Heat Pump / Chiller Plant Model

[gtfierro]

Target branch for PRs related to heat pumps and chiller plants:

• heat pump classes (Heat pump classes #252)
• example configurations in the examples/ folder
• discuss and decide on the brick:connectsTo property
• add documentation to explain the role of enumerations for dynamic graph structures

Development is being done through the Ontology Working Group. Recent discussions can be found on the Brick wiki; in particular, this meeting informed many of the design choices explored here.

---

• Added heat pump classes

• added non and reversible subclasses for hp

• broke up class tags into simpler tags

• added non- and -reversible air to air hp classes

• added air to refrigerant hp classes

• fixed names to title case

• broke up single heat pump tag into two tags

Co-authored-by: Gabe Fierro [email protected]

[MatthewSteen]

Here are my comments based on experience as a design consultant doing energy modeling of new commercial buildings. I haven't been in the working group meetings, so I'm sorry if these issues have already been discussed. I'm happy to suggest a different structure and formally review if you'd like.

I'm a proponent of using established standards whenever possible, so I think the following should be considered.

• ASHRAE Terminology for formal definitions.
• OmniClass Table 21 (ISO 12006) and Table 22 for class hierarchy (I haven't found a better standard yet).

General

1. Heat pump equipment by definition have a reversing valve and can both cool and heat, so I don't think it makes sense to have NonreversibleHeatPump and ReversibleHeatPump classes, which seems overly complex and potentially confusing. A non-reversible heat pump is just an air conditioner right (chiller or cooler more generally)?

   For example, do Nonreversible Ground to Air Heat Pumps or Nonreversible Water to Air Heat Pumps even exist? I don't know of GSHPs or WSHPs without a reversing valve that only cool. Similarly, a Nonreversible Air to Air Heat Pump is just an AC.

2. With (1) in mind, I don't think Chillers are a child of HeatPump. There are "heat pump chillers" or "reversing chiller" (e.g. Denver Water's central plant), but those are heat pumps since they also heat.

[MatthewSteen]

Heat Pumps

Heat pumps cool or heat air, water, or refrigerant by moving heat from a source to a sink via the VCR cycle.
https://xp20.ashrae.org/terminology/index.php?term=heat+pump&submit=Search

heat pump
thermodynamic heating/refrigerating system to transfer heat. The condenser and evaporator may change roles to transfer heat in either direction. By receiving the flow of air or other fluid, a heat pump is used to cool or heat. Heat pumps may be the air source with heat transfer between the indoor air stream to outdoor air or water source with heat transfer between the indoor air stream and a hydronic source (ground loop, evaporative cooler, cooling tower, or domestic water).

• Air-Source Heat Pump = air is the heat source/sink
• Ground-Source Heat Pump = ground is the heat source/sink
• Water-Source Heat Pump = water is the heat source/sink (typically a condenser loop served by cooling tower and boiler)

OmniClass Table 22

Note, it's missing GSHP, but I think that might be a subclass/child of WSHP based on the ASHRAE definition. Not to be confused with geothermal electric generation equipment.

[MatthewSteen]

Chillers

Consider using ASHRAE's Chiller definitions.

chiller
(1) direct-expansion chillers are complete refrigerating systems consisting of a compressor, condenser, and evaporator with all operating and safety controls. Compressor types include the following: reciprocating, centrifugal, or screw design. Compare to absorption chiller. (2) refrigerating machine used to transfer heat between fluids. Chillers are either direct expansion with a compressor or absorption type.

OmniClass Table 22

[gtfierro]

For this PR:

• pull in substances
• connectsTo property
• reversing valve + reversing valve command

[MatthewSteen]

Link to gist that I don't think is included here. https://gist.github.com/gtfierro/c5ed6e25a99c60053c43befbebe1f740

[epaulson]

We put this off until after Brick 1.3 but I did want to come back to it - maybe we start simple and not worry too much about getting the full heat pump hierarchy in-place but start with the 'leaf nodes' and at least get a couple of chiller classes in. I really like the idea of aligning to Omniclass, though I wonder if we should be using table 23 (though it's not that different than 22:

(at some point Omniclass might have moved these things around? From a different version I found at https://www.startbim.com/2017/06/omniclass-23-products-list.html

I also didn't see anything on the Haystack side where they're really digging into different chiller types so I don't think we're going to go too far from anything we might eventually to align. 223 also looks like they're pretty basic, and I don't think they have enough in different compressor types to build up these different chiller types.

We probably need some way - either in Brick or to get it from 223 - of just being able to talk about the different loops and what the evaporator/condenser/compressors/hx etc are on the loop, so you can create the different variations if there's something we don't have in Brick - like JCI's got a dual-compressor chiller: https://hvacpproducts.com/2015/08/york-yd-model-c-dual-compressor-centrifugal-chiller-available-with-optispeed-vsd/

[gtfierro]

I like the idea of going with the Table 23 chiller hierarchy. Would we want to put 'split system' chillers vs 'packaged' chillers in different trees? Then we could have rules about those different kinds of subsystems while still preserving the difference between screw/scroll/etc in the subclasses

[epaulson]

Just as a random comment, I found a fun site from PNNL (it's got quite a pedigree - it's domain is still PNL and not PNNL) with some useful documentation, and also a good example of what a real application is looking for. Here's the help:
https://energycode.pnl.gov/COMcheckWeb/robohelp/Software_Compliance_Guide.htm

the docs are all frames so you might have to dig around, but a good page on just how they use chillers: https://energycode.pnl.gov/COMcheckWeb/robohelp/Plant_Cooling_Equipment_Details.htm

[epaulson]

[MatthewSteen]

@epaulson following up on this.

OmniClass

This could be a good starting point. However, I'm not sure I agree with their organization levels of compressor type => condenser location (packaged vs. split). Condenser type (air-cooled, evap-cooled, water-cooled, etc.) might be a better primary organization level.

ComCheck

I've used this tool a few times for energy code compliance work and it should just align with ASHRAE 90.1, which then refers to other equipment-specific standards such as AHRI.

Others

AHRI

Could also serve as a good starting point. https://www.ahrinet.org/sites/default/files/2023-02/AHRI%20Standard%20550%20590-2023%20I-P_0.pdf

ASHRAE

Handbook of HVAC Systems and Equipment, Chapter 43, Liquid Chilling Systems.

IFC

IFC 7.5.2.6 IfcChillerTypeEnum doesn't appear detailed enough.

Constant	Description
AIRCOOLED	Air cooled chiller.
WATERCOOLED	Water cooled chiller.
HEATRECOVERY	Heat recovery chiller.
USERDEFINED	User-defined chiller type.
NOTDEFINED	Undefined chiller type.

[epaulson]

I'm doing a Thanksgiving tab sweep, and one thing I've had open for a bit, kinda related: JCI puts out BIM models of its chillers - here's one where we put in a suggested Omniclass classification (among other classification systems) and even include some of the nameplate properties:

https://www.bimobject.com/en-us/johnsoncontrols/product/jci-yvaa

[gtfierro]

Closing so we can continue development in a single location on a more recent version of Brick (see #589)

[connorjcantrell]

@MatthewSteen @gtfierro Here is the new PR: #590