Monitoring of hydrocarbon vapor diffusion in air using a thermal wave interferometer

Abstract

A discussion on the use of thermal wave interference ͑TWI͒ for the monitoring of the transients of hydrocarbon in air is presented. The thermal wave signal was modeled using the logarithm-mixing model for the thermal diffusivity of a two-phase gas system in which the hydrocarbon vapor concentration in the air-filled TWI cell is a varying function of time. The time varying hydrocarbon vapor concentration was described assuming the simple Fick's model for mass diffusion of the hydrocarbon vapor in the stagnant air column of the TWI cell. The transient TWI signal amplitude data fitting yielded two parameters, namely, the saturation concentration and the characteristic diffusion time. From the corresponding values of the diffusion time the hydrocarbon mass diffusivities were straightforwardly obtained. The obtained values for the hydrocarbon mass diffusivities were found to be in good agreement with the ones reported in the literature.

Photothermal methods and atomic force microscopy images applied to the study of poly(3‐hydroxybutyrate) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) dense membranes

“…1,2 For characterization of materials, photothermal techniques are a powerful tool. Some applications that should be mentioned are determination of thermal properties of ceramics 3 and polymers, 4 study of vapor diffusion in air, 5 and recently, determination of diffusion coefficients in polymers. 6 Advantages of PA and photothermal techniques include their simplicity, requirement of minimal sample preparation, high sensitivity, and applicability to a wide range of materials, including biological specimens.…”

Photothermal Detection of Adulterants in Automotive Fuels

“…Photothermal Methodology. The PTGA experimental setup has been discussed in detail elsewhere, , and it is schematically shown in Figure . It consists of a temperature-controlled closed glass cell, adequately adapted for gas exchange and control of ambient parameters, in which the PTGA sensor is enclosed.…”

“…In recent years, there has been a great deal of interest among the specialists in the development of photothermal techniques especially suitable to the thermal properties characterization of liquids and gases. − One of these techniques, the so-called thermal wave interferometer, has been recently used to monitor hydrocarbon vapor diffusion in air, as well as to characterize the thermal diffusivity of automotive fuels, and culminated with the development of a photothermal gas analyzer. The basic design of the photothermal gas analyzer (hereafter designated as PTGA) consists of two walls separated by a gas-filled gap of variable length L .…”

Photothermal characterization of natural gas automotive fuel

“…In recent years, there has been a great deal of interest in the development of photothermal techniques especially suitable for the thermal properties' characterization of liquids and gases [1][2][3][4][5][6][7][8][9][10]. One of these techniques, the so-called thermal wave interferometer, has been recently used to monitor hydrocarbon vapour diffusion in air [9,10], as well as to characterize the presence of adulterants in automotive fuels [10,11], and culminated with the development of a photothermal gas analyser. The basic design of the photothermal gas analyser (hereafter designated as PTGA) consists of two walls separated by a gas-filled gap of variable length L. One of the walls is a thermal wave generator and the other is a temperature sensing wall.…”