ControlCycWindACOutput Subroutine

private subroutine ControlCycWindACOutput(WindACNum, FirstHVACIteration, OpMode, QZnReq, PartLoadFrac, HXUnitOn)

Uses:
General
Arguments

Type	Intent		Name
integer,	intent(in)	::	WindACNum
logical,	intent(in)	::	FirstHVACIteration
integer,	intent(in)	::	OpMode
real(kind=r64),	intent(in)	::	QZnReq
real(kind=r64),	intent(out)	::	PartLoadFrac
logical,	intent(inout)	::	HXUnitOn
Source Code

SUBROUTINE ControlCycWindACOutput(WindACNum,FirstHVACIteration,OpMode,QZnReq,PartLoadFrac, HXUnitOn)

          ! SUBROUTINE INFORMATION:
          !       AUTHOR         Fred Buhl
          !       DATE WRITTEN   May 2000
          !       MODIFIED       Shirey, May 2001
          !       RE-ENGINEERED  na

          ! PURPOSE OF THIS SUBROUTINE:
          ! Determine the part load fraction of the air conditioner for this time step

          ! METHODOLOGY EMPLOYED:
          ! Linear interpolation between max and min outputs

          ! REFERENCES:
          ! na

          ! USE STATEMENTS:
  USE General, ONLY: TrimSigDigits

  IMPLICIT NONE    ! Enforce explicit typing of all variables in this routine

          ! SUBROUTINE ARGUMENT DEFINITIONS:
  INTEGER, INTENT (IN)  :: WindACNum          ! Unit index in fan coil array
  LOGICAL, INTENT (IN)  :: FirstHVACIteration ! flag for 1st HVAV iteration in the time step
  INTEGER, INTENT(IN)   :: OpMode             ! operating mode: CycFanCycCoil | ContFanCycCoil
  REAL(r64)   , INTENT(IN)   :: QZnReq             ! cooling output needed by zone [W]
  REAL(r64)   , INTENT (OUT) :: PartLoadFrac       ! unit part load fraction
  LOGICAL, INTENT (INOUT) :: HXUnitOn         ! Used to control HX heat recovery as needed

          ! SUBROUTINE PARAMETER DEFINITIONS:
          !
INTEGER, PARAMETER  ::   MaxIter = 50         !maximum number of iterations
REAL(r64), PARAMETER     ::   MinPLF = 0.0d0         !minimum part load factor allowed

          ! INTERFACE BLOCK SPECIFICATIONS
          ! na

          ! DERIVED TYPE DEFINITIONS
          ! na

          ! SUBROUTINE LOCAL VARIABLE DECLARATIONS:
REAL(r64) :: FullOutput   ! unit full output [W]
REAL(r64) :: NoCoolOutput ! output when no active cooling [W]
REAL(r64) :: ActualOutput ! output at current partloadfrac [W]
REAL(r64) :: Error        ! error between QznReq and ActualOutput [W]
REAL(r64) :: ErrorToler   ! error tolerance
INTEGER :: Iter      ! iteration counter
!CHARACTER(len=20) :: ErrNum
!INTEGER,SAVE :: ErrCount=0
REAL(r64) :: DelPLF
REAL(r64) :: Relax

! DX Cooling HX assisted coils can cycle the heat exchanger, see if coil ON, HX OFF can meet humidity setpoint if one exists
IF(WindAC(WindACNum)%DXCoilType_Num == CoilDX_CoolingHXAssisted)THEN
  ! Check for a setpoint at the HX outlet node, if it doesn't exist always run the HX
  IF(Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRatMax .EQ. SensedNodeFlagValue) THEN
    HXUnitOn = .TRUE.
  ELSE
    HXUnitOn = .FALSE.
  END IF
ELSE
  HXUnitOn = .FALSE.
END IF

IF (WindAC(WindACNum)%EMSOverridePartLoadFrac) THEN

  PartLoadFrac = WindAC(WindACNum)%EMSValueForPartLoadFrac
ENDIF

! Get result when DX coil is off
CALL CalcWindowACOutput(WindACNum,FirstHVACIteration,OpMode,0.0d0,HXUnitOn,NoCoolOutput)

! If NoCoolOutput < QZnReq, the coil needs to be off
IF (NoCoolOutput < QZnReq) THEN
  PartLoadFrac = 0.0d0
  RETURN
END IF

! Get full load result
CALL CalcWindowACOutput(WindACNum,FirstHVACIteration,OpMode,1.0d0,HXUnitOn,FullOutput)

! Since we are cooling, we expect FullOutput to be < 0 and FullOutput < NoCoolOutput
! Check that this is the case; if not set PartLoadFrac = 0.0 (off) and return
IF (FullOutput >= 0.0d0 .OR. FullOutput >= NoCoolOutput) THEN
  PartLoadFrac = 0.0d0
  RETURN
END IF

! If the QZnReq <= FullOutput the unit needs to run full out
IF (QZnReq  <=  FullOutput .AND. WindAC(WindACNum)%DXCoilType_Num /= CoilDX_CoolingHXAssisted) THEN
  PartLoadFrac = 1.0d0
  RETURN
END IF

! If the QZnReq <= FullOutput and a HXAssisted coil is used, check the node setpoint for a maximum humidity ratio set piont
! HumRatMax will either equal -999 if no setpoint exists or could be 0 if no moisture load is present
IF (QZnReq  <=  FullOutput .AND. WindAC(WindACNum)%DXCoilType_Num == CoilDX_CoolingHXAssisted .AND. &
    Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRatMax .LE. 0.0d0) THEN
  PartLoadFrac = 1.0d0
  RETURN
END IF

