<br><font size=2 face="sans-serif">Agreed that all manufacturers can and
will do a custom chiller selection and provide performance on the selection.
</font>
<br><font size=2 face="sans-serif"><br>
<br>
<br>
Michael Hupel,</font><font size=1 face="sans-serif"> B. Tech., LEED AP</font><font size=2 face="sans-serif"><br>
Account Executive<br>
Project & Business Development<br>
Johnson Controls L. P.<br>
3070 Mainway Drive <br>
Burlington, ON L7N 3X1<br>
(905) 335-3325 ext. 237<br>
(905) 730-9642 cell</font>
<br>
<br>
<br>
<table width=100%>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">From:</font>
<td><font size=1 face="sans-serif">Paul Diglio <paul.diglio@sbcglobal.net></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">To:</font>
<td><font size=1 face="sans-serif">Carol Gardner <cmg750@gmail.com>,
"John T. Forester" <JohnTF@bvhis.com></font>
<tr>
<td valign=top><font size=1 color=#5f5f5f face="sans-serif">Cc:</font>
<td><font size=1 face="sans-serif">"equest-users@lists.onebuilding.org"
<equest-users@lists.onebuilding.org></font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Date:</font>
<td><font size=1 face="sans-serif">11/03/2010 02:33 PM</font>
<tr valign=top>
<td><font size=1 color=#5f5f5f face="sans-serif">Subject:</font>
<td><font size=1 face="sans-serif">Re: [Equest-users] Chiller Curves (oh
boy!)</font></table>
<br>
<hr noshade>
<br>
<br>
<br><font size=2 face="Roman">John:<br>
<br>
In my opinion one needs to get the chiller modeled by the factory as the
catalogs do not contain nearly enough information.<br>
<br>
See attached spreadsheet. The top portion was provided by Trane.
It models this chiller at Standard, Maximum and Minimum condenser
water flows. I performed the calculations in the red border.<br>
<br>
I needed to model this in Excel for a utility incentive. I was implementing
variable condenser water flow. The kW/Ton increases using a variable
flow sequence.<br>
<br>
My total kWh savings for varying the speed of the condenser pumps was approximately
250,000. The chiller consumed approximately 50,000 kWh more with
minimum condenser water flow.<br>
<br>
Trane modeled this project several times for me, they had a self-interest
because I was contracting them to perform some board upgrades as part of
the energy efficiency project.<br>
<br>
Paul Diglio</font>
<br>
<br>
<hr><font size=2 face="Tahoma"><b>From:</b> Carol Gardner <cmg750@gmail.com><b><br>
To:</b> John T. Forester <JohnTF@bvhis.com><b><br>
Cc:</b> "equest-users@lists.onebuilding.org" <equest-users@lists.onebuilding.org><b><br>
Sent:</b> Wed, November 3, 2010 1:54:35 PM<b><br>
Subject:</b> Re: [Equest-users] Chiller Curves (oh boy!)</font><font size=3 face="Roman"><br>
<br>
I agree with you, John, but have a couple of other thoughts to add. The
first is I have not met a mechanical engineer that does not select a chiller
that is capable of supplying all loads. In fact, they generally oversize
a bit to accommodate possible future loads. The only piece of equipment
I have ever seen selected at over 100% was a VRV system and that is because
they actually work better at 120% loading. The second is that you can generally
get a catalog from a manufacturer to have on your shelf that has technical
information like how the chiller unloads based on temperatures and what
the efficiency is at part load so you can look up the chiller you need
info for and not need to bother the ME or the vendor. If you can't get/don't
want a hard copy, most of this info is on line, just look for technical
specifications.<br>
<br>
Best,<br>
<br>
Carol<br>
</font>
<br><font size=3 face="Roman">On Wed, Nov 3, 2010 at 9:48 AM, John T. Forester
<</font><a href=mailto:JohnTF@bvhis.com target=_blank><font size=3 color=blue face="Roman"><u>JohnTF@bvhis.com</u></font></a><font size=3 face="Roman">>
wrote:</font>
<br><font size=2 color=#000080 face="Arial">Nick,</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">I think you＊re on the right
track. Below are some of my thoughts on your conclusions. I
hope the modeling community will set me straight if I＊m wrong here.</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<br><font size=2 face="sans-serif">1. </font><font size=2 color=#000080 face="Arial">Getting
multiple performance runs from vendors that show part-load performance
