Keywords: drying equipment, willow, low temperature convective dehydration, grinding.


The article presents an analysis of the technological stages of the production of solid biofuel from energy wood species, it is noted that up to 70% of the total energy consumption is spent on drying processes in technological processes. The urgency and advantages of low-temperature drying of such wood have been substantiated. It is noted in the work that the heat and humidity modes should ensure an increase in the energy efficiency of the process and a high calorific value of the resulting fuel.

The purpose of the article is to intensify the process of dehydration of energy wood to obtain solid biofuel, to determine the effect on the process of convective low-temperature drying of the operating parameters of the drying agent, the size and shape of the raw material, and the specific load on the drying surface.

Energy willow was used as an object for dehydration, the initial moisture content of which varied over a wide range from 45 to 60% per wet weight; dehydration was carried out until the material reached residual moisture content of 5...6%.

Studies on the effect of the temperature of the drying agent on the kinetics of moisture exchange prove that an increase in temperature from 80 to 100 °C intensifies heat and mass transfer and reduces the duration of the process by up to 25%. The results of experimental studies of the effect of the specific load on the dehydration process showed that an increase in load has a positive effect on the productivity of the drying unit and increases the volume of processed raw materials. At the same time, the total duration of dehydration from the minimum load to the maximum increases by 3.5 times. It is noted in the work that a significant parameter of influence on the kinetics of drying and increasing the efficiency of the process is the method of grinding the raw material. The most intensive mode corresponds to the method of grinding willow by combining abrasion and impact. With this method of grinding, the drying time is reduced from 15 to 25% in comparison with the others considered.

The combination of the specified conditions and parameters of low-temperature drying provides an economical process and obtaining dried willow with low and evenly distributed residual moisture. The use of such material in the technological cycle of biofuel production guarantees the reliable operation of the combustion device for a long time.


1. Korzhov V.L. [The value of tree biomass in the process of optimizing the energy balance of Ukraine]. [Science works of the Forestry Academy Sciences of Ukraine: Coll. Science papers], 2008. V. 6. P. 20–24. (in Ukr.)
2. Kenney W.A. Multipurpose tree plantations and the sustainability of energy biomass production. J. Sustainable Forest. 1993. № 3. P.105–119.
3. Shapar R.O., Husarova O.V., Korinchuk D.M. [Low-temperature drying of energy wood]. [Environmental Protection. Energy saving. Balanced nature management: a collection of materials of the 6th int. Congress], Lviv, Nat. Lviv Polytechnic University, 2020. P. 96. (in Ukr.)
4. Fuchylo Ya.D., Onyskiv M.I., Sbytna M.V. [Biological and technological bases of plantation afforestation: monograph]. Kiev: NNTs IAE, 2006. 394 p. (in Ukr.)
5. Kuntso I.O., Humentyk Ya.M. [Growing energy willow as a raw material for the production of solid biofuels in the forest-steppe of Ukraine]. [Scientific works of the Institute of Bioenergy Crops and Sugar Beets]. 2013. № 19. P. 59–62. (in Ukr.)
6. Patrick Perre, Roger Keey. Drying of wood: principles and practices. Handbook of industrial drying. – 2014. – p. 797–846. – ISSN 978-1-4665-9665-8. – doi: 10.1201/b17208-44.
7. Energy from field energy crops – a handbook for energy producers. [Електронний ресурс]. URL (дата звернення 15.10.2020).
8. [Features of cultivation and use of energy crops]. Available at: (in Ukr.)
9. Edgars Vigants, Girts Vigants, Ivars Veidenbergs, Dace Lauka, Krista Klavina, Dagnija Blumberga. Analysis of energy consumption for biomass drying process // Environment. Technology. Resources, Rezekne, Latvia Proceedings of the 10th International Scientific and Practical Conference. – 2015. - Vol. II. – p. 317-322. doi:
10. Anna Vidlund. Sustainable production of bio-energy products in the sawmill industry. Licentiate thesis. Dept. of Chemical Engineering and Technology / Energy Processes KTH, Stockholm, Sweden. – 2004. – 57 p.
11. Sujala Bhattarai, Jae-Heun Oh, Seung-Hee Euh, Dae Hyun Kim, Liang Yu. Simulation study for pneumatic conveying drying of sawdust for pellet production // Drying Technology. – 2014. –Vol. 32. – p. 1142–1156. – ISSN 0737-3937. – doi:10.1080/07373937.2014.884575.
12. Gorohovskij A.G., Shishkina E.E., Gorohovskij A.A., Petrov M.S., Bazhenov A.A. [Effective modes of low-temperature drying of sawn timber], [UALTU electronic archive], Available at: (in Rus.)
13. Zaripov Sh.G, Zarinova N.Sh. [Energy characteristic of the low-temperature drying process of larch sawn timber], [KrasGAU Bulletin]. 2013. № 11. P. 257–261. (in Rus.)
14. Pat. CN101236048A China, IPC B27K1/00; F26B5/04; F26B7/00. Wood drying method / Songlin YI, Yongdong ZHou – CN200810100904A; appl. 26.02.2008; pub. 06.08.2008.
15. Kudra T. Energy performance of convective dryer // Drying technology. – 2012. – Vol. 30. – Iss. 11–12. P. 1190 – 1198.
16. Vasile Minea. Efficient energy recovery with wood drying heat pumps // Drying Technology: An International Journal. - 2012. - Vol. 30:14. – p. 1630-1643.
17. Krista Kļaviņa, Aivars Žandeckis, Claudio Rochas, Alvydas Zagorskis. Low temperature drying as a solution for sustainable use of biomass // Proceedingsofthe 17th Conferencefor Junior Researchers „Science – FutureofLithuania“. 10 April 2014, Vilnius, Lithuania, 2014. – P. 1. ISSN 2029-2341 print / ISSN 2029-2252 online.
18. Jan-Olof Anderson. Energy and Resource Efficiency in Convective Drying Systems in the Process Industry. Doctoral thesis. – Luleå, Sweden. - 2014. – 122 p. - ISSN 1402-1544. ISBN 978-91-7439-872-4 (print). ISBN 978-91-7439-873-1 (pdf).
19. Trohin, A.H., Moisiev, V.F., Telnov, I.A. and Zavinski, S.I. Development of processes and equipment for the production of fuel pellets from biomass // Eastern-European Journal of Enterprise Technologies – 2010. – № 8/45 (3). – С. 36–40. – ISSN 1729-3774.
20. Dakhnovska O. V., Cpivak O. Yu., Yefremov Ya. A. [Experimental studies of low-temperature drying of wood waste in a chamber convective dryer], [Collection of scientific works of Vinnytsia National Agrarian University. Series: Technical Sciences]. Vinnytsia, № 1 (91). 2015. P. 62–65. (in Ukr.)
21. Pat. CN104930577B China, IPC F24D3/18; F25B30/00. Double-effect heat supply device of low-temperature superconducting source heat pump – CN201510298155A; appl. 07.07.2015; pub. 10.04.2018.
22. Buhler. Available at:
23. Sniezhkin Yu.F., Shapar R.O. [Heat-mass exchange technologies for pectin-containing raw materials processing], [Sik Hrup Ukraine], 2018. 228 p. ISBN 978–617–7457–69–4 (in Ukr.)

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How to Cite
Shapar, R., Husarova, O., & Korinchuk, D. (2020). REGULARITIES OF CONVECTIVE LOW TEMPERATURE DRYING OF ENERGY SPECIES WOOD. Thermophysics and Thermal Power Engineering, 42(4), 41-49.
Heat and Mass Transfer Processes and Equipment, Theory and Practice of Drying