Dear All,
I am using two different 2 pipe loops for both HW and CHW produced by a
ground coupled heat pump. Each of these loops is only in heating or
cooling mode throughout the year. This is necessary as eQuest requires a
2 pipe loop for modeling a chiller heat pump (although the CHW 2 pipe
loop might also have been a cooling loop - but the result does not change).
Attached is a simple model that features what I have just described. The
simulation run always gives the error that there is zero design flow in
the loops, whatever I try (I have tried using secondary loops as well
but did not work).
It would help me a lot if anyone could point out what could be wrong
with this set-up?
Best,
?mer Moltay, LEED AP BD+C, ASHRAE BEMP, ASHRAE CPMP
Mimta EcoYapi, LEED Proven Provider
Hekimsuyu Cad. 559. Sk.
No:39 34255 Kucukkoy Istanbul Turkey
Tel: 90-212-617-2296
Fax: 90-212-617-2297
Mobile: 90-533-957-1394
www.eco-yapi.com
Hello Omer:
FYI, I'd check the "samp" files, and/or other files on the DOE-2 web site that come with DOE-2.2. These are supposed to have examples of all the different types of systems.
Jeff
Jeff S. Haberl, Ph.D., P.E.inactive, FASHRAE,FIBPSA
Department of Architecture
Texas A&M University
College Station, TX 77845-3581
Office: 979-845-6507, Lab: 979-845-6065
Fax 979-862-2457
jhaberl at tamu.edu,www.esl.tamu.edu
Omer
It seems to me that a loop-to-loop heat pump would better represent the system you are describing.?? It can feed hot water and chilled water loops rather than requiring a 2-pipe loop to dictate whether it is in heating or cooling mode.?? Further,? it can respond to the higher of the heating or cooling loop loads.
Brian
Hi Jeff,
I saw your post about these sample files ("samp" files) and they
sound interesting and potentially very useful (I did not know they exist).
I could not find them on the DOE-2 website, can you please provide a link.
Thanks!
Christina
*Christina LaPerle* PE, BEMP, CEM, CBCP!
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On Sun, Jan 22, 2023 at 11:30 AM Haberl, Jeff via Equest-users <
Just to share one more fundamental approach that requires a little extra setup, but offers some unique flexibilities that I?ve had repeat success with:
Considering various limitations/restrictions inherent to DOE2 heat pump chillers, you can also effectively model (real-world) 2-pipe system in the energy model as a 4 pipe system. You would define the exact same pump/loop properties for both the heating and cooling loops, then just make an effort to schedule each loop in a fashion that will prevent simultaneous operation.
Commonly when emulating 2-pipe systems, a set of snap schedules is an ?ideal? control approach which is fine for getting through prescriptive/performance modeling efforts, however out in the real-world I have much more commonly encountered manual (not automated by temperature) heating/cooling season switchover processes. Those are more accurately modeled with calendar schedules to align with typical/historical changeover dates, and that may be easier than snap schedules ultimately if you need to define a ?no heat no cool? period where neither boilers or chillers are operated.
Sorry for digressing! Back to the modeling approach: You can alternatively/additionally schedule when heating/cooling is available from the airside systems). From there it can sometimes be easier to define waterside equipment effectively matching your real-world machine?s cooling & heating performance characteristics, separately.
This can all be a little more work than necessary for a given model/application, so I wouldn?t call it my ?Plan A,? but could be a useful strategy to keep in mind and try out sometime if you have the opportunity.
~Nick
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