Measurement method of electrical conductivity of solution stimulated by sine wave superimposed signals of two frequencies

Abstract

The invention discloses a measurement method of the electrical conductivity of a solution stimulated by sine wave superimposed signals of two frequencies. Two sine wave superimposed signals are used to stimulate an electrode. Electrode response current is filtered through two channels. One channel carries out low pass filtering to precipitate a sine wave signal of a low frequency component. The other channel carries out high pass filtering (or band pass filtering) to precipitate a sine wave signal of a high frequency component. Amplitude and phase detection are respectively carried out on the sine wave signal of the low frequency component and the sine wave signal of the high frequency component, wherein the signals are precipitated by two channels. By combining the parameters of the stimulating signals and detected amplitude and phase of the response current with an electrical conductivity cell equivalent physical model, a joint equation is listed and is solved to acquire Rx, wherein the resistance Rx of the solution to be measured, the electrode distribution capacitance Cp, the electrode polarization impedance, the double electrical layer capacitance Cx of the electrode are unknowns of the joint equation. Electrode constants are combined to calculate the electrical conductivity of the solution. According to the technical scheme, the effects of the electrode distribution capacitance, the electrode polarization impedance and the double electrical layer capacitance of the electrode on measurement can be removed.

Description

technical field

[0001] The invention relates to a method for measuring the conductivity or resistivity of a solution, in particular to a method for measuring the conductivity of a solution excited by two frequency sine wave superposition signals. Background technique

[0002] The basic measurement method of solution conductivity is to measure the voltage U applied across the electrodes placed in the solution. D and the current I flowing through the electrodes, calculate the resistance R=U between the electrodes D / I, use G=K / R to calculate the conductivity of the solution, where K is the electrode constant. However, the electrode placed in the solution will be polarized after being energized, so that the measured voltage U D In essence, it is not the voltage across the solution itself, but the voltage applied to the two virtual electronic devices in series, the solution resistance and the electric double layer capacitance involving the solution / metal electrode interface pr...

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