| Type: | Package |
| Title: | Psychrometric Properties of Moist and Dry Air |
| Version: | 2.5.2 |
| Maintainer: | Hongyuan Jia <hongyuanjia@outlook.com> |
| Description: | Implementation of 'PsychroLib' https://github.com/psychrometrics/psychrolib library which contains functions to enable the calculation properties of moist and dry air in both metric (SI) and imperial (IP) systems of units. References: Meyer, D. and Thevenard, D (2019) <doi:10.21105/joss.01137>. |
| Depends: | R (≥ 3.0.0) |
| Imports: | Rcpp |
| Suggests: | testthat (≥ 2.1.0), covr |
| License: | MIT + file LICENSE |
| URL: | https://github.com/psychrometrics/psychrolib |
| BugReports: | https://github.com/psychrometrics/psychrolib/issues |
| LinkingTo: | Rcpp |
| Encoding: | UTF-8 |
| RoxygenNote: | 7.0.2 |
| NeedsCompilation: | yes |
| Packaged: | 2021-05-26 01:27:18 UTC; hongy |
| Author: | Hongyuan Jia 
[aut, cre],
The PsychroLib Contributors [ctb, cph] (Authors listed in
inst/PSYCHROLIB_AUTHORS.txt),
ASHRAE [cph] (Copyright 2017 ASHRAE Handbook Fundamentals
(https://www.ashrae.org) for equations and coefficients published
ASHRAE Handbook Fundamentals Chapter 1.) |
| Repository: | CRAN |
| Date/Publication: | 2021-05-29 06:10:02 UTC |
PsychroLib: Psychrometric Properties of Moist and Dry Air
Description
Contains functions for calculating thermodynamic properties of gas-vapor mixtures and standard atmosphere suitable for most engineering, physical and meteorological applications.
Details
Most of the functions are an implementation of the formulae found in the 2017 ASHRAE Handbook - Fundamentals, in both International System (SI), and Imperial (IP) units. Please refer to the information included in each function for their respective reference.
psychroLib is a port of the psychrolib library for R.
Pakcage options
-
psychrolib.unitsThe default unit system. Should be either be"SI"or"IP".
Note
We have made every effort to ensure that the code is adequate, however, we make no representation with respect to its accuracy. Use at your own risk. Should you notice an error, or if you have a suggestion, please notify us through GitHub at https://github.com/psychrometrics/psychrolib/issues.
Author(s)
Hongyuan Jia and Jason Banfelder for R implementation.
D. Thevenard and D. Meyer for the core library implementations.
Equations and coefficients published ASHRAE Handbook — Fundamentals, Chapter 1 Copyright (c) 2017 ASHRAE Handbook — Fundamentals (https://www.ashrae.org)
See Also
Useful links:
Report bugs at https://github.com/psychrometrics/psychrolib/issues
Examples
library(psychrolib)
# Set the unit system, for example to SI (can be either SI or IP)
SetUnitSystem("SI")
# Calculate the dew point temperature for a dry bulb temperature of 25 C
# and a relative humidity of 80%
GetTDewPointFromRelHum(25.0, 0.80)
Calculate psychrometric values from relative humidity.
Description
Utility function to calculate humidity ratio, wet-bulb temperature, dew-point temperature, vapour pressure, moist air enthalpy, moist air volume, and degree of saturation of air given dry-bulb temperature, relative humidity and pressure.
Usage
CalcPsychrometricsFromRelHum(TDryBulb, RelHum, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
RelHum |
A numeric vector of relative humidity in range [0, 1] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A list with named components for each psychrometric value computed:
- HumRatio
Humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
- TWetBulb
Wet-bulb temperature in degreeF [IP] or degreeC [SI]
- TDewPoint
Dew-point temperature in degreeF [IP] or degreeC [SI]
- VapPres
Partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
- MoistAirEnthalpy
Moist air enthalpy in Btu lb-1 [IP] or J kg-1 [SI]
- MoistAirVolume
Specific volume of moist air in ft3 lb-1 [IP] or in m3 kg-1 [SI]
- DegreeOfSaturation
Degree of saturation [unitless]
Examples
SetUnitSystem("IP")
CalcPsychrometricsFromRelHum(80:100, 0.13, 14.69)
SetUnitSystem("SI")
CalcPsychrometricsFromRelHum(25:40, 0.5, 101325.0)
Calculate psychrometric values from dew-point temperature.
