Controlled Reservoir (2P)

A tank with a two-phase liquid at varying temperature and pressure.

blockType: AcausalFoundation.TwoPhaseFluid.Elements.ControlledReservoir

Path in the library:

/Physical Modeling/Fundamental/Two Phase Fluid/Elements/Controlled Reservoir (2P)

Description

Block Controlled Reservoir (2P) sets the boundary conditions in a two-phase liquid network. The reservoir is considered infinitely large.

Port A represents the entrance to the tank. The flow resistance between port A and the inside of the tank is considered negligible. Therefore, the pressure in port A is equal to the pressure inside the tank.

The specific enthalpy and specific internal energy at the tank inlet depend on the flow direction. The liquid leaves the tank at a pressure and specific internal energy that are equal to the pressure and specific internal energy of the tank. The liquid enters the tank at a pressure that is equal to the pressure in the tank, but the specific internal energy is determined by the network of the two-phase liquid located upstream.

The unit provides independent selection of pressure and energy parameters using the parameters Reservoir pressure specification and Reservoir energy specification. Depending on the selected parameters, the block provides additional parameters for setting the values of the selected values.

For some combinations of parameters, the pressure inside the tank must be less than the critical pressure, since the saturation curves are not defined above the critical point. When selecting such a combination, the parameter Reservoir pressure above critical allows you to determine what will happen when the fluid pressure exceeds the critical pressure.

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

Ports

Conserving

# A — entrance to the reservoir
two-phase liquid

Details

The port of the two-phase liquid corresponds to the entrance to the tank.

Program usage name

port

Input

# T — temperature control signal, K
scalar

Details

Input port that determines the temperature of the supercooled liquid or the temperature of the superheated steam, depending on the parameter Reservoir energy specification.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Subcooled liquid temperature or Superheated vapor temperature.

Data types	`Float64`
Complex numbers support	No

# P — pressure control signal, Pa
scalar

Details

The inlet port that determines the pressure value in the tank.

Dependencies

To use this port, set the parameter Reservoir pressure specification meaning Specified pressure.

Data types	`Float64`
Complex numbers support	No

# X — control signal for the mass fraction of steam, dimensionless
scalar

Details

The input port that determines the value of the mass fraction of steam in the tank.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Vapor quality.

Data types	`Float64`
Complex numbers support	No

# a — volume fraction control signal, dimensionless
scalar

Details

The input port that determines the value of the volume fraction of steam in the tank.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Vapor void fraction.

Data types	`Float64`
Complex numbers support	No

# H — liquid specific enthalpy control signal, J/kg
scalar

Details

The input port that determines the value of the specific enthalpy of the liquid in the tank.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Specific enthalpy.

Data types	`Float64`
Complex numbers support	No

# U — the control signal of the specific internal energy of the liquid, J/kg
scalar

Details

The input port that determines the value of the specific internal energy of the liquid in the tank.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Specific internal energy.

Data types	`Float64`
Complex numbers support	No

# SC — liquid supercooling degree control signal, deltaK
scalar

Details

An input port that determines the value of the degree of supercooling of the liquid in the tank, that is, the difference between the saturation temperature of the liquid and the temperature of the liquid.

This input signal specifies the temperature difference in deltaK units, not the absolute temperature.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Degree of subcooling.

Data types	`Float64`
Complex numbers support	No

# SH — liquid overheating control signal, deltaK
scalar

Details

An input port that determines the degree of overheating of the liquid in the tank, that is, the difference between the temperature of the liquid and the saturation temperature of the steam.

This input signal specifies the temperature difference in deltaK units, not the absolute temperature.

Dependencies

To use this port, set the parameter Reservoir energy specification meaning Degree of superheating.

Data types	`Float64`
Complex numbers support	No

# Tc — condensation temperature control signal in the tank, K
scalar

Details

The input port that determines the value of the condensation temperature in the tank.

Dependencies

To use this port, set the parameter Reservoir pressure specification meaning Saturation pressure at specified condensing temperature.

Data types	`Float64`
Complex numbers support	No

# Te — evaporation temperature control signal in the tank, K
scalar

Details

The input port that determines the value of the evaporation temperature in the tank.

