blockSpeed

Output design speed of condenser water pumps at current stage
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Information

Block that outputs the number of operating condenser water pumps and design pump speed for current stage, according to ASHRAE Guideline 36-2021, section 5.20.9 Condenser water pumps, part 5.20.9.5, and 5.20.9.6.

If the plant has the fixed speed condenser water pump (fixSpe=true) and does not have the wateside economizer (have_WSE=false):

  • The number of operating condenser water pumps shall match the number of operating chillers.

Otherwise:

  • The number of operating condenser water pumps yConWatPumNum and design condenser water pump speed yDesConWatPumSpe shall be set by chiller stage per the table below.
Chiller stage Number of pump ON Design pump speed setpoint for current stage
0 0 N/A, Off
0+WSE 1 Per TAB to provide design flow through HX
1 1 Per TAB to provide design flow through chiller
1+WSE 2 Per TAB to provide at least design flow through both chiller and WSE
2 2 Per TAB to provide at least design flow through both chillers
2+WSE 2 Per TAB to provide at least design flow through both chillers and WSE, or 100% speed if design flow cannot be achieved.

Note that this sequence is for the plants with the condenser water pumps are equally sized.

Parameters

TypeNameDefaultDescription
Booleanhave_WSEtrueFlag to indicate if the plant has water side economizer
BooleanfixSpefalseFlag to indicate if the plant has fix speed condenser water pump
IntegernPlaSta6Total number of plant stages, including stage zero and the stages with a WSE, if applicable
IntegernChiSta3Total number of chiller stages, including stage zero but not the stages with a WSE, if applicable
Real[nPlaSta]staVec{0, 0.5, 1, 1.5, 2, 2.5}Plant stage vector, element value like x.5 means chiller stage x plus WSE
Setpoint according to stage
Real[nPlaSta]desConWatPumSpe{0, 0.5, 0.75, 0.6, 0.75, 0.9}Design condenser water pump speed setpoint, according to current chiller stage and WSE status
Integer[nPlaSta]desConWatPumNum{0, 1, 1, 2, 2, 2}Design number of condenser water pumps that should be ON, according to current chiller stage and WSE status
Integer[nChiSta]desChiNum{0, 1, 2}Design number of chiller that should be ON, according to current chiller stage

Connectors

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Interfaces.IntegerInputuChiStaCurrent chiller stage index that does not include the WSE
Buildings.Controls.OBC.CDL.Interfaces.BooleanInputuWSEWater side economizer status: true = ON, false = OFF
Buildings.Controls.OBC.CDL.Interfaces.IntegerOutputyConWatPumNumDesign number of operating condenser water pumps at current stage
Buildings.Controls.OBC.CDL.Interfaces.RealOutputyDesConWatPumSpeDesign condenser water pump speed at current stage

Revisions

  • January 28, 2019, by Jianjun Hu:
    First implementation.