37 results on '"Čaja, Alexander"'
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2. Prediction of particulate matter during the combustion of wood pellets with the addition of face mask waste
- Author
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Kantová, Nikola Čajová, Nosek, Radovan, Čaja, Alexander, and Holubčík, Michal
- Published
- 2024
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3. The energy assessment of COVID-19 medical waste as a potential fuel
- Author
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Čajová Kantová, Nikola, Cibula, Robert, Szlek, Andrzej, Čaja, Alexander, Nosek, Radovan, and Belany, Pavol
- Published
- 2023
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4. Determination of pressure loss of silencers during air transport in air conditioning
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Kubas, Šimon, Kapjor, Andrej, Vantúch, Martin, and Čaja, Alexander
- Published
- 2021
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5. Transport of phytomass in combustion process from plant to small combustion plant
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Backa, Alexander and Čaja, Alexander
- Published
- 2021
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6. The flowing of particulate matter through baffles depending on their number in the flue gas tract
- Author
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Kantová, Nikola, Jandačka, Jozef, Sładek, Sławomir, Holubčík, Michal, and Čaja, Alexander
- Published
- 2019
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- View/download PDF
7. Aerosol Measurements Before and During Combustion of Various Pellets from Spruce Sawdust and Face Masks FFP2
- Author
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Čajová Kantová Nikola, Čaja Alexander, and Hrabovský Peter
- Subjects
aerosols ,mass concentration ,combustion ,face masks ,pellets ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Aerosols in the atmosphere affect our health and quality of life. The most commonly measured property is their mass concentration. In this work was measured the mass concentration of aerosols by optical particle sizer in the range from 0.3 μm to 10 μm. It was realized in the laboratory with an automatic heat source for pellet combustion. Aerosols were firstly measured before the combustion process, then during combustion of three types of samples: pellets from pure sawdust, pellets from 5 % of disintegrated face masks FFP2 blended with spruce sawdust and from10 % of disintegrated face masks FFP2 blended with spruce sawdust. The lowest total mass concentration was measured during the combustion of pellets from pure spruce sawdust. However, results indicate that the combustion process does not have an impact on aerosol mass concentration in the laboratory space for the particle range 0.3-10 μm when an automatic heat source for pellets is used.
- Published
- 2022
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8. Comparison of Performance Parameters of Four Types of Refrigerants
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Čaja Alexander, Čajová Kantová Nikola, Kapjor Andrej, and Vantúch Martin
- Subjects
refrigerants ,heat pumps ,global warming potential coefficient of performance ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The use of refrigerants requires to meet ecology and legislation requirements. The aim of the legislation is also to reduce the global warming potential (GWP). Natural refrigerants such as carbon dioxide, ammonia, and hydrocarbons such as propane, isobutene, and propylene are used mainly because of their environmental benefits compared to synthetic refrigerants. This work compares two natural refrigerants: R-744 and R-290 and two synthetic refrigerants: R-134a and R-32. All these refrigerants are used mainly in heat pumps. In this work were calculated and compared the following performance parameters: heat rejected in the condenser, cooling power, compressor power, and the coefficient of performance (COP). The most important parameter is the coefficient of performance because when it decreases, electric energy consumption increases. It requires reaching a high value of COP. Further, this work deals with the economic analyses of selected refrigerants. The last aim of this article is their ecologic analysis based on the GWP factor.
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- 2022
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9. PIV Observation of the Baffle Position in the Flue Gas Tract for Particle Flowing
- Author
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Čaja Alexander, Patsch Marek, and Backa Alexander
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Solid fuel combustion accompanies particulate matter production. These particles negatively affect human health, so ways of capturing them are being sought. Local heat sources are a major producer, with this article focusing on the flue gas tract of this heat source. A baffle has been placed in the flue gas tract, the position of which is changing. It is observed the impact of particulate matter flowing through this baffle with a focus on the settling areas. Particles are trapped in the settling areas and do not flow further through the flue gas tract. Particulate matter flowing was investigated by the visualization method called Particle image velocimetry (PIV). Visualizing the flow allows to get a figure of the flow and a dynamic record of the state of the object. The result of the visualization is the assessment of the monitored flow, the determination of its trajectory and streamlines.
