APPLICATION OF «STEFAN CONDITIONS» FOR SOLVING HEAT TASKS IN OBJECTS OF THE FOREST COMPLEX
Abstract and keywords
Abstract (English):
A two-phase formulation of the problems of "thermal shock" is considered when two homogeneous half-spaces come into contact at an initial instant of time with different phases and temperatures different from the phase transition temperature. In the absence of convection and thermal sources for constant thermophysical parameters, which can be formulated as the problem of conjugation of two temperature fields on the moving solidification front with additional boundary conditions (Stefan conditions). From a practical point of view, this kind of problem can be the arrival of processes occurring in the objects of the forest complex: in the production of particle board, the processing of ponds and reservoirs, the freezing (thawing) of soils, etc. The solution was carried out using the Laplace integral transformation. The exact analytical dependence obtained in this way explicitly determines the law of interference in each phase. These functions are used for integral transformations. The resulting temperature field corresponds to the known Gaussian distribution, and the velocity of the interphase boundary movement is inversely proportional to the square root of the crystallization time. The data of the approximate numerical calculation carried out for the water-ice system corresponds to a freezing (thawing) rate of approximately 10-3 mm / s. The obtained results can be used for research work in the field of construction thermal physics, geophysics and metallurgy.

Keywords:
Stefan's condition, Laplace transform, reservoir, original.
Text
Text (PDF): Read Download

Явления фазовых переходов, когда вещество переходит из одного агрегатного состояния в другое с поглощением или выделением тепла, наблюдаются в различных природных и технологических процессах. Поэтому возникает необходимость в описании этих явлений. Подобного рода задачи имеют большое практическое значение в металлургии [1], строительной теплофизике, промерзании и оттаивании грунтов под строениями [2, 3, 4], производстве льда [5], теплотехнике [6, 7] и других прикладных дисциплинах.
Изменение агрегатного состояния, в общем случае, сопровождается фазовым превращением первого рода с выделением скрытой теплоты кристаллизации (плавления) при неизменной температуре на границе раздела фаз, а также скачкообразным изменением некоторых теплофизических свойств вещества, влияющих на протекание тепловых процессов. Кроме того, происходит движение межфазной границы по заранее неизвестному закону.

References

1. Chubinsky A.N., Sergeevichev V.V. Modelirovanie processov skleivanija drevesnyh materialov [Modeling the processes of gluing woody materials]. Saint Petersburg, 2007, 176 p. (In Russian).

2. Kumitsky B.M., Savrasova N.A., Chuikin S.V. Teplovye processy pri ostyvanii vodnogo bassejna [Thermalprocesses during cooling of an aquatic basin] Mezhdunarodnaja nauchno-prakticheskaja konferencija «Razvitie idej G.F. Morozova pri perehode k ustojchivomu lesoupravleniju» 20 - 21 aprelja 2017 g. [International Scientific and Practical Conference "Development of ideas G.F. Morozov in the transition to sustainable forest management "20 - 21 April 2017]. Voronezh, 2016, pp. 208-212. (In Russian).

3. Bartenev I.M., Vinokurov V.N. Jekologizacija tehnologii i lesnoj tehniki [Ecologization of technology and forest machinery [Text] Lesnoe hozjajstvo [Forestry]. 1992, no. 4-5, pp. 5-7. (In Russian).

4. Matveev N.N., Kamalova N.S., Evsikova N.Yu. Anomalii teplovyh svojstv celljulozy pri perehodah kristallkristall [Anomalies of the thermal properties of cellulose in crystal-crystal transitions] Plasticheskie massy [Plastic masses]. - 2015, no. 3-4, pp. 30-32. (In Russian).

5. Parfentieva N.A., Samarin O.D., Kashintseva V.L. O primenenii i reshenii zadachi Stefana v stroitel'noj teplofizike [On the application and solution of the Stefan problem in building thermophysics] Vestnik MGSU, 2001, no. 4, pp. 323-328. (In Russian).