Description
Utility function to calculate humidity ratio, wet-bulb temperature, relative humidity, vapour pressure, moist air enthalpy, moist air volume, and degree of saturation of air given dry-bulb temperature, dew-point temperature, and pressure.
Usage
CalcPsychrometricsFromTDewPoint(TDryBulb, TDewPoint, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TDewPoint |
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A list with named components for each psychrometric value computed:
- HumRatio
Humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
- TWetBulb
Wet-bulb temperature in degreeF [IP] or degreeC [SI]
- RelHum
Relative humidity in range [0, 1]
- VapPres
Partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
- MoistAirEnthalpy
Moist air enthalpy in Btu lb-1 [IP] or J kg-1 [SI]
- MoistAirVolume
Specific volume of moist air in ft3 lb-1 [IP] or in m3 kg-1 [SI]
- DegreeOfSaturation
Degree of saturation [unitless]
Examples
SetUnitSystem("IP")
CalcPsychrometricsFromTDewPoint(80:100, 40.0, 14.696)
SetUnitSystem("SI")
CalcPsychrometricsFromTDewPoint(25:40, 20.0, 101325.0)
Calculate psychrometric values from wet-bulb temperature.
Description
Utility function to calculate humidity ratio, dew-point temperature, relative humidity, vapour pressure, moist air enthalpy, moist air volume, and degree of saturation of air given dry-bulb temperature, wet-bulb temperature, and pressure.
Usage
CalcPsychrometricsFromTWetBulb(TDryBulb, TWetBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TWetBulb |
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A list with named components for each psychrometric value computed:
- HumRatio
Humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
- TDewPoint
Dew-point temperature in degreeF [IP] or degreeC [SI]
- RelHum
Relative humidity in range [0, 1]
- VapPres
Partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
- MoistAirEnthalpy
Moist air enthalpy in Btu lb-1 [IP] or J kg-1 [SI]
- MoistAirVolume
Specific volume of moist air in ft3 lb-1 [IP] or in m3 kg-1 [SI]
- DegreeOfSaturation
Degree of saturation [unitless]
Examples
SetUnitSystem("IP")
CalcPsychrometricsFromTWetBulb(80:100, 65.0, 14.696)
SetUnitSystem("SI")
CalcPsychrometricsFromTWetBulb(25:40, 20, 101325.0)
Return the degree of saturation (i.e humidity ratio of the air / humidity ratio of the air at saturation at the same temperature and pressure) given dry-bulb temperature, humidity ratio, and atmospheric pressure.
Description
Return the degree of saturation (i.e humidity ratio of the air / humidity ratio of the air at saturation at the same temperature and pressure) given dry-bulb temperature, humidity ratio, and atmospheric pressure.
Usage
GetDegreeOfSaturation(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of degree of saturation in arbitrary unit
Note
This definition is absent from the 2017 Handbook. Using 2009 version instead.
References
ASHRAE Handbook - Fundamentals (2009) ch. 1 eqn 12
Examples
SetUnitSystem("IP")
GetDegreeOfSaturation(80:100, 0.01, 14.175)
SetUnitSystem("SI")
GetDegreeOfSaturation(20:30, 0.01, 95461.0)
Return dry-air density given dry-bulb temperature and pressure.
Description
Return dry-air density given dry-bulb temperature and pressure.
Usage
GetDryAirDensity(TDryBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of dry air density in lb ft-3 [IP] or kg m-3 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Eqn 14 for the perfect gas relationship for dry air.
Eqn 1 for the universal gas constant.
The factor 144 in IP is for the conversion of Psi = lb in-2 to lb ft-2.
Examples
SetUnitSystem("IP")
GetDryAirDensity(77:87, 14.696)
SetUnitSystem("SI")
GetDryAirDensity(25:30, 101325)
Return dry-air enthalpy given dry-bulb temperature.