independent of the CW and CHW temps can often be challenging. Adding
the ※maximum capability§ task to that for each of the conditions requires
a pretty detailed understanding of the selection software. I＊d say
if you can get PLR data for 3-4 different CHW temps while holding the CW
temps constant at 85, 75, 65 (and sometimes lower) 每 you＊re ahead of
most modelers. Working with the Mechanical Design Engineer and the
vendor together has been successful for me in the past.</font>
<br><font size=2 face="sans-serif">2. </font><font size=2 color=#000080 face="Arial">Defining
the chiller capabilities at the ※maximum§ may only come into play if
you expect your model to overload the chiller above the specified design
capacity (I＊m thinking building additions or process loads). At this point,
this data (or knowing what the default eQuest curves do in that range)
would be useful. Depending on your project, the time spent on developing
curves for PLR >1.0 may not be justified.</font>
<br><font size=2 face="sans-serif">3. </font><font size=2 color=#000080 face="Arial">If
you don＊t have ※max§ data and don＊t want eQuest to assume performance
at a part-load ratio >1.0, you can set the DESIGN-PLR to 1.0.</font>
<br><font size=2 face="sans-serif">4. </font><font size=2 color=#000080 face="Arial">Either
way, you want your curves to be normalized at whatever condition you specify
(Design or Rated) and you want to enter those values on the Basic Specifications
tab.</font>
<br><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">John</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<br><font size=1 color=#808080 face="Arial">John T. Forester, P.E., LEED
AP, Mechanical Design Engineer </font><font size=1 color=#0000a1 face="Arial"><b>I
BVH Integrated Services I</b></font><font size=1 face="Arial"><b> </b></font><font size=1 color=#808080 face="Arial">617.658.9008
tel </font><font size=1 color=#0000a1 face="Arial"><b>I</b></font><font size=1 color=#808080 face="Arial"><b>
</b>617.244.3753 fax</font><font size=1 color=#0000a1 face="Arial"> <b>I</b></font><font size=1 color=#808080 face="Arial"><b>
</b>One Gateway Center Suite 506, Newton MA 02458 </font><font size=1 color=#0000a1 face="Arial"><b>I
</b></font><a href=http://www.bvhis.com/ target=_blank><font size=1 color=blue face="Arial"><b><u>www.bvhis.com</u></b></font></a><font size=1 color=#0000a1 face="Arial"><b>
I Hartford ♂ New Haven ♂ Boston</b></font>
<div align=center>
<br><font size=3 face="Times New Roman">size=2 width="100%" align=center
tabindex=-1> </font></div>
<p><font size=2 face="Tahoma"><b>From:</b> Nick Caton [mailto:</font><a href=mailto:ncaton@smithboucher.com target=_blank><font size=2 color=blue face="Tahoma"><u>ncaton@smithboucher.com</u></font></a><font size=2 face="Tahoma">]
<b><br>
Sent:</b> Wednesday, November 03, 2010 12:06 PM<b><br>
To:</b> John T. Forester; </font><a href="mailto:equest-users@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users@lists.onebuilding.org</u></font></a>
<br><font size=2 face="Tahoma"><b><br>
Subject:</b> RE: [Equest-users] Chiller Curves (oh boy!)</font>
<br><font size=3 face="Times New Roman"> </font>
<p><font size=2 color=#004080 face="Calibri">John,</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">The design/max ratio is exactly
what I＊m discussing below when I say ※DESIGN-PLR ratio,§ so we＊re definitely
in the same ballpark =).</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">I＊d like to apply/paraphrase
your advice to a few conditions to be sure I＊m getting it correctly: </font>
<p><font size=2 color=#004080 face="Calibri">-</font><font size=1 color=#004080 face="Times New Roman">
</font><font size=2 color=#004080 face="Calibri">If
we create all 3 custom curves, and normalize each to a point at maximum
(not design) capacity, then the design-to-max ratio (DESIGN-PLR) should
be set to 1.00.</font>
<p><font size=2 color=#004080 face="Calibri">-</font><font size=1 color=#004080 face="Times New Roman">
</font><font size=2 color=#004080 face="Calibri">If
we create <u>only</u> the part load efficiency curve (EIR-FPLR or EIR-FPLR&dT),
and wish to use the library defaults for EIR-FT and CAP-FT, then we should
normalize this curve＊s data points to ARI conditions (as that＊s what
the library curves are normalized to, per James＊s email 每 I think I＊ve
