modelEnableAndModeControl

Validation model for sidestream HRC enable and mode control
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Information

This model validates Buildings.Templates.Plants.Controls.HeatRecoveryChillers.Enable and Buildings.Templates.Plants.Controls.HeatRecoveryChillers.ModeControl. Consequently, it also validates Buildings.Templates.Plants.Controls.HeatRecoveryChillers.Controller, which is composed of the two former blocks.

The validation uses varying ∆T for HW across the HRC condenser and CHW across the HRC evaporator. The model verifies that:

  • The HRC is effectively disabled when it is controlled in cooling mode and the leaving HW temperature is high.
  • The HRC control mode switches from cooling to heating when the cooling load exceeds the calculated evaporator heat flow rate in heating mode.

Parameters

TypeNameDefaultDescription
Realcp_default4184Default specific heat capacity used to compute required capacity
Realrho_default996Default fluid density used to compute required capacity
Information provided by designer
RealCOPHea_nominal2.8Heating COP at design heating conditions
Nominal condition
RealcapHea_nominal1E6Installed heating capacity
RealTHeaWatSup_nominal323.15Design HW supply temperature
RealTHeaWatRet_nominal315.15Design HW return temperature
RealVHeaWat_flow_nominalcapHea_nominal/abs(THeaWatSup_nominal - THeaWatRet_nominal)/cp_default/rho_defaultDesign HW volume flow rate
RealcapCoo_nominalcapHea_nominal*(1 - 1/COPHea_nominal)Installed cooling capacity
RealTChiWatSup_nominal280.15Design CHW supply temperature
RealTChiWatRet_nominal285.15Design CHW return temperature
RealVChiWat_flow_nominalcapCoo_nominal/abs(TChiWatSup_nominal - TChiWatRet_nominal)/cp_default/rho_defaultDesign CHW volume flow rate

Components

TypeNameDefaultDescription
Buildings.Controls.OBC.CDL.Reals.Sources.TimeTableratV_flowSource signal for volume flow rate ratio – Index 1 for HW, 2 for CHW
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTHeaWatRetHWRT
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTChiWatRetCHWRT
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameterVHeaWat_flowScale by design flow
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameterVChiWat_flowScale by design flow
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTHeaWatSupHWST
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantTChiWatSupCHWST
Buildings.Controls.OBC.CDL.Reals.GreaterThresholdu1HeaCompute heating plant enable signal
Buildings.Controls.OBC.CDL.Reals.GreaterThresholdu1CooCompute cooling plant enable signal
StagingRotation.LoadAverageloaChiWatAvailable CHW load
Buildings.Templates.Plants.Controls.HeatRecoveryChillers.Enableena
StagingRotation.LoadAverageloaHeaWatAvailable HW load
Components.Controls.StatusEmulatorstaEmulate HRC status
ModeControlsetModSet mode
Buildings.Controls.OBC.CDL.Reals.Sources.SindTHeaWatHW Delta_T across HRC condenser
Buildings.Controls.OBC.CDL.Reals.AddTHeaWatHrcLvgHRC leaving HWT
Buildings.Controls.OBC.CDL.Reals.DivideratFloFlow ratio
Buildings.Controls.OBC.CDL.Reals.MultiplydTRatFloHW Delta-T times flow ratio
Buildings.Controls.OBC.CDL.Reals.MultiplyByParameterdTChiWatHRC leaving CHWT
Buildings.Controls.OBC.CDL.Logical.PrepreModPrevious mode setting
Buildings.Controls.OBC.CDL.Reals.MaxbouBound to avoid division by zero
Buildings.Controls.OBC.CDL.Reals.Sources.ConstantcstConstant
Buildings.Controls.OBC.CDL.Reals.Maxbou1Bound to avoid unrealistic values
Buildings.Controls.OBC.CDL.Reals.Sources.Constantcst1Constant
Buildings.Controls.OBC.CDL.Reals.AddTChiWatHrcLvgHRC leaving CHWT
Buildings.Controls.OBC.CDL.Conversions.BooleanToRealstaToRealConvert status to real
Buildings.Controls.OBC.CDL.Reals.MultiplydTEnaNon-zero HW Delta-T when HRC on
Buildings.Controls.OBC.CDL.Logical.MultiAndmulAndMake status come and go at low load
Buildings.Controls.OBC.CDL.Reals.GreaterThresholdgreLoaChiWatTrue if load greater than minimum before cycling
Buildings.Controls.OBC.CDL.Reals.GreaterThresholdgreLoaHeaWatTrue if load greater than minimum before cycling

Revisions

  • December 10, 2024, by Michael Wetter:
    Updated input of hysteresis block and changed threshold to guard against numerical noise.
    This is for issue 4074.
  • May 31, 2024, by Antoine Gautier:
    First implementation.