Study On Measurement Of Carbon Dioxide Concentration Based On Ultrasonic Principle

Excessive carbon emissions are currently exacerbating greenhouse effect.Enhancing the measurement of carbon emissions has become an urgent call.In industry,the main methods to detect gas component concentration are gas chromatography and chemical methods.They are accurate but are of high cost and long detection period.In contrast,acoustic detection technology,which is of low cost,quick detection and low power consumption,has broad prospects for development.Since the method based on sound attenuation can detect more kinds of gases and achieve higher precision measurement,it becomes an alternative to the method based on sound velocity.This paper proposes two new methods: a dual-frequency point measurement method based on voltage peak and a gas concentration calculation method based on discrete curve.According to these methods,several works had been down.First,the detection platform was designed and manufactured,including mechanical structure,ultrasonic transducer,hardware and software.Second,the detection scheme was formulated,which determines the distance between ultrasonic transducers and the method of sensitivity compensation.Third,a preliminary research on temperature influence was conducted.Forth,the acoustic attenuation spectrum was obtained by measuring the standard gases.Fifth,the relationship between the spectrum and the concentration was obtained by analyzing the features of the spectrum.Finally,the proposed method was confirmed by the verifying experiment.