Investigation of Heat and Mass Transfer in the Process of Convective Heat Treatment and Drying of Thermal Insulation Materials and Approximate Equation of the Drying Curve

The results of the study of heat treatment in the drying processes of thin thermal insulation materials based on the most general laws of convective drying of wet bodies with the establishment of the equation of the drying curve are presented. The numerical values of heat and mass transfer Biot numbers for the period of decreasing drying rate are established, too. Based on the study and analysis of numerous sources, the ranges of changes in the Lykov, Posnov, and phase transformation criteria for the processes of heat treatment of ceramics, asbestos, felt, and clay plates have been approximately determined. It is demonstrated that for values of Biot numbers less than one, for Lykov criteria value of 0.05–0.13 and for Posnov criteria value of 0.03–0.08 for drying modes with a temperature of 90–120 ° C, the task of drying, as a heat and mass transfer process, is external, and internal transfer does not affect the conditions of interaction of the material surface with the environment. It is also shown that the drying of thin materials takes place when the Biot number is less than one and, under the conditions of an external problem, the similarity criteria do not affect convective drying. The intensity of moisture evaporation from the body surface is determined by the value of the heat transfer coefficient in the Biot number and the regime parameters of the process. It has been established that the processes of drying materials are low-intensity processes. Based on the elements of the theory of thermal regular regime, the rate of heating of a wet body and the rate of decrease in moisture content are determined. The problem of constructing drying curves without conducting experiments to determine the duration of drying of thermal insulation materials based on approximate equations is considered; this problem is of interest for the practice of drying. The constructed drying curves do not coincide with the actual curve with an error of 4–5 %.

1. Lykov A. V. (1968) Theory of Drying. Moscow, Energiya Publ. 472 (in Russian).

2. Akulich P. V. (2010) Calculations of Drying and Heat Exchange Installations. Minsk, Belaruskaya Navuka Publ. 443 (in Russian).

3. Krasnikov V. V. (1973) Conductive Drying. Moscow, Energia Publ. 288 (in Russian).

4. Sazhin B. S. (1997) Scientific Fundamentals of Drying Techniques. Moscow, Nauka Publ. 447 (in Russian).

5. Rudobashta S. P. (1980) Mass Transfer in Systems with a Solid Phase. Moscow, Khimiya Publ. 248 (in Russian).

6. Lykov A. V., Mikhailov Yu. A. (1963) Theory of Heat and Mass Transfer. Moscow – Leningrad, Gosenergoizdat Publ. 535 (in Russian).

7. Lykov A. V. (1961) Theoretical Foundations of Construction Thermophysics. Minsk, BSSR Academy of Sciences Publ. 519 (in Russian).

8. Lykov A. V. (1956) Heat and Mass Transfer in Drying Processes. Moscow, Gosenergoizdat Publ. 464 (in Russian).

9. Kuts P. S., Ol'shanskii A. I. (1977) Some Features of Heat and Moisture Transfer and Approximate Methods of Calculating the Drying Kinetics of Moist Materials. Journal of Engineering Physics, 32, 650–656. https://doi.org/10.1007/BF00862568.

10. Vasiliev V. N., Kutsakova V. E., Frolov S. V. (2013) Drying Technology. Fundamentals of Heat and Mass Transfer. St. Petersburg, Giord Publ. 224 (in Russian).

11. Mikhailov Yu. A. (1957) Influence of Similarity Criteria on Heat and Mass Transfer During Convective Drying. Izvestiya Akademii Nauk Latviyskoy SSR [Proceedings of the Academy of Sciences of the Latvian SSR], (6) (in Russian).

12. Ol′shanski A. I. (2016) Regular Thermal Regime and Influence of Heat and Mass Transfer Similarity Criteria on the Process of Convective Drying of Porous Ceramics. Journal of Engineering Physics and Thermophysics, 89, 38–49. https://doi.org/10.1007/s10891-016-1351-6.

13. Rabinovich G. D. (1966) A New Method of Calculation of Convective Drying of Thin Materials. Journal of Engineering Physics, 11, 98–104. https://doi.org/10.1007/BF00831262.

14. Ol′shanskii A. I. (2016) Investigation of the Drying of Thin Materials with the use of Generalized Complex Variables. Journal of Engineering Physics and Thermophysics, 89, 886–895. https://doi.org/10.1007/s10891-016-1450-46.

15. Zhuravleva V. P. (1972) Mass Transfer During Heat Treatment and Drying of Capillary-Porous Construction Materials. Minsk, Nauka i Tekhnika Publ. 189 (in Russian).