- Published
- 2020
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10. Influence of Selected Parameters on the Rate Nucleation of Methane Hydrates
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Hečko Dávid, Malcho Milan, Mičko Pavol, and Čaja Alexander
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The demand for energy is growing in the world, and therefore attention has been focused on the use of possible alternative energy sources. For countries with limited access to common hydrocarbon gases, methane hydrates appear to be a potential source of energy. Under certain pressure and temperature conditions, it is also possible to produce hydrates of hydrocarbon gases under laboratory conditions. However, we are currently at a very early stage in the development of methane hydrates. The transition from scientific theory to practical extraction is currently underway. This article describes the influence of selected physical parameters on the nucleation rate of hydrocarbon gas hydrates.
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- 2020
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11. The Analytical Model of Biomass Combustion
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Backa Alexander, Nosek Radovan, and Čaja Alexander
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Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
The standard detection of the emission and power parameters of the combustion process can be time and money consuming due to the performance of experimental measurements with the necessary measuring instruments. Alternatives to describe the combustion process are mathematical models. Their variability is high and therefore, depending on the need for use, an analytical mathematical model was chosen. Among the computationally faster and less time-consuming models is the analytical model, which can not only describe some parameters of the combustion process (power, emissions and others) but also predict the parameters of the combustion process according to the selected input values. This work is focused on the prediction of selected emission parameters through an analytical model for 100 % straw and 100 % wood pellets.
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- 2020
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12. Mathematical model for heat transfer limitations of heat pipe
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Nemec, Patrik, Čaja, Alexander, and Malcho, Milan
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- 2013
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13. The properties of wood pellets formed from biowaste.
- Author
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Kantová, Nikola Čajová, Čaja, Alexander, Kolková, Zuzana, Belány, Pavol, and Hrabovský, Peter
- Subjects
- *
WOOD pellets , *PINE cones , *SEED harvesting , *WASTE products , *BIOMASS energy , *FUEL quality - Abstract
Waste biomass presents an energy source. However, a lot of waste biomass rots in landfills without further usage. Although it has an energy value and can be used for fuel production. One of the waste biomass is pine cones. They present waste products after seed harvesting. In this work, pine cones were compressed together with spruce sawdust into wood pellets. At first, pellets were created from pure spruce sawdust, then shredded pine cones were added in the content of 10 %, 20 %, 30 %, 40 %, and 50 %. The formed pellets were subjected to elemental and proximate analysis. Then calorific values and densities were also determined. In general, it is important to know the properties of the fuel with respect to its quality, potential applications, also power, and emission parameters. Based on the results it can be concluded that the carbon content decreases slightly with the increasing content of pine cones, the nitrogen content increases with the increasing content of pine cones, and calorific values decrease slightly with the increasing content of pine cones. Higher ash content was formed at samples with higher content of pine cones, specifically of wood pellets with 40 % and 50 % of the content of pine cones. Individual values of density are in the range from 1150.29 kg·m-3 to 1245.02 kg·m−3. The lowest density was found during the sample with 50 % of the content of pine cones. [ABSTRACT FROM AUTHOR]
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- 2023
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14. Co-Combustion Investigation of Wood Pellets Blended with FFP2 Masks: Analysis of the Ash Melting Temperature.
- Author
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Čajová Kantová, Nikola, Holubčík, Michal, Čaja, Alexander, Trnka, Juraj, Hrabovský, Peter, and Belány, Pavol
- Subjects
WOOD pellets ,MEDICAL masks ,MELTING ,CO-combustion ,TEMPERATURE ,COVID-19 pandemic - Abstract
The COVID-19 pandemic brought a period of high consumption of protective masks and an increase in their waste. Therefore, it was necessary to look at possibilities for their disposal. This article is focused on the disposal of FFP2 masks in the form of pellets blended with sawdust. Further, their ash melting behavior was observed. The method of ash preparation can impact the resulting values of melting temperatures. Therefore, this article investigates the resulting values of ash melting temperatures determined during different ash preparations, such as temperatures (550 °C and 815 °C) and ash size (non-sifted, smaller than 50 µm and 100 µm). All measured deformation temperatures were higher than 1100 °C and even higher than 1200 °C for some samples. Moreover, the presence of FFP2 masks in pellets only insignificantly affected the values of melting temperatures compared to pure wood pellets. The measured values also showed that increasing the temperature of ash preparation from 550 to 815 °C can increase the resulting values of melting temperature. The most significant proportion of the fraction size on the resulting melting temperatures was observed for beech with 5% and 10% of masks at an ash temperature of 550 °C and for spruce with 10% of masks at an ash temperature of 815 °C. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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15. Analysis of Ash Melting Temperatures of Agricultural Pellets Detected during Different Conditions.
