Development and investigation of mathematical model of an optoelectronic sensor of methane concentration

Abstract

A mathematical model of a methane concen- tration sensor has been developed and studied, which takes into account the use of materials with different optical properties in the channel, spectral and spatial adjustment of the sensor components, losses at modu- lation and signal processing, as well as scattering and absorption of the optical emission flux in the channel. Taking into account results of modelling and experi- mental studies of the prototype sensor, confirming the adequacy of the proposed model, types of optoelectronic sensor components, as well as its design parameters with allowable deviations in manufacturing, have been substantiated and selected. The emission losses in the optical channel have been minimized when the infor- mative parameter is maximized, which is absorption of optical emission by the measured methane concentra- tion, by providing the length of the sensor measuring channel not more than 30 mm and the use of light and photodiodes with covering of their sensitive ele- ments with chalcogenide glass. It has been established that the main measurement error of methane concen- tration with the application of these recommendations is not more than 0.04 vol. % with the regulated value of 0.20 vol. % in the range from 0 to 5 vol. %, which signif- icantly exceeds metrological characteristics of the exist- ing prototypes of the methane concentration sensor for coal mine atmosphere.