Description
Return dry-air enthalpy given dry-bulb temperature.
Usage
GetDryAirEnthalpy(TDryBulb)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of dry air enthalpy in Btu lb-1 [IP] or J kg-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 28
Examples
SetUnitSystem("IP")
GetDryAirEnthalpy(77:87)
SetUnitSystem("SI")
GetDryAirEnthalpy(10:30)
Return dry-air volume given dry-bulb temperature and pressure.
Description
Return dry-air volume given dry-bulb temperature and pressure.
Usage
GetDryAirVolume(TDryBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of dry air volume in ft3 lb-1 [IP] or in m3 kg-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Eqn 14 for the perfect gas relationship for dry air.
Eqn 1 for the universal gas constant.
The factor 144 in IP is for the conversion of Psi = lb in-2 to lb ft-2.
Examples
SetUnitSystem("IP")
GetDryAirVolume(77:87, 14.696)
SetUnitSystem("SI")
GetDryAirVolume(25:30, 101325)
Return humidity ratio from enthalpy and dry-bulb temperature.
Description
Return humidity ratio from enthalpy and dry-bulb temperature.
Usage
GetHumRatioFromEnthalpyAndTDryBulb(MoistAirEnthalpy, TDryBulb)
Arguments
MoistAirEnthalpy |
A numeric vector of moist air enthalpy in Btu lb-1 [IP] or J kg-1 |
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
Note
Based on the GetMoistAirEnthalpy function, rearranged for humidity ratio.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 30.
Examples
SetUnitSystem("IP")
GetHumRatioFromEnthalpyAndTDryBulb(42.6168, 76:86)
SetUnitSystem("SI")
GetHumRatioFromEnthalpyAndTDryBulb(81316.0, 20:30)
Return humidity ratio given dry-bulb temperature, relative humidity, and pressure.
Description
Return humidity ratio given dry-bulb temperature, relative humidity, and pressure.
Usage
GetHumRatioFromRelHum(TDryBulb, RelHum, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
RelHum |
A numeric vector of relative humidity in range [0, 1] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetHumRatioFromRelHum(80:100, 0.5, 14.175)
SetUnitSystem("SI")
GetHumRatioFromRelHum(20:30, 0.5, 95461.0)
Return the humidity ratio (aka mixing ratio) from specific humidity.
Description
Return the humidity ratio (aka mixing ratio) from specific humidity.
Usage
GetHumRatioFromSpecificHum(SpecificHum)
Arguments
SpecificHum |
A numeric vector of specific humidity in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Dry_Air-1 [IP] or kg_H2O kg_Dry_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 9b (solved for humidity ratio)
Examples
SetUnitSystem("IP")
GetHumRatioFromSpecificHum(seq(0.006, 0.016, 0.001))
SetUnitSystem("SI")
GetHumRatioFromSpecificHum(seq(0.006, 0.016, 0.001))
Return humidity ratio given dew-point temperature and pressure.
Description
Return humidity ratio given dew-point temperature and pressure.
Usage
GetHumRatioFromTDewPoint(TDewPoint, Pressure)
Arguments
TDewPoint |
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 13
Examples
SetUnitSystem("IP")
GetHumRatioFromTDewPoint(50:80, 14.175)
SetUnitSystem("SI")
GetHumRatioFromTDewPoint(20:30, 95461.0)
Return humidity ratio given dry-bulb temperature, wet-bulb temperature, and pressure.
Description
Return humidity ratio given dry-bulb temperature, wet-bulb temperature, and pressure.
Usage
GetHumRatioFromTWetBulb(TDryBulb, TWetBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TWetBulb |
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 33 and 35
Examples
SetUnitSystem("IP")
GetHumRatioFromTWetBulb(80:100, 77.0, 14.175)
SetUnitSystem("SI")
GetHumRatioFromTWetBulb(20:30, 19.0, 95461.0)
Return humidity ratio given water vapor pressure and atmospheric pressure.
Description
Return humidity ratio given water vapor pressure and atmospheric pressure.
