# Interface (2P-G)

Two-phase fluid and gas network interface

• Library:
• Simscape / Fluids / Fluid Network Interfaces

## Description

The Interface (2P-G) block represents a flow connection between a two-phase fluid network and a gas network. Pressure, temperature, and mass flow rate are equal at the interface. The fluid properties of each fluid network are not transmitted across the interface. To conserve fluid properties, ensure that fluid properties blocks on either side of the interface block have the same network properties.

The fluid on the two-phase fluid side must be superheated. If the fluid vapor fraction at the two-phase fluid port falls below `1` during a simulation, the block will return an error.

### Mass and Momentum Balance

Mass is conversed through the block:

`${\stackrel{˙}{m}}_{2P}+{\stackrel{˙}{m}}_{G}=0,$`

where:

• ${\stackrel{˙}{m}}_{G}$ is the mass flow rate at port G.

• ${\stackrel{˙}{m}}_{2P}$ is the mass flow rate at port 2P.

The internal and port pressures are equal:

`${P}_{G}={P}_{I}={P}_{2P}.$`

### Energy Balance

The temperature is maintained between the two fluid ports. The energy balance over the interface is calculated as:

`${\Phi }_{G}+{\Phi }_{2P}={\stackrel{˙}{m}}_{G}\left({h}_{I,G}+\frac{{w}_{I,G}^{2}}{2}\right)+{\stackrel{˙}{m}}_{2P}\left({u}_{I,2P}+{p}_{I}{v}_{I,2P}+\frac{{w}_{I,2P}^{2}}{2}\right),$`

where:

• ΦG is the energy flow rate at port G.

• Φ2P is the energy flow rate at port 2P.

• hI,G is the specific enthalpy of the gas at the internal node I.

• pI is the pressure of the fluids at the internal node I.

• vI,G is the specific volume of the gas at the internal node I.

• uI,2P is the specific energy of the two-phase fluid at the internal node I.

• vI,2P is the specific volume of the two-phase fluid at the internal node I.

• wI,2P is the speed of the fluid on the two-phase fluid side at internal node I:

`${w}_{I,2P}=\frac{{\stackrel{˙}{m}}_{2P}{v}_{I,2P}}{S},$`

where S is the value of the Cross-sectional area at ports 2P and G parameter.

• wI,G is the speed of the fluid on the gas side at internal node I:

`${w}_{I,G}=\frac{{\stackrel{˙}{m}}_{G}{v}_{I,G}}{S}.$`

## Ports

### Conserving

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Entry or exit port to the two-phase fluid network.

Entry or exit port to the gas network.

## Parameters

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Cross-sectional area of the thermal liquid and two-phase fluid ports.