Reservoir (G)

Boundary conditions for gas network at constant pressure and temperature

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Libraries:
Simscape / Foundation Library / Gas / Elements

Description

The Reservoir (G) block represents an infinite reservoir at fixed pressure and temperature. The reservoir and its inlet can be at atmospheric pressure or at a specified pressure. Port A, a gas conserving port, represents the reservoir inlet.

The volume of gas inside the reservoir is assumed infinite. Therefore, the flow is assumed quasi-steady.

Gas enters and leaves the reservoir at the reservoir pressure, but its temperature is determined by the direction of gas flow. If gas flows into the reservoir, its temperature is determined by the gas network upstream. The reservoir acts as a heat sink. If gas flows out of the reservoir, its temperature equals that of the reservoir. The reservoir acts as a heat source.

This block also functions as a reference point for pressure and temperature measurements in a gas network. These measurements are relative to the reservoir pressure and temperature, respectively. Connect the reservoir to port B of a Pressure and Temperature Sensor (G) block to measure relative pressure and temperature of a node connected to the A port of the sensor.

Assumptions and Limitations

• Reservoir pressure and temperature are constant.

• Gas in the reservoir is quasi-steady.

Examples

Pneumatic Actuation Circuit

How the Foundation Library gas components can be used to model a controlled pneumatic actuator. The Directional Valve is a masked subsystem created from Variable Local Restriction (G) blocks to model the opening and closing of the flow paths. The Double-Acting Actuator is a masked subsystem created from Translational Mechanical Converter (G) blocks to model the interface between the gas network and the mechanical translational network.

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Pneumatic Motor Circuit

How a pneumatic vane motor can be modeled using the Simscape™ language. The Pneumatic Motor component is built using the Simscape Foundation gas domain. It inherits from the foundation.gas.two_port_steady base class, which contains common equations that implement the upwind energy flow rate and the gas properties at the ports. The Pneumatic Motor subclass implements equations that describe behaviors specific to the component, such as the motor torque and flow rate characteristics and the mass and energy balance. The Pneumatic Motor block is inserted into the model using the Simscape Component block without the need to generate a separate library.

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Ports

Conserving

A — Reservoir inlet

gas

Gas conserving port associated with the reservoir inlet.

Parameters

Reservoir pressure specification — Select specification method for reservoir pressure

Atmospheric pressure (default) | Specified pressure

Select a specification method for the reservoir pressure:

• Atmospheric pressure — Use the atmospheric pressure, specified by the Gas Properties (G) block connected to the circuit.

• Specified pressure — Specify a value by using the Reservoir pressure parameter.

Reservoir pressure — Pressure in the reservoir

0.101325 MPa (default)

Enter the desired pressure in the reservoir. This pressure remains constant during simulation.

Dependencies

Enabled when the Reservoir pressure specification parameter is set to Specified pressure.

Reservoir temperature — Temperature in the reservoir

293.15 K (default)

Enter the desired temperature in the reservoir. This temperature remains constant during simulation.

Cross-sectional area at port A — Area normal to flow path at the reservoir inlet

0.01 m^2 (default)

The cross-sectional area of the reservoir inlet, in the direction normal to gas flow path.

Extended Capabilities

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

Version History

Introduced in R2016b