Pressure & Temperature Sensor (MA)

Measure pressure and temperature in moist air networks

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Libraries:
Simscape / Foundation Library / Moist Air / Sensors

Description

The Pressure & Temperature Sensor (MA) block represents an ideal sensor that measures pressure and temperature in a moist air 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.

Temperature measurements are different from pressure measurements, because the energy flow rate depends on the flow direction. The temperature measurement represents the temperature upstream of the measured node. For example, if port A of the Pressure & Temperature Sensor (MA) is connected to a node between pipe 1 and pipe 2 and the moist air flows from pipe 1 to pipe 2, then the temperature measured at port A is the temperature of the moist air volume in pipe 1. If the air flow then switches direction and flows from pipe 2 to pipe 1, then the temperature measured at port A is the temperature of the moist air volume in pipe 2. If the temperatures of the two moist air volumes are different, then the measured temperature changes when the flow direction switches. If there are two or more upstream flow paths merging at the node, then the temperature measurement at the node represents the weighted average based on the ideal mixing of the merging flow.

Four 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.

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

Aircraft Environmental Control System

Models an aircraft environmental control system (ECS) that regulates pressure, temperature, humidity, and ozone (O3) to maintain a comfortable and safe cabin environment. Cooling and dehumidification are provided by the air cycle machine (ACM), which operates as an inverse Brayton cycle to remove heat from pressurized hot engine bleed air. Some hot bleed air is mixed directly with the output of the ACM to adjust the temperature. Pressurization is maintained by the outflow valve in the cabin. This model simulates the ECS operating from a hot ground condition to a cold cruise condition and back to a cold ground condition.

• Open Model

Medical Ventilator with Lung Model

Models a positive-pressure medical ventilator system. A preset flow rate is supplied to the patient. The lungs are modeled with the Translational Mechanical Converter (MA), which converts moist air pressure into translational motion. By setting the Interface cross-sectional area to unity, displacement in the mechanical translational network becomes a proxy for volume, force becomes a proxy for pressure, spring constant becomes a proxy for respiratory elastance, and damping coefficient becomes a proxy for respiratory resistance.

• 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.

Conserving

A — Sensor inlet

moist air

Moist air conserving port. Use this port to measure absolute pressure or temperature.

B — Sensor outlet

moist air

Moist air conserving port. When the sensor measures absolute pressure or temperature, this port is hidden because the sensor contains an implicit reference node. Enable this port to measure relative 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.

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 R2018a

R2023a: Usability enhancement for moist air sensors

Moist air sensor blocks with multiple output ports now have conditional port 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 Pressure & Temperature Sensor (MA) 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 (MA) 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 Pressure & Temperature Sensor (MA) block in your models. 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.moist_air.sensors.pressure_temperature_sensor;	sensor = foundation.moist_air.sensors.pressure_temperature_sensor(reference=foundation.enum.MeasurementReference.difference, temperature=true);