[Equest-users] Question: Modeling Specific Chillers
Philip Kennedy
philip at kiltechcontrols.com
Thu Sep 19 10:39:13 PDT 2013
I suggest taking a look at the Taylor Engineering website, they used to
have an excel sheet with a considerable amount of VBA code in the back end
that generated the DOE coefficients for constant speed, variable speed and
chiller systems that utilize variable condenser water flow rate (requires
equation to be solved for Cwrt not Cwst).
Regards Phiip
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*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *Jeremy
McClanathan
*Sent:* September-19-13 1:32 PM
*To:* 'Hall, Brendan'; 'Sunil Nair'; 'David Eldridge'
*Cc:* 'equest-users at lists.onebuilding.org'
*Subject:* Re: [Equest-users] Question: Modeling Specific Chillers
As a word of caution, I tried going down that road before and ended up not
being able to use the E+ curves. The parameters from a bi-quadratic
equation in metric units cannot be used in eQuest. As Brendan mentioned,
you would have to convert to Fahrenheit. I would imagine this would
require backing out the parameters necessary to construct a curve from the
metric equations, converting to US units, then reconstructing a curve. I
don’t know this for a fact though.
Cheers,
Jeremy
*___________________________________________*
*Jeremy McClanathan*, P.E., BEMP, HFDP, LEED® AP
*[image: CDi_Engineers_logo_color.jpg]***
19203 36th Avenue W, Suite 200, Lynnwood, WA 98036**
P 425-672-1071 | F 425-778-8769
P *Please consider the environment before printing this email.*
*From:* Hall, Brendan [mailto:BHall at karpinskieng.com]
*Sent:* Thursday, September 19, 2013 10:14 AM
*To:* Jeremy McClanathan; 'Sunil Nair'; 'David Eldridge'
*Cc:* 'equest-users at lists.onebuilding.org'
*Subject:* RE: [Equest-users] Question: Modeling Specific Chillers
In general, there is also a database of chiller curves that is provided for
energyplus that I believe are also valie for eQuest if you convert them
into Fahrenheit temperatures. If the one in questions happens to be on that
list it could be helpful.
http://simulationresearch.lbl.gov/modelica/releases/latest/help/Buildings_Fluid_Chillers_Data_ElectricEIR.html
Brendan Hall
*From:* equest-users-bounces at lists.onebuilding.org [
mailto:equest-users-bounces at lists.onebuilding.org<equest-users-bounces at lists.onebuilding.org>]
*On Behalf Of *Jeremy McClanathan
*Sent:* Thursday, September 19, 2013 12:58 PM
*To:* 'Sunil Nair'; 'David Eldridge'
*Cc:* 'equest-users at lists.onebuilding.org'
*Subject:* Re: [Equest-users] Question: Modeling Specific Chillers
Hello Sunil,
It sounds like the manufacturer may be trying to get you a capacity for a
given set of condenser and evaporator temperatures. What you need is the
manufacturer to tell you what the full load (and part load) capacities of
the machine are with the lift conditions you specified. So, for higher
lift conditions, the machine will have lower capacities. He doesn’t need
to match the capacity you selected the chiller at to all the lift
conditions you specify.
If it helps, the spreadsheet I use to generate custom chiller curves can be
downloaded from here:
*
http://www.esimforums.com/equest/viewtopic.php?f=13&t=116&start=0&view=viewpoll
*
Cheers,
Jeremy
*___________________________________________*
*Jeremy McClanathan*, P.E., BEMP, HFDP, LEED® AP
*[image: CDi_Engineers_logo_color.jpg]***
19203 36th Avenue W, Suite 200, Lynnwood, WA 98036**
P 425-672-1071 | F 425-778-8769
P *Please consider the environment before printing this email.*
*From:* Sunil Nair
[mailto:energymodel.sunil at gmail.com<energymodel.sunil at gmail.com>]
*Sent:* Wednesday, September 18, 2013 9:55 PM
*To:* David Eldridge
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Question: Modeling Specific Chillers
I think I am hitting a roadblock here, trying to get the necessary data to
model the chillers. I have gone through the EDR document on simulating HVAC
systems and other posts on modeling chillers here on the mailing list. I
think I can get the part load data from the manufacturer.
Trying to get the full load data has been difficult though. The chiller
manufacturer tells me that if I want the full load capacity at reduced
condenser entering and/or higher evaporator leaving temperatures, he can
only provide up to about 5% higher capacity than design capacity. Beyond
this he will need to change the expansion device in his selection software
to get the total capacity. I don't believe changing the expansion device is
the right way to go.
I have attached a sample data sheet with various data points that I thought
I should get from the manufacturers. The data points I have in the sheet
are what will be practically seen in operation here. However they are all
lower than the design temperatures of the chiller. I'm not sure if I am
going in the right direction with this one.
Any inputs are appreciated.
