METHOD OF DETERMINING DIFFUSION COEFFICIENT IN SHEET ORTHOTROPIC CAPILLARY-POROUS MATERIALS Russian patent published in 2024 - IPC G01N15/08 

FIELD: measurement.

SUBSTANCE: invention relates to measurement equipment and can be used in the study of mass transfer processes and to determine diffusion coefficients of solvents in orthotropic capillary-porous materials in paper, light, construction and other industries. Method for determining the diffusion coefficient of solvents in sheet orthotropic capillary-porous materials is that in the analysed sheet material, a uniform initial content of the solvent distributed in the solid phase is created, then the analysed material is placed on a flat substrate from a solvent-impermeable material, and the upper surface of the material is waterproofed. At the initial moment of time, pulsed moistening of the analysed material is carried out along a straight line with a moving source of a solvent of constant output in a given direction of the orthotropic material, electrodes of the galvanic sensors that are less distant first and more distant second from the source of galvanic sensors are made in the form of rectilinear sections and are placed on both sides of the pulse humidification line on straight lines, parallel to the pulse humidification line, and at different distances x₁ and x₂ from it, respectively, of the first and second sensors, time moments are recorded τ₁ and τ₂, at which the same values of signals of the first E₁ and the second E₂ sensors from range of (0.7–0.9)E_e are achieved on the descending branches of the curves of change of signals in time of these two sensors, and the diffusion coefficient is calculated. At that, trial pulse linear moistening of the top surface of the investigated article is made in the specified direction of the orthotropic material along a straight line with a moving source of a solvent of constant capacity. If the dose of test moistening is insufficient, then the signals of both sensors are less than (0.7)E_e, then performing a new linear pulse action with a (x₂/x₁) times increased dose of solvent, wherein this procedure is repeated until identification of the pronounced maximum of the signal of any of the sensors in range 1>E_max/E_e≥0.7. If the dose of the trial pulse linear humidification is excessive, at which the maxima of the signals of both sensors are in the zone of saturation of the sensors E_max/E_e≈1 and are not identified, then a new pulse linear exposure is performed with a (x₂/x₁) times reduced dose of the solvent and the procedure is repeated until observing the pronounced maximum of the signal of any of the sensors in range of 1>E_max/E_e≥0.7. After that, depending on the relative value of the signal maximum E_max2/E_e, a new pulse action is performed and the desired diffusion coefficient is calculated.

EFFECT: high accuracy of measuring the diffusion coefficient and shortening the duration of the experiment.

4 cl, 3 dwg, 4 tbl