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Moravian-Silesian Region
DEM Solutions Ltd.
Graduate Student or Post Graduate
01 September 2012 - 01 May 2019
University Educator/Researcher
01 September 2012 - 30 August 2021
Researcher, Engineer & Lab worker VSB - Technical University of Ostrava, CENET, Bulk Solids Centre of Czech Republic + Junior Researcher + Research in field of particulates + Powders characterization + Discrete Element Modelling + Experimental methods + Engineering equipment design
The knowledge of a grinder structure, its performance parameters and characteristics of biomaterials breakage are crucial for this research whose aim is to determine the dependencies between performance parameters and comminution indicators. The aim of this study is to investigate the relationships between multi-disc mill performance parameters such as discs angular speed, batch dosing speed and comminution characteristics: power consumption, specific energy consumption, throughput and size reduction ratio. To achieve these goals, an experiment was conducted on a five-disc mill with a special monitoring system. The research program was established, with disc angular speed at different configurations and different batch dosing speeds. The results show that power consumption, specific energy consumption and size reduction ratio depend on the total increase in angular speed of discs SΔω in such a way that an increase in SΔω causes an increase in the abovementioned comminution indicators. In turn, an increase in batch dosing speed W causes an increase in throughput. The fitting curves of comminution indicators in dependence of selected performance parameters are also presented in this study.
Weronika Kruszelnicka; Jakub Hlosta; Jan Diviš; Łukasz Gierz. Study of the Relationships between Multi-Hole, Multi-Disc Mill Performance Parameters and Comminution Indicators. Sustainability 2021, 13, 8260 .
AMA StyleWeronika Kruszelnicka, Jakub Hlosta, Jan Diviš, Łukasz Gierz. Study of the Relationships between Multi-Hole, Multi-Disc Mill Performance Parameters and Comminution Indicators. Sustainability. 2021; 13 (15):8260.
Chicago/Turabian StyleWeronika Kruszelnicka; Jakub Hlosta; Jan Diviš; Łukasz Gierz. 2021. "Study of the Relationships between Multi-Hole, Multi-Disc Mill Performance Parameters and Comminution Indicators." Sustainability 13, no. 15: 8260.
Cooling is an important process during the production of pellets (as post-treatment). The pellet cooling process significantly impacts the quality of the pellets produced and the systematic use of energy. However, the cooling systems currently in use sometimes encounter technical problems, such as clogging of the perforated grids (sieves), the discharge hopper, or pellet degradation may occur. Therefore, a prototype of a new pellet cooling system using a vibrating feeder was tested. The aim of the study is to present a new variation of pellet cooling system using spiral vibration cooler as a possible solution next to a counterflow cooler. The presented system was tested (critically evaluated and discussed) in two design variants. The first variant consists in cooling by chaotic movement of the pellets. The second is then in combination with the chaotic movement of the pellets together with the action of intense air flow using specially placed air hoses. All tests involved pelletization of rapeseed straw. It was found that both cooling system variants could, realistically, be used. However, the variant with an intense air flow was more energy-intensive, a factor which is, however, offset by the higher quality of the pellets. No negative impact of vibrations to pellets quality was occur. Studies provide insight into new usable technologies that do not reduce the efficiency of the process as a result of grate clogging.
David Žurovec; Lucie Jezerská; Jan Nečas; Jakub Hlosta; Jan Diviš; Jiří Zegzulka. Spiral Vibration Cooler for Continual Cooling of Biomass Pellets. Processes 2021, 9, 1060 .
AMA StyleDavid Žurovec, Lucie Jezerská, Jan Nečas, Jakub Hlosta, Jan Diviš, Jiří Zegzulka. Spiral Vibration Cooler for Continual Cooling of Biomass Pellets. Processes. 2021; 9 (6):1060.
Chicago/Turabian StyleDavid Žurovec; Lucie Jezerská; Jan Nečas; Jakub Hlosta; Jan Diviš; Jiří Zegzulka. 2021. "Spiral Vibration Cooler for Continual Cooling of Biomass Pellets." Processes 9, no. 6: 1060.
