Experimental research findings on polarization characteristics of stem wall of forage grasses

Abstract

Increasing the energy efficiency of such electrotechnological processes as electroosmotic dehydration and electroplasmolysis of forage grasses is closely related to increasing the technological component and reducing the thermal component of the current which is an urgent scientific and technical problem. In the above mentioned electrotechnological processes, the plant material is an element of electric circuit; it is reasonable to simulate its electrophysical properties by an electrical equivalent substitution scheme. The research goal is the experimental confirmation of the hypothesis about the presence of asymmetric nonlinear volt-ampere characteristic at the stem wall of forage grasses. The basic provisions of the theory of electrical engineering, electrochemistry, biophysics, electrical measurements, experiment planning and statistical methods of measurement results processing were used. The analysis of the obtained polarization characteristics allows stating that the wall of the forage grass stem has a non-symmetrical nonlinear polarization (volt-ampere) characteristic and is a source of constant EMF which outer surface is positively charged and the inner one carries a negative charge. The value of potential difference is 0.5...0.7 V (awnless brome of 80% moisture content). With increasing frequency of electromagnetic oscillations, the rectifying properties of the stem wall weaken. For example, at a frequency of 180 Hz, the rectification coefficient is 0.5. The shape of the polarization characteristic allows assuming that when a “direct” current crosses the stem wall in the direction from its inner surface to the outer one, the internal potential barrier (the stem wall itself) is limiting the rate of current and moisture transfer. The boundary potential barrier (interface of two phases or double electric layer) is limiting the speed of moisture transfer in the “reverse” direction during the current flowing through the stem wall in the direction from its outer surface to the inner one. Consequently, the mentioned potential barrier is displaced towards the outer surface of the stem wall. This determines the presence of a non-ideal so-called vent effect. The revealed regularities are the basis for synthesizing the equivalent electrical substitution scheme of the stem wall and substantiation of ways to increase the technological component of the current and reduce its thermal effect.