Name | Description |
---|---|
![]() | Derivative of dewPointTemperature function |
![]() | Function to compute the dew point temperature of moist air |
![]() | Collection of models that illustrate model use and test models |
![]() | Humidity ratio for given water vapor pressure |
Derivative of dew point temperature calculation for moist air above freezing temperature.
Type | Name | Default | Description |
---|---|---|---|
Temperature | T | Dew point temperature [K] | |
Real | dT |
Type | Name | Description |
---|---|---|
Real | dp_w | Differential of water vapor partial pressure |
function der_dewPointTemperature "Derivative of dewPointTemperature function"input Modelica.SIunits.Temperature T "Dew point temperature"; input Real dT; output Real dp_w "Differential of water vapor partial pressure"; protected constant Real C8 = -5.800226E3; constant Real C9 = 1.3914993E0; constant Real C10= -4.8640239E-2; constant Real C11 = 4.1764768E-5; constant Real C12= -1.4452093E-8; constant Real C13 = 6.5459673E0; algorithm dp_w := Modelica.Math.exp(C8/T + C9 + T * ( C10 + T * ( C11 + T * C12)) + C13 * Modelica.Math.log(T)) * (-C8/T/T+C10+2*C11*T+3*C12*T*T+C13/T)*dT; end der_dewPointTemperature;
Dew point temperature calculation for moist air above freezing temperature.
The correlation used in this model is valid for dew point temperatures between 0 degC and 200 degC. It is the correlation from 2005 ASHRAE Handbook, p. 6.2. In an earlier version of this model, the equation from Peppers has been used, but this equation yielded about 15 Kelvin lower dew point temperatures.
Type | Name | Default | Description |
---|---|---|---|
Temperature | T | Dew point temperature [K] |
Type | Name | Description |
---|---|---|
Pressure | p_w | Water vapor partial pressure [Pa] |
function dewPointTemperature "Function to compute the dew point temperature of moist air" annotation(derivative=der_dewPointTemperature);input Modelica.SIunits.Temperature T "Dew point temperature"; output Modelica.SIunits.Pressure p_w "Water vapor partial pressure"; protected constant Real C8 = -5.800226E3; constant Real C9 = 1.3914993E0; constant Real C10= -4.8640239E-2; constant Real C11 = 4.1764768E-5; constant Real C12= -1.4452093E-8; constant Real C13 = 6.5459673E0; algorithm p_w := Modelica.Math.exp(C8/T + C9 + T * ( C10 + T * ( C11 + T * C12)) + C13 * Modelica.Math.log(T)); end dewPointTemperature;
Partial Block to compute the relation between humidity ratio and water vapor partial pressure.
If use_p_in is false (default option), the p parameter is used as atmospheric pressure, and the p_in input connector is disabled; if use_p_in is true, then the p parameter is ignored, and the value provided by the input connector is used instead.
Extends from Modelica.Blocks.Interfaces.BlockIcon (Basic graphical layout of input/output block).
Type | Name | Default | Description |
---|---|---|---|
Boolean | use_p_in | true | Get the pressure from the input connector |
Pressure | p | 101325 | Fixed value of pressure [Pa] |
Type | Name | Description |
---|---|---|
input RealInput | p_in | Atmospheric Pressure [Pa] |
partial block HumidityRatioVaporPressure "Humidity ratio for given water vapor pressure" extends Modelica.Blocks.Interfaces.BlockIcon;parameter Boolean use_p_in = true "Get the pressure from the input connector"; parameter Modelica.SIunits.Pressure p = 101325 "Fixed value of pressure"; Modelica.Blocks.Interfaces.RealInput p_in(final quantity="Pressure", final unit="Pa", min = 0) if use_p_in "Atmospheric Pressure"; protected Modelica.Blocks.Interfaces.RealInput p_in_internal "Needed to connect to conditional connector"; equation connect(p_in, p_in_internal); if not use_p_in then p_in_internal = p; end if; end HumidityRatioVaporPressure;