Usage
GetHumRatioFromVapPres(VapPres, Pressure)
Arguments
VapPres |
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 20
Examples
SetUnitSystem("IP")
GetHumRatioFromVapPres(seq(0.4, 0.6, 0.01), 14.175)
SetUnitSystem("SI")
GetHumRatioFromVapPres(seq(3000, 4000, 100), 95461)
Return moist air density given humidity ratio, dry bulb temperature, and pressure.
Description
Return moist air density given humidity ratio, dry bulb temperature, and pressure.
Usage
GetMoistAirDensity(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of moistAirDensity: Moist air density in lb ft-3 [IP] or kg m-3 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 11
Examples
SetUnitSystem("IP")
GetMoistAirDensity(80:100, 0.02, 14.175)
SetUnitSystem("SI")
GetMoistAirDensity(20:30, 0.02, 95461)
Return moist air enthalpy given dry-bulb temperature and humidity ratio.
Description
Return moist air enthalpy given dry-bulb temperature and humidity ratio.
Usage
GetMoistAirEnthalpy(TDryBulb, HumRatio)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Value
A numeric vector of moist air enthalpy in Btu lb-1 [IP] or J kg-1
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 30
Examples
SetUnitSystem("IP")
GetMoistAirEnthalpy(80:100, 0.02)
SetUnitSystem("SI")
GetMoistAirEnthalpy(20:30, 0.02)
Return moist air specific volume given dry-bulb temperature, humidity ratio, and pressure.
Description
Return moist air specific volume given dry-bulb temperature, humidity ratio, and pressure.
Usage
GetMoistAirVolume(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of specific volume of moist air in ft3 lb-1 of dry air [IP] or in m3 kg-1 of dry air [SI]
Note
In IP units, R_DA_IP / 144 equals 0.370486 which is the coefficient appearing in eqn 26.
The factor 144 is for the conversion of Psi = lb in-2 to lb ft-2.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 26
Examples
SetUnitSystem("IP")
GetMoistAirVolume(80:100, 0.02, 14.175)
SetUnitSystem("SI")
GetMoistAirVolume(20:30, 0.02, 95461)
Return relative humidity given dry-bulb temperature, humidity ratio, and pressure.
Description
Return relative humidity given dry-bulb temperature, humidity ratio, and pressure.
Usage
GetRelHumFromHumRatio(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of relative humidity in range [0, 1]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetRelHumFromHumRatio(80:100, 0.01, 14.175)
SetUnitSystem("SI")
GetRelHumFromHumRatio(20:30, 0.01, 95461.0)
Return relative humidity given dry-bulb temperature and dew-point temperature.
Description
Return relative humidity given dry-bulb temperature and dew-point temperature.
Usage
GetRelHumFromTDewPoint(TDryBulb, TDewPoint)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TDewPoint |
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of relative humidity in range [0, 1]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 22
Examples
SetUnitSystem("IP")
GetRelHumFromTDewPoint(80:100, 65)
SetUnitSystem("SI")
GetRelHumFromTDewPoint(20:30, 15)
Return relative humidity given dry-bulb temperature, wet bulb temperature and pressure.
Description
Return relative humidity given dry-bulb temperature, wet bulb temperature and pressure.
Usage
GetRelHumFromTWetBulb(TDryBulb, TWetBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TWetBulb |
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of relative humidity in range [0, 1]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetRelHumFromTWetBulb(80:100, 79.9, 14.696)
SetUnitSystem("SI")
GetRelHumFromTWetBulb(25:40, 20, 101325.0)
Return relative humidity given dry-bulb temperature and vapor pressure.
Description
Return relative humidity given dry-bulb temperature and vapor pressure.
Usage
GetRelHumFromVapPres(TDryBulb, VapPres)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
VapPres |
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI] |
Value
A numeric vector of relative humidity in range [0, 1]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 12, 22
Examples
SetUnitSystem("IP")
GetRelHumFromVapPres(70:80, 0.0149)
SetUnitSystem("SI")
GetRelHumFromVapPres(20:30, 12581)
Return saturated air enthalpy given dry-bulb temperature and pressure.
Description
Return saturated air enthalpy given dry-bulb temperature and pressure.
