Multiple Efficiency Curves
(Adiabatic and Polytropic Efficiency Curves)
Multiple efficiency curves are used when the efficiency curves are dependent on the inlet or outlet pressure. These curves can be based on either adiabatic efficiencies or polytropic efficiencies. The choice depends on the parameter selected for the pressure, work or head specification.
Fan Laws are applied to modify the efficiency curves when the operating speed of the compressor is different from the reference speed. The Fan Law's exponent has a default value of 1.0 which can be changed if needed.
Usage
From the Compressor Main Window...
1. Select a multiple efficiency curve choice (adiabatic or polytropic) and push the Enter Curve button. The Multiple Efficiency Curve Window will be displayed.
From the Multiple Efficiency Curve Window...
2. Select the pressure basis for the efficiency curves, which can be either the inlet or the outlet pressure.
3. Enter the pressure values for which efficiency curves are available. Push the Enter curve button to display the Efficiency Curve Window.
From the Efficiency Curve Window...
4. Enter at least two values of volumetric flowrates and the corresponding efficiencies. Duplicate volumetric flowrate entries are not allowed. These values cannot be referenced using the Define system.
5. Push the OK button to accept the entered values or the Cancel button to cancel the operation. This returns you to the Multiple Efficiency Curve Window.
From the Multiple Efficiency Curve Window...
6. Repeat Steps 4 and 5 for other pressure entries.
7. Change the Fan Law's exponent if required.
8. Push the OK button to accept the entered values or the Cancel button to cancel all the operations performed in this window and in the Efficiency Curve Windows.
From the Compressor Main Window...
9. If the compressor's operating speed is different from the reference speed, enter the values for Reference and Operating Speed parameters.
See Editing Tabular Data for additional information on editing operations for the pressure and efficiency tables.
Related Topics
Efficiency or Outlet Temperature Specification