Constant Properties
This gas property assumes constant fluid properties with no enthalpy flow between the components.
Description
Equations
Gas Parameters
Global Settings
This property block assumes constant values for the thermodynamic properties of gas in the simulation. The system follows the assumptions below.
Ideal Gas Law equation is used to calculate the gas properties for models.
The specific enthalpy flow is assumed to be constant throughout the simulation. The enthalpy into the component is calculated based on the environmental temperature and the specific heat capacity, c__p.
The default gas properties assumed in this block are for the air.
Note: Place this component at the same level as the other pneumatic components or subsystem to which the gas model is applied. If multiple models are created in the same canvas referring to different gas properties then each component must be provided with the respective gas property block name. This can be done by clearing the Use default medium (fluidModel1) check box in the component properties. If Use default medium (fluidModel1) is selected, the component will refer to the default air properties.
Specific heat capacity at constant pressure, c__p = R + c__v Gas Ratio, γ = c__pc__vReference Density, ρ__0 = fp,T, c__p Specific Enthalpy , hflow = fp,T, c__p
ρ__= P__xR⋅T__env h__flow = C__p⋅T__env
Parameters
Fluid Properties
Name
Default
Units
Modelica ID
R
288
Jkg⋅K
Specific Gas constant
c__v
718
Specific heat capacity at constant volume
cv
μ
0.000001458
Pa·s
Reference Dynamic Viscosity
mu
The global settings are used by most of the components in the library. All the parameters defined in this block can be accessed by each component.
patm
101325
Pa
Atmospheric pressure
p_atm
T__env
293.15
K
Environmental temperature
T_env
b__min
0.0001
−
Minimum allowable critical pressure ratio
b_min
b__max
0.8
Maximum allowable critical pressure ratio
b_max
See Also
Pneumatics Library
Download Help Document