[Equest-users] New eQuest VRF capabilities - Questions
Doug Maddox
doug at maddoxenergy.com
Sat Nov 10 10:04:35 PST 2018
Nick,
Here are some answers to your questions:
1. I believe Bill is correct in his response yesterday.
2. NUMBER-OF-UNITS is an alternative to MAX-CAP/UNIT. However,
MAX-CAP/UNIT will still have an effect if the total system capacity divided
by NUMBER-OF-UNITS exceeds the MAX-CAP/UNIT value. This prevents having
unrealistically high capacity handled by the refrigerant piping.
3. Refrigerant line insulation is not editable. The thickness of
insulation depends on pipe size and whether it is a liquid pipe or a gas
pipe as follows.
High Pressure Liquid Pipe:
<= 0.375 inch nominal pipe size: 0.375 inch insulation thickness
Larger pipe: 0.5 inch insulation thickness
Suction Gas Pipe:
< 2 inch nominal pipe size: 1 inch insulation thickness
Smaller pipe: 0.75 inch insulation thickness
Insulation conductivity is 0.25 Btu/hr-in-F
4. The only system diagram I have is shown below. Leader is the line from
the outdoor unit to the first branch, header is the main line from the first
branch to the last branch, and a branch is from the header to an indoor
unit.
5. The AUX-POWER represents energy for controls, not backup heating. Maybe
electric baseboards could work for supplemental. Probably should be
addressed in a future release.
From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On
Behalf Of Nicholas Caton via Equest-users
Sent: Friday, November 9, 2018 4:40 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] New eQuest VRF capabilities - Questions
Hi everyone!
I have a couple questions to pose as I'm wading into the new VRF
capabilities built into the new eQuest build 3.65-7175, in doe 2.3 mode.
Curious if anyone else in parallel has solved any of the following, or else
would like to pile on with additional queries:
1. Where in the eQuest interface can I review/edit the input for
MAX-CAP/UNIT in a VRF system? I've seen repeated references to this between
the SIM outputs and the reference help files, and I know the default is
affected by the indoor cassette type selection (VRF-TERM-TYPE). I just
can't find the input in the airside system (PVVT), zonal inputs, or
Condensing unit input windows. Probably I'm just missing it, but is it
perhaps missing in the interface?
2. Expanding on the last question, am I correct in understanding the
NUMBER-OF-UNITS input within the preceding reference article for
MAX-CAP/UNIT is referring to this input under "Unit Staging" in the Basics
tab for Air-Side Systems? Seems from the article this could serve as a
proxy for MAX-CAP/UNIT in effect.
3. For determining thermal losses, is refrigerant line insulation an
editable input for branch (airside system) and leader/header (condensing
unit) refrigerant piping? Is that just a constant omitted for simplicity of
inputs?
4. For illustration, is there a system diagram anywhere at present in
the reference manual, similar to those provided for existing SYSTEM
articles? (I'm thinking this might provide an overview of the terminology
like leader vs header vs branch piping, and diagram the split between what
inputs are specified at the CONDENSING-UNIT vs the airside SYSTEM)
5. I don't have the impression that the condenser inputs for AUX-POWER
are intended to cover auxiliary/secondary heat sources for when a VRF's
heating capacity needs an extra kick during wintertime operation. I reckon
electric baseboards are the natural answer for supplemental heat at the
zone, but which inputs fields are most appropriate (if any) for radiators in
an outdoor unit enclosure (Literature:
https://www.daikinac.com/content/assets/DOC/White-papers-/BPG-EXTAMB.pdf)?
6. Would it be possible to identify makes/models of real world
equipment that the library performance curves are based upon?
. Answering my own question: Comments within the BDLLIB.DAT file (eQuest
Data Directory --> ../DOE23/BDLLIB.DAT), starting on line 25094, provide
some sources for the VRF library performance curves.
Here is a curve commentary reference I made for myself - may as well share:
VRF Curve Comment
VRF-FAN-EIR-FPLR $1.4 exponent for
multi-speed fans
VRF-HP-Resys-ClCap-fSST&ODB $Daikin RXYMQ48MVJU, no SST
dependence
VRF-HP-Resys-ClEIR-fSST&ODB $Daikin RXYMQ48MVJU, no SST
dependence
VRF-HP-Resys-ClEIR-fPLR $Coefficients from
Daikin for EER~11 excluding indoor fan heat
VRF-HP-Resys-Cycle-fPLR $Estimated, 1.6 minutes
at 50% cycle
VRF-HP-Resys-HtCap-fSCT&OWB $Daikin RXYMQ48MVJU, no SCT
dependence
VRF-HP-DefrostCap-fOWB $Daikin and Mitsubishi
similar
VRF-HP-Resys-HtEIR-fSCT&OWB $Daikin RXYMQ48MVJU, no SCT
dependence
VRF-HP-Resys-HtEIR-fPLR * no comment *
VRF-HP-Resys-Crankcase-fPLR $Used for both heating and
cooling
VRF-EP-Cap-fSDT&SST $From EnergyPlus
sample input - high speed curve
VRF-EP-EIR-fSDT&SST $From EnergyPlus
sample input - high speed curve
VRF-EP-EIR-fPLR $From
EnergyPlus sample input, refitted - Ratio & DT
VRF044-Cap-fSST&SDT $DanFoss VZH028-035-044
VRF044-EIR-fSST&SDT $DanFoss
VZH028-035-044
VRF044-EIR-fPLR $DanFoss
VZH028-035-044
VRF088-Cap-fSST&SDT $DanFoss VZH088AG
VRF088-EIR-fSST&SDT $DanFoss VZH088AG
VRF088-EIR-fPLR $DanFoss
VZH088AG
VRF_CL_ThermLoss_fPLR&SST $From typical piping layout for
20 ton system
VRF_HT_ThermLoss_fPLR&SDT $From typical piping layout for
20 ton system
VRF_COOL_DTSAT_fSST $From typical piping
layout for 20 ton system
VRF_HEAT_DTSAT_fSDT $From typical piping
layout for 20 ton system
Thanks,
~Nick
Nick Caton, P.E., BEMP
Senior Energy Engineer
Regional Energy Engineering Manager
Energy and Sustainability Services
Schneider Electric
D 913.564.6361
M 785.410.3317
F 913.564.6380
E <mailto:nicholas.caton at schneider-electric.com>
nicholas.caton at schneider-electric.com
15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States
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