- Author
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Čajová Kantová, Nikola, Holubčík, Michal, Trnka, Juraj, and Čaja, Alexander
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AGRICULTURE ,RENEWABLE energy sources ,AGRICULTURAL wastes ,MELTING ,COMPRESSED air - Abstract
Agricultural and other residues are promising renewable energy sources. However, they can cause problems in combustion processes. One of these problems is also low ash melting temperatures. Except, the ash melting behavior can be impacted by many factors, such as ash preparation or used atmosphere. This article deals with comparing different atmosphere conditions during measurements of ash melting temperatures of three agricultural pellets: alfalfa, straw, and hay. The first one was oxidizing with compressed air and nitrogen. The second atmosphere was reduced with the air purge, and the last was only reduced, consisting of 60% carbon monoxide and 40% carbon dioxide. Differences between individual atmospheres were none, up to 9.8%. The most significant differences have appeared between oxidizing and reducing atmospheres. In general, the oxidizing atmosphere presents a less expensive way. More attention should be paid to the use of oxidizing atmosphere for applications in heat sources mainly due to its similarity to the combustion process. However, it would be suitable to realize more comprehensive research regarding ash preparation in different ways and with using of different types of fuel. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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16. Comparison of particulate matter in combustion of wood chips and sawdust at nominal and reduced output
- Author
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Čaja Alexander and Kantová Nikola
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
Biomass has been still on the rise in recent years in the world. But combustion of biomass led to the increase of emissions in the atmosphere. Mainly in winter time is formed a large amount of particulate matter. They have adverse impact on our health when human breathes them. This is a reason why is important to produce low level of these emissions. However, several aspects impact on their formation. This article examines impact of type of fuel and operation of heat source on PM formation. It compares particulate matter from combustion of wood chips and sawdust at nominal and reduced output.
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- 2018
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17. Flow modelling of particulate matter by using baffles placed in the flue tract of wood stove
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Kantová Nikola, Čaja Alexander, Holubčík Michal, and Jandačka Jozef
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
It is very important to separate particulate matter before their leaving into the air because of their harmful impact on human health. It exists a lot of devices, which can separate these particles. But their implementation and operation in small heat source can be considerably difficult on finances, and often have complex maintenance. Therefore, it is important to look for solutions of reduction the producing of particulate matter with easier maintenance and also less financial difficulty. This article deals with flow modelling of particulate matter by using baffles placed in the flue tract of wood stove. Influence of baffles is observed by using CFD simulations.
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- 2018
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18. Comparison of Energy Properties of Pellets from Shells of Different Nut Species.
- Author
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Trnka, Juraj, Kantová, Nikola Čajová, Holubčík, Michal, Čaja, Alexander, Najser, Tomáš, and Najser, Jan
- Subjects
NUTS ,WASTE recycling ,WOOD pellets ,WOOD waste ,SPECIES ,PISTACHIO ,PROBLEM solving - Abstract
Bio-waste is a source of energy-rich material. Therefore, it can be used in further processes and efficiently utilized. Further processes of waste utilization include compressing them to pellets. However, this type of pellet often has a low bulk density, high ash content, low ash melting temperature, and low calorific value. This research dealt with the energy properties of peanut and pistachio nut shells that were pure or mixed with spruce sawdust in half proportion and compressed into pellets. As a continuation of previous research, the properties of these pellets prepared were measured and compared with pure spruce pellets and with pellets from walnut shells. The tested shell pellets had calorific values similar to wood pellets from spruce. However, mixing nut shells with spruce solved the problems of high ash content and low ash melting temperatures. The amount of wood present in the pellets resulted in increased ash melting temperatures and decreased the ash content. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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19. The Performance and Emission Parameters Based on the Redistribution of the Amount of Combustion Air of the Wood Stove.
