Among the so-called primary methods of decrease of the NOx emissions, the flue gas recirculation ... more Among the so-called primary methods of decrease of the NOx emissions, the flue gas recirculation and the reburning are by far the most widely used in industry because they prevent NOx formation in accordance with the limit level of the regulation at a lower cost acceptable to manufacturers. In this paper the implementations of flue gas recirculation and reburning were analysed on the test combustion facilities regarding its reduction and combustion efficiency at combustion of natural gas. The flue gas recirculation was shown as a very effective method in reduction of the NOx emissions, and the reburning has equally good efficiency in reduction and combustion.
The article is presented an analysis of the unit operation for drying and heating of steel- pouri... more The article is presented an analysis of the unit operation for drying and heating of steel- pouring ladles and proposed a variant of its reconstruction. It is shown that using the developed lid seal assembly improves the uniformity of the ladle heating, reduces the cold air suction into the ladle and ensures considerable natural gas saving.
The authors of the study focused on the problem of hydrogasifying coal extracted from a particula... more The authors of the study focused on the problem of hydrogasifying coal extracted from a particular location. Since hydrogen is transparent to radiation, it can only be heated by convection. To achieve this, we developed a swirler and utilized Fluent software (version 19.0) to simulate the primary flow vectors and the temperature distribution of hydrogen in the hydrogasification reactor. The process was carried out under varying conditions, including temperatures ranging up to 1173 K, pressures of up to 8 MPa, and gas flow rates between 0.5 and 5 dmn3 min−1. The results showed that the carbon reactivity of the char was high up to a certain level of carbon conversion. In this study, the kinetic equations of the hydrogasification process were developed based on the theory of active centers. The researchers also evaluated the kinetic constants at the maximum reaction rate for the analyzed chars. The analysis was conducted for four extreme cases of process parameters, which included temp...
Advances in Thermal Processes and Energy Transformation
Article focuses on the description of the experimental gasification reactor design, those has bee... more Article focuses on the description of the experimental gasification reactor design, those has been designed to solve the needs of the project VUKONZE. The characteristics of the low - power gasification generators show to problems with increased tar production, the relatively low calorific value of the gas produced as well as the supply and redistribution of the gasification air. The paper points out the differentiation of the area thermal load of the reactor in comparison with the general parameters for this kind of reactors. An integral part of the design of the reactor is also the location of the fuel charging point and the way of its realization.
Coal mining is still proceeding in some countries today, although EU countries have agreed to mov... more Coal mining is still proceeding in some countries today, although EU countries have agreed to move to a carbon-neutral economy by 2050. Mine gases were developed during coalification. The quantity of gas inside the coal deposits depends on the: level of coalification, quantity of colliery tip and on conditions, which have contributed to the keeping of gas inside the coal deposits. Mine gases are endangering mining operation hence it is necessary to assure their dilution or extraction. We can use the extracted mine gas in different ways from supplies to the system of natural gas up to using it in different appliances. This article deals with the formation, acquisition and extraction of mine gas locally during mining operation. This technology increases the safety of the mining area. It contributes to the reduction of CH4 emissions and uses them for energy purposes.
Modern heating furnaces use combined modes of heating the charge. At high heating temperatures, m... more Modern heating furnaces use combined modes of heating the charge. At high heating temperatures, more radiation heating is used; at lower temperatures, more convection heating is used. In large heating furnaces, such as pusher furnaces, it is necessary to monitor the heating of the material zonally. Zonal heating allows the appropriate thermal regime to be set in each zone, according to the desired parameters for heating the charge. The problem for each heating furnace is to set the optimum thermal regime so that at the end of the heating, after the material has been cross-sectioned, there is a uniform temperature field with a minimum temperature differential. In order to evaluate the heating of the charge, a mathematical model was developed to calculate the heat fluxes of the moving charge (slabs) along the length of the pusher furnace. The obtained results are based on experimental measurements on a test slab on which thermocouples were installed, and data acquisition was provided ...
Advances in Thermal Processes and Energy Transformation
In this paper, the authors present the design of an experimental device for measuring small flow ... more In this paper, the authors present the design of an experimental device for measuring small flow rates of gaseous media. For the design and construction, materials were used to create a local pressure resistance and thus allow the pressure gradient to be measured upstream and downstream of the measuring element. The proposed measuring devices can serve as an alternative to actual measuring devices for detecting the instantaneous quantity flowing in the measuring assembly. The results obtained from the experimental measurements are used to determine the characteristics of the proposed measuring elements. The aim is to establish dependencies that will serve for the use of the proposed measuring elements for research and educational purposes.
