Borisov V. Improvement of experimental methods for determining the moisture content of wood in technological processes

Object of research - determining the moisture content of wood. Purpose: to improve the experimental methods for determining the moisture content of wood in technological processes to control the amount of free and bound moisture. Research methods: experiment; method of physical-chemical analysis; mathematical and physical modeling; methods of analysis and synthesis of electric circuits; approximation method; methods of parametric and structural optimization. Scientific novelty: 1) for the first time a dielectric pulse method of wood moisture control was developed, which, according to the polarization currents, allows to determine the concentration of water in free and bound forms; 2) the mathematical model of the two-dimensional distribution of the sensitivity of the conductivity meter of the moisture meter was synthesized, which made it possible to reduce the random error of the moisture content into the sensor of the developed design; 3) the mathematical model of the dependence of the equilibrium amount of adsorption and microcapsular water in the wood on humidity and temperature of the environment was improved, which enabled to take into account the influence of the heat of phase transitions of water in the wood on its heat capacity and to explain the linearity of the temperature dependence of its specific heat; 4) experimentally established for the first time: the dependence of the amount of microcapillary water on the amount of free and on mechanical stresses in the wood, which made it possible to explain the influence of the size of the sample on the sorption hysteresis and indicates the independence of the size and mechanical properties of the wood from the amount of microcapillary water; the phenomenon of evaporation of free water from wood in a steam-rich air; which testifies to the impossibility of condensation of free water in the wood; the value of the constant time of polarization of microcapsular water in the wood, which testifies to its solubility and the leveling of the energy of its connection with the wood in the sample volume; 5) developed a new equivalent circuit for the electrical conductivity of wood, taking into account the currents of each phase of moisture and the corresponding mathematical models of electric currents of wood, which became the basis of the developed HMI. Practical value: it is expedient to use the following work results in the production and laboratory conditions: 1) improved methods for determining the electrical and acoustic parameters of wood and related devices. In order to improve the accuracy of measurements and simplify the procedure for their implementation, in particular, improved acoustic methods are the basis for creating an acoustic moisture content of the average moisture content of a rectangular timber sample; 2) developed as a means of the HMI hardware and software complex makes it possible to carry out non-destructive control of the phase state of moisture in the wood in the processes of wood processing (implementation act at the Ukrainian-Czech joint venture "Royek-Lviv", Lviv, dated April 28, 2016); 3) the developed HMI makes it possible to quickly evaluate the density of wood "at the root" or in the "upper store" for the sorting of the material in order to optimize the drying or selection of special purpose wood; 4) the design of a plate moisture sensor, which reduces the random error of measurement of moisture; 5) developed non-destructive experimental methods for determining the time to reach the established values of humidity and temperature in the sample volume according to its electrical parameters give an opportunity to choose the optimal duration of the process of leveling the moisture content of the surface and internal layers of the sample wood; 6) the revealed phenomenon of evaporation of free water from the wood in a steamed vapor allows to simplify the methods of studying the point of saturation of the fiber and to develop rational regimes of hydrothermal processing; 7) the composition and structure of the specialized climatic chamber have been developed, which helps to increase the reliability of the results of the tests of wood. Field of use: woodworking ..