MoistAir  Thermodynamic properties of moist air
This package provides a model, MoistAirModel
to compute thermodynamic properties of moist air, using the ThermoState interface. The model uses real gas correlations as recommended by ASHRAE (see reference [5]).
This package also provides the underlying models used for moist air, namely, dry air (ASHRAEDryAir
) and water vapor (ASHRAEWaterVapor
). those models have the same interface as the moist air model.
This is a fork of Psychro.jl working with julia 1.5+.
Instalation
julia> ]
(v1.5) pkg> add MoistAir
User interface  Thermodynamic properties of moist air, dry air and saturated water vapor.
The models defined in this package accept the following ThermoState
thermodynamic states:
ASHRAEDryAir
: pressure,temperatureASHRAEWaterVapor
: pressure,temperatureMoistAirModel
: pressure, temperature, amounts (any of
mol_fraction
,mass_fraction
,mol_number
,mass_number
)  pressure,temperature, humidity spec*
 pressure, temperature, amounts (any of
The models defined in this package support the following ThermoState
functions:
mol_enthalpy
,mass_enthalpy
,total_enthalpy
mol_entropy
,mass_entropy
,total_entropy
mol_volume
,mass_volume
,total_volume
mol_enthalpy
,mass_enthalpy
compressibility_factor
The package also provides its own functions, with ThermoState
syntax, specific for moist air:

Dry properties: properties per 1 kg of dry air:
dry_volume
,dry_enthalpy
,dry_entropy

rel_hum
: Relative humidity, defined as the fraction between the amount of water in the air and the amount of water of saturated air at the same temperature and pressure (between 0 and 1) 
hum_massfrac
: kg of water / kg of moist air 
hum_molfrac
: mol of water / mol of moist air 
hum_wetbulb
: wetbulb temperature or adiabatic saturation temperature is the temperature a volume of air would have if cooled adiabatically to saturation by evaporation of water into it, always lower than the specified temperature (also known as drybulb temperature) 
hum_ratio
: Humidity ratio (kg of vapor / kg of dry air) 
hum_dewpoint
temperature to which moist air must be cooled to become saturated,always lower than the specified temperature.
Humidity Spec
As mentioned before, the MoistAirModel accepts thermodynamic states of the form pressuretemperaturehumidity spec. you can use the same function names as keywords in the ThermoState.state
function.
Usage
using ThermoState,Unitful,MoistAir
air = MoistAirModel() #Moist air model
λ = VariableSpec() #to create a variable model
st = state(hum_wetbulb = 25.0u"°C",t=λ,p=1u"atm")
dryh = dry_enthalpy(air,st(32u"°C")) #custom units
x = mol_fraction(air,st(300.15)) #molar fraction of the mixture airwater
xw = hum_molfrac(air,st(300.15)) #molar fraction of water
dew = hum_dewpoint(air,st(300.15)) #dew point of water
last(x) == xw #true
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.