METHOD OF DETERMINING DIFFUSION COEFFICIENT IN MASSIVE ARTICLES FROM 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 in capillary-porous materials for determining the diffusion coefficient of solvents in building materials and structures, as well as in food, chemical and other industries. Method of determining the diffusion coefficient in massive articles made from orthotropic capillary-porous materials consists in creating a uniform initial content of a solvent distributed in the solid phase in the test sample. Upper flat surface of the sample is waterproofed. At the initial moment of time, pulse linear moistening of the upper surface of the investigated article is carried out in a given direction of the orthotropic material along a straight line by a moving source of a solvent of constant efficiency. Electrodes of galvanic sensors, which 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 line of pulse humidification on straight lines parallel to the line of pulse humidification and at different distances r₁ and r₂ from it respectively of the first and second sensors. Time moments τ₁ and τ₂ are recorded, at which are achieved the same values of signals of the first E₁ and the second E₂ sensors from range of (0.7–0.9)E_e on the descending branches of the curves of the change of signals in time of these two sensors, and the diffusion coefficient is calculated. At the same time, at first, a test pulse moistening of the upper surface of the investigated article is made in a given direction of the orthotropic material along a straight line with a moving source of a solvent of constant capacity. Then, if the dose of the trial pulse linear humidification is insufficient, at which the maxima of the signals of both sensors after applying this effect are less than (0.7)E_e or are not observed at all, then a new linear pulse exposure is performed with a (r₂/r₁)² times increase in the solvent dose, wherein said procedure is repeated till the moment of identification of expressed maximum of signal of any of sensors in range of 1˃E_max/E_e≥0.7. If the dose of the trial pulsed linear moistening is excessive, at which, after applying this exposure, 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 (r₂/r₁)² times reduced dose of the solvent, wherein this 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. E_e is the maximum possible value of the sensor signal corresponding to the transition of the solvent from the region associated with the solid phase of the analysed material into the region of the free state.

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

4 cl, 3 dwg, 4 tbl