The use of sorption and excess sorption isotherm in the mathematical modeling of the unsteady-state heat and humidity regime of the building envelope

In the given article the development of the moisture transfer equation based on the theory of moisture potential is considered. The task of combined heat and moisture transfer is one of the most complicated tasks in the building thermal physics field. The classical equations of moisture transfer by K.F. Fokin representing the transfer of moisture under the action of partial transfer potentials - the gradient of the partial pressure of water vapor and the gradient of humidity F – are listed. The possibility of uniform accounting of the combined water vapor transfer on the basis of the moisture potential F is described. The sorption isotherm for aerated concrete is constructed in accordance with the experiment carried out in a desiccator with an aqueous solution of sulfuric acid. A new equation of moisture transfer which takes into account moistening with vaporous moisture in the sorption zone of moisture and liquid moisture in the excess sorption zone of moisture is derived. In order to simplify the work with the obtained equation a new value of the relative potential capacity is introduced. А graph construction of sorption and excess sorption isotherms which are obtained using an analytical expression for the relative potential capacity is proposed. In the sorption zone of humidification the sorption and excess sorption isotherms coincide with the classical sorption isotherm. Meanwhile, in the excess sorption zone of humidification the sorption and excess sorption isotherms depend on temperature. © 2021 Institute of Physics Publishing. All rights reserved.

Authors
Zhou Z.1, 2 , Zubarev K.P. 3, 4, 5
Conference proceedings
Publisher
Institute of Physics Publishing
Number of issue
5
Language
English
Status
Published
Number
052072
Volume
2131
Year
2021
Organizations
  • 1 Harbin Institute of Technology, 92, Xidazhi Street, Harbin, 150001, China
  • 2 Key Laboratory of Cold Region Urban and Rural Human Settlement Environment Science and Technology (Harbin Institute of Technology), Ministry of Industry and Information Technology, 92, Xidazhi Street, Harbin, 150001, China
  • 3 Moscow State University of Civil Engineering, 26, Yaroslavskoye Shosse, Moscow, 129337, Russian Federation
  • 4 Research Institute of Building Physics of Russian Academy of Architecture and Construction Science, 21, Lokomotivny proezd, Moscow, 127238, Russian Federation
  • 5 Peoples' Friendship University of Russia (RUDN University), 6, Miklukho-Maklaya Street, Moscow, 117198, Russian Federation
Keywords
Concretes; Moisture control; Sorption; Water vapor; %moisture; Building envelopes; Combined heat transfer; Equation based; Heat and moisture transfer; Moisture transfer; Potential capacity; Sorption isotherms; Transfer equation; Unsteady state; Adsorption isotherms
Date of creation
06.07.2022
Date of change
06.07.2022
Short link
https://repository.rudn.ru/en/records/article/record/84381/
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