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Ammonia nitrogen stripping from liquid suspensions
Strádal, Jakub ; Krištof, Ondřej (referee) ; Kalivoda, Josef (advisor)
This diploma thesis is focuses on the optimization of the designed semi-operational technological stripping device, which was used to separate ammonia nitrogen from a solution simulating fugate. The operation of biogas plants produces digestate and its liquid part (fugate) contains a high concentration of ammoniacal nitrogen, which complicates the use of fugate as fertilizer. Optimal experimental conditions for ammonia separation were investigated on a semi-operating device with considering to economic and time burden. The determination of ammonia nitrogen was measured by UV-VIS spectrometry using the indophenol method. The results found will be used to select the optimum input conditions to be practiced on a real fugate.
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Truck oil cooler
Pobořil, Martin ; Krištof, Ondřej (referee) ; Bartuli, Erik (advisor)
This diploma thesis deals with designing, fabrication and testing of transmission oil cooler of a truck made of polymeric hollow fibers. Literary research was done in the field of currently used vehicle gearboxes. An overview of properties and a distribution of oils was presented. Oils perform mainly lubricating, hydraulic and cooling function in the gearbox. The thesis contains a design of a cooler according to the specified parameters and its manufacturing process which was done by fiber winding technology. The device X-Winder was used. The program controlling all movements of the machine was programmed. The manufactured cooler passed tear tests and a measurement of characteristic parameters was taken. The pressure drop in fibers was measured at 80 °C . The aim of measurement at 60 and 70 °C was to get a pressure drop in shell and a thermal performance of the cooler. It was found out that the pressure drop dependence on a the shell flow is almost identical for both temperatures, which implies that the effect of the temperature on the pressure drop is negligible. The measurement of thermal performance was done under the same conditions as the measurement of the shell pressure drop. Its maximum achieved reading was 4,8 kW, at shell flow 100 liters per hour and at the temperature 59 °C. The achieved thermal performance is comparable to the thermal performance of standard metal coolers.
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Development of a Fluid Curtain for Gaseous Exhalations Absorption
Krištof, Ondřej ; Fekete, Roman (referee) ; Lapčík,, Lubomír (referee) ; Svěrák, Tomáš (advisor)
The dissertation thesis deals with the application of absorption methods for the separation of gaseous pollutants from polluted gaseous mixtures using a pilot plant scrubber. The efficiency of the gaseous pollutant removal was determined based on the hydrodynamic distribution of fluids inside the spray chamber. A TF-28 150 spiral nozzle, which was used to spray the absorption liquid, was experimentally characterized. Specifically, the pressure impact pattern of the liquid produced by the nozzle was investigated using intrusive methods and the effective spray angles, the modes of primary and secondary atomization, the droplet size and liquid velocity distributions were determined using non-intrusive optical methods. Numerical simulations of flow of model gas phase inside the sprinkler head and spraying of the liquid through the spiral nozzle were also carried out. The obtained data can be applied to estimate the interface area and together with the determination of the coefficient of total mass transfer thus define the kinetics of chemisorption for a given absorbent/absorbate combination.
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Separation of aerosol particles using polymeric membranes
Morcinek, Tomáš ; Krištof, Ondřej (referee) ; Bulejko, Pavel (advisor)
This diploma thesis deals with the separation of aerosol particles on membranes from polypropylene hollow fibers. As a source of particles, a desktop 3D printer using polymer filaments was used. Filtration efficiency and a pressure drop on a hollow polypropylene fiber membrane and a high efficiency particulate filter (HEPA filter) were monitored during filtration of particles from 3D print using filaments of acrylonitrile butadiene styrene, acrylonitrile styrene acrylate, polylactic acid and polyethylene terephthalate glycol at nearly the same air flow. The results achieved by both filer media are then compared and discussed. The results show that the hollow fiber membrane achieves better filtration efficiency at higher particle concentrations, while using the less emitting materials, the efficiency of the HEPA filter was higher or the same. The total filtration efficiency calculated from all experiments with all filaments was higher for the hollow fiber membrane with higher pressure drop at the same time.
