Gas sensor and method for determining a concentration of gas in a two-component mixture

摘要

The described sensor allows determination of the concentration of a gas in a two-component mixture at variable pressure by measuring the diffusivity and the thermal conductivity. The sensor is provided to alternately heat the membrane (12) of a thermally conductive cell (1) and allow it to cool such that the temperature TM of the membrane passes from a first stable value to a second stable value and vice versa via a transient mode. The cell produces a signal representative of the temperature TM of the membrane and the sensor extracts from the signal a first and a second parameter that respectively relate to said first stable value and said transient mode of the signal. A value of the concentration of said gas and of the pressure of said two-mixture is calculated from these two parameters.

主权项

1. A sensor for determining the concentration of a gas in a two-component mixture at variable pressure, comprising:
a measurement cell located in the two-component mixture, comprising a membrane of low thermal inertia, on which heating means for said membrane and measuring means that supplies a signal representative of the temperature TM of said membrane are arranged side by side, a source of alternating current of a predetermined frequency f for supplying said heating means and an electronic circuit, wherein said predetermined frequency f enables the heating means to heat and alternately allow said membrane to be cooled so that its temperature TM passes from a first stable value to a second stable value and vice versa via a transient mode, said first and second stable values being respectively a high stable temperature TH of said membrane and a low stable temperature TB, and said transient mode being a transient cooling mode tHB of said membrane, and wherein the electronic circuit processes said signal to extract therefrom a first and a second parameter respectively relating to said first stable value and to the transient mode, and calculates a value of the concentration of said gas and of the pressure of said two-component mixture from these parameters with the assistance of a previously established mathematical function and characteristic coefficients of said sensor, said first parameter being representative of said high stable temperature TH and said second parameter being representative of the rate of cooling of said membrane ptHB during said transient cooling mode.