[Equest-users] Question: Modeling Specific Chillers

[Sunil Nair]

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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