David Žurovec; Jan Nečas; Jiří ROZBROJ; Jakub Hlosta; Jiří ZEGZULKA. The Effect of Setting the Operating Conditions of the Sampling Device on the Representative Sample of Coal. GeoScience Engineering 2021, 67, 47 -51.
AMA StyleDavid Žurovec, Jan Nečas, Jiří ROZBROJ, Jakub Hlosta, Jiří ZEGZULKA. The Effect of Setting the Operating Conditions of the Sampling Device on the Representative Sample of Coal. GeoScience Engineering. 2021; 67 (2):47-51.
Chicago/Turabian StyleDavid Žurovec; Jan Nečas; Jiří ROZBROJ; Jakub Hlosta; Jiří ZEGZULKA. 2021. "The Effect of Setting the Operating Conditions of the Sampling Device on the Representative Sample of Coal." GeoScience Engineering 67, no. 2: 47-51.
This paper’s goal was to select methods and a calibration procedure which would lead to the determination of relevant parameters of a discrete element method (DEM) and virtual material creation. Seven particulates were selected with respect to their shape (spherical and non-spherical), size and density. The first calibration experiment involved “packing test” to determine the shape accuracy and bulk density of virtual packed particulates. The series of simulations were compared with real experiments, and the size, shape and density of virtual particles were optimized. Using three apparatuses, the input parameter values were experimentally determined for a contact model that defines the behavior of particulates in DEM simulations. The research part of the paper examines the influence of factors such as particle number; pile formation method; and the method of evaluation of the angle of repose on the process of the calibration of virtual material. The most reproducible results were achieved by the “pilling” method and by the rotating drum—both evaluated by the geometric method. However, it is always advisable to make an overall visual comparison of the slope shape between the calibration simulation and the experimental curves. The bowl’s diameter to particle size ratio should be greater than 25, and the calibration experiment should contain approximately 4000 particles to ensure representative results during angle of repose calibration experiment.
Jakub Hlosta; Lucie Jezerská; Jiří Rozbroj; David Žurovec; Jan Nečas; Jiří Zegzulka. DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 1—Determination of the DEM Parameters and Calibration Process. Processes 2020, 8, 222 .
AMA StyleJakub Hlosta, Lucie Jezerská, Jiří Rozbroj, David Žurovec, Jan Nečas, Jiří Zegzulka. DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 1—Determination of the DEM Parameters and Calibration Process. Processes. 2020; 8 (2):222.
Chicago/Turabian StyleJakub Hlosta; Lucie Jezerská; Jiří Rozbroj; David Žurovec; Jan Nečas; Jiří Zegzulka. 2020. "DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 1—Determination of the DEM Parameters and Calibration Process." Processes 8, no. 2: 222.
The process of homogenization of particulates is an indispensable part of many industrial processes, and, therefore, it is necessary to pay a special attention to this area and develop it. This paper deals with a complex study of homogenization of particulate matters in a rotary drum in terms of shape, size, and density of particles. In addition, the influence of operating parameters, such as drum filling capacity, rotational speed, and drum filling pattern are also investigated. Studies of reproducibility of discrete element method simulations, effects of rotary drum sizes or effects of drum volumetric filling to the mixture homogeneity index were also carried out. In general, the least satisfactory values of the homogeneity index resulted from the mixing of particles with different densities. The dominating factor of homogenization was the drum filling-up degree. The course of the homogeneity index in 140, 280, and 420 mm drums was very similar and after five revolutions of the drum, identical values of the homogeneity index were achieved for all the drum diameters. The optimal drum filling-up degree is at 40–50% for the spherical particles and 30–40% for the sharp-edged particles. The repeatability of simulations showed the maximum relative standard deviation of the homogeneity index at 0.6% from ten simulation repetitions with the same parametric conditions.
