[Equest-users] Water cooled VRF with DOAS

[Nicholas Caton]

Bryan:

I’ve poked around a bit over the last week.  Have a couple questions/prompts questions that may help you directly, or help others in advising you.

Can you assert:

  *   What are your expectations for what CW supply temps (seen @ each VRF for heat transfer) should look like as a function of season / conditions /etc?  You might in parallel want to look hard at what’s simulated in the moment.
  *   Please contrast the (intended) CW supply temps against the conditions used to assert the heating/cooling capacities entered for each VRF

I’ll also observe, as this may be tied to some of the unmet hours you’re tackling in the moment – you may have a few issues in your implementation of the dummy zone approach/workaround:

  *   Your VRF systems (as named) aren’t consistently using the OA-FROM-SYSTEM input, as may be intended
  *   Be mindful the DOAS system and its dummy zone are “in a bubble” with respect to the conditioning loads for the ventilation air.  If there is any humidity control to occur at the DOAS, you might struggle with such a high drybulb limit for economizer operations.   On the flip side, if it’s expected the DOAS will pass overly-humid air to the distributed cooling coils, I don’t think this workaround in doe2.2 will do the job of transmitting that latent load for you – it may be a manual process of defining some small process space saunas or similar ;-).

For all:  These nuances in VRF/DOAS implementation are part of the reason I really try to stress with friends to utilize the newer doe2.3 feature sets for VRF and DOAS when feasible.  In Bryan’s case, I don’t think waterside VRF has made the transition just yet… but I bring this up to make clear I am not endorsing doe2.2-era workarounds for DOAS/VRF where they are avoidable in this day and age.

~Nick

[cid:image004.jpg at 01D6432C.55CFEBC0]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Energy and Sustainability Services
  Energy Performance Contracting
D
M
E

913 . 564 . 6361
785 . 410 . 3317
nicholas.caton at se.com<mailto:nicholas.caton at se.com>
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219

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From: Equest-users <equest-users-bounces at lists.onebuilding.org> On Behalf Of Bryan Papaj via Equest-users
Sent: Tuesday, June 2, 2020 9:02 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Water cooled VRF with DOAS


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________________________________


Hello,

Hello,

I have a water-cooled VRF system with a DOAS. I modeled this as each individual zone getting its own individual PSZ and followed the eQuest modeling tutorial from Mitsubishi. The DOAS was modeled with a dummy zone and feeds each VRF zone with the OA-From DOAS. The problem that I am facing is that when I am simulating I have many unmet hours for the VRF zones and when I review the SS-A System Loads Summary Report I see that there is no cooling or heating energy. Has anyone experienced this before and if so how can I load the VRF system? Also, is there a way to see the individual zone heating or cooling contributions from the DOAS.

I have attached my pd2 and inp eQuest files.

Regards,
--
Bryan Papaj
Energy Engineer

C. J. Brown Energy, P.C.
4245 Union Rd, Suite 204
Buffalo, NY 14225
Phone: (716) 565-9190   Fax: (716) 633-5598
Email: bmp at cjbrownenergy.com<mailto:bmp at cjbrownenergy.com>


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