[Equest-users] Complex chiller/heat recovery/heat pump to model question

Paul Riemer Paul.Riemer at dunhameng.com
Fri May 7 09:16:13 PDT 2010


Paul,
I have been lukewarm on air cooled chillers lately but the integral water side economizer coil options and now your heat recovery are interesting efficiency twists.

How you stage and control the chiller and the heat pumps will be an interesting challenge.

You started by asking the chiller so I will stick with that. (Plus I can't take the time to understand your full scenario).

Trane has a water side heat recovery application guide available on their website for purchase or you might be able to get it from the selling rep.
It is based on water cooled heat recovery chillers (which is why I am reading it today) but it may be valuable to you especially if they do not have one for your product.

My recollection is that is easy to plug heat into a DOE-2 model (as a process loads etc so) I think you need to focus on determining
1)  the cooling performance of the unit as you intend to operate it
2) the profile of heat available for recovery (magnitude and timing)
3) usable portion of that heat based on your heating load profile

To what temperature and how often are you going to maintain a condenser temperature higher than the outside air conditions would require so you can recover heat?
Answering that question may inform your modeling path and specifically your chiller selection (air cooled, air cooled with remote condenser, water cooled, heat recovery, etc)
The air cooled with remote condenser looks interesting for its purported ability to control condenser temperature.
Either way I expect you will need some creative sequencing and custom performance curves to model this.  Good luck,

Paul Riemer
Dunham


From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Brooks
Sent: Friday, May 07, 2010 11:09 AM
To: Matthew Dubrovich
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Complex chiller/heat recovery/heat pump to model question

Matt:

So far, I have not been able to model the chiller as such.  I am an advanced beginner modeler, and am not totally sure on what I can do in detail mode.  But, I had hoped I could...but it appeasr I cannot model the chiller in heat recovery

________________________________
From: Matthew Dubrovich <mdubrovich at emcengineers.com>
To: Paul Brooks <equestpaul at yahoo.com>
Cc: "equest-users at lists.onebuilding.org" <equest-users at lists.onebuilding.org>
Sent: Fri, May 7, 2010 11:57:57 AM
Subject: RE: [Equest-users] Complex chiller/heat recovery/heat pump to model question
Hi Paul,

Though I haven’t had the opportunity to use either yet, eQuest has options for both heat recovery chillers and heat pump chillers, correct?  You can tie the heat recovery chiller into your hot water loop and it should show both a heating savings and condenser fan savings (eliminating those hand calcs hopefully).  The heat pump chillers can be sequenced through Equipment Controls and Load Management to only come on as necessary, after the 165 ton chiller is maxed out.  Coupling the heat pumps with your hot water system may be more of a challenge.  Good luck.

Matt

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Paul Brooks
Sent: Friday, May 07, 2010 9:26 AM
To: Carol Gardner
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Complex chiller/heat recovery/heat pump to model question

Yes, I did.

Yes, it is an air-cooled Trane Chiller that has total energy recovery.  It is a non-US product, made by Trane in Europe.

The concept is that the chiller provids chilled water, and the energy recovery side provides hot water for reheat at VAV boxes when needed.

In addition, there are two heat pumps (reversible chillers as the liturature says)that will pprovide additional capacity to etther the chilled water loop or the hot water loop as needed.

This is for a 110,000 sf high end office building in Uruguay.  Uruguay is ASHRAE climate zone 3, similar to the US southeast, primarily Georga/northern Florida.

Links to product information:

Chiller with energy recovery:  http://doc.trane-eur.com/marketing/cdtrane.nsf/PdfByName/RLC-PRC026-E4_1205.pdf/$file/RLC-PRC026-E4_1205.pdf

Heat pumps:  http://doc.trane-eur.com/Marketing/CdTrane.nsf/PdfByName/CG-PRC015-E4_0708.pdf/$file/CG-PRC015-E4_0708.pdf

I am thinking i will need to do a lot of hand calcs for energy use of the chiller and how much "free" heating water I will get.  the hard part is going to be how to account for saving by not running condenser fans.  Yes, it will be a challenge to get it through GBCI review, but if the logic is sound, it will not be that hard.

Any suggestions on how to wet up a model in eQuest to minimize amount of hand calculations?



________________________________
From: Carol Gardner <cmg750 at gmail.com>
To: Paul Brooks <equestpaul at yahoo.com>
Cc: equest-users at lists.onebuilding.org
Sent: Fri, May 7, 2010 1:54:56 AM
Subject: Re: [Equest-users] Complex chiller/heat recovery/heat pump to model question

It looks like you stunned everyone into silence, Paul.

So you have 1) an air cooled chiller, 2) heat recovery sending HW to only your reheat coils, 3) 2 air cooled heat pumps that can also provide cool or hot water to circulation loops, 4)  french hens, and a partridge in a pear treee...OOPS, its late!

This looks like entropy to me. Try once more to share all of this. I would suggest an itemized list that identifies the equipment type, it's specific use, it's model no. etc. and any comments. Maybe an excel spreadsheet would work best.

Another issue: this project will be neigh on impossible for a LEED reviewer to review, too. That is neither good or bad, it just is.

I will help you as I can, when I can, but I must work for food too. Nobody pays me, yet, to help anyone.

Keep the faith,
Carol
On Thu, May 6, 2010 at 1:47 PM, Paul Brooks <equestpaul at yahoo.com<mailto:equestpaul at yahoo.com>> wrote:
I am modeling a building in Uruguay that has a Trane 165 ton Air cooled chiller, (RTAD 165 SE, not available in US.)  In addition to air-cooling, the chiller has a heat exchanger to recover heat for whatever use you want.   Obviously the heat recovery means that in the right condisitons the condenser fans will not run as much.

For this application, the heat is to be recovered to provide heating hot water VAV box re-heat coils.  In addition to this, there are two air cooled heat pumps (CXAN 214, not available in US) that are available to augment the chiller or the hot wateer loop.

So, my dilemma, is how to model this in eQuest. I am still more or less a novice user.  I am in the detail mode, and see that I can do some things with condenser water, but then how do I model the condenser fans?  How do I tie in the heat pump loops?

Lastly, this is a LEED model.  So, any thoughts on how to get data and then do hand calcs to prove savings are also welcome.

Thanks!

If interestede in seeing info on the equipment, go to Trane-eur.com<http://trane-eur.com/>.  information is available in english for these models. Your local trane rep will probably not be able to help.


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