Psychro - Thermodynamic properties of moist air

This package provides Julia with functions to compute some thermodynamic properties of moist air. The model uses real gas correlations as recommended by ASHRAE (see reference [5]).

Besides moist air, this package also calculates the properties of dry air and saturated water vapor. It is part of a larger effort to model the thermodynamic (and transport) properties of different types of fluids.

instalation

(v1.5) pkg> add https://github.com/termolivre/Psychro.jl/

or

(v1.5) pkg> add Psychro

User interface - Thermodynamic properties of moist air, dry air and saturated water vapor.

The methods listed below calculate thermodynamic properties of moist air:

volume(MoistAir, T, HumidityType, humidity, P[, outunit]) 
volume(MoistAir, T, HumidityType, humidity, P[, outunit]) 
density(MoistAir, T, HumidityType, humidity, P[, outunit])
enthalpy(MoistAir, T, HumidityType, humidity, P[, outunit])
enthalpym(MoistAir, T, HumidityType, humidity, P[, outunit])
entropy(MoistAir, T, HumidityType, humidity, P[, outunit])
entropym(MoistAir, T, HumidityType, humidity, P[, outunit])
compressfactor(MoistAir, T, HumidityType, humidity, P[, outunit])
dewpoint(MoistAir, T, HumidityType, humidity, P[, outunit]) 
wetbulb(MoistAir, T, HumidityType, humidity, P[, outunit]) 
humrat(MoistAir, T, HumidityType, humidity, P) 
relhum(MoistAir, T, HumidityType, humidity, P) 
humrat(MoistAir, T, HumidityType, humidity, P) 
spechum(MoistAir, T, HumidityType, humidity, P) 
molarfrac(MoistAir, T, HumidityType, humidity, P) 

The methods listed above calculate the following thermodynamic properties of moist air:

• volume Specific volume
• volumem Molar volume
• density Density
• enthalpy Specific enthalpy
• enthalpym Molar enthalpy
• entropy Specific entropy
• entropym Molar entropy
• compressfactor Compressibility factor Z
• dewpoint Dew point temperature
• wetbulb Adiabatic saturation temperature
• humrat Humidity ratio
• relhum Relative humidity
• spechum Specific humidity
• molarfrac Molar fraction of water vapor

The humidity is specified using two parameters:

• How the humidity is specified
• The actual value of humidity

The following types are used to characterize the humidity.

• WetBulb for wet bulb temperature, actually adiabatic saturation temperature
• DewPoint Dew point temperature
• RelHum Relative humidity
• HumRat Humidity ratio (kg of vapor / kg of dry air)
• SpecHum Specific humidity (kg of vapor / kg of moist air)
• MolarFrac Molar fraction of water vapor.

Examples

julia> volume(MoistAir, 293.15, WetBulb, 291.15, 101325.0)
0.8464079202783964

julia> volume(MoistAir, 293.15, DewPoint, 291.15, 101325.0)
0.8475219875187474

julia> volume(MoistAir, 293.15, RelHum, 0.7, 101325.0)
0.843889817602806

julia> volume(MoistAir, 20.0u"°C", DewPoint, 60.0u"°F", 1.0u"atm")
0.8449934929585231 kg^-1 m^3

julia> volumem(MoistAir, 293.15, RelHum, 0.5, 93000.0)
0.026199080086890276

julia> volumem(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa", u"inch^3/kmol")
1.598733210336603e6 in^3 kmol^-1

julia> density(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
1.0976075893895811 kg m^-3

julia> density(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa", u"lb/inch^3")
3.965358988338535e-5 in^-3 lb

julia> volumem(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa", u"inch^3/kmol")
1.598733210336603e6 in^3 kmol^-1

julia> enthalpy(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
50667.43014746832 kg^-1 J

julia> enthalpym(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
1439.6551689935861 J mol^-1

julia> compressfactor(MoistAir, -90.0u"°C", RelHum, 0.01, 4.5u"MPa")
0.8552758629097985

julia> wetbulb(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa", u"°C")
17.0 °C

julia> dewpoint(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa", u"°C")
15.475836053510477 °C

julia> humrat(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
0.012032930694441925

julia> relhum(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
0.7517801524436909

julia> spechum(MoistAir, 20.0u"°C", WetBulb, 17.0u"°C", 93u"kPa")
0.011889860823189923

References

• [1] Wexler, A. and Hyland, R. W., "Formulations for the thermodynamic properties of the saturated phases of H2O from 173.15 K to 473.15 K", ASHRAE Transactions, 1983.
• [2] Wexler, A. and Hyland, R. W., "Formulations for the thermodynamic properties of dry air from 173.15 K to 473.15 K, and of saturated moist air from 173.15 K to 372.15 K at pressures to 5 MPa
• [3] Himmelblaum D. M., "Solubilities of inert gases in water, 0oC to near the critical point of water", Journal of Chemical and Engineering Data, Vol. 5, No. 1, January 1960.
• [4] Kell, George S., "Density, thermal expansivity, and compressibility of liquid water from 0oC to 150oC: correlations and tables for atmospheric pressure and saturation reviewed and expressed on 1968 temperature scale", Journal of Chemical and Engineering Data, Vol. 20, No. 1, 1975.
• [5] ASHRAE, "Psychrometrics: Theory and Practice", ASHRAE, 1996.