Abstract
Experimentally obtained courses of drying for representative porous building materials were investigated. With use of analytical and numerical solutions of the diffusion equation the moisture transport parameters of the materials were identified from the experimental data and modelled in relation to the parameters of their pore structure. The capillary models of moisture diffusivity based on the pore size distribution of given material were used in this analysis. It was confirmed that the character of drying rates specific both for their constant and falling periods is dependent on combination of only a few important pore structure parameters specific for each material. In concordance with the capillary models the pore volumes equivalent to critical degrees of water saturation during drying as the critical moisture content, the capillary moisture content and the full saturation are in a correlation with the drying rates and can serve as indicators of the actual evaporation potential of given material.
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Abbreviations
- Α :
-
Water absorption coefficient (kg/m2 s0.5)
- β :
-
Surface water vapour diffusion coefficient (kg/m2 s Pa)
- d :
-
Thickness (m)
- D(w):
-
Material moisture diffusivity (m2/s)
- D a :
-
Binary water vapour diffusion coefficient in air
- G :
-
Relative evaporation (−)
- h c :
-
Convective surface heat transfer coefficient (W/m2 K)
- K(w):
-
Permeability (s)
- p sat :
-
Saturation water vapour pressure (Pa)
- p crit :
-
Material water vapour pressure at critical moisture content (Pa)
- p :
-
Water vapour pressure (Pa)
- p c :
-
Capillary pressure (Pa)
- q :
-
Drying rate density (kg/m2 s)
- r :
-
Pore radius (m)
- R :
-
Gas constant (J/kg K)
- S :
-
Degree of saturation (−)
- SSA :
-
Specific surface area (m2/m3)
- t :
-
Time (s), water film thickness (m)
- T :
-
Temperature (K)
- t d :
-
Duration of the first period drying (h)
- w :
-
Volumetric moisture content (kg/m3, m3/m3)
- w cap :
-
Capillary moisture content (kg/m3, m3/m3)
- w crit :
-
Critical moisture content (kg/m3, m3/m3)
- x :
-
Space coordinate (m)
- φ :
-
Relative humidity (%)
- ξ(ω):
-
Moisture capacity (kg/kg Pa)
- μ :
-
Diffusion resistance factor (−)
- ρ :
-
Density (kg/m3)
- η :
-
Dynamic viscosity (Pa s)
- σ lg :
-
Surface tension for water (N/m)
References
Barreira E, Delgado JMPQ, Ramos NMM, de Freitas VP (2013) Experimental evaluation of drying kinetics of building materials. In: 2nd central European symposium on building physics, Vienna, pp 745–750
Bear J, Bachmat Y (1991) Introduction to modelling of transport phenomena in porous media. Kluver Academic Publishers, New York
Bruce RR, Klute A (1956) The measurement of soil moisture diffusivity. Soil Sci Soc Am Proc 20:458–462
Carmeliet J, Hens H, Roels S, Adan O, Brocken H, Cerny R, Pavlik Z, Hal C, Kumaran K, Pel L (2004) Determination of the liquid water diffusivity from transient moisture transfer experiments. J Build Phys 27:277–305
Carslaw HS, Jaeger JC (1959) Conduction of heat in solids. Oxford at the Clarendon Press, Oxford
Crank J (1975) The mathematics of diffusion. Clarendon Press, Oxford
Derdour L, Desmorieux H (2004) Model for internal moisture diffusivity during the regular regime. Comparison with experimental data obtained on plaster and spirulina. In: Proceedings of the 14th international drying symposium, vol. A. São Paulo, pp 718–725
Descamps F (1997) Continuum and discrete modelling of isothermal water and air transfer in porous media. PhD dissertation, Leuven, KU
Deryaguin BV, Tshurayew NV, Muller VM (1985) Surface forces, Nauka. Moscow. (In Russian)