read this somewhere also), specify an ARI capacity, EIR and conditions
on the basic specifications tab, and enter a DESIGN-PLR of [ARI capacity/maximum
capacity (for the same conditions)].</font>
<p><font size=2 color=#004080 face="Calibri">-</font><font size=1 color=#004080 face="Times New Roman">
</font><font size=2 color=#004080 face="Calibri">If
we create all 3 custom curves, and try to normalize each to either ARI
or design conditions, then we should specify capacity, EIR, CHWT, CWT and
condenser GPM corresponding to either the ARI or design conditions of that
normalizing point. In that case, we also specify a DESIGN-PLR using
either the ARI or design capacity divided by the maximum capacity for the
same conditions.</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri"><u>Profound (to me) Conclusion</u>:
In <u>No</u> instance should we <u>Ever</u> attempt creating custom
curves and NOT have at least one run from our manufacturer telling us what
the maximum (not design) capacity is for the normalizing point. This
conclusion would only apply to centrifugal chillers only.</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">Does this all sound right?</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">~Nick</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">James, </font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">Yeah, if all the part load
data you received held the same CHWT and CWT equal, you might be able to
make your part-load curve if it could have been a quadratic EIR-FPLR curve
(like a reciprocating chiller), but not a bi-quadratic EIR-FPLR&dT
(as with my centrifugal VSD chiller). You definitely could not approach
generating custom EIR-FT or CAP-FT curves without varying condenser and
chilled water temps. That exact issue happened to me the first few
times I tried to reign my chiller reps in =). </font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">This time, I convinced my
rep to give me multiple part load runs holding the CHWT constant and varying
the CWT incrementally. This let me build the bi-quadratic EIR-FPLR&dT
curve as I had at least three different dT＊s represented in my part load
data points. I plotted the 3D curve in excel to check my work and
darned if the generated coefficients seem to be really accurate =)!
It＊s currently looking like a bittersweet revelation however 每 the library
curve for a water-cooled centrifugal VSD chiller (see attached visualization)
seems a LOT more generous (more efficient) at low part loads than the one
I＊ve generated which matches my rep＊s data＃ I might share a visual
of my custom curve for comparison once I＊m dead-sure it＊s accurate 每
I＊m trying to clarify a few things with my rep right now.</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">~Nick</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<br>
<p><font size=2 color=#37605e face="Stylus BT"><b> </b></font>
<p><font size=2 color=#37605e face="Stylus BT"><b>NICK CATON, E.I.T.</b></font>
<p><font size=1 color=#bfbf00 face="Calibri">PROJECT ENGINEER</font>
<p><font size=2 color=#37605e face="Calibri">25501 west valley parkway</font>
<p><font size=2 color=#37605e face="Calibri">olathe ks 66061</font>
<p><font size=2 color=#37605e face="Calibri">direct 913 344.0036</font>
<p><font size=2 color=#37605e face="Calibri">fax 913 345.0617</font>
<p><font size=2 color=#37605e face="Calibri"><i>Check out our new web-site
@ </i></font><a href=http://www.smithboucher.com/ target=_blank><font size=2 color=blue face="Calibri"><u>www.smithboucher.com</u></font></a><font size=2 color=blue face="Calibri"><u>
</u></font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<br><font size=2 face="Tahoma"><b>From:</b> John T. Forester [mailto:</font><a href=mailto:JohnTF@BVHis.com target=_blank><font size=2 color=blue face="Tahoma"><u>JohnTF@BVHis.com</u></font></a><font size=2 face="Tahoma">]
<b><br>
Sent:</b> Wednesday, November 03, 2010 10:29 AM<b><br>
To:</b> Nick Caton; </font><a href="mailto:equest-users@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users@lists.onebuilding.org</u></font></a><font size=2 face="Tahoma"><b><br>
Subject:</b> RE: [Equest-users] Chiller Curves (oh boy!)</font>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=2 color=#000080 face="Arial">Nick,</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">When defining a centrifugal
