blockPartLoadRatios
Information
Calculates operative part load ratios (OPLR) per sections 5.20.4.5, section 5.20.4.9, section 5.20.4.10 and stage part load ratios (SPLR, up or down) per section 5.20.4.14 of Guideline 36-2021.
OPLR is a ratio of the current capacity requirement to a given design or minimal stage capacity, such as:
- Current stage design OPLR(y).
- Current stage minimal OPLR(yMin).
- Next available higher stage nominal OPLR(yUp).
- Next available higher stage minimal OPLR(yUpMin).
SPLRup yStaUp or SPLRdown yStaDown value depends on the
stage type staTyp as indicated in the table below.
Note that the rules are prioritized by stage type column, from left to right
The stage type is determined by the Buildings.Controls.OBC.ASHRAE.G36.Plants.Chillers.Staging.SetPoints.Subsequences.Configurator subsequence based on the type of chillers staged.
| Row: Stage / Column: Stage Type | Any Constant Speed Centrifugal | All Positive Displacement | Any Variable Speed and no Constant Speed Centrifugal |
| Next Available Up | yStaUp=conSpeCenMult | N/A | >N/A |
| Current | yStaDown=conSpeCenMult | yStaUp=posDisMult | yStaUp=f(uLif, uLifMin, uLifMax) |
| Next Available Down | N/A | yStaDown=posDisMult | yStaDown=f(uLif, uLifMin, uLifMax) |
For operation outside of the recommended staging order as provided in the table
above a constant SPLRup and SPLRdown value anyOutOfScoMult is set to prevent
simulation interruption, accompanied with a warning.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | anyVsdCen | true | Plant contains at least one variable speed centrifugal chiller |
| Integer | nSta | 3 | Number of chiller stages, does not include zero stage |
| Real | posDisMult | 0.8 | Positive displacement chiller type staging multiplier |
| Real | conSpeCenMult | 0.9 | Constant speed centrifugal chiller type staging multiplier |
| Real | anyOutOfScoMult | 0.9 | Outside of G36 recommended staging order chiller type SPLR multiplier |
| Real | varSpeStaMin | 0.45 | Minimum stage up or down part load ratio for variable speed centrifugal stage types |
| Real | varSpeStaMax | 0.9 | Maximum stage up or down part load ratio for variable speed centrifugal stage types |
| Real | avePer | 300 | Moving mean time period for staging multiplier calculation for variable speed centrifugal stage types |
Connectors
Revisions
-
January 03, 2020, by Milica Grahovac:
First implementation.