Roman","serif";color:#CC9900'><o:p></o:p></span></p>
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<p class=MsoNormal><span style='font-size:10.0pt;color:#2D4D5E'>fax 913
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<p class=MsoNormal><i><span style='font-size:10.0pt;color:#2D4D5E'>Check out
our new web-site @ </span></i><span style='color:#1F497D'><a
href="www.smithboucher.com" title="blocked::www.smithboucher.com"><span
style='font-size:10.0pt'>www.smithboucher.com</span></a></span><u><span
style='font-size:10.0pt;color:blue'> </span></u><span style='color:#1F497D'><o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
equest-users-bounces@lists.onebuilding.org
[mailto:equest-users-bounces@lists.onebuilding.org] <b>On Behalf Of </b>Jeremy
McClanathan<br>
<b>Sent:</b> Friday, November 05, 2010 4:40 PM<br>
<b>To:</b> equest-users@lists.onebuilding.org<br>
<b>Subject:</b> [Equest-users] FW: [eSimForums] Custom Chiller Curves<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoPlainText>Hello,<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>I have a couple more questions to add to the chiller
curve conversations going on. I posted the question to eSimForums so the
spreadsheet would stay with the topic and am forwarding the question
along. Below are the questions, and here is a link to the post:<o:p></o:p></p>
<p class=MsoPlainText><a
href="http://www.esimforums.com/equest/viewtopic.php?f=13&t=105&view=unread%23unread">http://www.esimforums.com/equest/viewtopic.php?f=13&t=105&view=unread#unread</a><o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Thanks for any advice,<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Jeremy<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>-----Original Message-----<br>
From: admin@esimforums.com [mailto:admin@esimforums.com] <br>
Sent: Friday, November 05, 2010 2:18 PM<br>
Subject: [eSimForums] Custom Chiller Curves<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>New post:<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Hello all,<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Attached is a spreadsheet I used to gather information from
a manufacturer<o:p></o:p></p>
<p class=MsoPlainText>and create custom chiller curves using the EDR guidelines
for modeling<o:p></o:p></p>
<p class=MsoPlainText>energy efficient chillers (link to the document at the
bottom of the post).<o:p></o:p></p>
<p class=MsoPlainText> I have been testing the curves in two models. In a
test wizard model (also<o:p></o:p></p>
<p class=MsoPlainText>attached), both curves work. In another real model
(which I can't upload)<o:p></o:p></p>
<p class=MsoPlainText>the curves that I expected to be correct cause the
chiller to create<o:p></o:p></p>
<p class=MsoPlainText>energy. The difference between the curves is the
PLR equation. So, I have<o:p></o:p></p>
<p class=MsoPlainText>a few questions regarding gathering information from
manufacturers and the<o:p></o:p></p>
<p class=MsoPlainText>PLR equation.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>1) <o:p></o:p></p>
<p class=MsoPlainText>When I specify a %load for a part-load data point, does
this automatically<o:p></o:p></p>
<p class=MsoPlainText>dictate an operating capacity that a manufacturer must
input into their<o:p></o:p></p>
<p class=MsoPlainText>program? For example, in the attached spreadsheet,
I chose to ask for 90%<o:p></o:p></p>
<p class=MsoPlainText>load with a CHWS & ECT of 42 & 78. I take
this to mean that I am asking<o:p></o:p></p>
<p class=MsoPlainText>the manufacturer to input an operating capacity of 90% of
the full load<o:p></o:p></p>
<p class=MsoPlainText>capacity at the same CHWS & ECT’s (0.9*343=308.7 tons
in the attached<o:p></o:p></p>
<p class=MsoPlainText>spreadsheet) into their software and give me the
corresponding power drawn<o:p></o:p></p>
<p class=MsoPlainText>by the chiller. However, in the EDR guidelines for
modeling energy<o:p></o:p></p>
<p class=MsoPlainText>efficient chillers, there is an example Manufacturer Data
Request Form<o:p></o:p></p>
<p class=MsoPlainText>which has a note in both the capacity and power columns
that says “Note to<o:p></o:p></p>
<p class=MsoPlainText>Chiller Manufacturer Rep., Please allow your program to
size (don’t input<o:p></o:p></p>
<p class=MsoPlainText>capacity and kW into your program)”. This makes
