Patent ID: 6213724
Filing Date: 2001-04-10
Classification: F04D

Abstract:
A method for detecting the change in the compressible fluid mass flow rate that accompanies surge in a compressor, the compressor having means for sensing a first fluid temperature, means for sensing a first pressure, means for sensing a second pressure, and means for measuring current drawn by a compressor prime mover, the method comprising the steps of:(A) calculating the time rate of change of the first fluid temperature for a time interval by sensing a present first fluid temperature and subtracting a previous value first fluid temperature from the present first fluid temperature;(B) calculating the time rate of change of the first fluid pressure for a time interval by sensing a present first fluid pressure and subtracting a previous value first fluid pressure from the present first fluid pressure;(C) calculating the time rate of change of the second fluid pressure for a time interval by sensing a present second fluid pressure and subtracting a previous value second fluid pressure from the present second fluid pressure;(D) calculating the time rate of change of current drawn by the compressor prime mover by sensing a present drawn current and subtracting a previous value prime mover current drawn;(E) calculating the mass flow rate by combining the rates of change calculated in steps (A), (B), (C), and (D); and(F) comparing the calculated mass flow rate to a predetermined acceptable mass flow rate to determine if surge is present.