Design Of Ultrasonic Methane Concentration Detection System Based On TDC

The detection in concentration of methane is of great significance in the field of coal mine safety.In the field of detection of methane concentration,there has been a lack of a detection scheme with wide detection range and simple structure.Ultrasonic detection technology has strong signal penetration and non-contact detection.The advantages are applied in all measurement fields,and the methane concentration measurement requirements are met in terms of the feasibility of the test and the measurement requirements.In this paper,an ultrasonic methane concentration detection system based on time-to-digital conversion chip TDC-GP21 is designed for the problem of methane gas concentration detection.The design of the TDC-based ultrasonic pulse method is presented.The principle of ultrasonic measurement of methane concentration by pulse method is expounded.The relationship between gas concentration and ultrasonic propagation time and temperature is derived.The detection scheme is proposed and the design of ultrasonic methane concentration detection system is completed.In this design,the ultrasonic sound velocity is obtained by measuring the propagation time of the ultrasonic wave in a fixed sound path,and the time measurement and temperature measurement are completed by using the ultra-high precision time digital conversion chip TDC-GP21,and the measured time and temperature values are digital quantities.It is sent to the MCU through the serial communication interface,and the MCU calculates the methane concentration value.The implementation of the system includes the design of each part of the scheme,as well as the construction of the hardware circuit and the writing of the software program.The hardware circuit includes: the single chip system,the power supply,the ultrasonic drive,the receiving circuit,the time and temperature measuring circuit;the software program includes: the main program,Ultrasonic driver,calibration program,measurement control program,data acquisition and processing program,etc.The designed prototype was tested and verified using the laboratory's standard concentration of methane gas.The experiment showed that the designed methane concentration detection system met the measurement requirements.