Usage
GetSatAirEnthalpy(TDryBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of saturated air enthalpy in Btu lb-1 [IP] or J kg-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetSatAirEnthalpy(80:100, 14.696)
SetUnitSystem("SI")
GetSatAirEnthalpy(20:30, 101325)
Return humidity ratio of saturated air given dry-bulb temperature and pressure.
Description
Return humidity ratio of saturated air given dry-bulb temperature and pressure.
Usage
GetSatHumRatio(TDryBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of humidity ratio of saturated air in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 36, solved for W
Examples
SetUnitSystem("IP")
GetSatHumRatio(80:100, 14.696)
SetUnitSystem("SI")
GetSatHumRatio(20:30, 101325)
Return saturation vapor pressure given dry-bulb temperature.
Description
Return saturation vapor pressure given dry-bulb temperature.
Usage
GetSatVapPres(TDryBulb)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of vapor pressure of saturated air in Psi [IP] or Pa [SI]
Note
Important note: the ASHRAE formulae are defined above and below the freezing point but have a discontinuity at the freezing point. This is a small inaccuracy on ASHRAE's part: the formulae should be defined above and below the triple point of water (not the feezing point) in which case the discontinuity vanishes. It is essential to use the triple point of water otherwise function GetTDewPointFromVapPres, which inverts the present function, does not converge properly around the freezing point.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 5 & 6
Examples
SetUnitSystem("IP")
GetSatVapPres(80:100)
SetUnitSystem("SI")
GetSatVapPres(20:30)
Return sea level pressure given dry-bulb temperature, altitude above sea level and pressure.
Description
Return sea level pressure given dry-bulb temperature, altitude above sea level and pressure.
Usage
GetSeaLevelPressure(StationPressure, Altitude, TDryBulb)
Arguments
StationPressure |
A numeric vector of observed station pressure in Psi [IP] or Pa [SI] |
Altitude |
A numeric vector of altitude in ft [IP] or m [SI] |
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of sea level barometric pressure in Psi [IP] or Pa [SI]
Note
The standard procedure for the US is to use for TDryBulb the average of the current station temperature and the station temperature from 12 hours ago.
References
Hess SL, Introduction to theoretical meteorology, Holt Rinehart and Winston, NY 1959, ch. 6.5; Stull RB, Meteorology for scientists and engineers, 2nd edition, Brooks/Cole 2000, ch. 1.
Examples
SetUnitSystem("IP")
GetSeaLevelPressure(14.68, 300:400, 62.94)
SetUnitSystem("SI")
GetSeaLevelPressure(101226.5, 105:205, 17.19)
Return the specific humidity from humidity ratio (aka mixing ratio).
Description
Return the specific humidity from humidity ratio (aka mixing ratio).
Usage
GetSpecificHumFromHumRatio(HumRatio)
Arguments
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Dry_Air-1 [IP] or kg_H2O kg_Dry_Air-1 [SI] |
Value
A numeric vector of specific humidity in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 9b
Examples
SetUnitSystem("IP")
GetSpecificHumFromHumRatio(seq(0.006, 0.016, 0.001))
SetUnitSystem("SI")
GetSpecificHumFromHumRatio(seq(0.006, 0.016, 0.001))
Return standard atmosphere barometric pressure, given the elevation (altitude).
Description
Return standard atmosphere barometric pressure, given the elevation (altitude).
Usage
GetStandardAtmPressure(Altitude)
Arguments
Altitude |
A numeric vector of altitude in ft [IP] or m [SI] |
Value
A numeric vector of standard atmosphere barometric pressure in Psi [IP] or Pa [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 3
Examples
SetUnitSystem("IP")
GetStandardAtmPressure(seq(-500, 1000, 100))
SetUnitSystem("SI")
GetStandardAtmPressure(seq(-500, 1000, 100))
Return standard atmosphere temperature, given the elevation (altitude).
Description
Return standard atmosphere temperature, given the elevation (altitude).
