CalculateDailySolarCoeffs Subroutine

private subroutine CalculateDailySolarCoeffs(DayOfYear, A, B, C, AnnVarSolConstant, EquationOfTime, SineSolarDeclination, CosineSolarDeclination)

Arguments

Type	Intent		Name
integer,	intent(in)	::	DayOfYear
real(kind=r64),	intent(out)	::	A
real(kind=r64),	intent(out)	::	B
real(kind=r64),	intent(out)	::	C
real(kind=r64),	intent(out)	::	AnnVarSolConstant
real(kind=r64),	intent(out)	::	EquationOfTime
real(kind=r64),	intent(out)	::	SineSolarDeclination
real(kind=r64),	intent(out)	::	CosineSolarDeclination
Called By

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Source Code

CalculateDailySolarCoeffs
Source Code

SUBROUTINE CalculateDailySolarCoeffs(DayOfYear,A,B,C,AnnVarSolConstant,EquationOfTime,SineSolarDeclination,CosineSolarDeclination)

          ! SUBROUTINE INFORMATION:
          !       AUTHOR         George Walton
          !       DATE WRITTEN   May 1985
          !       MODIFIED       1999 for EnergyPlus
          !       RE-ENGINEERED  2001; LKL; Remove need for English -> SI conversion
          !                      Implement Tarp "fix" for Southern Hemisphere

          ! PURPOSE OF THIS SUBROUTINE:
          ! This subroutine computes the daily solar coefficients used in other
          ! calculations.  Specifically, this routine computes values of the solar declination, equation
          ! of time, and ashrae sky coefficients a, b, and c for a given
          ! day of the year.


          ! METHODOLOGY EMPLOYED:
          ! The method is the same as that recommended in the ASHRAE loads
          ! algorithms manual, except that the fourier series expressions
          ! have been extended by two terms for greater accuracy.
          ! coefficients for the new expressions were determined at USACERL
          ! using data from the cited references.

          ! REFERENCES:
          ! J. L. Threlkeld, "Thermal Environmental Engineering", 1970,
          ! p.316, for declination and equation of time.
          ! "ASHRAE Handbook of Fundamentals", 1972, p.387 for sky
          ! coefficients a, b, and c.
          ! See SUN3 in SolarShading. See SUN2 in BLAST.  See SUN3 in Tarp.

          ! USE STATEMENTS:
          ! na

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

          ! SUBROUTINE ARGUMENT DEFINITIONS:
  INTEGER, INTENT(IN) :: DayOfYear              ! Day of year (1 - 366)
  REAL(r64), INTENT(OUT)   :: A                      ! ASHRAE "A" - Apparent solar irradiation at air mass = 0 [W/M**2]
  REAL(r64), INTENT(OUT)   :: B                      ! ASHRAE "B" - Atmospheric extinction coefficient
  REAL(r64), INTENT(OUT)   :: C                      ! ASHRAE "C" - Diffuse radiation factor
  REAL(r64), INTENT(OUT)   :: AnnVarSolConstant      ! Annual variation in the solar constant
  REAL(r64), INTENT(OUT)   :: EquationOfTime         ! Equation of Time
  REAL(r64), INTENT(OUT)   :: SineSolarDeclination   ! Sine of Solar Declination
  REAL(r64), INTENT(OUT)   :: CosineSolarDeclination ! Cosine of Solar Declination

          ! SUBROUTINE PARAMETER DEFINITIONS:
  REAL(r64), PARAMETER :: DayCorrection=PI*2.d0/366.d0
  REAL(r64), PARAMETER, DIMENSION(9) :: SineSolDeclCoef = &  !Fitted coefficients of Fourier series
        (/ .00561800d0, .0657911d0, -.392779d0,   .00064440d0,-.00618495d0, & ! Sine of declination coefficients
          -.00010101d0,-.00007951d0,-.00011691d0, .00002096d0 /)
  REAL(r64), PARAMETER, DIMENSION(9) :: EqOfTimeCoef = &  !Fitted coefficients of Fourier Series
        (/ .00021971d0,-.122649d0,   .00762856d0,-.156308d0,  -.0530028d0,  & ! Equation of Time coefficients
          -.00388702d0,-.00123978d0,-.00270502d0,-.00167992d0 /)
  REAL(r64), PARAMETER, DIMENSION(9) :: ASHRAE_A_Coef = &  !Fitted coefficients of Fourier Series
        (/  1161.6685d0, 1.1554d0, 77.3575d0, -0.5359d0, -3.7622d0,         & ! ASHRAE A Factor coefficients
            0.9875d0, -3.3924d0, -1.7445d0, 1.1198d0 /)
! English (original) units:
!              368.49341,.366502,24.538624,-.169983,-1.193417,            &
!              .313261,-1.076093,-.543376,.355197 ,                       &

  REAL(r64), PARAMETER, DIMENSION(9) :: ASHRAE_B_Coef = &  !Fitted coefficients of Fourier Series
        (/ .171631d0,-.00400448d0,-.0344923d0,.00000209d0,.00325428d0,         & ! ASHRAE B Factor coefficients
          -.00085429d0,.00229562d0,.0009034d0,-.0011867d0 /)
  REAL(r64), PARAMETER, DIMENSION(9) :: ASHRAE_C_Coef = &  !Fitted coefficients of Fourier Series
        (/ .0905151d0,-.00322522d0,-.0407966d0,.000104164d0,.00745899d0,        & ! ASHRAE C Factor coefficients
          -.00086461d0,.0013111d0,.000808275d0,-.00170515d0 /)

