Interface (G-MA)
Libraries:
Simscape /
Fluids /
Fluid Network Interfaces
Description
The Interface (G-MA) block represents a flow connection between a gas network and moist air network. Pressure, temperature, and mass flow rate are equal at the interface. The block does not transfer the fluid properties of each fluid network across the interface. To conserve fluid properties, ensure that the Gas Properties (G) block and the Moist Air Properties (MA) block have the same settings. When moist air leaves port MA, the block assigns the values of the Interface specific humidity and Interface trace gas mass fraction parameters to the signal. However, when moist air enters port MA, the block retains the upstream values.
You can choose whether to maintain constant moisture and trace gas amounts at the interface or to specify them using the W or Tw and TG ports, respectively.
Mass and Momentum Balance
The block conserves mass such that
where:
ṁG is the mass flow rate into port G.
ṁMA is the mass flow rate into port MA.
The block maintains equal port pressures and temperatures such that
Energy Balance
The block calculates the energy balance over the interface as
where:
ΦG is the energy flow rate into port G.
ΦMA is the energy flow rate into port MA.
hG is the specific enthalpy at port G.
hMA is the specific enthalpy at port MA.
vG is the specific volume at port G.
vMA is the specific volume at port MA.
wG is the flow velocity at port G.
wMA is the flow velocity at port MA.
For a given cross-sectional area, S, the block defines wG as
and wMA as
where:
The specific gas constant of the mixture at the interface is a function of the fluid on either side such that
where:
RA is the dry air specific gas constant.
RW is the water vapor specific gas constant.
RG is the trace gas specific gas constant.
xWI is the interface specific humidity. The block determines this value when the flow exits port MA, based on your parameter settings:
When Moisture and trace gas specification is
Constant
, the block calculates xWI based on the method specified with the Interface moisture specification parameter.When Moisture and trace gas specification is
Controlled
, the block bases xWI on the input that you supply at port W or port Tw.
xGI is the interface trace gas mass fraction. The block determines this value when the flow exits port MA, based on your parameter settings:
When Moisture and trace gas specification is
Constant
, the block calculates xGI based on the value of the Interface trace gas mass fraction or Interface trace gas mole fraction parameter.When Moisture and trace gas specification is
Controlled
, the block bases xGI on the input that you supply at port TG.