chiller in eQuest, one of the items on the Basic Specifications tab under
the Design vs. Rated Conditions is a Design/Max Cap ratio. By default,
this is 92% for a water cooled unit. I believe this gets at the discussion
in the help pages that talks about maximum capacity versus design capacity
and how the chiller vendor will spec a piece of equipment. Typically,
vendors don＊t often get asked (or provide) what the ※Maximum§ capacity
of a spec＊d unit is. Therefore the performance data that they provide
are at ※design conditions.§</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">If you change the chiller type
to a reciprocating chiller, this ※Design/Max Cap§ ratio is disabled and
the default specified condition changes from ※Design Conditions§ to ※Rated
Conditions.§ This suggests that there is little ※extra§ capacity
when a selection is done for that type of chiller.</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">If you do get ※maximum capacity§
data and create curves from that data, you will want to change the Design/Max
Cap ratio to 1.0 so eQuest knows that there isn＊t any spare capacity at
the chiller. Also if the data points you are using to normalize your
curves are different than the design conditions for your energy model,
you will want to change the ※Chiller Specified at§ value to ※Rated Conditions§
and enter the rated conditions for CHW temp, CW temp and CW gpm/ton to
match your normalized curves.</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">Hope this helps,</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<p><font size=2 color=#000080 face="Arial">John</font>
<p><font size=2 color=#000080 face="Arial"> </font>
<br><font size=1 color=#808080 face="Arial">John T. Forester, P.E., LEED
AP, Mechanical Design Engineer </font><font size=1 color=#0000a1 face="Arial"><b>I
BVH Integrated Services I</b></font><font size=1 face="Arial"><b> </b></font><font size=1 color=#808080 face="Arial">617.658.9008
tel </font><font size=1 color=#0000a1 face="Arial"><b>I</b></font><font size=1 color=#808080 face="Arial"><b>
</b>617.244.3753 fax</font><font size=1 color=#0000a1 face="Arial"> <b>I</b></font><font size=1 color=#808080 face="Arial"><b>
</b>One Gateway Center Suite 506, Newton MA 02458 </font><font size=1 color=#0000a1 face="Arial"><b>I
</b></font><a href=http://www.bvhis.com/ target=_blank><font size=1 color=blue face="Arial"><b><u>www.bvhis.com</u></b></font></a><font size=1 color=#0000a1 face="Arial"><b>
I Hartford ♂ New Haven ♂ Boston</b></font>
<div align=center>
<br><font size=3 face="Times New Roman"><hr size=2 width="100%"
align=center tabindex=-1> </font></div>
<p><font size=2 face="Tahoma"><b>From:</b> </font><a href="mailto:equest-users-bounces@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users-bounces@lists.onebuilding.org</u></font></a><font size=2 face="Tahoma">
[mailto:</font><a href="mailto:equest-users-bounces@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users-bounces@lists.onebuilding.org</u></font></a><font size=2 face="Tahoma">]
<b>On Behalf Of </b>Nick Caton<b><br>
Sent:</b> Wednesday, November 03, 2010 11:03 AM<b><br>
To:</b> Carol Gardner; </font><a href="mailto:equest-users@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users@lists.onebuilding.org</u></font></a><font size=2 face="Tahoma"><b><br>
Subject:</b> Re: [Equest-users] Chiller Curves (oh boy!)</font>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=2 color=#004080 face="Calibri">Thanks for the response Carol!</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">That 120% load case is what
I＊m getting at 每 let me try to explain a little further:</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">In the DOE2 help files, the
vocabulary for centrifugal chillers is ※design capacity§ and ※maximum
capacity,§ where ※design§ means the capacity at the rated or designed
conditions (at which you define / specify your chiller), and ※maximum§
means the capacity the chiller is really capable of under the same conditions
if it runs balls-out (maximum power to the refrigerant drive).</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">The help file excerpt I copied
below with the red line is pretty explicitly telling us to normalize the
part load values to the <u>maximum</u> capacity for centrifugal chillers.