6. Parfentiev N.A. Matematicheskoe modelirovanie teplovogo rezhima konstrukcij pri fazovyh perehodah [Mathematical modeling of the thermal regime of structures during phase transitions] Vestnik MGSU, 2011, no. 4, pp. 340-345. (In Russian).

7. Nagornova T.A. Matematicheskoe modelirovanie processa promerzanija nasy-shhennogo vlagoj grunta [Mathematical modeling of the freezing process of a soil saturated with moisture] Izvestija Tomskogo politehnicheskogo universiteta [Izvestiya Tomsk Polytechnic University], 2005, Vol. 308, no. 6, pp. 127-129. (In Russian).

8. Karslou, G., Eger D. Teploprovodnost' tverdyh tel [Thermal conductivity of solids]. Moscow, 1964, 488 p. (In Russian).

9. Daniljuk, I.I. O zadache Stefana [On the Stefan problem] Uspehi matematicheskih nauk [Successes of mathematical Sciences], 1985, Vol. 40, no. 5, p. 133-185. (In Russian).

10. Mejramov A.M. Zadacha Stefana [Zadacha Stefan] Novosibirsk, 1986, 239 p. (In Russian).

11. Krasnoshlyk I.A., Bogatyrev A.O. Chislennoe reshenie zadach s podvizhny-mi mezhfaznymi granicami [Numerical solution of problems with mobile interphase boundaries] Vestnik Cherkasskogo universiteta [Bulletin of the University of Cherkassy], 2011, Vol. 194, pp. 16-24. (In Russian).

12. Kartashov Je.M., Krotov G.S. Analiticheskoe reshenie odnofaznoj zadachi Stefana [Analytical solution of the single-phase Stefan problem] Matematicheskoe modelirovanie [Mathematical modeling], 2008, Vol. 20, no. 3, pp.77-86. (In Russian).

13. Ditkin V.A., Prudnikov A.P. Integral'nye preobrazovanija i operacionnoe ischislenie [Integral transformations and operational calculus] Moscow, 1961, 381 p. (In Russian).

14. Dmitriev O.S., Mishchenko S.V., Seregin A.Yu. Prjamaja i obratnaja zadachi teploprovodnosti v processe pressovanija drevesnostruzhechnyh plit [Direct and inverse problems of heat conduction in the process of pressing wood chipboards] Vestnik TGTU [Bulletin of TSTU]. 2003, Vol. 9, no. 2, pp. 243-251. (In Russian).

15. Samarsky A.A., Vabishhevich P.N. Vychislitel'naja teploperedacha [Computational heat transfer] Moscow, 2003, 784 p. (In Russian).

16. Gupta S.C. The classical Stefan Problem. Basic Concepts, Modelling and Abalysis, Elsevier, 2003, 375 p.

17. Stefan J. Ubereinige Probleme der Theorieder Warmeleitung. Sitzungsberichte der Wissenschaften in Wien. MathematischNaturwissenschaftiescheKlasse. 1889. Bd. 98. Abth, pp. 473-484.

18. Stefan J Uber die Theorie der Eisbildung in Polarmeere Warmeleitung. Sitzungsberichte der Keiserlicht Akademie der Wissenschaften in Wien. Mathematisch Naturwissenschaftiesche Klasse, 1889. Bd. 98. Abth, pp. 965-983.

19. Lavrentiev M.A., Shabant B.V. Metody teorii funkcii kompleksnogo peremennogo [Methods of the theory of a function of a complex variable]. Moscow, 1965. (In Russian).

20. Fikhtengolts G.M. Kurs differencial'nogo i integral'nogo ischislenija [Course of differential and integral calculus] Moscow, 2001. (In Russian).

21. Korn G., Korn T. Spravochnik po matematike dlja nauchnyh rabotnikov i inzhenerov [Handbook on Mathematics for Scientists and Engineers]. Moscow, 1968, 720 p. (In Russian).

22. Zhou Y., North T.H. Kinetic modelling of Diffusi-on-Controlled/Two -phase moving interacts problems. Modell. Simul. Mater. Sci. Eng. 1993, Vol.1, no. 4, pp. 505-516


Login or Create
* Forgot password?