Patent ID: 6151557
Filing Date: 2000-11-21
Classification: G01F

Abstract:
An apparatus for determining a mass flow rate of a fluid in a pipe, the apparatus comprising:a microprocessor for receiving a differential pressure signal indicative of a differential pressure value measured between two points in the fluid, the pipe having a substantially constant cross-sectional area between the two points, the microprocessor additionally for:determining a calculated mass flow rate by selecting a friction factor coefficient, and multiplying the square-root of the differential pressure value by a mass flow constant, and the friction factor coefficient;determining a change in calculated mass flow rate by:determining a Reynolds number based on a calculated mass flow rate;determining a revised friction factor coefficient based on the Reynolds number;multiplying the revised friction factor coefficient by the mass flow constant and the square-root of the differential pressure to produce a revised mass flow rate; andsubtracting the revised mass flow rate from the calculated mass flow rate to produce a change in calculated mass flow rate;retrieving a convergence criterion from a memory;repeating the step of determining a change in calculated mass flow rate while using the last revised mass flow rate as the calculated mass flow rate until the change in calculated mass flow rate is less than the convergence criterion; anda memory, coupled to the microprocessor, for storing the mass flow constant.