I＊ve highlighted a second line for clarity. The EDR guidelines
I linked below are saying you can instead normalize to the <u>design</u>
capacity for the EIR-PLR curve if that＊s all your field measurements or
manufacturer rep can provide.</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">I＊m asking 每 are both approaches
right? </font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">My first and second questions
are kinda tied together＃ How would choosing to normalize to either the
maximum or design conditions affect how we should handle the DESIGN-PLR
ratio, if at all?</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p><font size=2 color=#004080 face="Calibri">~Nick.</font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<p>
<p><font size=2 color=#37605e face="Stylus BT"><b> </b></font>
<p><font size=2 color=#37605e face="Stylus BT"><b>NICK CATON, E.I.T.</b></font>
<p><font size=1 color=#bfbf00 face="Calibri">PROJECT ENGINEER</font>
<p><font size=2 color=#37605e face="Calibri">25501 west valley parkway</font>
<p><font size=2 color=#37605e face="Calibri">olathe ks 66061</font>
<p><font size=2 color=#37605e face="Calibri">direct 913 344.0036</font>
<p><font size=2 color=#37605e face="Calibri">fax 913 345.0617</font>
<p><font size=2 color=#37605e face="Calibri"><i>Check out our new web-site
@ </i></font><a href=http://www.smithboucher.com/ target=_blank><font size=2 color=blue face="Calibri"><u>www.smithboucher.com</u></font></a><font size=2 color=blue face="Calibri"><u>
</u></font>
<p><font size=2 color=#004080 face="Calibri"> </font>
<br><font size=2 face="Tahoma"><b>From:</b> Carol Gardner [mailto:</font><a href=mailto:cmg750@gmail.com target=_blank><font size=2 color=blue face="Tahoma"><u>cmg750@gmail.com</u></font></a><font size=2 face="Tahoma">]
<b><br>
Sent:</b> Tuesday, November 02, 2010 10:04 PM<b><br>
To:</b> Nick Caton<b><br>
Cc:</b> </font><a href="mailto:equest-users@lists.onebuilding.org" target=_blank><font size=2 color=blue face="Tahoma"><u>equest-users@lists.onebuilding.org</u></font></a><font size=2 face="Tahoma"><b><br>
Subject:</b> Re: [Equest-users] Chiller Curves (oh boy!)</font>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=3 face="Times New Roman">Let me take a crack at this. If
by design capacity you mean the chiller running at 100% load, you would
create the curve(s) by normalizing around your ARI design conditions i.e.
the PLR curve would be 1.0 at this point, call it ARI Cap and the other
points would be 90% Cap/ARI Cap, 80% Cap/ARI Cap, etc. The same would go
for your temp curves. If, however, your chiller is operating at 120%, or
some such other level, I would normalize the curve around the ARI design
conditions of the chiller at 120%. I had to do this for a VRV hp that was
selected at the 120% design condition.<br>
<br>
I find this from the DOE2 manual the most helpful:</font>
<br><font size=3 face="Times New Roman"> </font>
<br><a href=http://volume2dictionary.htm/ target=_blank><font size=3 color=blue face="Times New Roman"><u>Volume
2: Dictionary</u></font></a><font size=3 face="Times New Roman"> > </font><a href=http://hvaccomponents.htm/ target=_blank><font size=3 color=blue face="Times New Roman"><u>HVAC
Components</u></font></a><font size=3 face="Times New Roman"> > </font><a href=http://curvefit.htm/ target=_blank><font size=3 color=white face="Times New Roman"><u>CURVE</u></font><font size=3 color=blue face="Times New Roman"><u>-</u></font><font size=3 color=white face="Times New Roman"><u>FIT</u></font></a><font size=3 face="Times New Roman">
> </font><a href=http://inputtypedata.htm/ target=_blank><font size=3 color=blue face="Times New Roman"><u>INPUT-TYPE
= DATA</u></font></a>
<p><font size=2 face="Times New Roman"><b>INDEPENDENT-2</b></font>
<p><font size=3 face="Times New Roman">Used for all </font><font size=3 color=white face="Times New Roman">curves</font><font size=3 face="Times New Roman">
having two independent variables. A list of up to twenty values of the
second independent variable. The number of values should be the same as
for DEPENDENT.</font>
<p><font size=3 face="Arial"><b>Example 1</b></font><font size=3 face="Roman">:
defining a </font><font size=3 color=white face="Roman">curve</font><font size=3 face="Roman">
by inputting a set of data points.</font>
<p><font size=3 face="Times New Roman">A packaged system (PZS) has cooling
performance significantly different from that used in the default model.
