VSD Isentropic Efficiency Estimator

For VSD compressors, the CAGI datasheet doesn't always report isentropic efficiency. When it does, it reports it at a single test point, which may not represent the typical operating point. Use this calculator to back-calculate isentropic efficiency from measured specific power data.

First, analyze the CT data in order to figure out the average operating power. To do this, average all non-near-zero values. Then, take that power and figure out the corresponding airflow. You will likely need to interpolate.

Measured Flow Rate (CFM):

Average non-near-zero flow from CT data

Measured Power (kW):

Average power at the measured flow point

Discharge Pressure (PSI):

Inlet Temperature (°C):

Temperature at test conditions (CAGI standard: 20°C)

Enter values above to calculate isentropic efficiency.