The Study Of Gas Detection Experiment System Based On Acoustic Absorption Spectrum

Gas detection has many applications in real life.With the practical application of ultrasonic parameters and detection theory model proposed,the use of sound waves in the gas propagation characteristics(sound velocity,sound absorption coefficient)will make complex gas exploration become possible.The experimental data obtained by developing the experimental device for measuring the gas acoustic relaxation spectrum can be used to validate the theoretical model.At the same time,the intelligent ultrasonic sensor with qualitative detection of unknown gas can be developed on the basis of this experimental device.In this paper,a gas detection experimental system based on acoustic absorption spectrum is designed and implemented.It can be used to measure the dimensionless sound absorption coefficient of ultrasonic waves with different frequencies under certain measured gas conditions.The system uses the single-chip AT89S52,the waveform generator AD9833,the signal chip CD4051 and the external circuit to achieve the ultrasonic transducer rail system.It includes the single-chip control board,the signal generating / receiving circuit and the driving circuit.The ultrasonic transducer rail system bracket are equipped with five fixed frequency(75KHz,100 KHz,200KHz,300 KHz and 400KHz)ultrasonic transducers,which can be completed 5 sets of frequency ultrasonic signal transmission and reception.The stepper motor module is achieved to complete different distances of five groups ultrasonic transmitter and receiver signal measurement.The vacuum chamber is used to change the pressure.Changing the gas pressure is equivalent to reversing the frequency of the ultrasonic wave.The transformer range is 0.1atm ~ 1atm,equivalent to five groups of frequency ultrasound extended to 75 KHz ~ 4MHz frequency.It makes the requirement measuring dimensionless sound absorption coefficient at a wide frequency point.After the system is implemented,we use it to carry out a large number of detection experiments.The experimental data of the dimensionless acoustic absorption coefficient of the measured carbon dioxide gas were compared with the theoretical sound absorption spectra.The comparison results show that the system can operate reliably and has achieved the desired goal.