Dependencies

To use this port, set the parameter Reservoir pressure specification meaning Saturation pressure at specified evaporating temperature.

Data types	`Float64`
Complex numbers support	No

Parameters

# Reservoir pressure specification — the method of setting the pressure in the tank
Specified pressure | Saturation pressure at specified condensing temperature | Saturation pressure at specified evaporating temperature

Details

The method of setting the pressure in the tank:

Specified pressure — specify the value using the control signal on the P port.
Saturation pressure at specified condensing temperature — use the pressure along the saturation curve of the liquid corresponding to the temperature set by the control signal on the Tc port. When this parameter is selected, the unit limits the pressure to a value less than or equal to the critical pressure.
Saturation pressure at specified evaporating temperature — use the pressure along the vapor saturation curve corresponding to the temperature set by the control signal on the Te port. When this parameter is selected, the unit limits the pressure to a value less than or equal to the critical pressure.

Values	`Specified pressure` \| `Saturation pressure at specified condensing temperature` \| `Saturation pressure at specified evaporating temperature`
Default value	`Specified pressure`
Program usage name	`pressure_type`
Evaluatable	No

Details

A thermodynamic variable used to set energy:

Subcooled liquid temperature — Specify the temperature of the supercooled liquid inside the tank using the control signal on the T port. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure. The unit also limits the input value at port T to the range between the minimum temperature and the saturation temperature of the liquid in order to avoid a gap in the corresponding specific internal energy or specific enthalpy when the input temperature changes near the saturation temperature.
Superheated vapor temperature — Specify the temperature of the superheated steam inside the tank using the control signal on the T port. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure. The unit also limits the input value at port T to the range between the vapor saturation temperature and the maximum temperature in order to avoid a gap in the corresponding specific internal energy or specific enthalpy when the input temperature changes near the saturation temperature.
Vapor quality — Specify the degree of dryness in the tank using the control signal on port X. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure. You can specify the state of the liquid and steam mixture. You cannot specify supercooled liquid or superheated steam, because the degree of dryness of wet steam is 0 and 1 accordingly, in the entire range. In addition, the unit limits the pressure to a value below the critical pressure.
Vapor void fraction — specify the volume vapor content in the tank using the control signal on port a. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure. You can specify the state of the liquid and steam mixture. You cannot specify supercooled liquid or superheated steam, because the degree of dryness of wet steam is 0 and 1 accordingly, in the entire range. In addition, the unit limits the pressure to a value below the critical pressure.
Specific enthalpy — Specify the specific enthalpy of the liquid in the tank using the control signal on the H port. This option does not limit the state of the liquid.
Specific internal energy — Specify the specific internal energy of the liquid in the tank using the control signal on the U port. This option does not limit the state of the liquid.
Degree of subcooling — specify the degree of supercooling of the liquid in the tank using the control signal on the SC port. The degree of hypothermia is the difference between the saturation temperature of a liquid and the temperature of a liquid. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure.
Degree of superheating — indicate the degree of overheating of the liquid in the tank using the control signal on the SH port. The degree of overheating is the difference between the temperature of the liquid and the saturation temperature of the steam. When this option is selected, the unit limits the pressure to a value less than or equal to the critical pressure.

Values	`Subcooled liquid temperature` \| `Superheated vapor temperature` \| `Vapor quality` \| `Vapor void fraction` \| `Specific enthalpy` \| `Specific internal energy` \| `Degree of subcooling` \| `Degree of superheating`
Default value	`Subcooled liquid temperature`
Program usage name	`energy_type`
Evaluatable	No

# Cross-sectional area at port A — the area normal to the flow direction at the reservoir inlet
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the inlet A to the tank.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.01 m^2`
Program usage name	`port_area`
Evaluatable	Yes

# Reservoir pressure above critical — determine the actions that need to be taken when the pressure in the tank exceeds the critical pressure.
Limit to critical pressure | Error

Details

Determine the actions when the critical pressure in the tank is exceeded:

Limit to critical pressure — the block limits the pressure to a critical level, but the simulation continues without warning;
Error — the simulation stops with an error.

Values	`Limit to critical pressure` \| `Error`
Default value	`Limit to critical pressure`
Program usage name	`pressure_assert_action`
Evaluatable	No