METHOD OF DETERMINING DIFFUSION COEFFICIENT IN SOLID ARTICLES FROM CAPILLARY-POROUS MATERIALS Russian patent published in 2024 - IPC G01N13/00 G01N27/26 

FIELD: measuring equipment.

SUBSTANCE: invention relates to measurement equipment and can be used in the study of mass transfer processes to determine the diffusion coefficient in construction products from capillary-porous materials, as well as in food, chemical and other industries. Method of determining diffusion coefficient in massive articles from capillary-porous materials consists in the fact that a uniform initial content of the solvent distributed in the solid phase is created in the investigated article, the upper flat surface of the sample is waterproofed, at the initial moment of time, pulse point moistening of the upper surface of the investigated article is performed. Change in time of signals of galvanic sensors less distant first and more distant second from source is measured, which are located at distances r₁ and r₂ respectively from point of application of pulse by dose of solvent. Time moments τ₁ and τ₂ are recorded, 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 the same time, first, a test pulse moistening of the upper surface of the investigated article is made with a dose of a solvent. If the dose of the test pulse point humidification is insufficient, at which maxima of signals of both sensors after application of this effect are less (0.7)E_e or not observed at all, then a new point pulse exposure is carried out with increased by (r₂/r₁)³ times dose of the solvent. Procedure is repeated until 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 test pulse point humidification is excessive, at which, after applying this effect, the maxima of the signals of both sensors are in the plateau zone of saturation of the sensors E_max/E_e≈1 and are not identified, then a new pulse point exposure is performed with reduced by (r₂/r₁)³ times dose of the solvent. 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. If the relative value of the maximum of the signal E_max2/E_e, which is more remote from the point of application of the pulse action of the second sensor, is identified in range of 0.75>E_max2/E_e≥0.7, then a new pulse action is performed, which exceeds the previous one by approximately 1.2 times, and then calculating the desired diffusion coefficient. If the relative value of the maximum of the signal E_max1/E_e less than the distance from the point of application of the pulse action of the first sensor is identified in range of 0.75>E_max1/E_e≥0.7, then a new pulse action is performed, which exceeds the previous one by approximately 1.2×(r₂/r₁)³ times. Desired diffusion coefficient is then calculated. If the relative value of the maximum of the signal farther from the point of application of the pulse action of the second sensor is identified within 1>E_max2/E_e≥0.95, then a new pulse exposure is carried out with a dose of the solvent reduced by 2.25 times, then the desired diffusion coefficient is calculated. If the relative value of the maximum of the signal E_max1/E_e less distant from the point of application of the pulse action of the first sensor is identified in range 1>E_max1/E_e≥0.95, then the dose of the next pulse is increased by (r₂/r₁)³/2.25 times, after which the desired diffusion coefficient is calculated. If the relative value of the maximum of the signal E_max2/E_e more remote from the point of application of the pulse action of the second sensor is identified in range of 0.95>E_max2/E_e≥0.75, then the desired diffusion coefficient is calculated. If the relative value of the maximum of the signal less distant from the point of application of the pulse action of the first sensor is identified in range of 0.95>E_max1/E_e≥0.75, then the next exposure is carried out with dose increased by (r₂/r₁)³ times, and then 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