Usage
GetStandardAtmTemperature(Altitude)
Arguments
Altitude |
A numeric vector of altitude in ft [IP] or m [SI] |
Value
A numeric vector of standard atmosphere dry-bulb temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 4
Examples
SetUnitSystem("IP")
GetStandardAtmTemperature(seq(-500, 1000, 100))
SetUnitSystem("SI")
GetStandardAtmTemperature(seq(-500, 1000, 100))
Return station pressure from sea level pressure.
Description
Return station pressure from sea level pressure.
Usage
GetStationPressure(SeaLevelPressure, Altitude, TDryBulb)
Arguments
SeaLevelPressure |
A numeric vector of sea level barometric pressure in Psi [IP] or Pa [SI] |
Altitude |
A numeric vector of altitude in ft [IP] or m [SI] |
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of station pressure in Psi [IP] or Pa [SI]
Note
This function is just the inverse of GetSeaLevelPressure.
References
See GetSeaLevelPressure.
Examples
SetUnitSystem("IP")
GetStationPressure(14.68, 300:400, 62.94)
SetUnitSystem("SI")
GetStationPressure(101226.5, 105:205, 17.19)
Utility function to convert temperature to degree Celsius (degreeC) given temperature in Kelvin (K).
Description
Utility function to convert temperature to degree Celsius (degreeC) given temperature in Kelvin (K).
Usage
GetTCelsiusFromTKelvin(TKelvin)
Arguments
TKelvin |
A numeric vector of temperature in degree Kelvin (K) |
Value
A numeric vector of temperature in Celsius (degreeC)
Notes
Exact conversion.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 section 3
Examples
GetTCelsiusFromTKelvin(300:400)
Return dew-point temperature given dry-bulb temperature, humidity ratio, and pressure.
Description
Return dew-point temperature given dry-bulb temperature, humidity ratio, and pressure.
Usage
GetTDewPointFromHumRatio(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetTDewPointFromHumRatio(80:100, 0.01, 14.175)
SetUnitSystem("SI")
GetTDewPointFromHumRatio(20:30, 0.01, 95461.0)
Return dew-point temperature given dry-bulb temperature and relative humidity.
Description
Return dew-point temperature given dry-bulb temperature and relative humidity.
Usage
GetTDewPointFromRelHum(TDryBulb, RelHum)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
RelHum |
A numeric vector of relative humidity in range [0, 1] |
Value
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetTDewPointFromRelHum(80:100, 0.2)
SetUnitSystem("SI")
GetTDewPointFromRelHum(20:30, 0.4)
Return dew-point temperature given dry-bulb temperature, wet-bulb temperature, and pressure.
Description
Return dew-point temperature given dry-bulb temperature, wet-bulb temperature, and pressure.
Usage
GetTDewPointFromTWetBulb(TDryBulb, TWetBulb, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TWetBulb |
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetTDewPointFromTWetBulb(80:100, 65.0, 14.696)
SetUnitSystem("SI")
GetTDewPointFromTWetBulb(25:40, 20, 101325.0)
Return dew-point temperature given dry-bulb temperature and vapor pressure.
Description
Return dew-point temperature given dry-bulb temperature and vapor pressure.
Usage
GetTDewPointFromVapPres(TDryBulb, VapPres)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
VapPres |
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI] |
Value
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI]
Note
The dew point temperature is solved by inverting the equation giving water vapor pressure at saturation from temperature rather than using the regressions provided by ASHRAE (eqn. 37 and 38), which are much less accurate and have a narrower range of validity.
The Newton-Raphson (NR) method is used on the logarithm of water vapour pressure as a function of temperature, which is a very smooth function.
Convergence is usually achieved in 3 to 5 iterations.
TDryBulb is not really needed here, just used for convenience.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn. 5 and 6
Examples
SetUnitSystem("IP")
GetTDewPointFromVapPres(70:80, seq(0.0149, 0.0249, 0.001))
SetUnitSystem("SI")
GetTDewPointFromVapPres(70:80, 12581:12591)
Return dry bulb temperature from enthalpy and humidity ratio.
Description
Return dry bulb temperature from enthalpy and humidity ratio.
