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Use of uranine-probe method to determine evaporation rate from porous media
Pohan, Tomáš ; Slavík, Martin (advisor) ; Mareš, Jakub (referee)
Evaporation from porous media affects many natural processes. In my work, I focused on the second evaporation phase, calculating the evaporation rate using Fick's law based on air temperature and air humidity above the surface, the water-vapor permeability of the porous material, and the evaporation front depth below the surface. To determine this depth, I used the uranine-probe method using sodium fluorescein. The work aimed to calculate the evaporation rate using Fick's law and values of the evaporation front depth determined by the uranine-probe, for 6 sandy soil samples and 3 types of rocks. A sub-goal was to verify the applicability of the uranine-probe for determining the depth of the evaporation front in sandy soil and in 12 different rock samples. Results show successful determination of evaporation front depth for both sand and rocks. The uranine-probe method's accuracy averaged 2.0 mm for sand. The difference in the values determined by the uranine-probe method compared to another, independent method (detection of the evaporation front from the color change of the fluorescein solution) in the sand was on average 1.7 mm, but I did not study this for the rock samples. All evaporation experiments confirmed that the evaporation rate, both measured and calculated, decrease with increasing depth...
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Permeability of natural surfaces of Hruba Skala sandstone in rock cities for water vapour and intensity of evaporation
Slavík, Martin ; Bruthans, Jiří (advisor) ; Pavlíková, Milena (referee)
Aim of this study was to describe capillary water and vapor transport in shallow subsurface of Hrubá Skála sandstone in the Bohemian Paradise. I have quantified permeability of Hrubá Skála sandstone for water vapor using "wet cup" method and also capillary water absorption of sandstone drill cores. I have found out general rules of evaporation and rate of evaporation from several sandstone outcrops in real microclimate. Important part of my work was to determine whether surface crust plays some role in studied parameters. Based on my results, permeability of different types of sandstones for water vapor does not vary significantly and surface crust has no effect on rate of water vapor diffusion. Rate of capillary water absorption is reduced by surface crust. Hrubá Skála sandstone is classified as medium or highly absorbing material. I have proved that evaporation from porous medium can be approximated by exponential function. Rate of evaporation is strongly controlled by climatic conditions, especially by relative humidity. Powered by TCPDF (www.tcpdf.org)
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Permeability of natural surfaces of Hruba Skala sandstone in rock cities for water vapour and intensity of evaporation
Slavík, Martin ; Bruthans, Jiří (advisor) ; Pavlíková, Milena (referee)
Aim of this study was to describe capillary water and vapor transport in shallow subsurface of Hrubá Skála sandstone in the Bohemian Paradise. I have quantified permeability of Hrubá Skála sandstone for water vapor using "wet cup" method and also capillary water absorption of sandstone drill cores. I have found out general rules of evaporation and rate of evaporation from several sandstone outcrops in real microclimate. Important part of my work was to determine whether surface crust plays some role in studied parameters. Based on my results, permeability of different types of sandstones for water vapor does not vary significantly and surface crust has no effect on rate of water vapor diffusion. Rate of capillary water absorption is reduced by surface crust. Hrubá Skála sandstone is classified as medium or highly absorbing material. I have proved that evaporation from porous medium can be approximated by exponential function. Rate of evaporation is strongly controlled by climatic conditions, especially by relative humidity. Powered by TCPDF (www.tcpdf.org)
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