- Author
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Holubčík, Michal, Čajová Kantová, Nikola, Jandačka, Jozef, and Čaja, Alexander
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WOOD combustion ,WOOD stoves ,PARTICULATE matter ,BIOMASS burning ,AIRDROP - Abstract
Several factors affect how particulate matter and gaseous emissions are formed during the combustion processes of biomass. The amount of combustion air, as well as its redistribution, is one of these factors. This article deals with the performance and emission parameters determined using different distributions of the amount of combustion air of the wood stove with beech wood as a fuel. Eighteen different settings of primary, secondary and tertiary air supplies were realized, while heat output, efficiency, particulate matter, carbon monoxide and nitrogen oxides were measured or determined. The aim of this article is to identify the optimal air distribution between primary, secondary, and tertiary air supplies focused on the mentioned parameters. Based on the results, two settings (25/50/25 and 0/100/0) could be the optimal variant. However, the concentration of particulate matter reached a higher value during the setting with a ratio of 25/50/25, similar to a ratio of 50/25/25. The measurement during the setting with a ratio of 0/100/0 could be influenced by the existing embers on the grid before the start of the measurement. However, it is important to supply all three types of combustion air with the main emphasis on the secondary air supply due to the completely use of the combustible gases. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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20. Energy Consumption Depending on the Durability of Pellets Formed from Sawdust with an Admixture of FFP2 Masks.
- Author
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Čajová Kantová, Nikola, Belány, Pavol, Holubčík, Michal, and Čaja, Alexander
- Subjects
WOOD pellets ,ENERGY consumption ,WOOD waste ,DURABILITY ,MEDICAL masks ,MANUFACTURING processes - Abstract
At present, we are still feeling the effects of the COVID-19 pandemic in connection with the huge amount of waste generated. However, the reuse of the produced waste in other processes requires energy consumption. This article deals with the reuse of face masks FFP2, which were added as an admixture to spruce or beech sawdust and then processed into pellets. During the production process of the pellets, energy consumption was measured and further converted to one ton of pellets, and also the consumption was reflected in the price of electricity. After storage, the mechanical durability and dimensions of the individual pellets were measured, and their density was calculated. Based on the results, it can be concluded that spruce pellets with 10% face masks FFP2 (consumption 747.41 kWh; durability 97.53%) and beech pellets with 5% face masks FFP2 (consumption 721.27 kWh; durability 97.38%) achieved higher values of mechanical durability and also consumed more energy than the remaining samples with lower values of durability without considering the sample with spruce sawdust and 5% FFP2 face masks (consumption 872.63 kWh; durability 91.68%). The production of spruce pellets with 5% FFP2 face masks was affected mainly by cold outside weather. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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21. Analyses of Pellets Produced from Spruce Sawdust, Spruce Bark, and Pine Cones in Different Proportions.
- Author
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Čajová Kantová, Nikola, Holubčík, Michal, Čaja, Alexander, Trnka, Juraj, and Jandačka, Jozef
- Subjects
WOOD waste ,PINE cones ,BIOMASS energy ,PELLETIZING ,ALTERNATIVE fuels ,SPRUCE ,ENERGY density ,NORWAY spruce - Abstract
A lot of residual biomass has energy value and can be used for further applications through suitable treatments, such as pelletization. This treatment can improve properties, mainly energy density, but can also lead to problems due to their low ash melting temperatures, high ash content, and the formation of harmful compounds during combustion. This article deals with the energy potential of pellets produced from spruce sawdust, spruce bark, and pine cones in different proportions. The impact of cone and bark contents on pellet properties was also observed. The energy properties of the produced pellets were measured, such as the contents of carbon, hydrogen, nitrogen, moisture, volatile, fixed carbon, and ash, as well as calorific values and ash melting temperatures. Based on the results, it can be concluded that the addition of pine cones and spruce bark to spruce sawdust mainly affected the contents of nitrogen and ash and melting temperatures. Despite this, all produced pellets met the standard EN ISO 17225-2 for the content of nitrogen, ash, and also lower calorific value at least B quality. However, only three pellet samples of five met this standard for A2 and B quality for ash melting behavior. Therefore, they present an alternative fuel with interesting energy potential. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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22. Analysis of long-time operation of micro-cogeneration unit with fuel cell
- Author
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Patsch Marek and Čaja Alexander
- Subjects
Physics ,QC1-999 - Abstract
Micro-cogeneration is cogeneration with small performance, with maximal electric power up to 50 kWe. On the present, there are available small micro-cogeneration units with small electric performance, about 1 kWe, which are usable also in single family houses or flats. These micro-cogeneration units operate on principle of conventional combustion engine, Stirling engine, steam engine or fuel cell. Micro-cogeneration units with fuel cells are new progressive developing type of units for single family houses. Fuel cell is electrochemical device which by oxidation-reduction reaction turn directly chemical energy of fuel to electric power, secondary products are pure water and thermal energy. The aim of paper is measuring and evaluation of operation parameters of micro-cogeneration unit with fuel cell which uses natural gas as a fuel.
