VRF fluid control heating: lacking coil capacity adjustment that increases capacity

[yujiex]

Issue overview

In the VRF physics-based model indoor unit coil calculation, the subcooling degree is adjusted only when the demand (or capacity limit imposed by the outdoor unit) is very small. In this example, the initial subcooling degree from user input is 11.5C. No matter how the system capacity (both the condenser and coil) changes, the subcooling degree does not go below 11.5C.

When the control target (the minimum of total IU output and the capacity limit imposed by the condenser through limitTUCapacity function) is in case 4, subcooling degree (SC) is kept at the initial value. There should be some further adjustment (decrease) to increase indoor unit capacity.

Details

Some additional details for this issue (if relevant):

• Platform (MacOS, 13.5)
• Version of EnergyPlus (23.1)
• Unmethours link or helpdesk ticket number

Defect files

idf

US+SF+CZ4A+hp+crawlspace+IECC_2006_VRF_cap4000.idf.txt
US+SF+CZ4A+hp+crawlspace+IECC_2006_VRF_cap7000.idf.txt
US+SF+CZ4A+hp+crawlspace+IECC_2006_VRF_cap10000.idf.txt
US+SF+CZ4A+hp+crawlspace+IECC_2006_VRF_cap15000.idf.txt

epw
USA_NY_New.York-John.F.Kennedy.Intl.AP.744860_TMY3.epw.txt

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• Defect file added (list location of defect file here)
• Ticket added to Pivotal for defect (development team task)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

[rraustad]

How do you propose (i.e., NFP) to explain to the development team what changes are suggested?

[yujiex]

hmmm maybe I should do a separate PR for this additional SC adjustment capability.