| The detection of gas concentration and type has broad application prospects in environmental protection,industrial processes,medical diagnosis and other fields.Spectroscopy technology is favored by gas detection researchers due to its strong stability,short response time,and high detection sensitivity.Absorption spectrum gas detection technology and photoacoustic spectrum gas detection technology are the main research hotspots.With the continuous development of social industrialization and the enhancement of human environmental protection awareness,the demand for gas detection has also increased.How to achieve more gas and more easy-to-operate real-time and accurate measurement is a direction worthy of continued research and discussion.This article will compare absorption spectroscopy and photoacoustic spectroscopy gas detection technologies from multiple perspectives,and introduce two new multi-component gas detection systems.The main contents are as follows:1.The research status of gas detection technology were investigated in detail.The problems of existing technology and the needs of multi-component gas detection were analyzed.2.The two branches of spectroscopy gas detection:absorption spectroscopy gas detection technology and photoacoustic spectroscopy gas detection technology were discussed.Including the basic principles of Tunable Diode Laser Absorption Spectroscopy(TDLAS)and Quartz Tuning Fork Photoacoustic Spectroscopy(QEPAS),the system structure of TDLAS and QEPAS technologies,the requirements for the light source,the requirements for the detection gas,and the selection of the light intensity detection device.Then,the noise floor of the two technologies was compared.At the same time,the theoretical simulation and actual experiment were carried out separately.Finally,the advantages and disadvantages of the two gas detection technologies were summarized.3.The differences between two gas detection technologies when detecting high-concentration gases were compared.In the derivation of the signal formula,the Beer-Lambert law needs to be approximated to simplify the calculation.This approximation is only suitable for weak absorption conditions,that is,the linear relationship between the detection signal and the gas concentration is limited to the weak absorption range.In the process of detecting high-concentration gas,if the original calibration standard for low-concentration detection is still used,the inferred result of gas concentration will be seriously deviated from the actual situation.Therefore,the high-concentration gas detection signal should be corrected to obtain more realistic gas concentration data.First,the study of high-concentration gas detection based on absorption spectroscopy was introduced from three aspects:theoretical analysis,software simulation,and experimental verification.Then,the high-concentration gas detection based on the quartz tuning fork photoacoustic spectroscopy was studied,and the differences between two technologies in high-concentration gas detection were summarized in detail.4.Two multi-component gas detection systems were proposed.First,a multi-component gas detection system based on TDLAS technology was proposed and discussed in detail,including detection principle,selection of gas absorption spectrum lines and system equipment.This system was compared with traditional time division and frequency division multiplexing systems.The range included signal amplitude,SNR,linearity and application scenarios.Then,a multi-component gas detection system based on photoacoustic spectroscopy was proposed,the design principles and performance advantages of the system were introduced,and the two multi-component gas detection systems were compared from the aspects of feasibility and stability. |
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