Jakub Hlosta; Lucie Jezerská; Jiří Rozbroj; David Žurovec; Jan Nečas; Jiří Zegzulka. DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 2—Process Validation and Experimental Study. Processes 2020, 8, 184 .
AMA StyleJakub Hlosta, Lucie Jezerská, Jiří Rozbroj, David Žurovec, Jan Nečas, Jiří Zegzulka. DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 2—Process Validation and Experimental Study. Processes. 2020; 8 (2):184.
Chicago/Turabian StyleJakub Hlosta; Lucie Jezerská; Jiří Rozbroj; David Žurovec; Jan Nečas; Jiří Zegzulka. 2020. "DEM Investigation of the Influence of Particulate Properties and Operating Conditions on the Mixing Process in Rotary Drums: Part 2—Process Validation and Experimental Study." Processes 8, no. 2: 184.
This article focuses on the monitoring of air tunnels in sand, which in common practice are characterised as flow disturbances in the flow of bulk materials inside storage devices, hoppers, silos etc. In this case air tunnels are monitored by the ECT (Electrical Capacitance Tomography) method. The basic principle of the ECT tomographic method is the measurement of permittivity of a measured non-conducting medium. The results gained by an ECT device are then compared with the real, precisely defined measured state. The measured results show that the monitoring of flow disturbances in storage devices using ECT is a new method which does not use optical methods during measurement.
David Žurovec; Jakub Hlosta; Jan Nečas; Jiří Rozbroj; Jiří Zegzulka. Monitoring of air tunnels in a cylindrical storage device using ECT tomography. MATEC Web of Conferences 2019, 263, 01008 .
AMA StyleDavid Žurovec, Jakub Hlosta, Jan Nečas, Jiří Rozbroj, Jiří Zegzulka. Monitoring of air tunnels in a cylindrical storage device using ECT tomography. MATEC Web of Conferences. 2019; 263 ():01008.
Chicago/Turabian StyleDavid Žurovec; Jakub Hlosta; Jan Nečas; Jiří Rozbroj; Jiří Zegzulka. 2019. "Monitoring of air tunnels in a cylindrical storage device using ECT tomography." MATEC Web of Conferences 263, no. : 01008.
This article addresses the optimization of a dosing tank using a spiral harmonic motion. The dosing tank is used for the short-term storage of cohesive sand, which is then released into a tubular mold. Originally, a solution based on the principle of wiping the material using rotary blades and...
David Zurovec; Jan Necas; Jan Diviš; Jakub Hlosta; Jiri Zegzulka; Katerina Urbanova. OPTIMIZATION OF DOSING TANK EMPTYING USING SPIRAL VIBRATION. Advances in Science and Technology Research Journal 2018, 12, 143 -149.
AMA StyleDavid Zurovec, Jan Necas, Jan Diviš, Jakub Hlosta, Jiri Zegzulka, Katerina Urbanova. OPTIMIZATION OF DOSING TANK EMPTYING USING SPIRAL VIBRATION. Advances in Science and Technology Research Journal. 2018; 12 (3):143-149.
Chicago/Turabian StyleDavid Zurovec; Jan Necas; Jan Diviš; Jakub Hlosta; Jiri Zegzulka; Katerina Urbanova. 2018. "OPTIMIZATION OF DOSING TANK EMPTYING USING SPIRAL VIBRATION." Advances in Science and Technology Research Journal 12, no. 3: 143-149.
There is hardly any industry that does not use transport, storage, and processing of particulate solids in its production process. In the past, all device designs were based on empirical relationships or the designer’s experience. In the field of particulate solids, however, the discrete element method (DEM) has been increasingly used in recent years. This study shows how this simulation tool can be used in practice. More specifically, in dealing with operating problems with a rotary cooler which ensures the transport and cooling of the hot fly ash generated by combustion in fluidized bed boilers. For the given operating conditions, an analysis of the current cooling design was carried out, consisting of a non-standard intake pipeline, which divides and supplies the material to two rotary coolers. The study revealed shortcomings in both the pipeline design and the cooler design. The material was unevenly dispensed between the two coolers, which combined with the limited transport capacity of the coolers, led to overflowing and congestion of the whole system. Therefore, after visualization of the material flow and export of the necessary data using DEM design measures to mitigate these unwanted phenomena were carried out.