          ! INTERFACE BLOCK SPECIFICATIONS:
          ! na

          ! DERIVED TYPE DEFINITIONS:
          ! na

          ! SUBROUTINE LOCAL VARIABLE DECLARATIONS:
  REAL(r64)    X     ! Day of Year in Radians (Computed from Input DayOfYear)
  REAL(r64)    CosX  ! COS(X)
  REAL(r64)    SinX ! SIN(X)


  X=DayCorrection*DayOfYear   ! Convert Julian date (Day of Year) to angle X

          ! Calculate sines and cosines of X
  SinX = SIN(X)
  CosX = COS(X)

  SineSolarDeclination = SineSolDeclCoef(1) + &
                           SineSolDeclCoef(2)*SinX +  &
                           SineSolDeclCoef(3)*CosX + &
                           SineSolDeclCoef(4)*(SinX*CosX*2.0d0) + &
                           SineSolDeclCoef(5)*(CosX**2 - SinX**2) + &
                           SineSolDeclCoef(6)*(SinX*(CosX**2 - SinX**2) + CosX*(SinX*CosX*2.0d0)) + &
                           SineSolDeclCoef(7)*(CosX*(CosX**2 - SinX**2) - SinX*(SinX*CosX*2.0d0)) + &
                           SineSolDeclCoef(8)*(2.0d0*(SinX*CosX*2.0d0)*(CosX**2 - SinX**2)) + &
                           SineSolDeclCoef(9)*((CosX**2 - SinX**2)**2 - (SinX*CosX*2.0d0)**2)
  CosineSolarDeclination=SQRT(1.0-SineSolarDeclination**2)

  EquationOfTime = EqOfTimeCoef(1) + &
                   EqOfTimeCoef(2)*SinX +  &
                   EqOfTimeCoef(3)*CosX + &
                   EqOfTimeCoef(4)*(SinX*CosX*2.0d0) + &
                   EqOfTimeCoef(5)*(CosX**2 - SinX**2) + &
                   EqOfTimeCoef(6)*(SinX*(CosX**2 - SinX**2) + CosX*(SinX*CosX*2.0d0)) + &
                   EqOfTimeCoef(7)*(CosX*(CosX**2 - SinX**2) - SinX*(SinX*CosX*2.0d0)) + &
                   EqOfTimeCoef(8)*(2.0d0*(SinX*CosX*2.0d0)*(CosX**2 - SinX**2)) + &
                   EqOfTimeCoef(9)*((CosX**2 - SinX**2)**2 - (SinX*CosX*2.0d0)**2)

  AnnVarSolConstant=1.000047d0 + .000352615d0*SinX + .0334454d0*CosX

  A = ASHRAE_A_Coef(1) + &
                   ASHRAE_A_Coef(2)*SinX +  &
                   ASHRAE_A_Coef(3)*CosX + &
                   ASHRAE_A_Coef(4)*(SinX*CosX*2.0d0) + &
                   ASHRAE_A_Coef(5)*(CosX**2 - SinX**2) + &
                   ASHRAE_A_Coef(6)*(SinX*(CosX**2 - SinX**2) + CosX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_A_Coef(7)*(CosX*(CosX**2 - SinX**2) - SinX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_A_Coef(8)*(2.0d0*(SinX*CosX*2.0d0)*(CosX**2 - SinX**2)) + &
                   ASHRAE_A_Coef(9)*((CosX**2 - SinX**2)**2 - (SinX*CosX*2.0d0)**2)

!                        Compute B and C coefficients

  IF (Latitude < 0.0d0) THEN
!                            If in southern hemisphere, compute B and C with a six month time shift.
    X = X - PI
    SinX = SIN(X)
    CosX = COS(X)
  ENDIF

  B = ASHRAE_B_Coef(1) + &
                   ASHRAE_B_Coef(2)*SinX +  &
                   ASHRAE_B_Coef(3)*CosX + &
                   ASHRAE_B_Coef(4)*(SinX*CosX*2.0d0) + &
                   ASHRAE_B_Coef(5)*(CosX**2 - SinX**2) + &
                   ASHRAE_B_Coef(6)*(SinX*(CosX**2 - SinX**2) + CosX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_B_Coef(7)*(CosX*(CosX**2 - SinX**2) - SinX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_B_Coef(8)*(2.0d0*(SinX*CosX*2.0d0)*(CosX**2 - SinX**2)) + &
                   ASHRAE_B_Coef(9)*((CosX**2 - SinX**2)**2 - (SinX*CosX*2.0d0)**2)

  C = ASHRAE_C_Coef(1) + &
                   ASHRAE_C_Coef(2)*SinX +  &
                   ASHRAE_C_Coef(3)*CosX + &
                   ASHRAE_C_Coef(4)*(SinX*CosX*2.0d0) + &
                   ASHRAE_C_Coef(5)*(CosX**2 - SinX**2) + &
                   ASHRAE_C_Coef(6)*(SinX*(CosX**2 - SinX**2) + CosX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_C_Coef(7)*(CosX*(CosX**2 - SinX**2) - SinX*(SinX*CosX*2.0d0)) + &
                   ASHRAE_C_Coef(8)*(2.0d0*(SinX*CosX*2.0d0)*(CosX**2 - SinX**2)) + &
                   ASHRAE_C_Coef(9)*((CosX**2 - SinX**2)**2 - (SinX*CosX*2.0d0)**2)

      RETURN

END SUBROUTINE CalculateDailySolarCoeffs
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