- Published
- 2015
- Full Text
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23. Mechanical and Energy Properties of Pellets Formed from Walnut Shells Blended with Spruce Sawdust .
- Author
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Kantová, Nikola Čajová, Čaja, Alexander, Belány, Pavol, Kolková, Zuzana, Hrabovský, Peter, Hečko, Dávid, and Mičko, Pavol
- Subjects
- *
WOOD waste , *MECHANICAL energy , *WALNUT , *WASTE treatment , *SPRUCE , *WASTE products , *ENERGY consumption - Abstract
Various waste materials have energy potential. It is important to make use of this potential and prepare the product for further use by treating the waste. Treatments such as compressing waste into pellets leads to increasing the energy density of this fuel, which benefits transport and storage costs. However, low bulk density, high ash content, low-ash melting temperatures, and low calorific values of non-woody pellets can cause problems during their combustion. This article deals with the energy usage of walnut shells, which were blended with spruce sawdust in various amounts and compressed into pellets. The mechanical and energy properties of these were measured and compared with recommended or standardized values. The formed pellets met the quality limit for bulk density, ash content, moisture content, the content of nitrogen and sulfur, and net calorific value according to ISO 17225. However, low ash melting temperatures were noticed for pellets from pure walnut shells, and also lower mechanical durability for produced pellets with walnut shells contents higher than 10% were detected. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. PIV Observation of the Baffle Position in the Flue Gas Tract for Particle Flowing.
- Author
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Lenhard, R., Kaduchová, K., Čaja, Alexander, Patsch, Marek, and Backa, Alexander
- Published
- 2020
- Full Text
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25. The Analytical Model of Biomass Combustion.
- Author
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Lenhard, R., Kaduchová, K., Backa, Alexander, Nosek, Radovan, and Čaja, Alexander
- Published
- 2020
- Full Text
- View/download PDF
26. Influence of Selected Parameters on the Rate Nucleation of Methane Hydrates.
- Author
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Lenhard, R., Kaduchová, K., Hečko, Dávid, Malcho, Milan, Mičko, Pavol, and Čaja, Alexander
- Published
- 2020
- Full Text
- View/download PDF
27. Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract.
- Author
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Čajová Kantová, Nikola, Čaja, Alexander, Patsch, Marek, Holubčík, Michal, Ďurčanský, Peter, and Juchelková, Dagmar
- Subjects
GAS flow ,PARTICLE image velocimetry ,COMPUTATIONAL fluid dynamics ,FLUE gases ,TURBULENCE ,PARTICULATE matter ,FLOW separation - Abstract
With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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28. Simulation of Biomass Combustion with Modified Flue Gas Tract.
- Author
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Čajová Kantová, Nikola, Sładek, Sławomir, Jandačka, Jozef, Čaja, Alexander, Nosek, Radovan, Fiori, Luca, and Musmarra, Dino
- Subjects
BIOMASS burning ,FLUE gases ,PARTICULATE matter ,BAFFLES (Mechanical device) ,COMBUSTION chambers ,CHEMICAL reactions ,SHEARING force - Abstract
The combustion of biomass is accompanied by the formation of particulate matter, the presence of which in the atmosphere harms human health. It is important to show the issues of reducing these pollutants and their impact on human health. This article focuses on the process of biomass combustion. The used model consists of two parts: the combustion chamber and the flue gas tract. The article shows four types of modification of the flue gas tract designed to reduce the amount of particulate matter in the atmosphere. Baffles are located in the flue gas tract, which is designed to capture the particulate matter. The final model is simulated by turbulent–viscosity models, k-ε realizable model, and then k-ω shear stress transport model. The interaction between turbulence and chemical reactions is expressed by using the Eddy Dissipation Concept model. The results then show different profiles of temperature, velocity, and particle distribution. Based on the evaluated data from two different calculations, it can be concluded that the baffles have a significant effect on the reduction of particulate matter in the atmosphere. The used baffles are able to capture mainly particles with a diameter greater than 100 µm. A significant number of particles with a diameter lower than 100 µm flows from the flue gas tract to the surrounding environment. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
29. The dependence of surface temperature on IGBTs load and ambient temperature
- Author
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Čaja Alexander and Patsch Marek
- Subjects
Physics ,Heat pipe ,Power electronics ,Nuclear engineering ,Loop heat pipe ,QC1-999 ,Bipolar junction transistor ,Significant part ,Water cooling ,Insulated-gate bipolar transistor ,Engineering physics - Abstract
Currently, older power electronics and electrotechnics are improvement and at the same time developing new and more efficient devices. These devices produce in their activities a significant part of the heat which, if not effectively drained, causing damage to these elements. In this case, it is important to develop new and more efficient cooling system. The most widespread of modern methods of cooling is the cooling by heat pipe. This contribution is aimed at cooling the insulated-gate bipolar transistor (IGBT) elements by loop heat pipe (LHP). IGBTs are very prone to damage due to high temperatures, and therefore is the important that the surface temperature was below 100°C. It was therefore created a model that examined what impact of surface temperature on the IGBT element and heat removal at different load and constant ambient temperature.