Advances in Thermal Processes and Energy Transformation
The aim of the article is to analyse the impact of adding hydrogen to natural gas. The main goal ... more The aim of the article is to analyse the impact of adding hydrogen to natural gas. The main goal is to analyze the influence of the increase of hydrogen during the combustion of the gas-air mixture on the emissivity of flue gases in the combustion chamber, applying calculation methods from known relations that can be used in the creation of mathematical models. The created mathematical model simulates the increase in the amount of hydrogen in natural gas. The results are graphical representations of the courses of the selected parameters depending on the increase of the hydrogen content in the mixture. The increase of hydrogen in the fuel mixture confirms a significant effect on the emissivity of exhaust gases, especially from 60% hydrogen content. Moreover, with already 45% of hydrogen in the fuel mixture, the composition and volume of the exhaust gases also changes significantly.
Advances in Thermal Processes and Energy Transformation
The performance of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sod... more The performance of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sodium sulphate’ is studied. An optimum composition of adsorbent ’silica gel – sodium sulphate’ is suggested to be of 20 % silica gel and 80 % sodium sulphate. The basic factors affected the net coefficient of energy performance of the adsorptive solar refrigerator were stated. Net coefficients of performance of solar adsorptive refrigerator based on composite ‘silica gel – sodium sulphate’ are stated to change from 0.25 to 0.34 during operating period. Utilization of the adsorption heat is suggested to warm the heat carrier which applied to heat adsorbent during regeneration.
Advances in Thermal Processes and Energy Transformation
The authors focused on 3 different constructions of experimental equipment based on the principle... more The authors focused on 3 different constructions of experimental equipment based on the principle of countercurrent Ranque-Hilsch Vortex Tube (RHVT). With the help of experimental devices, the separating effect of air can be demonstrated by means of a vortex effect. The constructions of the experimental facilities are based on the relationships published by the authors Takaham and Sonim. Based on the air inlet pressure and the hot outlet area, the outlet temperature of the hot and cold air fractions will be monitored. The temperature difference is evaluated and the suitability of the proposed parameters of the experimental equipment is assessed.
Among the so-called primary methods of decrease of the NOx emissions, the flue gas recirculation ... more Among the so-called primary methods of decrease of the NOx emissions, the flue gas recirculation and the reburning are by far the most widely used in industry because they prevent NOx formation in accordance with the limit level of the regulation at a lower cost acceptable to manufacturers. In this paper the implementations of flue gas recirculation and reburning were analysed on the test combustion facilities regarding its reduction and combustion efficiency at combustion of natural gas. The flue gas recirculation was shown as a very effective method in reduction of the NOx emissions, and the reburning has equally good efficiency in reduction and combustion.
The article is presented an analysis of the unit operation for drying and heating of steel- pouri... more The article is presented an analysis of the unit operation for drying and heating of steel- pouring ladles and proposed a variant of its reconstruction. It is shown that using the developed lid seal assembly improves the uniformity of the ladle heating, reduces the cold air suction into the ladle and ensures considerable natural gas saving.
The authors of the study focused on the problem of hydrogasifying coal extracted from a particula... more The authors of the study focused on the problem of hydrogasifying coal extracted from a particular location. Since hydrogen is transparent to radiation, it can only be heated by convection. To achieve this, we developed a swirler and utilized Fluent software (version 19.0) to simulate the primary flow vectors and the temperature distribution of hydrogen in the hydrogasification reactor. The process was carried out under varying conditions, including temperatures ranging up to 1173 K, pressures of up to 8 MPa, and gas flow rates between 0.5 and 5 dmn3 min−1. The results showed that the carbon reactivity of the char was high up to a certain level of carbon conversion. In this study, the kinetic equations of the hydrogasification process were developed based on the theory of active centers. The researchers also evaluated the kinetic constants at the maximum reaction rate for the analyzed chars. The analysis was conducted for four extreme cases of process parameters, which included temp...
Advances in Thermal Processes and Energy Transformation
Article focuses on the description of the experimental gasification reactor design, those has bee... more Article focuses on the description of the experimental gasification reactor design, those has been designed to solve the needs of the project VUKONZE. The characteristics of the low - power gasification generators show to problems with increased tar production, the relatively low calorific value of the gas produced as well as the supply and redistribution of the gasification air. The paper points out the differentiation of the area thermal load of the reactor in comparison with the general parameters for this kind of reactors. An integral part of the design of the reactor is also the location of the fuel charging point and the way of its realization.