The manufacturer lists the data shown in Table 46, for cooling capacity,
at 2000 cfm design air flow rate, as a function of outside dry-bulb temperature
and entering wet-bulb temperature.</font>
<p><a name=12c12a536c514b6a__Ref490744859></a><a name=12c12a536c514b6a__Ref490744804></a><font size=3 face="Times New Roman">Table
46 Cooling capacity (kBtu/hr) vs. temperature</font>
<p>
<table border=3 align=center>
<tr valign=top>
<td rowspan=2 bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>Outside<br>
Dry-bulb</b></font></div>
<td colspan=3 bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>Entering Wet-bulb</b></font></div>
<tr valign=top>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>72F</b></font></div>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>67F</b></font></div>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>62F</b></font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">85F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">69</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">65</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">60</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">95F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">68</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">63 (ARI)</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">57</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">105F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">65</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">60</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">53</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">115F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">62</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">55</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">49</font></div></table>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=3 face="Times New Roman">In this example the independent
variables are the entering wet-bulb temperature and the outside dry-bulb
temperature. Because there are two independent variables and they have
units of temperature, we input a </font><font size=3 color=white face="Times New Roman">curve</font><font size=3 face="Times New Roman">
of TYPE BI-QUADRATIC-T using the given data points. The dependent variable
is not the cooling capacity listed in the table but rather the cooling
capacity divided by the cooling capacity at the ARI rating point (95 F
outside dry-bulb and 67 F entering wet-bulb). In other words, the capacities
should be normalized to the ARI rating point., as shown in Table 47</font>
<p><a name=12c12a536c514b6a__Ref490745029></a><font size=3 face="Times New Roman">Table
</font><font size=3 face="Roman">47 Normalized capacity vs. temperature</font>
<p>
<table border=3 align=center>
<tr valign=top>
<td rowspan=2 bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>Outside<br>
Dry-bulb</b></font></div>
<td colspan=3 bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>Entering Wet-bulb</b></font></div>
<tr valign=top>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>72F</b></font></div>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>67F</b></font></div>
<td bgcolor=#00ffff>
<div align=center><font size=3 face="Times New Roman"><b>62F</b></font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">85F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">1.095</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">1.032</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.952</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">95F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">1.079</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">1.0 (ARI)</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.905</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">105F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">1.032</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.952</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.841</font></div>
<tr valign=top>
<td>
<div align=center><font size=3 face="Times New Roman">115F</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.984</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.873</font></div>
<td>
<div align=center><font size=3 face="Times New Roman">0.778</font></div></table>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=3 face="Times New Roman">The </font><font size=3 color=white face="Times New Roman">CURVE</font><font size=3 face="Times New Roman">-</font><font size=3 color=white face="Times New Roman">FIT</font><font size=3 face="Times New Roman">
input will look like the following:</font>
<p><font size=3 face="Times New Roman">CAP-</font><font size=3 color=white face="Times New Roman">CURVE</font><font size=3 face="Times New Roman">-1
