Engineering, Energy, Transport AIC

Mykola STADNIK – Doctor of Technical Sciences, Full Professor of the Department of Electric Power, Electrical Engineering and Electromechanics of Vinnytsia National Agrarian University (3, Sonyachna St., Vinnytsia, 21008, Ukraine. e-mail: stadnik_mykola@vsau.vin.ua, https://orcid.org/0000-0003-2109-6219).
Anatoly SPIRIN – Candidate of Technical Sciences, Associate Professor, Teacher of Separate structural subdivision «Ladyzhyn vocational college of Vinnytsia National Agrarian University» (Kravchik Petro St., 5, Ladyzhyn, Vinnytsia Region, Ukraine, 24321, e-mail: spirinanatoly16@gmail.com, https://orcid.org/0000- 0002-4642-6205).
Volodymyr RUTKEVYCH – Candidate of Technical Sciences, Associate Professor of the Department of Agricultural Machinery and Equipment, Vinnytsia National Agrarian University (3 Soniachna St., Vinnytsia, 21008, Ukraine. e-mail: v_rut@ukr.ner, https://orcid.org/0000-0002-6366-7772).
Oleksandr PUSHKO – Candidate of Technical Sciences, Associate Professor Vice-Rector for Scientific and Pedagogical Work and Infrastructure Development Uman National University (1 Institutskaya St., Uman, 20301, Ukraine. e-mail: pushka79@ukr.net,  http://orcid.org/0000-0002-6481-8536).

The article presents the results of comprehensive studies of the physical and mechanical characteristics of walnuts, which form the basis for constructing a mathematical model of the drying process in convective-vibration installations. The relevance of the work is justified by the need to increase energy efficiency and ensure high product quality amid growing demand for nuts on the global market. The current state of drying technologies is analyzed and the limitations associated with the thermolability of walnuts are emphasized: it is noted that at temperatures above 34–35 °C, the oil in the kernel degrades, which reduces the nutritional and biological value of the product.
To achieve the research objectives, a convective-vibration drying machine was developed, its design diagram and principle of operation are presented. A mathematical model of the drying process in a criterion form is proposed, which takes into account both external and internal factors of heat and mass transfer. Particular attention was paid to determining the dimensional and weight characteristics of the Ideal variety fruits. The average equivalent diameter of the nut (36.41 mm) and the sphericity index (89.71%) were experimentally established, which confirmed the possibility of approximating the shape of the fruit with a sphere. The bulk and actual density at different moisture levels (10–40%) were determined, which made it possible to estimate the change in the porosity of the nut layer within the range of 53.8–55.1%.
The results obtained made it possible to establish linear dependencies of density on moisture content and to substantiate the influence of the shape and mass parameters of fruits on the aerodynamic resistance of the layer. It has been shown that the use of vibration reduces the randomness of stacking, increases porosity, and reduces the resistance of the layer to the drying agent, which opens up prospects for intensifying the process without increasing the temperature. The conclusions confirm the scientific novelty and practical significance of the work, and further research is planned to assess the influence of fruit shape and size on the aerodynamic characteristics of the layer in the working chamber.

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