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Study of the flow of immiscible liquids
Malá, Kateřina ; Pochylý, František (referee) ; Fialová, Simona (advisor)
This thesis explores the topic of flow of two immiscible liquids in horizontal pipeline. For this purpose, the experimental apparatus has been set up, that allows to observe the flow of mixture through the transparent pipe. Moderately viscous oil and water (viscosity ratio: 52,81, density ratio: 0.86, interfacial tension: 41,64 mN/m) have been chosen for the experiment. Both fluids were introduced into the pipe through a T-junction. At the end of the apparatus, a mixture of liquids flowed into the separation tank, where both phases were separated. The separated oil was then reused for further measurements. The oil and water flow rates could be individually changed by use control valves, that led to identification of different flow regimes. These varied from stratified flows to fully dispersed ones as the mixture speed increased. All observed flow regimes were plotted in the flow map, that is a function of the inlet velocities of both fluids. For further analysis, a second type of flow map has been created that displays rates as a function of mixture velocity and phase volume fraction. Selected regime was also simulated using software ANSYS FLUENT. The VOF method was used to simulate multiphase flow. This thesis critically evaluates the results of the study and shows the direction for further research in the field of immiscible liquids flow.
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Transparent packing for optical experiments in Rotating packed beds
Hájek, Jiří ; Elcner, Jakub (referee) ; Malý, Milan (advisor)
Given the amount of energy and industrial processes that produce carbon dioxide, it is necessary to reduce the amount of CO2 emitted into the atmosphere. One option is to capture and store the carbon dioxide produced, called CCS (Carbon Capture and Storage). For effective capture, a rotating packed bed absorber can be used, which works on a similar principle to a static absorption column, but the driving force of the liquid is not gravity but centrifugal force. This allows the device to be very compact in size. To optimise the absorption process, it is necessary to analyse the nature of the flow inside the absorber. This work focuses on the design and testing of a unique packed bed with stainless steel wire filling and transparent plexiglass support parts for optical analysis of the internal flow. Using a high-speed camera, the nature of the fluid flow was recorded under different operating modes. The changed parameters were the operating speed, which ranged from 300 to 1,800 rpm, and the velocity of the fluid flow, ranging from 1.25 to 11.5 m/s. When evaluating the nature of the flow, attention was paid mainly to the inner part of the packing fill, where the droplet size and velocity change the most. However, the assessment of the flow across the entire packing was also evaluated. Recommendations for the choice of operating modes, evaluation of droplet size and, finally, the empirical correlation for the calculation of the absolute liquid velocity at the inner part of the packing is also discussed.
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Study of the flow of immiscible liquids
Malá, Kateřina ; Pochylý, František (referee) ; Fialová, Simona (advisor)
This thesis explores the topic of flow of two immiscible liquids in horizontal pipeline. For this purpose, the experimental apparatus has been set up, that allows to observe the flow of mixture through the transparent pipe. Moderately viscous oil and water (viscosity ratio: 52,81, density ratio: 0.86, interfacial tension: 41,64 mN/m) have been chosen for the experiment. Both fluids were introduced into the pipe through a T-junction. At the end of the apparatus, a mixture of liquids flowed into the separation tank, where both phases were separated. The separated oil was then reused for further measurements. The oil and water flow rates could be individually changed by use control valves, that led to identification of different flow regimes. These varied from stratified flows to fully dispersed ones as the mixture speed increased. All observed flow regimes were plotted in the flow map, that is a function of the inlet velocities of both fluids. For further analysis, a second type of flow map has been created that displays rates as a function of mixture velocity and phase volume fraction. Selected regime was also simulated using software ANSYS FLUENT. The VOF method was used to simulate multiphase flow. This thesis critically evaluates the results of the study and shows the direction for further research in the field of immiscible liquids flow.
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Processing flow visualisation records by correlation coefficient evaluation in sub-images
Tesař, Václav ; Něnička, Václav
Authors introduced a new method of processing flow visualisation images,aiming at identification of instability structures. In principle, the method utilises the structures' coherence. In two digital images, recorded at slightly differentinstants of time, the pixel pairs from the same position in the images are interrogated one by one. In each, vectors of the recorded quantity values are formed from n x n pixels in immediate neighbourhood, which form the sub-image. The correlation coefficient is then computed for the vector pair. High positive values of the coefficient indicate absence of change whereas values near zero indicate chaotic changes. Of interest are negative values, which indicate a coherent motion.
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