Documentation

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 fluid regime

Fluid phases present in the reservoir. Select Subcooled liquid for a reservoir that contains only liquid, Superheated vapor for a reservoir that contains only vapor, and Two-phase mixture for a reservoir that contains both liquid and vapor. The default setting is Subcooled liquid.

Reservoir temperature

Absolute temperature inside the reservoir. This temperature is fixed during simulation. This parameter is active only when the Reservoir fluid regime parameter is set to Subcooled liquid or Superheated vapor. The default value is 293.15 K.

Reservoir vapor quality

Mass fraction of the reservoir fluid that is in the vapor phase. This parameter is active only when the Reservoir fluid regime parameter is set to Two-phase mixture. The default value, 0.2, corresponds to a two-phase fluid with 20% vapor by mass.

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

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