Granger RJ, Gray DM (1989) Evaporation from natural nonsaturated surfaces. J Hydrol 111:21–29
Grunewald J (2000) Documentation of the numerical simulation program DIM3. 1. Volume 2. User’s guide. Insitute of building climatology, faculty of architecture. University of Technology Dresden, Dresden
Hall Ch, Hoff W (2002) Water transport in brick, stone and concrete. Taylor & Francis, New York
IEA-Annex 14 (1991) Condensation and energy. Final report, volume 1, source book
Kuenzel HM (1995) Simultaneous heat and moisture transport in building components. IRB Verlag, Stuttgart
Kumaran MK (1996) Heat, air, and moisture transfer in insulated enveloped parts. Final report. Task 3: material properties, IEA Annex 24, KU, Leuven
Li Ch, Li K, Chen Z (2008) Numerical analysis of moisture influential depth in concrete during drying-wetting cycles. Tsinghua Sci Technol 13:696–701
Lockington DA, Parlange J-Y, Barry DA, Leech CA (2003) Drying of porous building materials: hydraulic diffusivity and front propagation. Mater Struct 36:448–452
Mabirizi D, Bulut R (2009) Unsaturated soil moisture drying and wetting diffusion coefficient measurements in the laboratory. Report OTCREOS7.1-11-F, Oklahoma Transportation Center, Midwest City
Marshall TJ (1958) A relation between permeability and size distribution of pores. J Soil Sci 9:1–8
Mujumdar AS, Devahastin S (2000) Mujumdar’s practical guide to industrial drying. Exergex Corporation, Watertown, Massachusetts
Or D, Lehmann P, Shokri N (2007) Characteristic lengths affecting evaporation from heterogeneous porous media with sharp textural boundaries. Estudios de la Zona No Saturada del Suelo vol. VIII. J.V. Giráldez Cervera y F.J. Jiménez Hornero, Cordoba
Pel L, Brocken H, Kopinga K (1996) Determination of moisture diffusivity in porous media using moisture concentration profiles. Int J Heat Mass Transf 39:1273–1280
Pel L, Landman KA, Kaasschieter EF (2002) Analytic solution for the non-linear drying problem. Int J Heat Mass Transf 45:3173–3180
Pel L, Landman KA (2004) A sharp drying front model. Drying Technol 22:637–647
Shokri N, Lehmann P, Or D (2010) Evaporation from layered porous media. J Geophys Res 115:B06204. doi:10.1029/2009JB006743
Vu TH (2006) Influence of pore size distribution on drying bahaviour of porous media by a vontinuous model. PhD thesis, Otto von Guericke University, Magdeburg
Washburn EW (1921) The dynamics of capillary flows. Phys Rev 17:273–283
Wilson GW, Fredlund DG, Barbour SL (1997) The effect of soil suction on evaporative fluxes from soil surfaces. Can Geotech J 34:145–155
Yiotis AG, Boudouvis AG, Stubos AK, Tsimpanogiannis IN, Yortsos YC (2003) Effect of liquid films on the isothermal drying of porous media. Phys Rev E 68:037303
Yiotis AG, Boudouvis AG, Stubos AK, Tsimpanogiannis IN, Yortsos YC (2004) Effect of liquid films on the drying of porous media. AIChE J 50:2721–2737
Yiotis AG, Stubos AK, Boudouvis AG (2005) Pore-network modeling of isothermal drying in porous media. Transp Porous Med 58:63–86
Yiotis AG, Tsimpanogiannis IN, Stubos AK, Yortsos YC (2006) Pore-network study of the characteristic periods in the drying of porous materials. J Colloid Interface Sci 297:738–748
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Matiasovsky, P., Mihalka, P. (2014). Pore Structure Parameters and Drying Rates of Building Materials. In: Delgado, J. (eds) Drying and Wetting of Building Materials and Components. Building Pathology and Rehabilitation, vol 4. Springer, Cham. https://doi.org/10.1007/978-3-319-04531-3_4
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DOI: https://doi.org/10.1007/978-3-319-04531-3_4
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