Pressure, Temperature & Internal Energy Sensor (2P)

Measure pressure, temperature, and specific internal energy in two-phase fluid networks

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Libraries:
Simscape / Foundation Library / Two-Phase Fluid / Sensors

Description

The Pressure, Temperature & Internal Energy Sensor (2P) block represents an ideal sensor that measures pressure, temperature, and specific internal energy in a two-phase fluid network. There is no mass or energy flow through the sensor.

The sensor contains an implicit reference node, which means that you need only one port, port A, to make absolute measurements of pressure or temperature. Expose the second port, port B, only if you need to measure the difference in pressure or temperature between two nodes in the model. The measurements are positive when the values at port A are greater than the values at port B.

Five physical signal ports are available to output the measurement data:

• Port Pa outputs the absolute pressure.

• Port Pg outputs the gauge pressure.

• Port P outputs the pressure difference across the sensor.

• Port T outputs the temperature.

• Port U outputs the specific internal energy.

These ports have conditional port visibility on the block icon. Use the block parameters to expose only the ports that you need for measurements in a particular model.

Connect the measurement ports to PS-Simulink Converter blocks to transform the output physical signals into Simulink^® signals, for example, for plotting or additional data processing.

Examples

Two-Phase Fluid Refrigeration

Models a vapor-compression refrigeration cycle using two-phase fluid components. The compressor drives the R-134a refrigerant through a condenser, an expansion valve, and an evaporator. The hot gas leaving the compressor condenses in the condenser via heat transfer to the environment. The pressure drops as the refrigerant passes through the expansion valve. The drop in pressure lowers the saturation temperature of the refrigerant. This enables it to boil in the evaporator as it absorbs heat from the refrigerator compartment. The refrigerant then returns to the compressor to repeat the cycle. The controller turns the compressor on and off to maintain the refrigerator compartment temperature within a band around the desired temperature.

• Open Model

Ports

Output

Pa — Absolute pressure measurement, Pa

physical signal

Physical signal output port for absolute pressure measurement.

Dependencies

To enable this port, set the Measurement reference parameter to Absolute, select the Pressure check box, and set the Pressure type parameter to Absolute pressure.

Pg — Gauge pressure measurement, Pa

physical signal

Physical signal output port for gauge pressure measurement.

Dependencies

To enable this port, set the Measurement reference parameter to Absolute, select the Pressure check box, and set the Pressure type parameter to Gauge pressure.

P — Pressure difference measurement, Pa

physical signal

Physical signal output port for pressure difference measurement.

Dependencies

To enable this port, set the Measurement reference parameter to Difference and select the Pressure check box.

T — Temperature measurement, K

physical signal

Physical signal output port for temperature measurement.

Dependencies

To enable this port, select the Temperature check box.

U — Specific internal energy measurement, kJ/kg

physical signal

Physical signal output port for specific internal energy measurement.

Dependencies

To enable this port, select the Internal energy check box.

Conserving

A — Sensor inlet

two-phase fluid

Two-phase fluid conserving port. Use this port to measure absolute pressure, temperature, and specific internal energy.

B — Sensor outlet

two-phase fluid

Two-phase fluid conserving port. When the sensor performs absolute measurements, this port is hidden because the sensor contains an implicit reference node. Enable this port to measure relative pressure, temperature, or specific internal energy between two nodes in the model. The measurements are positive when the values at port A are greater than the values at port B.

Dependencies

To enable this port, set the Measurement reference parameter to Difference.

Parameters

Measurement reference — Select between absolute and relative measurements

Absolute (default) | Difference

Select between absolute and relative measurements:

• Absolute — The sensor measures pressure and temperature at port A. The sensor contains an implicit reference node, which means that you need only one port to make absolute measurements.

• Difference — The sensor measures the difference in pressure or temperature between two nodes in the model. Selecting this option exposes port B on the block icon.

Pressure — Control output port visibility for measuring pressure

On (default) | Off

Selecting this check box exposes the output port Pa, Pg, or P, to let you measure pressure.

Pressure type — Select between absolute and gauge pressure

Absolute pressure (default) | Gauge pressure

Select whether the sensor measures absolute or gauge pressure:

• Absolute pressure — The sensor measures absolute pressure at port A. Selecting this option exposes port Pa on the block icon.

• Gauge pressure — The sensor measures gauge pressure at port A. Selecting this option exposes port Pg on the block icon.

Dependencies

To enable this parameter, set Measurement reference to Absolute and select the Pressure check box.

Temperature — Control output port visibility for measuring temperature

Off (default) | On

Selecting this check box exposes the output port T, which lets you measure temperature.

Extended Capabilities

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

Version History

Introduced in R2015b

R2023a: Usability enhancement for two-phase fluid sensors

The Pressure & Internal Energy Sensor (2P) block has been renamed to Pressure, Temperature & Internal Energy Sensor (2P) because it can now also measure temperature.

The block ports now have conditional visibility on the block icon. You can use the block parameters to expose only the ports that you need for measurements in a particular model.

Additionally, the block now contains an implicit reference node, which means that you need only one port to make absolute measurements of pressure or temperature. Expose the second port only if you need to measure the difference in pressure or temperature between two nodes in the model.

In previous releases, to measure the absolute pressure and absolute temperature at port A, you needed to connect port B to an Absolute Reference (2P) block. This is no longer necessary because you can now make absolute measurements by setting the Measurement reference parameter to Absolute, but existing models that have these connections continue to work as before.

There is no compatibility impact when you use the block in your models. When you open an existing model, the Pressure & Internal Energy Sensor (2P) blocks within it are automatically replaced by Pressure, Temperature & Internal Energy Sensor (2P) blocks with the appropriate ports exposed.

However, if you use this block in your custom composite components, you need to update the composite component code.

Old Syntax	New Syntax
sensor = foundation.two_phase_fluid.sensors.pressure_internal_energy_sensor;	sensor = foundation.two_phase_fluid.sensors.pressure_internal_energy_sensor(reference=foundation.enum.MeasurementReference.difference, internal_energy=true);