Lumber Convective Drying Based on Controlled Moisture Transfer

Complete text of the article:

Download article (pdf, 0.4MB )

UDС

674.047.3

DOI:

10.37482/0536-1036-2022-1-166-172

Abstract

Wood drying (in particular lumber drying), which almost entirely determines the quality of the wooden products, is one of the most complicated and energy-consuming processes in wood processing. Convective drying of lumber, in all its varieties, remains the most common by far. Computer modeling of wood drying processes is usually based on solving systems of differential heat and mass transfer equations. The methods for solving such systems, both analytical and numerical, are well researched and developed. However, the most important methodological issue is the correct formulation of the boundary conditions that determine the process of interrelated heat and mass transfer at the interface (wood – moist air). The convective drying has traditionally used the boundary conditions of type III by Academician A.V. Lykov, which are characterized by a sufficiently close correspondence between the mass flows moving from the wood depth and at the interface. This correspondence is described by the value of the so-called Bio mass transfer criterion. A computational experiment was carried out to verify these assumptions. It enabled to determine the possible controllability of the moisture removal during low-temperature convective drying of conventional lumber using modes of three-step and stepless structure. Besides this, the influence of the moisture removal on the dynamics of the internal stresses in wood was also studied. The results have shown that the stepless drying modes, on the one hand, offer a significant improvement in drying quality with practically no loss of drying capacity, and on the other hand, have better controllability. The results of the previously conducted and mentioned studies made it possible to propose general principles and then to patent a system for automatic control of moisture transfer during wood drying, which is fundamentally different from the previously known wood drying control systems. The system controls the drying process by adjusting the ratio of external to internal moisture transfer, rather than the value of the media parameters in the chamber. The moisture transfer control system for convective drying of lumber is of limited control: it cannot fully stabilize the values of the Bio mass transfer criterion. However, its use maintains a certain balance between internal and external moisture transfer, ensures the required drying quality and almost completely eliminates the occurrence of defects.

---

This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) license • The authors declare that there is no conflict of interest

Authors

Alexandr G. Gorokhovsky, Doctor of Engineering, Prof.; ResearcherID: O-6030-2018, ORCID: https://orcid.org/0000-0001-8847-8217
Elena E. Shishkina, Doctor of Engineering, Prof.; ResearcherID: O-6021-2018, ORCID: https://orcid.org/0000-0002-2584-4897
Artem S. Agafonov, Postgraduate Student; ResearcherID: ABD-5832-2021, ORCID: https://orcid.org/0000-0002-0955-9068

Affiliation

Ural State Forest Engineering University, ul. Sibirskiy trakt, 37, Yekaterinburg, 620100, Russian Federation; e-mail: goralegr@yandex.ru, elenashishkina@yandex.ru

Keywords

drying control system, moisture transfer, lumber convective drying, Bio mass transfer criterion

For citation

Gorokhovsky A.G., Shishkina E.E., Agafonov A.S. Lumber Convective Drying Based on Controlled Moisture Transfer. Lesnoy Zhurnal [Russian Forestry Journal], 2022, no. 1, pp. 166–172. DOI: 10.37482/0536-1036-2022-1-166-172