Jakub Hlosta; David Žurovec; Jiří Rozbroj; Álvaro Ramírez-Gómez; Jan Nečas; Jiří Zegzulka. Analysis and Optimization of Material Flow inside the System of Rotary Coolers and Intake Pipeline via Discrete Element Method Modelling. Energies 2018, 11, 1849 .
AMA StyleJakub Hlosta, David Žurovec, Jiří Rozbroj, Álvaro Ramírez-Gómez, Jan Nečas, Jiří Zegzulka. Analysis and Optimization of Material Flow inside the System of Rotary Coolers and Intake Pipeline via Discrete Element Method Modelling. Energies. 2018; 11 (7):1849.
Chicago/Turabian StyleJakub Hlosta; David Žurovec; Jiří Rozbroj; Álvaro Ramírez-Gómez; Jan Nečas; Jiří Zegzulka. 2018. "Analysis and Optimization of Material Flow inside the System of Rotary Coolers and Intake Pipeline via Discrete Element Method Modelling." Energies 11, no. 7: 1849.
Monitoring the bulk material discharge from silos using electrical capacitance tomography (ECT) is an effective way to monitor dynamic flow profiles within silos. In our case bulk materials such as wheat and corn are used. These materials are typical crops in the agricultural industry. The basic differences of these materials are shape and size. The material properties are the main factors influencing the optimal discharge processes. In this paper, the ECT method is used to determine the flow profile during the discharge of each material from the silo. ECT is a non‐destructive and contact‐less method for measuring the inner space of the silo. The measured results show that the monitoring of discharge processes from the silo by using ECT is a new on‐line monitoring method with a wide application.
David Žurovec; Jakub Hlosta; Jiri Rozbroj; Jan Necas; Jiri Zegzulka. Monitoring of the Discharge Process of Bulk Material in Silos Using Electrical Capacitance Tomography. Chemical Engineering & Technology 2018, 41, 1559 -1565.
AMA StyleDavid Žurovec, Jakub Hlosta, Jiri Rozbroj, Jan Necas, Jiri Zegzulka. Monitoring of the Discharge Process of Bulk Material in Silos Using Electrical Capacitance Tomography. Chemical Engineering & Technology. 2018; 41 (8):1559-1565.
Chicago/Turabian StyleDavid Žurovec; Jakub Hlosta; Jiri Rozbroj; Jan Necas; Jiri Zegzulka. 2018. "Monitoring of the Discharge Process of Bulk Material in Silos Using Electrical Capacitance Tomography." Chemical Engineering & Technology 41, no. 8: 1559-1565.
Jakub Hlosta; David Žurovec; Jiří Rozbroj; Álvaro Ramírez-Gómez; Jan Nečas; Jiří Zegzulka. Experimental determination of particle–particle restitution coefficient via double pendulum method. Chemical Engineering Research and Design 2018, 135, 222 -233.
AMA StyleJakub Hlosta, David Žurovec, Jiří Rozbroj, Álvaro Ramírez-Gómez, Jan Nečas, Jiří Zegzulka. Experimental determination of particle–particle restitution coefficient via double pendulum method. Chemical Engineering Research and Design. 2018; 135 ():222-233.
Chicago/Turabian StyleJakub Hlosta; David Žurovec; Jiří Rozbroj; Álvaro Ramírez-Gómez; Jan Nečas; Jiří Zegzulka. 2018. "Experimental determination of particle–particle restitution coefficient via double pendulum method." Chemical Engineering Research and Design 135, no. : 222-233.
Jiří Rozbroj; Jan Nečas; David Žurovec; Jakub Hlosta; Daniel Gelnar; Jiří Zegzulka. Simulation of Material Flow Through a Sample Divider. Advances in Science and Technology Research Journal 2018, 12, 194 -199.
