Vorrichtung und Verfahren zur Messung und Regelung einer Gasströmung mit veränderlichem Volumen.

摘要

Methods and apparatus are disclosed for measuring gas volume flow rate through a duct (23) including a variable area orifice (24), e.g. in an air conditioning system. Respective sensors (S1, S2) reference the total pressure upstream of the orifice (24) to the static pressure downstream, and a first signal representing the differential pressure is fed, with a second signal representing the open orifice area, to a control computer (31) which calculates the gas flow rate through the duct (23) on the basis of the signal values and information in a stored gas flow volume database. The database is constructed from values of the first and second signals generated at known volumes of air, preferably as a single, non-dimensional curve for all amplitudes of the differential pressure signal. The open orifice area may be controlled in dependence on conditions e.g. temperature, pollution, detected by a sensor (37) downstream of the orifice (24).