= </font><font size=3 color=white face="Times New Roman">CURVE</font><font size=3 face="Times New Roman">-</font><font size=3 color=white face="Times New Roman">FIT</font><font size=3 face="Times New Roman"><br>
TYPE = BI-QUADRATIC-T<br>
INPUT-TYPE = DATA<br>
DEPENDENT = (1.000,1.079,0.905,1.032,0.952,0.841,<br>
0.984,0.873,0.778,1.095,1.032,0.952) ..<br>
IN-TEMP1 = ( 67, 72,
62, 72, 67, 62,<br>
72, 67, 62, 72, 67, 62)
..<br>
IN-TEMP2 = ( 95, 95,
95, 105, 105, 105,<br>
115, 115, 115, 85 85,
85) ..</font>
<p><font size=3 face="Arial"><b>Example 2:</b></font><font size=3 face="Roman">
Defining a </font><font size=3 color=white face="Roman">curve</font><font size=3 face="Roman">
by inputting coefficients</font>
<p><font size=3 face="Times New Roman">We want a furnace to have a constant
efficiency as a function of part load. To do this we must replace the default
FURNACE-HIR-FPLR with a </font><font size=3 color=white face="Times New Roman">curve</font><font size=3 face="Times New Roman">
that will give a constant efficiency. The </font><font size=3 color=white face="Times New Roman">curve</font><font size=3 face="Times New Roman">
TYPE is QUADRATIC in the part load ratio (PLR). PLR correction </font><font size=3 color=white face="Times New Roman">curves</font><font size=3 face="Times New Roman">
are always multiplied by the unit capacity, not the load, to obtain the
energy (fuel or electricity) use. Thus the </font><font size=3 color=white face="Times New Roman">curve</font><font size=3 face="Times New Roman">
we want is: 0.0 + 1.0*PLR + 0.0*PLR*PLR. The input will look like:</font>
<p><font size=3 face="Times New Roman">New-Furnace-HIR-fPLR = </font><font size=3 color=white face="Times New Roman">CURVE</font><font size=3 face="Times New Roman">-</font><font size=3 color=white face="Times New Roman">FIT</font><font size=3 face="Times New Roman"><br>
TYPE = QUADRATIC<br>
INPUT-TYPE = COEFFICIENTS<br>
COEFFICIENTS = (0.0,1.0,0.0) ..</font>
<p><font size=3 face="Times New Roman">Then in the SYSTEM command we include:</font>
<p><font size=3 face="Times New Roman"> FURNACE-HIR-FPLR =
New-Furnace-HIR-fPLR</font>
<p><font size=3 face="Times New Roman"> </font>
<br><font size=3 face="Times New Roman">On Tue, Nov 2, 2010 at 3:21 PM,
Nick Caton <</font><a href=mailto:ncaton@smithboucher.com target=_blank><font size=3 color=blue face="Times New Roman"><u>ncaton@smithboucher.com</u></font></a><font size=3 face="Times New Roman">>
wrote:</font>
<br><font size=3 color=#004080 face="Times New Roman">Hi everyone!</font>
<p><font size=3 color=#004080 face="Times New Roman"> </font>
<p><font size=3 color=#004080 face="Times New Roman">I think I have <u>finally</u>
wrapped my mind completely around custom chiller performance curves for
a centrifugal VSD chiller. I＊ve got a few specific questions now
that I＊m on the other side of the fence:</font>
<p><font size=3 color=#004080 face="Times New Roman"> </font>
<p><font size=3 color=#004080 face="Times New Roman">1.</font><font size=1 color=#004080 face="Roman">
</font><font size=3 color=#004080 face="Roman">Is
it necessary for the data points of a part load efficiency curve (EIR-FPLR&dT
in my case) to originate from data with a 1.0 (100%) PLR ratio corresponding
to a maximum vs. a design load capacity? From what I gather in </font><a href=http://www.energydesignresources.com/Portals/0/documents/DesignGuidelines/EDR_DesignGuidelines_%20HVAC_Simulation.pdf target=_blank><font size=3 color=blue face="Roman"><u>the
EDR reference</u></font></a><font size=3 color=#004080 face="Roman"> (re:
※Method 2§ on PDF page 32/65), this curve can be generated using part-load
readings assuming a <u>design</u> capacity at the 100% loading mark＃ but
the DOE2 help entry for ※EIR-FPLR§ seems to suggest otherwise (copied
below 每 see highlighted line).</font>
<p><font size=3 color=#004080 face="Times New Roman">2.</font><font size=1 color=#004080 face="Roman">
</font><font size=3 color=#004080 face="Roman">If
the above part load efficiency curve is created based on data where the
100% loading point corresponds to the maximum (not design) capacity, should
※DESIGN-PLR§ (the ratio of design to maximum capacity) be set to 1.00
and the capacity of the chiller be specified at its maximum (not design)
for the design/rated conditions? As I write this question it sounds
like I＊m chasing my tail 每 someone straighten me out =)!</font>
<p><font size=3 color=#004080 face="Times New Roman">3.</font><font size=1 color=#004080 face="Roman">
</font><font size=3 color=#004080 face="Roman">When
you veterans finish a project with sets of custom performance curves, do
you have any suggestions for a naming scheme for future reference/re-use?
