Name | Description |
---|---|
DewPointTemperature | Model to compute the dew point temperature of moist air |
Examples | Collection of models that illustrate model use and test models |
HumidityRatioPressure | Relation between humidity ratio and water vapor pressure |
WetBulbTemperature | Model to compute the wet bulb temperature |
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.
Extends from Buildings.BaseClasses.BaseIcon (Base icon).
Type | Name | Description |
---|---|---|
RealSignal | p_w | Water vapor partial pressure |
RealSignal | T | Dew point temperature [K] |
model DewPointTemperature "Model to compute the dew point temperature of moist air" extends Buildings.BaseClasses.BaseIcon; ObsoleteModelica3.Blocks.Interfaces.RealSignal p_w "Water vapor partial pressure"; ObsoleteModelica3.Blocks.Interfaces.RealSignal T(start=278.15, final quantity="ThermodynamicTemperature", final unit="K", min = 0, displayUnit="degC") "Dew point temperature"; 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; equation p_w = Modelica.Math.exp(C8/T + C9 + T * ( C10 + T * ( C11 + T * C12)) + C13 * Modelica.Math.log(T)); end DewPointTemperature;
Model to compute the relation between humidity ratio and water vapor partial pressure of moist air.
Extends from Buildings.BaseClasses.BaseIcon (Base icon).
Type | Name | Default | Description |
---|---|---|---|
Pressure | pAtm | 101325 | Fixed value of pressure [Pa] |
Type | Name | Description |
---|---|---|
RealSignal | p | Pressure [Pa] |
RealSignal | XWat | Species concentration at dry bulb temperature |
RealSignal | p_w | Water vapor pressure [Pa] |
model HumidityRatioPressure "Relation between humidity ratio and water vapor pressure" extends Buildings.BaseClasses.BaseIcon; parameter Modelica.SIunits.Pressure pAtm = 101325 "Fixed value of pressure"; ObsoleteModelica3.Blocks.Interfaces.RealSignal p( final quantity="Pressure", final unit="Pa", min = 0) "Pressure"; ObsoleteModelica3.Blocks.Interfaces.RealSignal XWat( nominal=0.01) "Species concentration at dry bulb temperature"; ObsoleteModelica3.Blocks.Interfaces.RealSignal p_w( final quantity="Pressure", final unit="Pa", displayUnit="Pa", min = 0) "Water vapor pressure"; Modelica.SIunits.MassFraction X_dryAir(min=0, max=1, nominal=0.01, start=0.001) "Water mass fraction per mass of dry air"; equation if cardinality(p)==0 then p = pAtm; end if; X_dryAir * (1-XWat) = XWat; ( p - p_w) * X_dryAir = 0.62198 * p_w; end HumidityRatioPressure;
Given a moist are medium model, this component computes the states of the medium at its wet bulb temperature.
For a use of this model, see for example Buildings.Fluids.Sensors.WetBulbTemperature
Extends from Buildings.BaseClasses.BaseIcon (Base icon).
Type | Name | Description |
---|---|---|
RealSignal | TDryBul | Dry bulb temperature [K] |
RealSignal | p | Pressure [Pa] |
RealSignal | TWetBul | Wet bulb temperature [K] |
RealSignal | Xi[Medium.nXi] | Species concentration at dry bulb temperature |
RealSignal | phi | Relative humidity (at dry-bulb state) in [0, 1] |
model WetBulbTemperature "Model to compute the wet bulb temperature" extends Buildings.BaseClasses.BaseIcon; replaceable package Medium = Modelica.Media.Interfaces.PartialCondensingGases "Medium model"; Medium.BaseProperties dryBul "Medium state at dry bulb temperature"; Medium.BaseProperties wetBul(Xi(nominal=0.01*ones(Medium.nXi))) "Medium state at wet bulb temperature"; ObsoleteModelica3.Blocks.Interfaces.RealSignal TDryBul( start=303, final quantity="ThermodynamicTemperature", final unit="K", min = 0) "Dry bulb temperature"; ObsoleteModelica3.Blocks.Interfaces.RealSignal p( final quantity="Pressure", final unit="Pa", min = 0) "Pressure"; ObsoleteModelica3.Blocks.Interfaces.RealSignal TWetBul( start=293, final quantity="ThermodynamicTemperature", final unit="K", min = 0) "Wet bulb temperature"; ObsoleteModelica3.Blocks.Interfaces.RealSignal Xi[ Medium.nXi] "Species concentration at dry bulb temperature"; ObsoleteModelica3.Blocks.Interfaces.RealSignal phi "Relative humidity (at dry-bulb state) in [0, 1]"; protected parameter Integer iWat(min=1, fixed=false) "Index for water vapor concentration"; initial algorithm iWat :=1; for i in 1:Medium.nC loop if ( Modelica.Utilities.Strings.isEqual(Medium.extraPropertiesNames[i], "Water")) then iWat := i; end if; end for; equation dryBul.p = p; dryBul.T = TDryBul; dryBul.Xi = Xi; wetBul.phi = 1; wetBul.p = dryBul.p; wetBul.h = dryBul.h + (wetBul.X[iWat] - dryBul.X[iWat]) * Medium.enthalpyOfLiquid(dryBul.T); TWetBul = wetBul.T; phi = dryBul.phi; end WetBulbTemperature;