Main Content

P-H Diagram (2P)

Thermodynamic scope for two-phase fluid networks

  • Library:
  • Simscape / Fluids / Two-Phase Fluid / Utilities

  • P-H Diagram (2P) block

Description

The P-H Diagram (2P) block plots a p-h diagram of the pressure with respect to the specific enthalpy of a thermodynamic, two-phase fluid. A p-h diagram indicates the fluid state at key points during a thermodynamic cycle.

The plot units are MPa for pressure, kJ/kg for specific enthalpy, and K for the temperature contours.

Each numbered point on the diagram indicates the fluid state after a dynamic process in the refrigeration cycle:

  1. Cool vapor at low pressure

  2. Hot vapor at high pressure

  3. Hot liquid at high pressure

  4. Mixed vapor and liquid at low pressure

To use the P-H Diagram (2P) block:

  1. Place a Thermodynamic Properties Sensor (2P) and a Pressure & Internal Energy Sensor (2P) block at each location you want to monitor.

    Note

    The Pressure & Internal Energy Sensor (2P) block measures a differential pressure. Connect port A to the monitor point and port B to an Absolute Reference (2P) block.

  2. Convert the Simscape physical signals to Simulink signals with a PS-Simulink Converter block.

  3. Use a Mux block to combine the pressure signals. Connect the output signal to the P-H Diagram (2P) p port.

  4. Use a Mux block to combine the converted specific enthalpy signals and connect the output signal to the h port.

  5. Before running the simulation, double-click the P-H Diagram (2P) block, then click the Select fluid properties button to set the network fluid properties.

    If you do not select the fluid properties, the block uses the default two-phase network fluid, which is water.

P-H Diagram Playback

You can also replay the animation from the most recent simulation. After running the model, double-click the block and use the buttons at the top of the window to control the animation. Use the drop-down menu to the right of the Time field to control the rate of the playback. The replay controls are disabled before you run a simulation, when the model is loaded, and when the simulation is running.

Use the playback slider or Time field to control the simulation cycle. If you enter a time that is not a model time step, the block displays the next closest time step.

To save the current iteration of the plot, point to the plot area. From the icons in the top-right corner of the plot, click the Export icon and select the Save As button to save the plot.

Ports

Input

expand all

Vector of pressures. The vector must have same number of elements as the enthalpy signal at port h

Vector of specific enthalpies. The vector must have same number of elements as the pressure signal at port p.

Extended Capabilities

Version History

Introduced in R2021a

expand all