Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.03.07
O. Voinov, Yu. V. Elkin
The global production created by the mankind has an intensively increasing harmful effect on the environment. As a result, we are facing the problem of the saving of natural environment and now the global community tries to find solution for this environmental problem. The power generation sector is the most environmentally aggressive of all industry branches. Technical power engineering facilities differ by a high degree of complexity making it difficult to increase the level of their environmental friendliness. In particular, centralized heat supply systems are rather complicated and responsible components of the power engineering industry. These differ by a high level of environmental aggressiveness. Hence, these need to increase a degree of their environmental friendliness. The purpose of this research was to analyze the condition of the interaction of the power generating sector with the natural environment and search for harmonization solutions of available contradictions of such an interaction. An increase of the environmental friendliness of the worn-out power equipment used by centralized heat supply systems is a topical problem. The purpose of this scientific paper was to suggest a solution for the problem of the environmental interaction of the centralized heat supply systems with natural environment using an approach of their partial renewal. The most environmentally aggressive elements of these systems are the boiler plants that emit heat and harmful substances into the environment. Domestic boiler plants have completely been worn-out. Therefore, the development of the domestic boiler building industry is of vital importance. It will enable the production of modern boiler plants instead of worn-out boiler systems. This process is impeded at the moment by the insufficiency of available resources. Contemporary requirements to the technological level of the functioning efficiency of the centralized heat-supply systems are rather high, especially as for its environmental component. Available centralized heat-supply systems have low efficiency due to a high wear-out level of their elements on the whole. There is an urgent need for an increase in the efficiency of these systems. One of the available ways of such an increase in the efficiency is a partial renewal of the equipment. The program of the partial renewal of available boiler plants allows us to provide an appropriate increase in the environmental friendliness of the worn-out equipment used by centralized heat-supply systems. The coverage of the entire fleet of the equipment available for the centralized heat-supply systems by this partial renewal program will allow for an increase in the level of its ecological friendliness on the whole.
{"title":"About the Effect on the Environmental Efficiency of the Centralized Heat Supply Systems","authors":"O. Voinov, Yu. V. Elkin","doi":"10.20998/2078-774x.2022.03.07","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.03.07","url":null,"abstract":"The global production created by the mankind has an intensively increasing harmful effect on the environment. As a result, we are facing the problem of the saving of natural environment and now the global community tries to find solution for this environmental problem. The power generation sector is the most environmentally aggressive of all industry branches. Technical power engineering facilities differ by a high degree of complexity making it difficult to increase the level of their environmental friendliness. In particular, centralized heat supply systems are rather complicated and responsible components of the power engineering industry. These differ by a high level of environmental aggressiveness. Hence, these need to increase a degree of their environmental friendliness. The purpose of this research was to analyze the condition of the interaction of the power generating sector with the natural environment and search for harmonization solutions of available contradictions of such an interaction. An increase of the environmental friendliness of the worn-out power equipment used by centralized heat supply systems is a topical problem. The purpose of this scientific paper was to suggest a solution for the problem of the environmental interaction of the centralized heat supply systems with natural environment using an approach of their partial renewal. The most environmentally aggressive elements of these systems are the boiler plants that emit heat and harmful substances into the environment. Domestic boiler plants have completely been worn-out. Therefore, the development of the domestic boiler building industry is of vital importance. It will enable the production of modern boiler plants instead of worn-out boiler systems. This process is impeded at the moment by the insufficiency of available resources. Contemporary requirements to the technological level of the functioning efficiency of the centralized heat-supply systems are rather high, especially as for its environmental component. Available centralized heat-supply systems have low efficiency due to a high wear-out level of their elements on the whole. There is an urgent need for an increase in the efficiency of these systems. One of the available ways of such an increase in the efficiency is a partial renewal of the equipment. The program of the partial renewal of available boiler plants allows us to provide an appropriate increase in the environmental friendliness of the worn-out equipment used by centralized heat-supply systems. The coverage of the entire fleet of the equipment available for the centralized heat-supply systems by this partial renewal program will allow for an increase in the level of its ecological friendliness on the whole.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122666921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.01.07
Anna Chyrkova, A. Khalatov
The funnel is the most important element of the thermal power station. An appropriate arrangement of the system for the removal of the gaseous products of fuel combustion inside the funnel results in no moisture condensation and proper maintenance of the operation conditions of the funnel. To measure the temperature of combustion products along the funnel height we need to define the boundary conditions of the third kind for the external surface of the funnel. The studies showed that in the case of the uniform velocity profile, the heat exchange and aerodynamics on the surface of the single vertically arranged funnel have specific features conditioned by the funnel configuration and the contact of its base with the ground surface. In particular, the rear part of the funnel is characterized by a periodic change in the static pressure, velocity and the height heat loss coefficient. The purpose of this research was to define the average heat loss along the height of the conical funnel situated at the industrial site of the thermal power station for different wind vectors and velocities. To simulate the heat exchange and aerodynamics near the funnel situated at the thermal power plant site we used the infrastructure that includes the following