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Heat transfer in the tubular exchangers
Horvát, Petr ; Krištof, Ondřej (referee) ; Svěrák, Tomáš (advisor)
Shell and tube heat exchangers and their use in cooling processes are the major topic of this thesis. The theoretical part of the thesis starts with the mechanisms of heat transfer and then deals with shell and tube heat exchangers. Their position, design specifications and equations for calculations are given. In the experimental part, the heat transfer on semi-operating shell and tube heat exchangers with baffles and glass or silicon carbide heat exchange surface is examined by cooling the humid air by 50% propylene glycol in tubes. For four or five coolant flows and three airflows, input and output flow temperatures including relative air humidity were measured. Differences in exchanged heat between the exchangers were negligible due to the low local air heat transfer coefficient, although silicon carbide has two orders of magnitude better thermal conductivity than glass. Much higher efficiency was performed by the carbide heat exchanger because the difference between air outlet temperature and liquid inlet temperature was one and half times higher for the glass heat exchanger. That was reflected in a decrease in mean temperature difference, which resulted in a 16 % higher experimental heat transfer coefficient compared with the glass surface. The theoretical model using the j factor, the correction factors for the baffles, and the correction for air humidity condensation have proven to be appropriate. For the glass surface, for the highest air flow rates the model gives an appropriate heat-transfer coefficient; at lower flow rates it gives slightly higher values. For the silicon carbide surface, it gives a lower heat-transfer coefficient because the model failed to consider a lower mean temperature difference. The results also evaluate the heat loss through the shell and the heat exchanged in addition by air humidity condensation.
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Air contaminants separation process
Krištof, Ondřej ; Pekař, Miloslav (referee) ; Svěrák, Tomáš (advisor)
The Diploma thesis is focused on the separation of gaseous pollutants from contaminated mixtures of gases into liquids using absorbent device. The theoretical part is mainly concerned with describing the absorption process, the method expression and the factors influencing the rate of transfer of contaminants between phases. The experimental part deals with the dependence of transfer of carbon dioxide contained in an air mixture into an aqueous solution of sodium hydroxide on the process conditions of separation in pilot scrubber.
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Bulk properties of fine particulate solids in the industrial practice.
Bógyiová, Csilla ; Krištof, Ondřej (referee) ; Svěrák, Tomáš (advisor)
This thesis focuses on the description of the characteristics and flow properties of powder materials. The study of powder material’s flow properties is demanding and hard. For a correctly designed technologic process it is necessary to know the flow behaviour of powder materials. Measuring is the best way to study flow properties. The aim of this thesis is to acquaintance the instruments which measure flow properties. Theoretical part of the thesis describes particular materials, ring shear tests with Jenike Shear Cell and evaluation using Mohr’s circles. Experiments were performed on two samples from the industrial practice. These samples are instant teas of various flavour. Attention was paid to the influence of humidity on the flowability of the materials. Results demonstrate that surface characteristics and humidity changes the flow behaviour of bulk properties. Consequently it is necessary to pay attention to these factors when technologic process is designed.
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The efficiency of heat exchangers in the cryogenic processes
Horvát, Petr ; Krištof, Ondřej (referee) ; Svěrák, Tomáš (advisor)
Heat exchangers and their use in cooling processes are the major topic of this thesis. The theoretical part of the thesis deals with the mechanisms of heat transfer, outlining their problems at low temperature. Furthermore, the thesis describes the types of heat exchangers used in practice, then a relatively large part dealing with the problem of calculations connected with tube heat exchangers is included. Relations for both normal and cryogenic conditions are given. In the experimental part, the heat transfer on the semi-operating glass tube heat exchanger is examined by cooling the room air with 55% ethylene glycol in order to compare the heat-transfer coefficients determined from the heat balances and from the dimensionless criteria based on the relations mentioned in the theoretical part of the thesis. For a pair of coolant flows and four airflows, input and output flow temperatures, pressure and relative air humidity at the inlet were measured. At higher airflows, more than double efficiency of heat exchange was observed, at the lowest airflow the exchanged heat was up to half against the theoretical model. The reason for these deviations is probably the condensation of air humidity in the heat exchanger and the design of the heat exchanger. The flow of coolant had practically no influence on the amount of heat exchanged. As found, for the studied heat exchanger it is non-effective to operate in low airflow modes and it is unnecessary to operate at higher flow rates of the cooling medium.
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Truck oil cooler
Pobořil, Martin ; Krištof, Ondřej (referee) ; Bartuli, Erik (advisor)
This diploma thesis deals with designing, fabrication and testing of transmission oil cooler of a truck made of polymeric hollow fibers. Literary research was done in the field of currently used vehicle gearboxes. An overview of properties and a distribution of oils was presented. Oils perform mainly lubricating, hydraulic and cooling function in the gearbox. The thesis contains a design of a cooler according to the specified parameters and its manufacturing process which was done by fiber winding technology. The device X-Winder was used. The program controlling all movements of the machine was programmed. The manufactured cooler passed tear tests and a measurement of characteristic parameters was taken. The pressure drop in fibers was measured at 80 °C . The aim of measurement at 60 and 70 °C was to get a pressure drop in shell and a thermal performance of the cooler. It was found out that the pressure drop dependence on a the shell flow is almost identical for both temperatures, which implies that the effect of the temperature on the pressure drop is negligible. The measurement of thermal performance was done under the same conditions as the measurement of the shell pressure drop. Its maximum achieved reading was 4,8 kW, at shell flow 100 liters per hour and at the temperature 59 °C. The achieved thermal performance is comparable to the thermal performance of standard metal coolers.
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