GetVapPresFromHumRatio Function

  1. psychrolib.f90
  2. psychrolib
  3. GetVapPresFromHumRatio

public function GetVapPresFromHumRatio(HumRatio, Pressure) result(VapPres)

Return vapor pressure given humidity ratio and pressure. Reference: ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 20 solved for pw

Arguments

Type IntentOptional AttributesName
real, intent(in) :: HumRatio

Humidity ratio in lb_H₂O lb_Air⁻¹ [IP] or kg_H₂O kg_Air⁻¹ [SI]
real, intent(in) :: Pressure

Atmospheric pressure in Psi [IP] or Pa [SI]

Return Value real

Partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]


Called by

proc~~getvappresfromhumratio~~CalledByGraph proc~getvappresfromhumratio GetVapPresFromHumRatio proc~gettdewpointfromhumratio GetTDewPointFromHumRatio proc~gettdewpointfromhumratio->proc~getvappresfromhumratio proc~calcpsychrometricsfromrelhum CalcPsychrometricsFromRelHum proc~calcpsychrometricsfromrelhum->proc~getvappresfromhumratio proc~calcpsychrometricsfromrelhum->proc~gettdewpointfromhumratio proc~gettwetbulbfromhumratio GetTWetBulbFromHumRatio proc~calcpsychrometricsfromrelhum->proc~gettwetbulbfromhumratio proc~getrelhumfromhumratio GetRelHumFromHumRatio proc~getrelhumfromhumratio->proc~getvappresfromhumratio proc~calcpsychrometricsfromtwetbulb CalcPsychrometricsFromTWetBulb proc~calcpsychrometricsfromtwetbulb->proc~getvappresfromhumratio proc~calcpsychrometricsfromtwetbulb->proc~gettdewpointfromhumratio proc~calcpsychrometricsfromtwetbulb->proc~getrelhumfromhumratio proc~calcpsychrometricsfromtdewpoint CalcPsychrometricsFromTDewPoint proc~calcpsychrometricsfromtdewpoint->proc~getvappresfromhumratio proc~calcpsychrometricsfromtdewpoint->proc~getrelhumfromhumratio proc~calcpsychrometricsfromtdewpoint->proc~gettwetbulbfromhumratio proc~calcminimaldxheating CalcMinimalDXHeating proc~calcminimaldxheating->proc~getrelhumfromhumratio proc~calcminimaldxheating->proc~gettwetbulbfromhumratio proc~getrelhumfromtwetbulb GetRelHumFromTWetBulb proc~getrelhumfromtwetbulb->proc~getrelhumfromhumratio proc~getvaporpressuredeficit GetVaporPressureDeficit proc~getvaporpressuredeficit->proc~getrelhumfromhumratio proc~gettdewpointfromtwetbulb GetTDewPointFromTWetBulb proc~gettdewpointfromtwetbulb->proc~gettdewpointfromhumratio proc~gettwetbulbfromhumratio->proc~gettdewpointfromhumratio proc~simminimaldxheating SimMinimalDXHeating proc~simminimaldxheating->proc~calcminimaldxheating proc~calcminimaldxcooling CalcMinimalDXCooling proc~calcminimaldxcooling->proc~gettwetbulbfromhumratio proc~gettwetbulbfromrelhum GetTWetBulbFromRelHum proc~gettwetbulbfromrelhum->proc~gettwetbulbfromhumratio proc~gettwetbulbfromtdewpoint GetTWetBulbFromTDewPoint proc~gettwetbulbfromtdewpoint->proc~gettwetbulbfromhumratio proc~simminimaldxcooling SimMinimalDXCooling proc~simminimaldxcooling->proc~calcminimaldxcooling

Contents

Source Code

GetVapPresFromHumRatio

Source Code

  function GetVapPresFromHumRatio(HumRatio, Pressure) result(VapPres)
    !+ Return vapor pressure given humidity ratio and pressure.
    !+ Reference:
    !+ ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 20 solved for pw

    real, intent(in)  ::  HumRatio
      !+ Humidity ratio in lb_H₂O lb_Air⁻¹ [IP] or kg_H₂O kg_Air⁻¹ [SI]
    real, intent(in)  ::  Pressure
      !+ Atmospheric pressure in Psi [IP] or Pa [SI]
    real              ::  VapPres
      !+ Partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
    real              ::  BoundedHumRatio
      !+ Humidity ratio bounded to MIN_HUM_RATIO

    if (HumRatio < 0.0) then
      error stop "Error: humidity ratio is negative"
    end if
    BoundedHumRatio = max(HumRatio, MIN_HUM_RATIO)

    VapPres = Pressure * BoundedHumRatio / (0.621945 + BoundedHumRatio)
  end function GetVapPresFromHumRatio