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CONTROL_MARGIN_UNIT

MODELS / [...] / STAGES / CONTROL_MARGIN_UNIT

Description​

This keyword defines the unit of the surge control margin for a variable speed compressor chart.

The CONTROL_MARGIN_UNIT is given as a percentage or fraction of the rate difference between minimum- and maximum flow.

It is defined when setting up the stages in a Variable speed compressor train model or Variable speed compressor train model with multiple streams and pressures.

It is currently only possible to define a surge control margin for variable speed compressors.

See Surge control margin for variable speed compressor chart for more details.

Format​

MODELS:
  - NAME: <model name>
    TYPE: VARIABLE_SPEED_COMPRESSOR_TRAIN
    FLUID_MODEL: <reference to fluid model, must be defined in MODELS>
    ...
    COMPRESSOR_TRAIN:
      STAGES:
        - INLET_TEMPERATURE: <inlet temperature in Celsius for stage>
          COMPRESSOR_CHART: <reference to compressor chart model for first stage, must be defined in MODELS or FACILITY_INPUTS>
          CONTROL_MARGIN: <Default value is zero>
          CONTROL_MARGIN_UNIT: <FRACTION or PERCENTAGE, default is PERCENTAGE>
          ....

Example​

MODELS:
  - NAME: compressor_model
    TYPE: VARIABLE_SPEED_COMPRESSOR_TRAIN
    FLUID_MODEL: fluid_model
    ...
    COMPRESSOR_TRAIN:
      STAGES:
        - INLET_TEMPERATURE: 20
          COMPRESSOR_CHART: 1_stage_chart
          CONTROL_MARGIN: 0.1
          CONTROL_MARGIN_UNIT: FRACTION
          ....