INVESTIGATION OF MASS-EXCHANGE AND MASS-CONDUCTION CHARACTERISTICS OF THE PROCESS OF EXTRACTION OF FIR NEEDLES WITH SATURATED WATER VAPOR

The article presents the results of the study of mass-transfer and mass-conductivity characteristics of the process of essential oil extraction from fir needles with saturated water vapor. The absence of numerical values of mass-transfer coefficients reflecting the intensity of the process in the external phase and coefficient of constrained diffusion taking into account the efficiency of internal transfer of essential oil in the needle matrix determined the purpose of this study. Experimental studies of the kinetics of the yield of essential oil at different processing temperatures were carried out. It was found that at a saturated steam temperature of 110 - 120 °C, the highest yield of essential oil is achieved, and at higher temperatures, the process is not advisable due to the decomposition of the oil structure and changes in the chemical composition of the extract. The physical characteristics of fir needles as an object of extraction, which are important for assessing mass-transfer processes, are determined. The mathematical description of the process is presented based on Fick's law under the corresponding boundary conditions, the mass transfer coefficients and constrained diffusion are calculated, and the correlation dependences of the said coefficients on the saturated steam temperature are obtained. By comparing the data of mathematical modeling and the experimental results, the adequacy of determining the mass transfer and mass conductivity characteristics in the range from 100 °C to 120 °C is established. The calculation error does not exceed 10.7%. The research results are the basis for subsequent mathematical modeling and optimization of the process parameters of wood greenery extraction with saturated water vapor.