sense for the full load<o:p></o:p></p>
<p class=MsoPlainText>capacity, but does it apply to the part load? If
so, what is the<o:p></o:p></p>
<p class=MsoPlainText>difference between %load and part load capacity?<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>2) <o:p></o:p></p>
<p class=MsoPlainText>Does there need to be a part load data point for every
full load data<o:p></o:p></p>
<p class=MsoPlainText>point?<o:p></o:p></p>
<p class=MsoPlainText>a. <o:p></o:p></p>
<p class=MsoPlainText>I would say yes based on page 26 of the EDR guidelines,
which says “each<o:p></o:p></p>
<p class=MsoPlainText>part-load point must have a corresponding full-load data
point with<o:p></o:p></p>
<p class=MsoPlainText>matching evaporator and temperatures.” This seems
to answer my question. <o:p></o:p></p>
<p class=MsoPlainText>But, on page 28 of the same document in the example
Manufacturer’s Data<o:p></o:p></p>
<p class=MsoPlainText>Request Form, they do not ask for part-load points that
correspond to<o:p></o:p></p>
<p class=MsoPlainText>full-load points. This is a bit confusing, so I
would just like to<o:p></o:p></p>
<p class=MsoPlainText>confirm.<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>3) <o:p></o:p></p>
<p class=MsoPlainText>When asking for part load data from a manufacturer, does
it matter which<o:p></o:p></p>
<p class=MsoPlainText>%load I ask for at each data point corresponding to a
CHWS & ECT?<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>4) <o:p></o:p></p>
<p class=MsoPlainText>In the attached spreadsheet, the difference between
curves on the sheet<o:p></o:p></p>
<p class=MsoPlainText>named Curve 1 and the ones on sheet Curve 2 is the
divisor in the PLR<o:p></o:p></p>
<p class=MsoPlainText>equation (starting in cell W15). The given PLR
equation is PLR =<o:p></o:p></p>
<p class=MsoPlainText>Qi/(Qref*CAPFT). Curve 2 represents my
interpretation of this equation<o:p></o:p></p>
<p class=MsoPlainText>where Qref is a constant representing the capacity at the
point of unity. <o:p></o:p></p>
<p class=MsoPlainText>However, when I used this curve in a model, the chiller
energy came out<o:p></o:p></p>
<p class=MsoPlainText>negative (magically created energy instead of consuming
it). A colleague<o:p></o:p></p>
<p class=MsoPlainText>of mine read a document that suggested that Qref in the
PLR equation is a<o:p></o:p></p>
<p class=MsoPlainText>different Qref than in the other equations and it could
be interpreted as a<o:p></o:p></p>
<p class=MsoPlainText>variable reference (which I would call Qi, not
Qref). So, we tried it and<o:p></o:p></p>
<p class=MsoPlainText>it worked, or at least it caused the chiller to consume
energy instead of<o:p></o:p></p>
<p class=MsoPlainText>creating it. I have a difficult time believing that
Qref is a variable and<o:p></o:p></p>
<p class=MsoPlainText>not a constant, but the fact that the curve worked with
Qref as a variable<o:p></o:p></p>
<p class=MsoPlainText>and didn’t work as a constant forces me question
it. Since then, I tried<o:p></o:p></p>
<p class=MsoPlainText>the same curves in another model and they both work,
which confused the<o:p></o:p></p>
<p class=MsoPlainText>situation more. Is my interpretation that Qref is a
constant representing<o:p></o:p></p>
<p class=MsoPlainText>the capacity at the point of unity correct?<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>For ref, the EDR guidelines I am referring to can be
found at the following<o:p></o:p></p>
<p class=MsoPlainText>link:<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><a
href="http://www.energydesignresources.com/Resources/Publications/DesignGuidelines/tabid/73/articleType/ArticleView/articleId/138/Design-Guidelines-HVAC-Simulation-Guidelines.aspx">http://www.energydesignresources.com/Resources/Publications/DesignGuidelines/tabid/73/articleType/ArticleView/articleId/138/Design-Guidelines-HVAC-Simulation-Guidelines.aspx</a><o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText>Reply to this post at:<o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
<p class=MsoPlainText><a
href="http://www.esimforums.com/equest/viewtopic.php?f=13&t=105&view=unread%23unread">http://www.esimforums.com/equest/viewtopic.php?f=13&t=105&view=unread#unread</a><o:p></o:p></p>
<p class=MsoPlainText><o:p> </o:p></p>
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