Results of Experimental Study on the Polarization Characteristics of the Stem Wall of Forage Grasses

Improving the energy efficiency of such electrotechnological processes as the electroosmotic dehydration and electroplasmolysis of forage grasses is closely related to an increase in the technological component of the current and a decrease in its thermal component, which is a relevant scientific and technical problem. In the mentioned electrotechnological processes, the plant material is an element of an electrical circuit and its electrophysical properties can be reasonably simulated with an electrical equivalent substitution circuit. The goal of this study is to provide an experimental confirmation for the hypothesis about the existence of an asymmetric nonlinear voltage–current characteristic for the stem wall of forage grasses. The basic provisions from the theories of electrical engineering, electrochemistry, biophysics, electrical measurements, experiment design, and statistical methods for the processing of measurement results are used. Analysis of the obtained polarization characteristics makes it possible to state that the stem wall of forage grasses has an asymmetric nonlinear polarization (voltage–current) characteristic and is a constant EMF source, the outer surface of which is positively charged, and the inner surface of which carries a negative charge. The difference of the potentials is 0.5–0.7 V (bromegrass with a humidity of 80%). The rectifying properties of the stem wall are weakened with increasing frequency of electromagnetic oscillations. For instance, at a frequency of 180 Hz, the rectification factor is 0.5. The shape of the polarization characteristic makes it possible to conclude that the current- and moisture-transfer rate is controlled by the inner potential barrier (the stem wall itself), when the “forward” current crosses the stem wall in the direction from its inner to outer surface. The moisture-transfer rate is controlled by the boundary potential barrier (an interface between two phases or a double electrical layer), when the current passes through the stem wall in the “backwards” direction from its outer to inner surface. Therefore, the mentioned potential barrier proves to be shifted towards the outer surface of the stem wall, causing the nonideal so-called valve effect. The established regularities provide a basis for the synthesis of an electrical equivalent substitution circuit for the stem wall and the substantiation of ways to increase the technological component of the current and decrease its thermal effect.