Usage
GetTDryBulbFromEnthalpyAndHumRatio(MoistAirEnthalpy, HumRatio)
Arguments
MoistAirEnthalpy |
A numeric vector of moist air enthalpy in Btu lb-1 [IP] or J kg-1 |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Value
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI]
Note
Based on the GetMoistAirEnthalpy function, rearranged for temperature.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 30
Examples
SetUnitSystem("IP")
GetTDryBulbFromEnthalpyAndHumRatio(42.6168, seq(0.01, 0.02, 0.001))
SetUnitSystem("SI")
GetTDryBulbFromEnthalpyAndHumRatio(81316.0, seq(0.01, 0.02, 0.001))
Return dry-bulb temperature given moist air specific volume, humidity ratio, and pressure.
Description
Return dry-bulb temperature given moist air specific volume, humidity ratio, and pressure.
Usage
GetTDryBulbFromMoistAirVolumeAndHumRatio(MoistAirVolume, HumRatio, Pressure)
Arguments
MoistAirVolume |
A numeric vector of specific volume of moist air in ft3 lb-1 of dry air [IP] or in m3 kg-1 of dry air [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of tDryBulb : Dry-bulb temperature in degreeF [IP] or degreeC [SI]
Note
In IP units, R_DA_IP / 144 equals 0.370486 which is the coefficient appearing in eqn 26.
The factor 144 is for the conversion of Psi = lb in-2 to lb ft-2.
Based on the 'GetMoistAirVolume' function, rearranged for dry-bulb temperature.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 26
Examples
SetUnitSystem("IP")
GetTDryBulbFromMoistAirVolumeAndHumRatio(14.72, seq(0.02, 0.03, 0.001), 14.175)
SetUnitSystem("SI")
GetTDryBulbFromMoistAirVolumeAndHumRatio(0.94, seq(0.02, 0.03, 0.001), 95461)
Utility function to convert temperature to degree Fahrenheit (degreeF) given temperature in degree Rankine (degreeR).
Description
Utility function to convert temperature to degree Fahrenheit (degreeF) given temperature in degree Rankine (degreeR).
Usage
GetTFahrenheitFromTRankine(TRankine)
Arguments
TRankine |
A numeric vector of temperature in degree Rankine (degreeR) |
Value
A numeric vector of temperature in degree Fahrenheit (degreeF)
Notes
Exact conversion.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 section 3
Examples
GetTFahrenheitFromTRankine(500:600)
Utility function to convert temperature to Kelvin (K) given temperature in degree Celsius (degreeC).
Description
Utility function to convert temperature to Kelvin (K) given temperature in degree Celsius (degreeC).
Usage
GetTKelvinFromTCelsius(TCelsius)
Arguments
TCelsius |
A numeric vector of temperature in degree Celsius (degreeC) |
Value
A numeric vector of temperature in Kelvin (K)
Notes
Exact conversion.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 section 3
Examples
GetTKelvinFromTCelsius(20:30)
Utility function to convert temperature to degree Rankine (degreeR) given temperature in degree Fahrenheit (degreeF).
Description
Utility function to convert temperature to degree Rankine (degreeR) given temperature in degree Fahrenheit (degreeF).
Usage
GetTRankineFromTFahrenheit(TFahrenheit)
Arguments
TFahrenheit |
A numeric vector of temperature in degree Fahrenheit (degreeF) |
Value
A numeric vector of temperature in degree Rankine (degreeR)
Notes
Exact conversion.
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 section 3
Examples
GetTRankineFromTFahrenheit(1:100)
Return wet-bulb temperature given dry-bulb temperature, humidity ratio, and pressure.
Description
Return wet-bulb temperature given dry-bulb temperature, humidity ratio, and pressure.
Usage
GetTWetBulbFromHumRatio(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric Pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 33 and 35 solved for Tstar
Examples
SetUnitSystem("IP")
GetTWetBulbFromHumRatio(80:100, 0.01, 14.175)
SetUnitSystem("SI")
GetTWetBulbFromHumRatio(20:30, 0.01, 95461)
Return wet-bulb temperature given dry-bulb temperature, relative humidity, and pressure.
Description
Return wet-bulb temperature given dry-bulb temperature, relative humidity, and pressure.