AMA StyleJiří Rozbroj, Jan Nečas, David Žurovec, Jakub Hlosta, Daniel Gelnar, Jiří Zegzulka. Simulation of Material Flow Through a Sample Divider. Advances in Science and Technology Research Journal. 2018; 12 (1):194-199.
Chicago/Turabian StyleJiří Rozbroj; Jan Nečas; David Žurovec; Jakub Hlosta; Daniel Gelnar; Jiří Zegzulka. 2018. "Simulation of Material Flow Through a Sample Divider." Advances in Science and Technology Research Journal 12, no. 1: 194-199.
Jan Nečas; Jakub Hlosta; David Žurovec; Martin Žídek; Jiří Rozbroj; Jiří Zegzulka. Feeder Type Optimisation for the Plain Flow Discharge Process of an Underground Hopper by Discrete Element Modelling. Advances in Science and Technology Research Journal 2017, 11, 246 -252.
AMA StyleJan Nečas, Jakub Hlosta, David Žurovec, Martin Žídek, Jiří Rozbroj, Jiří Zegzulka. Feeder Type Optimisation for the Plain Flow Discharge Process of an Underground Hopper by Discrete Element Modelling. Advances in Science and Technology Research Journal. 2017; 11 (3):246-252.
Chicago/Turabian StyleJan Nečas; Jakub Hlosta; David Žurovec; Martin Žídek; Jiří Rozbroj; Jiří Zegzulka. 2017. "Feeder Type Optimisation for the Plain Flow Discharge Process of an Underground Hopper by Discrete Element Modelling." Advances in Science and Technology Research Journal 11, no. 3: 246-252.
The coefficient of thermal conductivity of particulates and powders is of great importance in process engineering. The prediction of thermal properties of powders using empirical equations is still difficult due to the wide range of specific attributes. This article describes a new measurement methodology for a laboratory device that can be used to determine the thermal conductivity of bulk solids. The presented results show that the created device is highly applicable in industrial practice. It is possible to examine the coefficient of thermal conductivity depending on the sample temperature, the granulometry results and the morphological composition, the moisture content, the degree of consolidation, and other variables that may enter into the entire process and affect it significantly.
Jakub Hlosta; David Zurovec; Daniel Gelnar; Jiri Zegzulka; Jan Necas. Thermal Conductivity Measurement of Bulk Solids. Chemical Engineering & Technology 2017, 40, 1876 -1884.
AMA StyleJakub Hlosta, David Zurovec, Daniel Gelnar, Jiri Zegzulka, Jan Necas. Thermal Conductivity Measurement of Bulk Solids. Chemical Engineering & Technology. 2017; 40 (10):1876-1884.
Chicago/Turabian StyleJakub Hlosta; David Zurovec; Daniel Gelnar; Jiri Zegzulka; Jan Necas. 2017. "Thermal Conductivity Measurement of Bulk Solids." Chemical Engineering & Technology 40, no. 10: 1876-1884.
Jiří Rozbroj; Jan Nečas; Daniel Gelnar; Jakub Hlosta; Jiří Zegzulka. VALIDATION OF MOVEMENT OVER A BELT CONVEYOR DRUM. Advances in Science and Technology Research Journal 2017, 11, 118 -124.
AMA StyleJiří Rozbroj, Jan Nečas, Daniel Gelnar, Jakub Hlosta, Jiří Zegzulka. VALIDATION OF MOVEMENT OVER A BELT CONVEYOR DRUM. Advances in Science and Technology Research Journal. 2017; 11 (2):118-124.
Chicago/Turabian StyleJiří Rozbroj; Jan Nečas; Daniel Gelnar; Jakub Hlosta; Jiří Zegzulka. 2017. "VALIDATION OF MOVEMENT OVER A BELT CONVEYOR DRUM." Advances in Science and Technology Research Journal 11, no. 2: 118-124.