foodsystFood systemsПищевые системы2618-97712618-7272Федеральный научный центр пищевых систем им. В.М. Горбатова РАН10.21323/2618-9771-2020-3-2-4-8foodsyst-72Research ArticleСтатьиСONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIESСONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIEShttps://orcid.org/0000-0002-8338-7006ZhukovV. G.ZhukovV. G.

Valery G. Zhukov — doctor of technical sciences, Chief Researcher.

140051, Moscow region, Kraskovo, Nekrasov str., 11.

Tel.: +7-916-086-33-91

Valery G. Zhukov — doctor of technical sciences, Chief Researcher.

140051, Moscow region, Kraskovo, Nekrasov str., 11.

Tel.: +7-916-086-33-91

z-v-gr@mail.ruhttps://orcid.org/0000-0002-2142-1897LukinN. D.LukinN. D.

Nikolay D. Lukin — doctor of technical sciences, Acting Director.

140051, Moscow region, Kraskovo, Nekrasov str., 11.

Tel.: +7-919-729-44-11

Nikolay D. Lukin — doctor of technical sciences, Acting Director.

140051, Moscow region, Kraskovo, Nekrasov str., 11.

Tel.: +7-919-729-44-11

vniik@arrisp.ruAll-Russian research Institute for Starch Products — Branch of V. M. Gorbatov Federal Research Center for Food Systems of RASРоссияAll-Russian research Institute for Starch Products — Branch of V. M. Gorbatov Federal Research Center for Food Systems of RASRussian Federation2020140720203248Copyright © Zhukov V.G., Lukin N.D., 20202020Zhukov V.G., Lukin N.D.Zhukov V.G., Lukin N.D.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.fsjour.com/jour/article/view/72

Porous medium are products of processing in food, agricultural, chemical and many other industries. Calculations of processes with wet porous medium are based on capillary properties of the liquid in a pore space. The capillary properties of liquids in porous media are established in pore models in the form of thin tubes of circular or slit transverse sections. The intensity of the processes occurring in it depends on the nature of the filling of the pore space with liquid. Filling with liquid and the formation of a capillary layer is possible only in small pores. However, there is no analytical justification for the transverse pore size, more than which it cannot be filled with liquid by capillary forces. With this in mind, the concept of the limiting transverse size of a capillary for a liquid under conditions of complete wetting is introduced. The limiting size calculation is based on two conditions: the shape of the axial section of the meniscus surface has the appearance of a semicircle and its extremum point is located at the level of the free surface of the fluid supplying the capillary. A capillary column cannot form in larger pores. The absence of formulas for calculating capillaries of the limiting sizes can introduce a significant error into the analytical calculation of the moisture content in the capillary layer of a liquid in porous media and moisture transfer processes. The aim of the study was to obtain formulas for calculating the limiting (largest) sizes of capillaries of a circular, flat slit section and annular transverse sections with complete wetting of their walls. For the conditions above, it was identified that the limiting distance between the walls was independent from annular capillary diameter. The formulas for the limiting transverse sizes of the flat slit and annular capillaries turned out to be the same under the assumptions above. This indicates a weak dependence of the limiting size of a slit capillary on the curvature of its transverse section. Examples of calculations of capillaries of the limiting sizes are performed.

Porous medium are products of processing in food, agricultural, chemical and many other industries. Calculations of processes with wet porous medium are based on capillary properties of the liquid in a pore space. The capillary properties of liquids in porous media are established in pore models in the form of thin tubes of circular or slit transverse sections. The intensity of the processes occurring in it depends on the nature of the filling of the pore space with liquid. Filling with liquid and the formation of a capillary layer is possible only in small pores. However, there is no analytical justification for the transverse pore size, more than which it cannot be filled with liquid by capillary forces. With this in mind, the concept of the limiting transverse size of a capillary for a liquid under conditions of complete wetting is introduced. The limiting size calculation is based on two conditions: the shape of the axial section of the meniscus surface has the appearance of a semicircle and its extremum point is located at the level of the free surface of the fluid supplying the capillary. A capillary column cannot form in larger pores. The absence of formulas for calculating capillaries of the limiting sizes can introduce a significant error into the analytical calculation of the moisture content in the capillary layer of a liquid in porous media and moisture transfer processes. The aim of the study was to obtain formulas for calculating the limiting (largest) sizes of capillaries of a circular, flat slit section and annular transverse sections with complete wetting of their walls. For the conditions above, it was identified that the limiting distance between the walls was independent from annular capillary diameter. The formulas for the limiting transverse sizes of the flat slit and annular capillaries turned out to be the same under the assumptions above. This indicates a weak dependence of the limiting size of a slit capillary on the curvature of its transverse section. Examples of calculations of capillaries of the limiting sizes are performed.

porous mediumcapillary modelscomplete wettingmeniscuslimiting sizescalculationsporous mediumcapillary modelscomplete wettingmeniscuslimiting sizescalculationsThe article was published as part of the research topic No. 0585-2019-0004 of the state assignment of the V. M. Gorbatov Federal Research Center for Food Systems of RAS.The article was published as part of the research topic No. 0585-2019-0004 of the state assignment of the V. M. Gorbatov Federal Research Center for Food Systems of RAS.ReferencesSchramm, L.L., Stasiuk, E.N., Marangoni, D.G. (2003). Surfactants and their applications. Annual Reports Section «C» (Physical Chemistry), 99, 3–48. https://doi.org/10.1039/b208499fSchramm, L.L., Stasiuk, E.N., Marangoni, D.G. (2003). Surfactants and their applications. Annual Reports Section «C» (Physical Chemistry), 99, 3–48. https://doi.org/10.1039/b208499fJasvanth, V.S., Ambirajan, A., Adoni, A.A., Arakeri, J.H. (2019). 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The authors declare that there are no conflicts of interest present.