Complex chiller/heat recovery/heat pump to model question

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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.? information is available in english for these models. Your local trane rep will probably not be able to help.

Paul Brooks's picture
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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

cmg750's picture
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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?

?

Paul Brooks's picture
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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

Matthew Dubrovich's picture
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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

Paul Brooks's picture
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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

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Hi Paul,

I think Matt is on to something. It does have options for both and you can
use Equip Control and maybe Load Management commands. This is heady stuff
for a newbie, however, so I would suggest you hire someone to do a peer
review with you or to work with you.

So, this is an existing building, right? You will also need to bill match,
etc. Where do you actually sit? In Uraguay?

Carol

cmg750's picture
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Carol:

I agree, and I am trying to digest all the info I am getting, and also plan on taking Pasha up on the offer of a phone call.? I also sent an email to Marlin, (trainer I had for eQuest).

The building is still on the drawing obpards, and is to be built in a duty-free office park in Montevideo, Uruguay.??I am in Richmond, VA.

?

Paul Brooks's picture
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I have talked to and received help from Pasha Korber-Gonzalez. I really
found her helpful (and a pleasure to talk with)

(A plug for her was the least I could do)

Jeurek's picture
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:) Thanks John--I'll send your tip in the mail.

Actually its nice to see that there are very few degrees of separation
between all of us. Carol has helped me, I've shown her a few tricks, and
the circles just keep going between all of us. It is our duty as
professionals to share our experiences and learn from each other only to
better the industry and educate our clients to the true value (and skills)
that are needed to provide quality simulation services.

We are all just trying to save our planet and improve the quality of life on
it.

Pasha :)

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Paul Brooks's picture
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I think Pasha rocks, too.

Carol

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