- Published
- 2015
30. Decreasing of Escaped Particulate Matter based on a Baffles Position in the Flue Gas Tract.
- Author
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Kantová, Nikola, Jandačka, Jozef, Holubčík, Michal, and Čaja, Alexander
- Subjects
PARTICULATE matter ,BAFFLES (Mechanical device) ,FLUE gases ,PUBLIC health ,SOLID-liquid interfaces ,MACHINE separators - Abstract
It is important to pay attention particulate matter mainly due to their negative effects on human health. Into the atmosphere, they are getting from various mobile, as well as stationary sources including combustion. These emissions consist of solid and liquid material dispersed in the atmosphere. It is important to separate particulate matter before their leaving in the atmosphere. Reduction of particulate matter can be achieved primarily by optimizing the flue gases flowing or secondary by using separators. Separators are useable in the big heat sources, but their realization in small heat source are difficult on finances and have complex maintenance. This article deals with primarily reduction of particulate matter in the wood stove, which is small heat source. To capture of these particles, baffles were designed in the flue gas tract of the combustion chamber and their flowing was observed depending on the position of the baffles by using CFD simulations. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
31. Observation of solid pollutants flowing during solid alternative fuel combustion.
- Author
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KANTOVÁ, Nikola, HOLUBČÍK, Michal, JANDAČKA, Jozef, and ČAJA, Alexander
- Abstract
Copyright of Waste Forum is the property of Czech Environment Management Center (CEMC) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2019
32. Downfall and Take-off Particulate Matter Velocity.
- Author
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Kantová, Nikola, Jandačka, Jozef, Holubčík, Michal, and Čaja, Alexander
- Subjects
PARTICULATE matter ,HEATING ,COMBUSTION ,DIAMETER ,SOLID fuel reactors - Abstract
Particulate matter arises also during combustion of solid fuels and then pollutes our atmosphere. Therefore, these particles are one of the most watched emissions. Several factors influence on their formation. It is possible to reduction of particulate matter formation with knowing and affecting these factors. Knowing of PM take-off velocity is important condition for their reduction during combustion process. Particles are taken away from heating grate depending on values of PM take-off velocity. In this article, there was calculated PM downfall velocity in consideration of their spherical shape. Further, there were observed samples of PM under a stereomicroscope and their downfall velocity was recalculated using by an equivalent spherical diameter due this observation. After all this, there was made a comparison between calculations of PM downfall velocity. Sizes and shapes of PM are not insignificant and they also have effect on calculation of PM downfall velocity. And finally, take-off velocity was experimental measured by model of wood stove track. This velocity was smaller than calculated downfall velocity especially during larger particles sizes. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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33. Fireplace Insert and its Parameters Depend On the Used Glazing.
- Author
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Papučík, Štefan and Čaja, Alexander
- Subjects
- *
GLAZING (Glass installation) , *HIGH temperatures , *EMISSIONS (Air pollution) , *PARAMETERS (Statistics) , *HEAT resistant materials , *GLASS - Abstract
The contribution deals with the analysis of the impact of using double glass to change the performance and emission parameters of the fireplace insert. Conventional fireplace inserts are equipped with heat-resistant glass, which is resistant to high temperatures. For this type of inserts are required to be radiant constituent maximized. Prevailing part of heat is into the interior gets just by radiation through the glazed part. The hot water fireplace inserts is the requirement that the radiant constituent to the environment to a minimum. Therefore, instead of a single glass using double glazing which is intended to reduce this part of heat transfer. The temperature in the furnace is increased, and transmitted most of the heat into the water. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Comparison of Particulate Matters Properties from Combustion of Wood Biomass and Brown Coal.