! QZnReq should now be greater than FullOutput and less than NoCoolOutput)
! Calculate the part load fraction

PartLoadFrac = MAX(MinPLF, ABS(QZnReq - NoCoolOutput) / ABS(FullOutput - NoCoolOutput))

  ErrorToler = WindAC(WindACNum)%ConvergenceTol !Error tolerance for convergence from input deck
  Error = 1.0d0             !initialize error value for comparison against tolerance
  Iter = 0                !initialize iteration counter
  Relax = 1.0d0

  DO WHILE ((ABS(Error) .GT. ErrorToler) .AND. (Iter .LE. MaxIter) .AND. PartLoadFrac .GT. MinPLF)
    ! Get result when DX coil is operating at partloadfrac
    CALL CalcWindowACOutput(WindACNum,FirstHVACIteration,OpMode,PartLoadFrac,HXUnitOn,ActualOutput)
    Error = (QZnReq - ActualOutput)/QZnReq
    DelPLF = (QZnReq-ActualOutput)/FullOutput
    PartLoadFrac = PartLoadFrac + Relax * DelPLF
    PartLoadFrac = MAX(MinPLF,MIN(1.0d0,PartLoadFrac))
    Iter = Iter + 1
    IF (Iter == 16) THEN
      Relax = 0.5d0
    END IF
  END DO
  IF (Iter .GT. MaxIter) THEN
    IF (WindAC(WindACNum)%MaxIterIndex1 == 0) THEN
      CALL ShowWarningMessage('ZoneHVAC:WindowAirConditioner="'//TRIM(WindAC(WindACNum)%Name)//  &
         '" -- Exceeded max iterations while adjusting compressor'// &
         ' sensible runtime to meet the zone load within the cooling convergence tolerance.')
      CALL ShowContinueErrorTimeStamp('Iterations='//TRIM(TrimSigDigits(MaxIter)))
    ENDIF
    CALL ShowRecurringWarningErrorAtEnd('ZoneHVAC:WindowAirConditioner="'//TRIM(WindAC(WindACNum)%Name)//  &
                 '"  -- Exceeded max iterations error (sensible runtime) continues...',WindAC(WindACNum)%MaxIterIndex1)
  END IF

  IF(WindAC(WindACNum)%DXCoilType_Num == CoilDX_CoolingHXAssisted .AND. &
     Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRatMax .LT. Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRat .AND. &
     Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRatMax .GT. 0.0d0) THEN

!   Run the HX to recovery energy and improve latent performance
    HXUnitOn = .TRUE.

!   Get full load result
    CALL CalcWindowACOutput(WindACNum,FirstHVACIteration,OpMode,1.0d0,HXUnitOn,FullOutput)

    IF(Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRatMax .LT. Node(WindAC(WindACNum)%CoilOutletNodeNum)%HumRat .OR. &
       QZnReq  <=  FullOutput) THEN
      PartLoadFrac = 1.0d0
      RETURN
    END IF

    Error = 1.0d0             !initialize error value for comparison against tolerance
    Iter = 0                !initialize iteration counter
    Relax = 1.0d0

    DO WHILE ((ABS(Error) .GT. ErrorToler) .AND. (Iter .LE. MaxIter) .AND. PartLoadFrac .GT. MinPLF)
      ! Get result when DX coil is operating at partloadfrac
      CALL CalcWindowACOutput(WindACNum,FirstHVACIteration,OpMode,PartLoadFrac,HXUnitOn,ActualOutput)
      Error = (QZnReq - ActualOutput)/QZnReq
      DelPLF = (QZnReq-ActualOutput)/FullOutput
      PartLoadFrac = PartLoadFrac + Relax * DelPLF
      PartLoadFrac = MAX(MinPLF,MIN(1.0d0,PartLoadFrac))
      Iter = Iter + 1
      IF (Iter == 16) THEN
        Relax = 0.5d0
      END IF
    END DO
    IF (Iter .GT. MaxIter) THEN
      IF (WindAC(WindACNum)%MaxIterIndex2 == 0) THEN
        CALL ShowWarningMessage('ZoneHVAC:WindowAirConditioner="'//TRIM(WindAC(WindACNum)%Name)//  &
           '" -- Exceeded max iterations while adjusting compressor'// &
           ' latent runtime to meet the zone load within the cooling convergence tolerance.')
        CALL ShowContinueErrorTimeStamp('Iterations='//TRIM(TrimSigDigits(MaxIter)))
      ENDIF
      CALL ShowRecurringWarningErrorAtEnd('ZoneHVAC:WindowAirConditioner="'//TRIM(WindAC(WindACNum)%Name)//  &
                 '"  -- Exceeded max iterations error (latent runtime) continues...',WindAC(WindACNum)%MaxIterIndex2)
    END IF

  END IF ! WindAC(WindACNum)%DXCoilType_Num == CoilDX_CoolingHXAssisted .AND. &

RETURN
END SUBROUTINE ControlCycWindACOutput
All Procedures

ControlCycWindACOutput Subroutine

Source Code

All Procedures

private subroutine ControlCycWindACOutput(WindACNum, FirstHVACIteration, OpMode, QZnReq, PartLoadFrac, HXUnitOn)

Uses:

Arguments

Calls

Called By

Source Code

Source Code

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