The Design Of A Miniaturized Multi-component Gas Detection System

With the deepening of the research on the detection of greenhouse gases and harmful gases at home and abroad,more and more attention has been paid to the infrared gas detection technology.In this design,a miniaturized multi-component gas detection system based on non-spectroscopic infrared(NDIR)technology is designed for the shortcomings of the traditional infrared detection device,especially the poor stability of the light source and can only detect single kind of gas at a time.It can accurately detect carbon monoxide,carbon dioxide and hydrocarbon gas,and display them in the upper computer.This paper mainly completes the following work:According to Lambert-Beer law,this design deduces the concentration calculation model,based on the principle of non-spectral infrared,USES the method of single-light multi-channel detection,proposes the overall design scheme of the detection system,designs the infrared gas chamber,selects the devices needed by the system,and completes the design of the hardware and software of the detection device.This design with PSo C microcontroller as the core,using single chip microcomputer internal function modules simplify the analog circuit of detection device in guarantee accuracy at the same time,also reduce the size of the detection device,reduce the cost of devices.The driving circuit of constant power light source is designed for infrared light source IRL715,which can solve the problem of radiation fluctuation of light source and improve the reliability.Using Lab VIEW virtual instrument as the design of PC software,via a serial port terminal to communicate with the machine detection,complete automation control of a machine,has realized the real-time data acquisition,processing,waveform display and automatic alarm function change trend,the computer PC window can see clearly the change of gas concentration,realize the convenient simple human-computer interaction.After completing the hardware design and software design,the system was debugged and the upper computer display was tested.By fitting the measured voltage data with the actual concentration data,the relation curve of voltage and concentration is obtained.The influence of each gas on different detection channels is analyzed,the error coefficient is obtained and the concentration formula is modified.Contrast experiment results and the theoretical formula,measured relative error within ±2%,stability and repeatability within ±1.5%,with good accuracy and stability.The innovation of this paper is as follows: a small multi-component greenhouse gas detection device is developed.A new air chamber is designed to enhance the optical path and reduce the transmission loss.PSo C hybrid integrated circuit CY8C29466 is adopted to reduce the device volume,simplify the circuit and reduce interference.The host computer is used to process data to adapt to the remote monitoring of the environment.