- Author
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Kantová, Nikola, Holubčík, Michal, Jandačka, Jozef, and Čaja, Alexander
- Subjects
COMBUSTION -- Environmental aspects ,PARTICULATE matter ,EMISSIONS (Air pollution) ,BIOMASS burning ,LIGNITE - Abstract
The combustion leads to pollution with particulate matters (PM). These emissions are considered to cause the greatest harm to human health. Particulate pollutants consist of the following substances: carbon, ammonium, metals, organic materials, nitrates and sulfates. This article deals with analysis of the particulate matters samples from wood biomass and brown coal. The analyses were carried out by elemental determinator and thermogravimetric analyzer. Thermogravimetric analyzer determines the composition of organic, inorganic, and synthetic materials. The elemental determinator is used to determine carbon, hydrogen, nitrogen and sulfur in organic matrices. Further analysis compares the size distribution of these samples. Size distribution was determined by using of vibratory sieve shaker machine. The shape of particles was observed by stereo microscope and density was also determined such as a ratio of their weight and volume. It is important to analyze chemical and physical properties of PM in order to decrease their concentration during combustion process. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
35. Analysis of long-time operation of micro-cogeneration unit with fuel cell.
- Author
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Patscha, Marek and Čaja, Alexander
- Subjects
- *
COGENERATION of electric power & heat , *FUEL cells , *ELECTRIC power , *STIRLING engines , *STEAM engines , *GAS as fuel - Abstract
Micro-cogeneration is cogeneration with small performance, with maximal electric power up to 50 kWe. On the present, there are available small micro-cogeneration units with small electric performance, about 1 kWe, which are usable also in single family houses or flats. These micro-cogeneration units operate on principle of conventional combustion engine, Stirling engine, steam engine or fuel cell. Micro-cogeneration units with fuel cells are new progressive developing type of units for single family houses. Fuel cell is electrochemical device which by oxidation-reduction reaction turn directly chemical energy of fuel to electric power, secondary products are pure water and thermal energy. The aim of paper is measuring and evaluation of operation parameters of micro-cogeneration unit with fuel cell which uses natural gas as a fuel. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
36. Visualization of heat transport in heat pipes using thermocamera.
- Author
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NEMEC, PATRIK, ČAJA, ALEXANDER, and LENHARD, RICHARD
- Subjects
- *
HEAT pipes , *HEAT transfer , *HEAT equation , *PHASE transitions , *DIFFERENTIABLE dynamical systems - Abstract
Heat pipes, as passive elements show a high level of reliability when taking heat away and they can take away heat flows having a significantly higher density than systems with forced convection. A heat pipe is a hermetically closed duct, filled with working fluid. Transport of heat in heat pipes is procured by the change of state of the working fluid from liquid state to steam and vice versa and depends on the hydrodynamic and heat processes in the pipe. This study have been focused on observing the impact these processes have on the heat process, the transport of heat within the heat pipe with the help of thermovision. The experiment is oriented at scanning the changes in the surface temperatures of the basic structural types of capillary heat pipes in vertical position. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
37. OBSERVATION OF PARTICULATE MATTER VELOCITIES IN THE FLUE TRACT OF LOCAL HEAT SOURCE.
- Author
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KANTOVÁ, Nikola, HOLUBČÍK, Michal, ČAJA, Alexander, and JANDAČKA, Jozef
- Subjects
PARTICULATE matter ,BAFFLES (Mechanical device) ,GRANULAR flow ,HEAT ,VELOCITY ,SIMULATION software - Abstract
Presence of particulate matter (PM) in the atmosphere is a problem mainly in the winter time. PM are getting into atmosphere from combustion of solid fuels in heat sources. Their impact on people health is harmful, when we breathe them. Therefore, it is necessary for reduction these emissions in the atmosphere. This article investigates downfall velocities of particulate matter based on calculations and then it observes velocity simulation of particulate matter flowing through baffles placed in the flue tract of local heat source by using program Ansys. These baffles are usable for separation of particulate matter in the flue tract. When particles reach downfall velocity, forces which acting on them are in equilibrium and they would not get into atmosphere from the flue tract of heat source. CFD simulation in program Ansys allows us to observe velocity distribution in flue tract and compare it with calculated downfall velocity of these particles. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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