СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES

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...

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Main Authors: V. G. Zhukov, N. D. Lukin
Format: Article
Language:Russian
Published: Russian Academy of Sciences, V.M. Gorbatov Federal Research Center for Food Systems 2020-07-01
Series:Пищевые системы
Subjects:
Online Access:https://www.fsjour.com/jour/article/view/72
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author V. G. Zhukov
N. D. Lukin
author_facet V. G. Zhukov
N. D. Lukin
author_sort V. G. Zhukov
collection DOAJ
description 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.
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spelling doaj-art-dde66b91fdbc4d9789f4ae347737f7832025-08-20T03:20:00ZrusRussian Academy of Sciences, V.M. Gorbatov Federal Research Center for Food SystemsПищевые системы2618-97712618-72722020-07-01324810.21323/2618-9771-2020-3-2-4-864СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIESV. G. Zhukov0N. D. Lukin1All-Russian research Institute for Starch Products — Branch of V. M. Gorbatov Federal Research Center for Food Systems of RASAll-Russian research Institute for Starch Products — Branch of V. M. Gorbatov Federal Research Center for Food Systems of RASPorous 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.https://www.fsjour.com/jour/article/view/72porous mediumcapillary modelscomplete wettingmeniscuslimiting sizescalculations
spellingShingle V. G. Zhukov
N. D. Lukin
СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
Пищевые системы
porous medium
capillary models
complete wetting
meniscus
limiting sizes
calculations
title СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
title_full СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
title_fullStr СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
title_full_unstemmed СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
title_short СONCEPT AND CALCULATION OF THE LIMIT TRANSVERSE SIZE OF CAPILLARIES
title_sort сoncept and calculation of the limit transverse size of capillaries
topic porous medium
capillary models
complete wetting
meniscus
limiting sizes
calculations
url https://www.fsjour.com/jour/article/view/72
work_keys_str_mv AT vgzhukov sonceptandcalculationofthelimittransversesizeofcapillaries
AT ndlukin sonceptandcalculationofthelimittransversesizeofcapillaries