Thanks,
Sunil Nair
*Ab Initio*
TMA House, Plot No. 6, 2nd Floor,
Main Road, Wagle Industrial Area,
Thane (West) - 400 604
Ph: +91-22 - 3243 7023
Cell: +91-8879595123
web: www.abinitio.co.in
On Fri, Aug 16, 2013 at 7:25 PM, David Eldridge <DEldridge at grummanbutkus.com>
wrote:
You should be able to look at the manufacturer data plotted vs ECWT and
load and determine if a single set of curves (one modeled chiller) or two
are needed to accurately model power usage by the chiller over the range of
load. (if you can get the data)
*
*
David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
*Grumman/Butkus Associates*
*
*
*From:* Sunil Nair [mailto:energymodel.sunil at gmail.com]
*Sent:* Thursday, August 15, 2013 11:40 PM
*To:* Busman, Michael R
*Cc:* David Eldridge; equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Question: Modeling Specific Chillers
Dave and Mike,
Thanks for your inputs.
Mike,
Yes, I am referring to the multistage chiller where the liquid is flashed
to the inlet of the second stage impeller. As you have mentioned this
process is internal to the chiller.
My thought initially was I may have to model multiple compressors per
circuit for a chiller without VFD. I did not find this option in eQUEST. As
I think about it now, my case would be quite different from having multiple
compressors per circuit.
I am in the process of obtaining data points for the chiller from the
manufacturer so I can input the data points into eQUEST.
I'll keep this thread updated.
Sincerely,
Sunil Nair
*Ab Initio*
TMA House, Plot No. 6, 2nd Floor,
Main Road, Wagle Industrial Area,
Thane (West) - 400 604
Ph: +91-22 - 3243 7023
Cell: +91-8879595123
web: www.abinitio.co.in
On Wed, Aug 14, 2013 at 10:56 PM, Busman, Michael R <MBusman at chevron.com>
wrote:
Sunil,
My understanding of an economizer for a multi-stage centrifugal is that
some of the liquid refrigerant flashes as it passes through the expansion
device. This flash gas, I believe is introduced to the input side of the
second stage impeller. Since the economizer is internal to the chiller,
one set of curves should be sufficient as there is only one mode of
operation as I understand it. You didn’t specify, so I’m assuming you are
not referring to a water-side economizer.
I haven’t custom defined a chiller yet in eQUEST, however, it appears that
several performance data points from the manufacturer are required for
eQUEST to generate the curves if you select this method. The other is to
generate your own curves. Many years ago when I used to work in VisualDOE,
I found the calculation methodology to define chiller curves from the
Pacific Gas & Electric web site, which I used to set up a spreadsheet to
calculate the curve coefficients. This was originally set up for constant
speed chillers. A number of months ago I added a spreadsheet tab to handle
variable speed chillers. To create the 3 sets of curve coefficients, at
least 10 full load data points at different chilled and condenser water
temperatures were required from the manufacturer in order to map the
compressor. There was no max or min limit for the part-load data points as
I recall.
If you’d like a copy of the spreadsheet, I can email it to you, however,
you might want to check the eQUEST manual or DOE-2.2 reference manuals
regarding directly entering data points into eQUEST and let the program
figure out the curves for you.
My best,
Mike Busman
*Michael R. Busman, CEM*
Lead Project Engineer II
*Chevron Energy Solutions*
A Division of Chevron U.S.A., Inc.
145 S. State College Blvd.
Brea, CA 92821
Direct 714-671-3561
Fax 714-671-3438
eFax 866-420-0335 (Include my Full Name followed by "CAI:MHTZ" on Cover
Sheet)
Mobile 310-387-2083
mbusman at chevron.com
*From:* equest-users-bounces at lists.onebuilding.org [mailto:
equest-users-bounces at lists.onebuilding.org] *On Behalf Of *David Eldridge
*Sent:* Wednesday, August 14, 2013 9:46 AM
*To:* Sunil Nair
*Cc:* equest-users at lists.onebuilding.org
*Subject:* Re: [Equest-users] Question: Modeling Specific Chillers
When the chiller runs on economizer it will use a separate set of curves
and be modeled as a distinct chiller.
One set of curves will be difficult to model both modes of operation.
DSE Mobile
On Aug 14, 2013, at 11:34 AM, "Sunil Nair" <energymodel.sunil at gmail.com>
wrote:
Hi All,
I have a couple of questions with respect to modeling specific chillers.
1) I am trying to model a centrifugal chiller with an economizer. The
chiller in question is a centrifugal chiller running on R123 with an
economizer installed to it. Do I just need to get data from the chiller
manufacturer and input the curves into the model? Is this the right way to
go?
2) How do you model multi stage centrifugal chillers without VFD's?
Thanks,
Sunil Nair
*Ab Initio*
TMA House, Plot No. 6, 2nd Floor,
Main Road, Wagle Industrial Area,
Thane (West) - 400 604
www.abinitio.co.in
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