Coal mining is still proceeding in some countries today, although EU countries have agreed to mov... more Coal mining is still proceeding in some countries today, although EU countries have agreed to move to a carbon-neutral economy by 2050. Mine gases were developed during coalification. The quantity of gas inside the coal deposits depends on the: level of coalification, quantity of colliery tip and on conditions, which have contributed to the keeping of gas inside the coal deposits. Mine gases are endangering mining operation hence it is necessary to assure their dilution or extraction. We can use the extracted mine gas in different ways from supplies to the system of natural gas up to using it in different appliances. This article deals with the formation, acquisition and extraction of mine gas locally during mining operation. This technology increases the safety of the mining area. It contributes to the reduction of CH4 emissions and uses them for energy purposes.
Modern heating furnaces use combined modes of heating the charge. At high heating temperatures, m... more Modern heating furnaces use combined modes of heating the charge. At high heating temperatures, more radiation heating is used; at lower temperatures, more convection heating is used. In large heating furnaces, such as pusher furnaces, it is necessary to monitor the heating of the material zonally. Zonal heating allows the appropriate thermal regime to be set in each zone, according to the desired parameters for heating the charge. The problem for each heating furnace is to set the optimum thermal regime so that at the end of the heating, after the material has been cross-sectioned, there is a uniform temperature field with a minimum temperature differential. In order to evaluate the heating of the charge, a mathematical model was developed to calculate the heat fluxes of the moving charge (slabs) along the length of the pusher furnace. The obtained results are based on experimental measurements on a test slab on which thermocouples were installed, and data acquisition was provided ...
Advances in Thermal Processes and Energy Transformation
In this paper, the authors present the design of an experimental device for measuring small flow ... more In this paper, the authors present the design of an experimental device for measuring small flow rates of gaseous media. For the design and construction, materials were used to create a local pressure resistance and thus allow the pressure gradient to be measured upstream and downstream of the measuring element. The proposed measuring devices can serve as an alternative to actual measuring devices for detecting the instantaneous quantity flowing in the measuring assembly. The results obtained from the experimental measurements are used to determine the characteristics of the proposed measuring elements. The aim is to establish dependencies that will serve for the use of the proposed measuring elements for research and educational purposes.
Advances in Thermal Processes and Energy Transformation
The aim of the article is to analyse the impact of adding hydrogen to natural gas. The main goal ... more The aim of the article is to analyse the impact of adding hydrogen to natural gas. The main goal is to analyze the influence of the increase of hydrogen during the combustion of the gas-air mixture on the emissivity of flue gases in the combustion chamber, applying calculation methods from known relations that can be used in the creation of mathematical models. The created mathematical model simulates the increase in the amount of hydrogen in natural gas. The results are graphical representations of the courses of the selected parameters depending on the increase of the hydrogen content in the mixture. The increase of hydrogen in the fuel mixture confirms a significant effect on the emissivity of exhaust gases, especially from 60% hydrogen content. Moreover, with already 45% of hydrogen in the fuel mixture, the composition and volume of the exhaust gases also changes significantly.
Advances in Thermal Processes and Energy Transformation
The performance of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sod... more The performance of adsorptive solar refrigerators based on composite adsorbents ‘silica gel - sodium sulphate’ is studied. An optimum composition of adsorbent ’silica gel – sodium sulphate’ is suggested to be of 20 % silica gel and 80 % sodium sulphate. The basic factors affected the net coefficient of energy performance of the adsorptive solar refrigerator were stated. Net coefficients of performance of solar adsorptive refrigerator based on composite ‘silica gel – sodium sulphate’ are stated to change from 0.25 to 0.34 during operating period. Utilization of the adsorption heat is suggested to warm the heat carrier which applied to heat adsorbent during regeneration.
Advances in Thermal Processes and Energy Transformation
The authors focused on 3 different constructions of experimental equipment based on the principle... more The authors focused on 3 different constructions of experimental equipment based on the principle of countercurrent Ranque-Hilsch Vortex Tube (RHVT). With the help of experimental devices, the separating effect of air can be demonstrated by means of a vortex effect. The constructions of the experimental facilities are based on the relationships published by the authors Takaham and Sonim. Based on the air inlet pressure and the hot outlet area, the outlet temperature of the hot and cold air fractions will be monitored. The temperature difference is evaluated and the suitability of the proposed parameters of the experimental equipment is assessed.
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Papers by Ján Kizek