Usage
GetTWetBulbFromRelHum(TDryBulb, RelHum, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
RelHum |
A numeric vector of relative humidity in range [0, 1] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetTWetBulbFromRelHum(80:100, 0.2, 14.696)
SetUnitSystem("SI")
GetTWetBulbFromRelHum(25:40, 0.2, 101325.0)
Return wet-bulb temperature given dry-bulb temperature, dew-point temperature, and pressure.
Description
Return wet-bulb temperature given dry-bulb temperature, dew-point temperature, and pressure.
Usage
GetTWetBulbFromTDewPoint(TDryBulb, TDewPoint, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
TDewPoint |
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of wet-bulb temperature in degreeF [IP] or degreeC [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1
Examples
SetUnitSystem("IP")
GetTWetBulbFromTDewPoint(80:100, 40.0, 14.696)
SetUnitSystem("SI")
GetTWetBulbFromTDewPoint(25:40, 20.0, 101325.0)
Return system of units in use.
Description
Return system of units in use.
Usage
GetUnitSystem()
Value
A string indicating system of units in use ("SI" or "IP")
Return vapor pressure given humidity ratio and pressure.
Description
Return vapor pressure given humidity ratio and pressure.
Usage
GetVapPresFromHumRatio(HumRatio, Pressure)
Arguments
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 20 solved for pw
Examples
SetUnitSystem("IP")
GetVapPresFromHumRatio(seq(0.02, 0.03, 0.001), 14.175)
SetUnitSystem("SI")
GetVapPresFromHumRatio(seq(0.02, 0.03, 0.001), 95461)
Return partial pressure of water vapor as a function of relative humidity and temperature.
Description
Return partial pressure of water vapor as a function of relative humidity and temperature.
Usage
GetVapPresFromRelHum(TDryBulb, RelHum)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
RelHum |
A numeric vector of relative humidity in range [0, 1] |
Value
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 12, 22
Examples
SetUnitSystem("IP")
GetVapPresFromRelHum(77, seq(0.1, 0.8, 0.1))
SetUnitSystem("SI")
GetVapPresFromRelHum(20, seq(0.1, 0.8, 0.1))
Return vapor pressure given dew point temperature.
Description
Return vapor pressure given dew point temperature.
Usage
GetVapPresFromTDewPoint(TDewPoint)
Arguments
TDewPoint |
A numeric vector of dew-point temperature in degreeF [IP] or degreeC [SI] |
Value
A numeric vector of partial pressure of water vapor in moist air in Psi [IP] or Pa [SI]
References
ASHRAE Handbook - Fundamentals (2017) ch. 1 eqn 36
Examples
SetUnitSystem("IP")
GetVapPresFromTDewPoint(12:20)
SetUnitSystem("SI")
GetVapPresFromTDewPoint(12:20)
Return Vapor pressure deficit given dry-bulb temperature, humidity ratio, and pressure.
Description
Return Vapor pressure deficit given dry-bulb temperature, humidity ratio, and pressure.
Usage
GetVaporPressureDeficit(TDryBulb, HumRatio, Pressure)
Arguments
TDryBulb |
A numeric vector of dry-bulb temperature in degreeF [IP] or degreeC [SI] |
HumRatio |
A numeric vector of humidity ratio in lb_H2O lb_Air-1 [IP] or kg_H2O kg_Air-1 [SI] |
Pressure |
A numeric vector of atmospheric pressure in Psi [IP] or Pa [SI] |
Value
A numeric vector of vapor pressure deficit in Psi [IP] or Pa [SI]
References
Oke (1987) eqn 2.13a
Examples
SetUnitSystem("IP")
GetVaporPressureDeficit(80:100, 0.01, 14.175)
SetUnitSystem("SI")
GetVaporPressureDeficit(20:30, 0.01, 95461.0)
Set the system of units to use (SI or IP).
Description
Set the system of units to use (SI or IP).
Usage
SetUnitSystem(units)
Arguments
units |
A string indicating the system of units chosen. Should be either
|
Check whether the system in use is IP or SI.
Description
Check whether the system in use is IP or SI.
Usage
isIP()
Value
TRUE if unit system is IP