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Reservoir (2P)

Two-phase fluid reservoir at constant temperature and pressure

Library

Two-Phase Fluid/Elements

Description

The Reservoir (2P) block sets pressure and temperature boundary conditions in a two-phase fluid network. The reservoir is assumed infinite in size, causing its pressure and specific internal energy to remain constant.

Port A represents the reservoir inlet. The flow resistance between port A and the reservoir interior is assumed negligible. The pressure at port A is therefore equal to that inside the reservoir.

The specific internal energy at the reservoir inlet depends on the flow direction. If fluid leaves the reservoir, the fluid at port A is at the specific internal energy of the reservoir. The reservoir acts as an energy source. If fluid enters the reservoir, the fluid at port A is at the specific internal energy upstream of the reservoir. The reservoir acts as an energy sink.

This block also serves as a reference connection for the Pressure & Internal Energy Sensor (2P) block. In this case, the measured pressure and specific internal energy are relative to the reservoir pressure and specific internal energy.

Assumptions and Limitations

  • The pressure and specific internal energy of the fluid are assumed constant in the reservoir.

  • The flow resistance between port A and the reservoir interior is negligible. Pressure is the same at port A and in the reservoir interior.

Parameters

Reservoir pressure specification

Pressurization characteristics of the reservoir. Select Atmospheric pressure to set the reservoir pressure to the atmospheric pressure specified in the Two-Phase Fluid Properties (2P) block. Select Specified pressure to set the reservoir pressure to a different value. The default setting is Atmospheric pressure.

Reservoir pressure

Absolute pressure inside the reservoir. This pressure is fixed during simulation. This parameter is active only when the Reservoir pressure specification parameter is set to Specified pressure. The default value, 0.101325 MPa, corresponds to atmospheric pressure at mean sea level.

Reservoir energy specification

Thermodynamic variable to use in defining the conditions of the reservoir. The default setting is Temperature.

Reservoir temperature

Absolute temperature inside the reservoir. This temperature is fixed during simulation. This parameter is active when the Reservoir energy specification option is set to Temperature. The default value is 293.15 K.

Reservoir vapor quality

Mass fraction of vapor in the reservoir. This value is fixed during simulation. This parameter is active when the Reservoir energy specification option is set to Vapor quality. The default value is 0.5.

Reservoir vapor void fraction

Volume fraction of vapor in the reservoir. This value is fixed during simulation. This parameter is active when the Reservoir energy specification option is set to Vapor void fraction. The default value is 0.5.

Reservoir specific enthalpy

Specific enthalpy of the fluid in the reservoir. This value is fixed during simulation. This parameter is active when the Reservoir energy specification option is set to Specific enthalpy. The default value is 1500 kJ/kg.

Reservoir specific internal energy

Specific internal energy of the fluid in the reservoir. This value is fixed during simulation. This parameter is active when the Reservoir energy specification option is set to Specific internal energy. The default value is 1500 kJ/kg.

Cross-sectional area at port A

Flow area of the reservoir inlet, represented by port A. The flow area must be greater than zero. The default value is 0.01 m^2.

Ports

The block has one two-phase fluid conserving port, A, representing the reservoir inlet.

Introduced in R2015b