[Equest-users] Heat recovery chiller

[Molly Curtz]

Eric,
I was working on a similar problem a while ago. I was unable to find any way to control the heat recovery chiller operation based on the Hot Water Loop loads (chillers would only sequence on the chilled water loop load). I ended up going the route of manipulating hourly results data in a spreadsheet.
 
Good Luck, and if you do determine a way to accomplish this, please post to report.
 
Regards,
 
Molly Curtz, P.E.
Mechanical Engineer
 
Arup
403 Columbia St., Suite 220
Seattle, WA 98104
direct: 206 493 2234
tel: 206 749 9674 ext. 25534
fax: 206 749 0665
molly.curtz at arup.com
www.arup.com <http://www.arup.com/> 
 

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From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Eric O'Neill
Sent: Friday, August 21, 2009 6:39 AM
To: Xavier Garcia Casals
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Heat recovery chiller



Thanks for the response Xavier,

 

The cooling load is 24/7 and is located in an interior zone of a building located in a cold climate, so there are simultaneous heating and cooling periods. What I'm hoping to create is a system that will act much like a boiler, in that whenever the HW loop needs heat, the HTREC chiller runs and provides heat while cooling the chilled water loop. I added the HTREC chiller because it's supposed to be able to supply higher condensing water temperatures (which I need for my HW loops) than my other boilers are. The DOE2.2 documentation leads me to believe that this chiller would automatically sequence on whenever there is a heating load on the loop, but this doesn't seem to be the case. Even if I delete the HTREC chiller and make my other three chillers recover heat to the HW loop, none of them do. 

 

The coils on the condensing loop are for the waterside economizer. There is more than sufficient heat for heat recovery (cooling load>>heating load), so I still need an economizer, although I want it to be secondary. I don't know if I can sequence that. My guess now after thinking about it is that the system is economizing whenever there is a heating load, so the chillers don't sequence on. Is there a way to make the chillers run if there is a load on the HW loop, but economize the remainder?

 

Eric

 

From: Xavier Garcia Casals [mailto:xgcasals at telefonica.net] 
Sent: Friday, August 21, 2009 3:20 AM
To: Eric O'Neill
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Heat recovery chiller

 

Hi Eric,
Are you sure your heating load is simultaneous with the cooling load (is not enough to have cooling load all the year arround if it does not coincidence in time with the heating load: Chiller off)?. Also, did you check that when there is heating load the Htrc chiller is scheduled before than the other 3 chillers you have? Otherwise would be impossible to recover heat. What about those coils you have on the condensing loop? Aren't they taking away the heat you want to recover from the condenser?

En/na Eric O'Neill ha escrit: 

All,

I'm trying to model a hot water loop that's being heated entirely by a heat recovery chiller (htrec) and supplying heating to a VAV system. I'd like to utilize condenser heat prior to rejection to the dry coolers (I have a large cooling load year around). The trouble is, even though it appears like it is set up correctly, the system doesn't want to reject ANY heat to the HW loop. When I just created the loop and ran a simulation, eQuest gave me an error saying I had no primary heat source on the HW loop. I tried adding a dummy boiler with virtually no capacity, and that got rid of the error and allowed me to run, but I still had no heat going to my HW loop. 

Has anyone had success with this? When reading the DOE2.2 dictionary, it appears this is exactly what the htrec chiller was designed to do, but nothing I change makes any difference. If anyone's willing, I can send you a copy of my input and pd2 files to look at.

Thanks,

Eric O'Neill

Mechanical Engineer, LEEDAP

Michaels Engineering

400 Main Street, Ste 200

La Crosse, WI 54601

direct: 608-785-3328

main: 608-785-1900

fax: 608-784-2270

elo at michaelsengineering.com

http://www.michaelsengineering.com

<<Water Loops.png>> <<Heat Recovery Setup.png>> 

 

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-- 



 
Xavier García Casals
 
Tel: (+34) 91 843 19 85
Móvil: 660 22 94 45
xgcasals at telefonica.net
 
 

 

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