Enthalpic method for numerical solution of thermal conductivity problems in frozen soils

• Main Authors: Plotnikov, Aleksander, Gurianov, Georgii
• Format: Conference Proceeding
• Language: English
• Subjects: Enthalpy; Frozen ground; Heat; Heat sources; Latent heat; Massifs; Mathematical models; Moisture effects; Numerical methods; Permafrost; Phase transitions; Specific heat; Temperature; Temperature dependence; Thermal conductivity; Thermal insulation; Thermophysical models; Thermophysical properties
• ISSN: 0094-243X; 1551-7616
• DOI: 10.1063/5.0121361

Considered is the solution of the problems of engineering permafrost associated with the calculation of non-stationary temperature fields in soil massifs, taking into account the latent heat of phase transitions of moisture in the spectrum of negative temperatures. The article describes an enthalpy model, where an integral variable is used as a thermophysical characteristic - enthalpy (heat content). Enthalpy, or effective heat capacity, takes into account not only the heat capacity of the soil itself, but also the heat of phase transitions in the spectrum of negative temperatures. As a result, the function of the dependence of enthalpy on temperature becomes continuous over the entire temperature range. A feature of this model is the elimination of the ambiguity of the enthalpy versus temperature function, as well as the temperature versus enthalpy, due to the smearing of the temperature front of the phase transitions of free water from 0 to -0.04 ℃. This will disambiguate the enthalpy versus temperature in that zone. An explicit MCR scheme was used as a numerical method, since it allows you to control the computation process at each time step and in each elementary block and to introduce additional heat sources. As an example, we investigate the possibility of preserving the soils of the base of a building in a frozen state without arranging a cold underground using vertical seasonal cooling devices (SCD) and effective horizontal thermal insulation.