References

1. Agapov V.P. Automation of Drying Process Control by Psychrometric Difference. Drying of Wood: Proceedings of the All-Union Scientific and Technical Meeting. Arkhangelsk, TsNIIMOD Publ., 1975, pp. 24–27.
2.Bogdanov E.S. Automation of Lumber Drying Processes. Moscow, Lesnaya promyshlennost’ Publ., 1979. 175 р.
3. Gorokhovsky A.G., Shishkina E.E. Features of Heat and Mass Transfer at Drying od Timber by Stepless Modes. Hvojnye boreal’noj zony [Conifers of the boreal area], 2019, vol. 37, no. 2, pp. 139–143.
4. Gorokhovsky A.G., Shishkina E.E., Gorokhovsky A.A. Modes of Convective Drying of Lumber: Optimization of the Structure and Values of Technological Parameters. Derevoobrabativaushaya promishlennost’ [Woodworking industry], 2010, no. 4, pp. 14–16.
5. Grinchik N.N., Gishkelyuk I.A., Kundas S.P. Modelling of Heat and Mass Transfer and Surface Phenomena in Capillaryporous Media Based on Equations of Two-Phase Filtration and Sorption Isotherms. Sovremennaya nauka: issledovaniya, idei, rezul’taty, tekhnologii [Modern Science: Researches, Ideas, Results, Technologies], 2011, no. 2(7), pp. 146–150.
6. Grinchik N.N., Akulich P.V., Kuts P.S., Pavlyukevich N.V., Terekhov V.I. On the Problem of Nonisothermal Mass Transfer in Porous Media. Inzhenerno-Fizicheskii Zhurnal [Journal of Engineering Physics and Thermophysics], 2003, vol. 76, no. 6, рр. 129‒141. DOI: https://doi.org/10.1023/B:JOEP.0000012041.81528.02
7. Kartashov E.M. Analytical Methods in the Theory of Thermal Conductivity of Solids. Moscow, Vysshaya shkola Publ., 2001. 550 p.
8. Kudinov V.A., Kartashov E.M., Kalashnikov V.V. Analytical Solutions for Problems of Heat and Mass Transfer and Thermoelasticity for Multilayer Structures. Moscow, Vysshaya shkola Publ., 2005. 432 p.
9. Lykov A.V. Drying Theory. Moscow, Energiya Publ., 1968. 470 p.
10. Morozov V.M. Automation of Lumber Drying as a Factor of Economical Consumption of Heat and Electric Energy. Rational Use of Energy Resources in Drying Lumber. Salaspils, 1983, pp. 32–36.
11. Gorokhovskij A.G., Shishkina E.E., Slivina E.V. Method for Drying Lumber. Patent RF no. RU 2638229 C2, 2017.
12. Savenko V.G., Savenko A.V., Petrukhin Yu.P. Improving the Control System Efficiency of the Lumber Drying Process. Derevoobrabativaushaya promishlennost’ [Woodworking industry], 2004, no. 4, pp. 15–17.
13. Starova E.V. Lumber Drying Technology with Optimized Structure Modes: Cand. Eng. Sci. Diss. Yekaterinburg, 2018. 163 р.
14. Shishkina E.E. Energy-Saving Technology for Convective Drying of Lumber Based on Controlled Moisture Transfer in Wood: Dr. Eng. Sci. Diss. Arkhangelsk, NArFU Publ., 2016. 40 p.
15. Shishkina E.E., Gorokhovsky A.G. Optimization of the Structure and Size of the Parameters Modes of Convective Drying Lumber in terms of Efficiency and Quality. Izvestia Sankt-Peterburgskoj Lesotehniceskoj Akademii [News of the Saint Petersburg State Forest Technical Academy], 2015, iss. 213, pp. 232–241.
16. Azzouz S., Ben Dhib K., Bahar R., Ouertani S., Elaieb M.T., Elcafsi A. Mass Diffusivity of Different Species of Wood in Convective Drying. European Journal of Wood and Wood Products, 2018, vol. 76, iss. 2, pp. 573–582. DOI: 10.1007/s00107-017-1212-9
17. Da Silva W.P., da Silva L.D., e Silva C.M.D.P.S., Nascimento P.L. Optimization and Simulation of Drying Processes Using Diffusion Models: Application to Wood Drying Using Forced Air at Low Temperature. Wood Science and Technology, 2011, vol. 45, iss. 4, pp. 787–800. DOI: 10.1007/s00226-010-0391-x
18. Da Silva W.P., e Silva C.M.D.P.S., Rodrigues A.F., de Figueirêdo R.M.F. One- Dimensional Numerical Solution of the Diffusion Equation to Describe Wood Drying: Comparison with Two- and Three-Dimensional Solutions. Journal of Wood Science, 2015, vol. 61, iss. 4, pp. 364–371. DOI: 10.1007/s10086-015-1479-6
19. Moises S.A., Pereira S.L. Dealing with Empty and Overabundant Answers to Flexible Queries. Journal of Data Analysis and Information Processing, 2014, vol. 2, no. 1, pp. 12–18. DOI: 10.4236/jdaip.2014.21003
20. Nakagawa K., Tamura A., Adachi S. Optimization of Food Dye (Betanin) Retention during Hot Air Drying: Design Space Calculation with Consideration of Reaction and Substrate Transfer Kinetics. Drying Technology, 2018, vol. 36, iss. 15, pp. 1920–1929. DOI: 10.1080/07373937.2018.1463538
21. Obataya E., Higashihara T. Reversible and Irreversible Dimensional Changes of Heat-Treated Wood during Alternate Wetting and Drying. Wood Science and Technology, 2017, vol. 51, iss. 4, pp. 739–749. DOI: 10.1007/s00226-017-0918-5
22. Safin R.R., Khasanshin R.R., Khakimzyanov I.F., Mukhametzyanov Sh.R., Kainov P.A. Increasing the Energy Efficiency of the Process of Oscillating Vacuum-Conductive Drying of Wood by Means of a Heat Pump. Journal of Engineering Physics and Thermophysics, 2017, vol. 90, iss. 2, pp. 310–317. DOI: 10.1007/s10891-017-1569-y