Description
This article is an overview of the topical problems in the investigation of thermophysical properties and the development of a database for porous materials. Determination of both apparent/measured and true thermophysical properties is discussed taking into account combined heat and mass transfer, latent heat effects during chemical and physical transformations, as well as structural changes. The approaches to the solution of these problems are demonstrated for a number of different classes of materials:
- Industrial refractories, ceramics, highly porous insulation;
- Moist materials and materials undergoing phase, chemical and structural transformations;
- Materials semitransparent for heat radiation.
The approaches being used in the development of a thermophysical properties database consist in a combination of theoretical and experimental methods.
The analysis, generalization, and extrapolation of available reference data can be conducted based on the models for classical (conduction, heat radiation, gas convection) and additional (novel) mechanisms and processes affecting the apparent thermophysical properties. The novel heat transfer mechanisms include:
- Heterogeneous heat and mass transfer processes occurring in pores existing at grain boundaries and in cracks, in particular, surface segregation and diffusion of impurities on pore surfaces and transport of gases produced from chemical reactions, evaporation, and sublimation.
- Microstructure changes due to non-uniform thermal expansion of particles and grains. These changes are caused by the mismatch of thermal expansion coefficients of different phases in the material and anisotropic thermal expansion of crystals.
Keywords
construction materials, apparent thermophysical properties, heat transfer calculation, environmental conditions
DOI
10.5703/1288284315538
Included in
Heat Transfer Mechanisms in Porous Materials and Contemporary Problems in Thermophysical Properties Investigations: Analyses and Solutions
This article is an overview of the topical problems in the investigation of thermophysical properties and the development of a database for porous materials. Determination of both apparent/measured and true thermophysical properties is discussed taking into account combined heat and mass transfer, latent heat effects during chemical and physical transformations, as well as structural changes. The approaches to the solution of these problems are demonstrated for a number of different classes of materials:
- Industrial refractories, ceramics, highly porous insulation;
- Moist materials and materials undergoing phase, chemical and structural transformations;
- Materials semitransparent for heat radiation.
The approaches being used in the development of a thermophysical properties database consist in a combination of theoretical and experimental methods.
The analysis, generalization, and extrapolation of available reference data can be conducted based on the models for classical (conduction, heat radiation, gas convection) and additional (novel) mechanisms and processes affecting the apparent thermophysical properties. The novel heat transfer mechanisms include:
- Heterogeneous heat and mass transfer processes occurring in pores existing at grain boundaries and in cracks, in particular, surface segregation and diffusion of impurities on pore surfaces and transport of gases produced from chemical reactions, evaporation, and sublimation.
- Microstructure changes due to non-uniform thermal expansion of particles and grains. These changes are caused by the mismatch of thermal expansion coefficients of different phases in the material and anisotropic thermal expansion of crystals.