Research on key technology of infrared methane detector based on LED light source

Abstract

According to the characteristics of the infrared absorption spectrum of methane gas mainly distributed in the middle infrared band of 3.2 μm˜3.4 μm, an infrared methane sensor and detector based on nondispersive infrared spectrum technology are developed based on the research of three key technologies of sensor optical path structure design, LED current drive and temperature compensation. The optical path consists of a light emitting diode with a peak wavelength of 3.4 μm, a measuring photodiode with a cutoff wavelength of 3.6 μm and a spherical emitting surface. Through the research of LED current drive control logic, the power consumption of optical measuring device is reduced to 10 mW. The influence of temperature change on the measurement results of methane concentration is studied experimentally. Through data analysis and linear fitting, the temperature compensation algorithm formula is obtained. The experimental results of the compensated sensor and detector platform show that the average power consumption of the sensor is 19.68mW, the influence of temperature change in the temperature range of -20°C˜50°C on the measured value is not more than 3.5% of the true value, the measured concentration value is less affected by water vapor, the response time is less than 20s, and the battery working time is more than 7 days.