In the study the questions of high-frequency heating were considered. The research was devot-ed to the nonuniformity of heating. The main rea-son of nonuniformity was wave nature of electro-magnetic field distribution in material. Nonuniformity increases with the increase of frequency and di-mensions of material. This problem is especially actual for high-frequency drying kilns because the length of loading can reach 8 m. Calculations of distribution of electric field strength were made at different frequencies to demonstrate the non-uniformity of the field. One-dimensional distribution was considered. Timber was chosen as dielectric. Calculations were carried out by 3 methods of mathematical description of wave phenomena. The first method was based on the system of Maxwell's equations and after a number of mathematical op-erations was transformed to a cosinusoidal view. The second method described the distribution of the electromagnetic field in the multilayered materi-al. Given method was offered by the authors and included Helmholtz's wave equation and boundary conditions of symmetry on free end of capacitor and Newton's boundary condition in the point of connection of the current distributor. Earlier ob-tained experimental data of voltage distribution on the length of working capacitor electrodes were given to check the accuracy of considered mathe-matical models. It was concluded that the first method was the least exact drawn on the analysis of calculated and experimental results. It was ex-plained by the neglect of the coefficient of attenua-tion which had essential value for damp timber. The second method was more exact, but as well as the first one, introduced additional error in voltage node. The maximum agreement with experimental results was provided by the model offered by the authors in the case of different ratios of wavelength and length of loading.
high-frequency heating of timber, distribution of electromagnetic field, vacuum and dielectric drying
1. Markov A.V. Matematicheskaya model' SVCh-termoobrabotki vlazhnyh materialov // Prikladnaya fizika. - 2005. - № 3. - S. 92-95.
2. Petrescu S., Ferariu L. Modeling of dielectric heating in radio-frequency applicator optimized for uniform temperature by means of genetic algorithms // International journal of computer, electrical, automation, control and information engineering. - 2008. - Vol. 2. - № 11. - P. 3668-3673.
3. Palade P.A., Vicaş S.M., Vuşcan F.B. Aspects regarding the wood processing in high fre-quency electromagnetic fields // Analele Uni-versitătii din Oradea Fascicula: Ecotoxicologie, zootehnie şi tehnologii de industrie alimentară. - 2010. - P. 1207-1214.
4. Hossan M.R., Dutta P. Effects of temperature dependent properties in electromagnetic heat-ing // International Journal of Heat and Mass Transfer. - 2012. - Vol. 55. - P. 3412-3422.
5. Kachanov A.N., Chukumov M.N. Povyshenie kachestva sushki na PMO “Aray” // Problemy kompleksnogo razvitiya regionov Kazahsta-na: mat-ly Mezhdunar. nauch.-prakt. konf. Ch. 1. - Almaty: Izd-vo KazgosINTI, 1996. - S. 131-134.
6. Kachanov A.N., Korenkov D.A. Povyshenie energoeffektivnosti kamer dlya vakuumno-dielektricheskoy sushki // Aktual'nye pro-blemy energosberezheniya i energoeffek-tivnosti v tehnicheskih sistemah: lekcii 2-y Mezhdunar. konf. s elementami nauchnoy shkoly. - Tambov: Izd-vo Pershina R.V., 2015. - S. 84-92.
7. Knyazhevskaya G.S., Firsova M.G., Kil'keev R.Sh. Vysokochastotnyy nagrev dielektri-cheskih materialov / pod red. A.N. Shamova. - 2-e izd., pererab. i dop. - L.: Mashino-stroenie, 1989. - 64 s.
8. Alpert Y., Jerby E. Coupled thermal-electromagnetic model for microwave heating of temperature-dependent dielectric media // IEEE Transactions on plasma science. - 1999. - Vol. 27. - № 2. - P. 555-562.
9. Korenkov D.A. Raspredelenie vnutrennih istochnikov teploty v processe sushki dre-vesiny vakuumno-dielektricheskim sposo-bom // Energo- i resursosberezhenie - XXI vek: sb. nauch. tr. XIII Mezhdunar. nauch.-prakt. internet-konf. - Orel, 2015. - S. 89-94.
10. Jolly P., Turner I. Non linear field solution of one dimensional microwave heating // Journal of microwave power and electromagnetic en-ergy. - 1990. - Vol. 25. - № 1. - P. 3-15.
11. D'yakonov K.F., Goryaev A.A. Sushka drevesi-ny tokami vysokoy chastoty. - M.: Lesn. prom-st', 1981. - 168 s.
12. Torgovnikov G.I. Dielectric properties of wood and wood based materials. - Berlin: Springer Verlag, 1993. - 194 p.
13. Spravochnik po sushke drevesiny / E.S. Bogdanov, V.A. Kozlov, V.B. Kuntysh [i dr.]. - 4-e izd., pererab. i dop. - M.: Lesn. prom-st',1990. - 304 s.
