Interface (2P-G)

Two-phase fluid and gas network interface

• 

Libraries:
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 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 Two-Phase Fluid Properties (2P) block have corresponding settings.

The fluid at the 2P port must remain superheated. You can use the Two-phase fluid superheated vapor check parameter to choose what action the block performs if the fluid does not meet this condition.

Mass and Momentum Balance

The block conserves mass such that

$${\dot{m}}_{2P}+{\dot{m}}_G=0,$$

where:

• $${\dot{m}}_G$$ is the mass flow rate into port G.

• $${\dot{m}}_{2P}$$ is the mass flow rate into port 2P.

The port pressures are equal:

$$P_G=P_{2P}.$$

Energy Balance

The temperature is constant between the two fluid ports. The block calculates the energy balance over the interface as

$${\Phi }_G+{\Phi }_{2P}={\dot{m}}_G\left(h_G+\frac{w_G^2}{2}\right)+{\dot{m}}_{2P}\left(h_{2P}+\frac{w_{2P}^2}{2}\right),$$

where:

• Φ_G is the energy flow rate into port G.

• Φ_2P is the energy flow rate into port 2P.

• h_G is the specific enthalpy at port G.

• h_2P is the specific enthalpy at port 2P.

• v_G is the specific volume at port G.

• v_2P is the specific volume at port 2P.

• w_G is the flow velocity at port G such that

  $$w_G=\frac{{\dot{m}}_G{v}_G}{S},$$

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

• w_2P is the flow velocity at port 2P such that

  $$w_{2P}=\frac{{\dot{m}}_{2P}{v}_{2P}}{S}.$$

Examples

Compare Two-Phase Fluid Interfaces

This example uses test harnesses to compare the Interface (2P-G), Interface (2P-MA), and Interface (2P-TL) blocks. A test harness is a minimum viable model that you can use to parameterize blocks or isolate dynamics.

This model contains two networks that both use water as the working fluid. In the top network, the water in the Reservoir (2P) block is 385 K and is fully vapor, which allows it to convert to gas or moist air at the respective interface. In the bottom network, the water in the Reservoir (2P) block is 293 K and fully liquid, which allows it to convert to thermal liquid at the interface.

Interface blocks preserve the overall fluid mixture Through and Across variables across the interface. The Scope blocks show that the temperatures of each fluid remain the same on either side of the interfaces.

Ports

Conserving

2P — Two-phase port

two-phase fluid

Two-phase fluid conserving port associated with the two-phase fluid at the interface.

G — Fluid port

gas

Gas conserving port associated with the gas at the interface.

Parameters

Cross-sectional area at ports 2P and G — Port area

0.01 m^2 (default) | positive scalar

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

Two-phase fluid superheated vapor check — Two-phase fluid superheated conditions check

None (default) | Warning | Error

Action to perform when the fluid at port 2P does not meet superheated conditions.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2021a