I＊m currently thinking to keep the curves grouped in an .inp snippet
I for importing along with an equipment cutsheet＃ but I＊m certain I＊ll
forget the all the details as quickly as humanly possible when this project
is behind me＃</font>
<p><font size=3 color=#004080 face="Times New Roman"> </font>
<p><font size=3 color=#004080 face="Times New Roman"> ~Nick</font>
<p><font size=3 color=#004080 face="Times New Roman"> </font>
<br>
<p><font size=3 color=#37605e face="Times New Roman"><b> </b></font>
<p><font size=3 color=#37605e face="Times New Roman"><b>NICK CATON, E.I.T.</b></font>
<p><font size=1 color=#bfbf00 face="Times New Roman">PROJECT ENGINEER</font>
<p><font size=2 color=#37605e face="Times New Roman">25501 west valley
parkway</font>
<p><font size=2 color=#37605e face="Times New Roman">olathe</font><font size=2 color=#37605e face="Roman">
ks 66061</font>
<p><font size=2 color=#37605e face="Times New Roman">direct 913 344.0036</font>
<p><font size=2 color=#37605e face="Times New Roman">fax 913 345.0617</font>
<p><font size=2 color=#37605e face="Times New Roman"><i>Check out our new
web-site @ </i></font><a href=http://www.smithboucher.com/ target=_blank><font size=2 color=blue face="Roman"><u>www.smithboucher.com</u></font></a><font size=2 color=blue face="Roman"><u>
</u></font>
<p><font size=2 face="Times New Roman"><b>EIR-FPLR</b></font>
<p><font size=3 face="Times New Roman">Takes the U-name of a curve that
adjusts the electric input ratio as a function of</font>
<p><font size=3 face="Symbol">﹞ </font><font size=3 face="Roman"><u>The
part load ratio (PLR)</u> 每 The PLR is defined as the ratio of the
hourly load to the hourly capacity; Load / Cap<sub>hour</sub></font>
<p><font size=3 face="Symbol">﹞ </font><font size=3 face="Roman"><u>The
evaporator/condenser dT</u> - The temperature differential between
the condenser and leaving chilled-water. The meaning of the condenser
temperature varies according to condenser type. </font>
<p><font size=3 face="Times New Roman">For most chillers, the dT has a
relatively small effect on part-load performance. However, for variable-speed
centrifugal chillers, the effect of dT is as important as the PLR. This
is because the pressure rise across the impeller is proportional to the
square of the impeller＊s speed. Unless some form on condenser temperature
relief is employed to reduce the temperature (and pressure) differential
across the chiller at part load, the performance of a variable-speed chiller
may not be significantly different than that of a constant-speed chiller.</font>
<p><font size=3 face="Times New Roman">To model power consumption as a
function of the PLR only, use a CURVE-FIT of TYPE = QUADRATIC or CUBIC.
To model as a function of both PLR and dT, use a BI-QUADRATIC-RATIO&DT
curve. </font><font size=3 color=red face="Times New Roman"><b>The curve
must be normalized to 1.0 at full load and the rated temperature differential.
</b></font>
<p><font size=3 color=red face="Times New Roman"><b>Note that, for centrifugal
chillers, ＆full load＊ is defined as the ＆maximum capacity＊, not the
＆design capacity＊.</b></font><font size=3 face="Roman"> Refer to the
DESIGN-PLR keyword for more information.</font>
<p><font size=3 face="Times New Roman"> </font>
<p><font size=3 face="Times New Roman"><br>
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<p><font size=3 face="Times New Roman"><br>
<br>
<br>
-- <br>
Carol Gardner PE</font>
<br><font size=3 face="Roman"><br>
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<br><font size=3 face="Roman"><br>
<br>
<br>
-- <br>
Carol Gardner PE</font>
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