Determination of the hot gas concentration from the difference between contact and remote measurements of the temperature

Abstract

A method of determining small concentration of hot gases from the difference between indications of sensors whose operation principles are based on contact and remote methods of measuring the temperature of a gas volume is suggested in the paper. It is assumed that the contact measurements allow the true kinetic gas temperature to be determined, and the remote pyrometric measurements yield the radiant temperature. The temperature difference depends unambiguously on the gas concentration, and for the proper chosen working spectral ranges corresponding to concrete requirements, the numerical value of the concentration can be found.Problems of ecological pollution of the atmosphere by industrial emissions force the researchers to search for simple and reliable methods of registration of the amount of exhausted gases. The modern methods are mainly based on measurements of gas concentrations with complex optical systems [1, 2], and they are used in media whose maximum temperatures do not exceed 300-400 K. However, the control over operation of various engines and high-temperature furnaces and monitoring of smelting works call for an analysis of gas mixtures at temperatures up to ∼2000 K. Investigation of combustion processes to produce means for extinguishing of forest and other fires provides the basis for the development of these means.The gaseous phase of forest fires and emissions of engines and industrial enterprises are thermodynamically inhomogeneous media with high temperature and pressure gradients resulting in wide variations of the optical density of the media.Achievements of modern spectroscopy allow the researchers to construct accurate dependences of the emissivity of hot gases on their concentrations for the most investigated gaseous combustion products, including water vapor and nitrogen and carbon oxides [3][4][5]. This became possible owing to the development of theoretical methods of computing the parameters of spectral lines formed by highly excited rotational-vibrational transitions that allow the ideology of line-by-line calculations of the spectral absorption and emission characteristics of inhomogeneous gases on high-performance computers to be used [6][7][8][9][10][11]. As a result, prerequisites were created for solving the inverse problem of determination of the gas concentration from its emission characteristics. However, a direct solution of this problem is considerably complicated for many reasons [2], primarily because of nonstationary combustion processes [10,12]. In addition, remote methods call for the application of the mathematical apparatus considering possible instability of the solution procedure.In the present paper, the principal feasibility of determining the gas concentration from the difference between the kinetic and radiant temperatures is discussed together with the possibility of its embodiment in a simple engineering technique bypassing the above-described difficulties. The determination of the concentration of a concrete gas under different environmental conditions is ...

Influence of plasma volume discharge in atmospheric- pressure air on the admittance of MIS structures based on MBE p-HgCdTe

“…An important characteristic of an MIS structure is the value of the differential resistance of the space-charge region (SCR) in the strong inversion mode (R SCR ) [5]. The research of the differential resistance of the SCR for MIS structures based on MBE n (p)-HgCdTe (x = 0.21-0.23) in a wide temperature range was carried out in other articles [6,7]. The studies of the differential resistance at 200 kHz showed that, at 77 K, it was about 1,800 Ohm for structures No.1 and No.2.…”