elements: mechanical compartment, substation, administrative building, warehouse and two cooling towers. The network model of the hydropower plant includes 1137782 units and 4741859 elements. A minimum orthogonal quality is 0.1 and a maximum biasing is 0.89. The ĝ RNG k- turbulence model, the Enhanced Wall Function and the Simplex algorithm were used for the velocity-pressure interrelation problem in steady flows. The air density is independent of the temperature at the computational volume inlet (the gravitation is neglected). The funnel surface temperature was specified as constant and equal to 100 C. The heat exchange near the funnel was studied at different wind directions in the wind velocity range of 5 to 25 m/s. Hence, the wind direction, the environmental infrastructure and the industrial thermal power plant site have an essential effect on the funnel height heat exchange distribution pattern. Evidently, it is defined to a great extent by the funnel aerodynamics. A maximum heat loss level is observed when the flow is rushed to the backside of the building at the south- to-north wind direction and a minimum heat loss level is observed for the east- to -west and west -to -east wind directions for the parallel flow. А minimum heat loss is observed at a longitudinal wind motion along the mechanical compartment building in west-to-east and east-to- west directions. These specific features should be taken into account when designing tall funnels with an optimal change in the combustion product temperature along the funnel height. We can draw a conclusion that the specific features of the heat exchange in question should be obligatory taken into account when designing tall funnels. Keywords: heat exchange, f
{"title":"Heat Exchange and Aerodynamics of the Vertical Conical Funnel at the Thermal Power Plant Site","authors":"Anna Chyrkova, A. Khalatov","doi":"10.20998/2078-774x.2022.01.07","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.01.07","url":null,"abstract":"The funnel is the most important element of the thermal power station. An appropriate arrangement of the system for the removal of the gaseous products of fuel combustion inside the funnel results in no moisture condensation and proper maintenance of the operation conditions of the funnel. To measure the temperature of combustion products along the funnel height we need to define the boundary conditions of the third kind for the external surface of the funnel. The studies showed that in the case of the uniform velocity profile, the heat exchange and aerodynamics on the surface of the single vertically arranged funnel have specific features conditioned by the funnel configuration and the contact of its base with the ground surface. In particular, the rear part of the funnel is characterized by a periodic change in the static pressure, velocity and the height heat loss coefficient. The purpose of this research was to define the average heat loss along the height of the conical funnel situated at the industrial site of the thermal power station for different wind vectors and velocities. To simulate the heat exchange and aerodynamics near the funnel situated at the thermal power plant site we used the infrastructure that includes the following elements: mechanical compartment, substation, administrative building, warehouse and two cooling towers. The network model of the hydropower plant includes 1137782 units and 4741859 elements. A minimum orthogonal quality is 0.1 and a maximum biasing is 0.89. The ĝ RNG k- turbulence model, the Enhanced Wall Function and the Simplex algorithm were used for the velocity-pressure interrelation problem in steady flows. The air density is independent of the temperature at the computational volume inlet (the gravitation is neglected). The funnel surface temperature was specified as constant and equal to 100 C. The heat exchange near the funnel was studied at different wind directions in the wind velocity range of 5 to 25 m/s. Hence, the wind direction, the environmental infrastructure and the industrial thermal power plant site have an essential effect on the funnel height heat exchange distribution pattern. Evidently, it is defined to a great extent by the funnel aerodynamics. A maximum heat loss level is observed when the flow is rushed to the backside of the building at the south- to-north wind direction and a minimum heat loss level is observed for the east- to -west and west -to -east wind directions for the parallel flow. А minimum heat loss is observed at a longitudinal wind motion along the mechanical compartment building in west-to-east and east-to- west directions. These specific features should be taken into account when designing tall funnels with an optimal change in the combustion product temperature along the funnel height. We can draw a conclusion that the specific features of the heat exchange in question should be obligatory taken into account when designing tall funnels. Keywords: heat exchange, f","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130836320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.03.05
Olexander Efimov, V. Kavertsev, Petro Lifshyts
This scientific paper gives a review of the available methods and approaches used for the strength computation of the covers, bottoms, assemblies and elements of the structures of steam generators of the two-loop NPPs with BBEP-1000 reactors. For most assemblies and elements of the structures of steam generators of NPPs, the main strains arising in them are the consequences of the uniform internal and external pressures. However, in many cases the assemblies and elements of the structures of steam generators of NPPs can also be exposed to additional loads (weight loads, efforts and moments that result from nonhomogeneous thermal expansion of different parts of steam generator, etc.). The values of the strains caused by additional loads can sometimes exceed the value of the main strain. These can be decreased by the arrangement of additional supports or compensators or by changing the structure configuration. Sometimes, it is reasonable to increase the wall thickness of the calculated elements of the structures in order to reduce the strains caused by additional loads. Before getting to the strength computations for the assemblies and elements of the structures of steam generators we need to define first the character of the external loads on them (constant or cyclic load) and the deformability of their structural materials (ductile material, brittle material or limited plasticity material) and then to select the method for their strength computation. To provide a reliable operation of the steam generators of NPPs it is important to provide appropriate strength characteristics for all its assemblies and elements. These elements include process pipelines that are connected to the steam generator structure. These represent a spatially branched pipeline systems of a different technological purpose whose structures are supported by special fastening elements (the supports of different types, spring suspenders, etc.). The strength computations done for such systems include static and cyclic strength computations, seismic action computations, etc.
