[Equest-users] Centrifugal Chiller Curves

[Michael Busman]

Jordan,

In order to map the compressor properly for CAPFT you need to have the min. of 10 full load data points (tons, kW) at different leaving chilled and entering condenser water temps I discussed previously.

The chiller mfg. sales engineers have the software to run this for you.  They probably don’t want to if they think there’s nothing in it for them.  Tell them you have a project to install new chillers and the ability to properly model them will dictate whether you select Trane, Carrier, York, McQuay, etc. for the project.  You might also tell them that the level of cooperation and assistance will influence the selection decision.

If your project is an energy savings performance contract where savings are guaranteed and there will be M&V of the chiller (certified mfg. test report or field tested), you might want to degrade the fouling factors a bit to add some conservatism to your model.

My best,

Mike

Mike Busman, C.E.M.
Lead Project Engineer

765 The City Dr South Suite 475
Orange, CA 92868
T.   657-216-3261
M. 310.387.2083
mbusman at opterraenergy.com<mailto:mbusman at opterraenergy.com>

[OpTerra]<opterraenergy.com/>

[Facebook-icon]<https://www.facebook.com/OpTerra>[Twitter-icon]<https://twitter.com/OpTerraEnergy> [LinkedIn-icon] <https://www.linkedin.com/company/opterra-energy-group>  [Instagram-icon] <http://instagram.com/opterraenergy>  [GooglePlus-icon] <https://plus.google.com/+Opterraenergy/>




From: jordan jackson [mailto:jordanfrankjackson at gmail.com]
Sent: Wednesday, April 08, 2015 3:31 PM
To: Michael Busman; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Centrifugal Chiller Curves

Michael,

Thanks for the spreadsheet. That is definitely more elaborate than the one I put together.

I was able to successfully model air-cooled screws using the spreadsheet I attached, but the issue I'm running into with the water-cooled centrifugals is that the capacity provided by the rep does not change as a result of entering condenser water temperature. KW changes, but tonnage does not. This creates an unrealistic curve for CAPFT and EIRFT.

I'm at the mercy of the reps to provide this data and so far I have struck out. I was just curious if there was something I'm missing. Does something need to be held constant that will allow the capacity to change based on entering condenser water temperature and leaving chilled water temperature?

On a similarly frustrating note... I'm trying to come up with a workaround to model series chillers in eQuest with free cooling on the upstream chiller. From reading the DOE manual it seems waterside economizer won't do what I need it to since I can't be in WSE and supplementing with the downstream chiller. I considered combining performance of the two chillers into one machine, but I haven't totally figured out how that will work.

Any ideas are welcome.

Thanks,

Jordan Jackson.


On Tue, Apr 7, 2015 at 8:44 AM, Michael Busman <mbusman at opterraenergy.com<mailto:mbusman at opterraenergy.com>> wrote:
Jordan,

Many, many years ago I used to do a lot of modeling in VisualDOE.  I don’t do much in eQUEST or other simulation program anymore.

Anyway, I’ve attached a spreadsheet I put together way back when that is based on calculation methodology that was published by Pacific Gas & Electric.  If you look through the tabs you’ll see that I have some sample data that is used to calculate the curve coefficients.  Originally it was based on a constant speed chiller, however, a few years ago I added a tab for a variable speed chiller.

Don’t expect the manufacturers’ reps to produce the curves for you but they should be able to generate the data you need.  Key to this for reasons I don’t recall is that the reps need to generate at least 10 data points of full load data at different chilled and condenser water temperatures in order to map the chiller.  You will also need several part load data points at different water temps also.  If you give the reps the blank data sheet they should be able to run their software to generate the data you need.

Browse through the spreadsheet tabs and hopefully it will make sense to you.  Any questions, I’ll do my best to answer you, however, please remember that it’s been a long time since I’ve developed custom curves.

My best,

Mike


Mike Busman, C.E.M.
Lead Project Engineer

765 The City Dr South Suite 475
Orange, CA 92868
T.   657-216-3261<tel:657-216-3261>
M. 310.387.2083<tel:310.387.2083>
mbusman at opterraenergy.com<mailto:mbusman at opterraenergy.com>

[Image removed by sender. OpTerra]<http://opterraenergy.com/>

[Facebook-icon]<https://www.facebook.com/OpTerra>[Twitter-icon]<https://twitter.com/OpTerraEnergy> [LinkedIn-icon] <https://www.linkedin.com/company/opterra-energy-group>  [Instagram-icon] <http://instagram.com/opterraenergy>  [GooglePlus-icon] <https://plus.google.com/+Opterraenergy/>




From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org<mailto:equest-users-bounces at lists.onebuilding.org>] On Behalf Of jordan jackson
Sent: Monday, April 06, 2015 3:55 PM
To: equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>
Subject: [Equest-users] Centrifugal Chiller Curves

I have been using eQuest to evaluate chiller performance for retrofit projects. I have not had a problem modeling air-cooled, but I can't seem to get the data from the reps that I would like for water-cooled centrifugal projects. I have settled on using standard curves for CAPFT and EIRFT and using a cubic curve with coefficients created through a curve fit in excel for EIRFPLR.

The manufacturers reps aren't able to produce a capacity or EIR curve as a function of temperature (entering condenser water temp). Has this been everyone's experience with this.

I'm attaching the excel file I created to calculate all of this.

Any feedback is appreciated. I'm just concerned about the data I'm reporting to the client without touching those curves.

Thanks,

Jordan Jackson.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0005.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image007.png
Type: image/png
Size: 1983 bytes
Desc: image007.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0025.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image008.png
Type: image/png
Size: 2053 bytes
Desc: image008.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0026.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image009.png
Type: image/png
Size: 2158 bytes
Desc: image009.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0027.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image010.png
Type: image/png
Size: 2196 bytes
Desc: image010.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0028.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image011.png
Type: image/png
Size: 2245 bytes
Desc: image011.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0029.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image002.jpg
Type: image/jpeg
Size: 431 bytes
Desc: image002.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20150409/af14d611/attachment-0005.jpg>