Patent ID: 6671584
Filing Date: 2003-12-30
Classification: G05D,Y10T

Abstract:
A mass flow rate-measuring method for measuring a real mass flow rate of a gas flowing through a flow passage in which a sonic nozzle having a known cross-sectional area is connected in series, said mass flow rate-measuring method comprising the steps of:storing a correspondenc table which defines a plurality of respective relationships between discharge coefficient values and theoretical mass flow rates, wherein said respective relationships are classified within respective regions in said correspondence table by a physical property value which is common to multiple gases, and wherein said discharge coefficient values define a relationship between said real mass flow rate and a theoretical mass flow rate through said flow passage; measuring a pressure and a temperature of said gas on an upstream side of said sonic nozzle when said real mass flow rate of said gas flowing through said flow passage is measured; determining said theoretical mass flow rate based on said physical property value of said gas flowing through said flow passage and said measured pressure and temperature; determining said discharge coefficient by making reference to said correspondence table with parameters of said determined theoretical mass flow rate and said physical property value of said gas flowing through said flow passage; and determining said real mass flow rate by obtaining a product of said determined discharge coefficient and said theoretical mass flow rate.