16. Lykov A. V. (1954) Transfer Phenomena in Capillary-Porous Bodies. Moscow, Gostekhizdat Publ. 296 (in Russian).

17. Gorobtsova N. E. (1968) Moisture Diffusion in Moist Materials. Journal of Engineering Physics, 15, 1183–1188. https://doi.org/10.1007/BF00828942.

18. Franchuk A. U. (1969) Tables of Thermal Performance of Construction Materials. Moscow, Research Institute of Construction Physics. 142 (in Russian).

19. Blasi V. (2005) Construction Physics. Designer's Handbook. Moscow, Tekhnosfera Publ. 536 (in Russian).

20. Grigoriev I. S., Meilikhov E. Z. (1991) Physical Quantities: A Handbook. Moscow, Energoatomizdat Publ. 1232 (in Russian).

21. Lykov A. V. (1972) Heat and Mass Transfer: A Handbook. Moscow, Energiya Publ. 552 (in Russian).

22. Mel’nikova I. S. (1958) Determination of Some Criteria for the Transfer of Heat and Matter During Evaporation from Solids. Teplo- i Massoobmen v Protsessakh Ispareniya: Sb. St. [Heat and Mass Transfer in Evaporation Processes. Collection of Articles]. Moscow, USSR Academy of Sciences Publ. 255 (in Russian).

23. Nesterenko A. V. (1962) Fundamentals of Thermodynamic Calculations of Ventilation and Air Conditioning. Moscow, Vysshaya shkola Publ. 355 (in Russian).

24. Lykov A. V., Kutz P. S., Ol’shanskii A. I. (1972) Kinetics of Heat Transfer during the Desiccation of Moist Materials. Journal of Engineering Physics, 23 (3), 1082–1086. https://doi.org/10.1007/bf00832214.

25. Sergeev G. T. (1961) Study of External Heat and Mass Transfer During the Evaporation of a Liquid by a Capillary-Porous Body. Inzhenerno-Fizicheskiy Zhurnal [Engineering and Physics Journal], 4 (5), 33–37 (in Russian).

26. Ol’shanskii A. I., Zhernosek S. V., Gusarov A. M. (2022) Investigation of Heat and Mass Transfer in the Processes of Heat Treatment and Drying of Thermal Insulation Materials. Enеrgеtika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Ob’edinenii SNG = Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations, 65 (2), 156–168. https://doi.org/10.21122/1029-7448-2022-65-2-156-168 (in Russian).

27. Ol’shanskii A. I. (2014) Regular Heat Regime of Heating of Moist Capillary-Porous Materials in the Process of Their Drying. Journal of Engineering Physics and Thermophysics, 87, 1362–1373. https://doi.org/10.1007/s10891-014-1139-5.

28. Ol’shanskii A. I., Gusarov A. M. (2017) Experimental Study of the Kinetics of Drying of Thin Plane Moist Materials by the Regular-Regime Method Using Generalized Complex Variables. Journal of Engineering Physics and Thermophysics, 90, 665–678. https://doi.org/10.1007/s10891-017-1614-x.

29. Ol’shanskii A. I., Zhernosek S. V., Gusarov A. M. (2018) Experimental Studies of Heat and Moisture Exchange in the Process of Convective Drying of Thin Wet Materials. Enеrgеtika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Ob’edinenii SNG = Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations, 61 (6), 564–578/ https://doi.org/10.21122/1029-7448-2018-61-6-564-578 (in Russian).

30. Ol’shanskii A. I., Golubev A. N. (2023) Investigation of the Kinetics of Heat and Moisture Exchange during Heat Treatment and Drying of Thin Wet Thermal Insulation Materials. Enеrgеtika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Ob’edinenii SNG = Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations, 66 (1), 66–79. https://doi.org/10.21122/1029-7448-2023-66-1-66-79 (in Russian).

31. Shorin S. N. (1964) Heat Transfer. Moscow, Vysshaya Shkola Publ. 491 (in Russian).

32. Kavkazov Yu. L. (1973) Heat and Mass Transfer in Leather and Footwear Technology. Moscow, Legkaya Promyshlennost' Publ. 272 (in Russian).

33. Ol’shanskii A. I. (2013) Investigation of the Processes of drying of Porous Ceramics by the Dokuchaev–Smirnov Method. Journal of Engineering Physics and Thermophysics, 86 (1), 80–87. https://doi.org/10.1007/s10891-013-0807-1.