Structural transformations in the system lanthanum bromide – water – electrical field

We found several manifestations of severe influence of relatively week direct electrical fields on interactions of water with lanthanum bromide. The rate of dissolution of these crystals in water at the negative electrode exceeds this value at the positive electrode by several times. Pulse-like growth of solid micro-rods at the negative electrode from the solution of lanthanum bromide subjected to direct electrical field was observed. Auto-oscillations between the contents of water bound in hydrated lanthanum bromide and free water were found. These oscillations are attributed to severe difference of the electrical polarizabilities of free and bound water.

Modeling of dielectric relaxation in clays at negative and positive temperatures

Experimental data on measuring the complex dielectric constant (CDP) of clays with full moistening with distilled water in the frequency range from 1 kHz to 8.5 GHz at temperatures from -15 to +25 °C are presented. The modeling of the dependences of is carried out by a multirelaxation model that takes into account the relaxation of free and bound water, as well as relaxation at the bound water - mineral and bound water - air boundaries. It is shown that at temperatures below -5 °C, a relaxation process appears in the CDP spectrum due to polarization at the bound water - ice or ice - mineral interface. The relationship between the parameters of this relaxation process and the petrophysical characteristics of the rock is found.

Modeling Latent Heat Fluxes of Water in Logs during their Freezing

This paper suggests a methodology for mathematical modelling and research of two interconnected problems: 2D non-stationary temperature distribution in logs subjected to freezing and change in the latent heat fluxes of the free and bound water in logs during the freezing process. For the purpose of this methodology, a 2-dimensional mathematical model has been created, solved, and verified for the transient non-linear heat conduction in logs during their freezing at convective boundary conditions. The model includes a mathematical description of the specific latent heat fluxes, qLHv-fw and qLHv-bw, formed by the freezing of the free and bound water in the logs, respectively. The paper presents solutions of the model with explicit form of the finite-difference method in the calculation environment of Visual Fortran Professional and its verification in accordance with our own experimental studies. The paper presents the results of simulation analysis of 2D non-stationary temperature distribution in the longitudinal section of pine log with a diameter of 0.24 m, length of 0.48 m, and moisture content above the hygroscopic range during its 30-hour freezing in a freezer at the temperature of the processing air medium of approximately –30 °C. The change in the latent heat fluxes qLHv-fw and qLHv-bw during the log freezing is presented, visualized, and analyzed.