This information is part of the Modelica Standard Library maintained by the Modelica Association.

This model produces psychrometric data from the moist air model in this library to be plotted in charts. The two most common chart varieties are the Mollier Diagram and the Psychrometric Chart. The first is widely used in some European countries while the second is more common in the Anglo-American world. Specific enthalpy is plotted over absolute humidity in the Mollier Diagram, it is the other way round in the Psychrometric Chart.
It must be noted that the relationship of both axis variables is not right-angled, the absolute humidity follows a slope which equals the enthalpy of vaporization at 0 °C. For better reading and in order to reduce the fog region the humidity axis is rotated to obtain a right-angled plot. Both charts usually contain additional information as isochores or auxiliary scales for e.g., heat ratios. Those information are omitted in this model and the charts below. Other important features of psychrometric chart data are that all mass specific variables (like absolute humidity, specific enthalpy etc.) are expressed in terms of kg dry air and that their baseline of 0 enthalpy is found at 0 °C and zero humidity.

Legend: blue - constant specific enthalpy, red - constant temperature, black - constant relative humidity

The model provides data for lines of constant specific enthalpy, temperature and relative humidity in a Mollier Diagram or Psychrometric Chart as they were used for the figures above. For limitations and ranges of validity please refer to the MoistAir package description. Absolute humidity x is increased with time in this model. The specific enthalpies adjusted for plotting are then obtained from:

• y_h: constant specific enthalpy
• y_T: constant temperature
• y_phi: constant relative humidity

p_const	Value: 1e5 Type: Pressure (Pa) Description: Pressure
n_T	Value: 11 Type: Integer Description: Number of isotherms
T_min	Value: 253.15 Type: Temperature (K) Description: Lowest isotherm
T_step	Value: 10 Type: Temperature (K) Description: Temperature step between two isotherms
n_h	Value: 16 Type: Integer Description: Number of lines with constant specific enthalpy
h_min	Value: -20e3 Type: SpecificEnthalpy (J/kg) Description: Lowest line of constant enthalpy
h_step	Value: 1e4 Type: SpecificEnthalpy (J/kg) Description: Enthalpy step between two lines of constant enthalpy
n_phi	Value: 10 Type: Integer Description: Number of lines with constant relative humidity
phi_min	Value: 0.1 Type: Real Description: Lowest line of constant humidity
phi_step	Value: 0.1 Type: Real Description: Step between two lines of constant humidity
x_min	Value: 0.00 Type: MassFraction Description: Minimum diagram absolute humidity
x_max	Value: 0.03 Type: MassFraction Description: Maximum diagram absolute humidity
t	Value: 1 Type: Time (s) Description: Simulation time
T_const	Value: array(T_min - T_step + i * T_step for i in 1:n_T) Type: Temperature[n_T] (K) Description: Constant temperatures
h_const	Value: array((i - 1) * h_step + h_min for i in 1:n_h) Type: SpecificEnthalpy[n_h] (J/kg) Description: Constant enthalpies
phi_const	Value: array((i - 1) * phi_step + phi_min for i in 1:n_phi) Type: Real[n_phi] Description: Constant relative humidities
diagSlope	Value: Medium.enthalpyOfVaporization(273.15) Type: Real Description: Rotation of diagram that zero degrees isotherm becomes horizontal outside the fog region
x_start	Value: x_min Type: MassFraction Description: Initial absolute humidity in kg water/kg dry air