{"title":"Methods of the Strength Computation for the Covers, Bottoms, Assemblies and Elements of the Structure of Steam Generators Used by the Two-Loop Nuclear Power Plants with BBEP-1000 Reactors","authors":"Olexander Efimov, V. Kavertsev, Petro Lifshyts","doi":"10.20998/2078-774x.2022.03.05","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.03.05","url":null,"abstract":"This scientific paper gives a review of the available methods and approaches used for the strength computation of the covers, bottoms, assemblies and elements of the structures of steam generators of the two-loop NPPs with BBEP-1000 reactors. For most assemblies and elements of the structures of steam generators of NPPs, the main strains arising in them are the consequences of the uniform internal and external pressures. However, in many cases the assemblies and elements of the structures of steam generators of NPPs can also be exposed to additional loads (weight loads, efforts and moments that result from nonhomogeneous thermal expansion of different parts of steam generator, etc.). The values of the strains caused by additional loads can sometimes exceed the value of the main strain. These can be decreased by the arrangement of additional supports or compensators or by changing the structure configuration. Sometimes, it is reasonable to increase the wall thickness of the calculated elements of the structures in order to reduce the strains caused by additional loads. Before getting to the strength computations for the assemblies and elements of the structures of steam generators we need to define first the character of the external loads on them (constant or cyclic load) and the deformability of their structural materials (ductile material, brittle material or limited plasticity material) and then to select the method for their strength computation. To provide a reliable operation of the steam generators of NPPs it is important to provide appropriate strength characteristics for all its assemblies and elements. These elements include process pipelines that are connected to the steam generator structure. These represent a spatially branched pipeline systems of a different technological purpose whose structures are supported by special fastening elements (the supports of different types, spring suspenders, etc.). The strength computations done for such systems include static and cyclic strength computations, seismic action computations, etc.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125711534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.03.10
Olexandr Stepanets, Yurii Mariiash
The purpose of the research was to find a solution for a decrease in the cost price of the basic oxygen furnace steel. It is conditioned by an increase in the scrap metal portion due to an increase in the СО to CO2 afterburn degree in the basic oxygen furnace cavity according to the optimal model predictive control of the parameters of the blowing mode. The optimal parameter control system was synthesized for the blowing mode of the oxygen-converter melting on the basis of the feedback based on the model-predictive control using the linear-quadratic functional and it enabled a simultaneous control of the blowing intensity and the lance position when programmatically changing the task for the oxygen consumption and CO2 content improving also the control quality and energy saving during the melting process due to an increased afterburn degree during the CO to CO2 conversion that is a consequence of an increased portion of the scrap metal. Closed CO to CO2 afterburn degree control systems were improved by the synthesis of the model-predictive controller taking into consideration process limitations imposed on the shifting rate of controlling mechanisms, improving thus the process control quality in the case of the limitations. The suggested solution enables certain process control quality improvement under the conditions of process limitations. A comparative investigation of the operation of the model – predictive controller and combined control system with PID–controllers showed that the obtained transition processes of the automatic control of the blowing mode for the basic oxygen furnace melting using the automatic model-predictive controller provided ISE values for the oxygen consumption loop equal to 5577 and the CO2 content equal to 43 in basic oxygen furnace gases with a maximum dynamic deviation of the CO2 content in converter gases equal to 0.95 %. The use of the model-predictive controller allowed us to improve the control quality for the oxygen consumption loop by a factor of 1.63 CO2 and by a factor of 32.5 for the CO2 content control loop in converter gases. A maximum dynamic deviation of the CO2 content in converter gases was reduced by 16.55 % in comparison to that in the combined control system equipped with PID-controllers.
{"title":"Синтез модельно-прогнозуючого регулятора режиму дуття киснево-конвертерного процесу","authors":"Olexandr Stepanets, Yurii Mariiash","doi":"10.20998/2078-774x.2022.03.10","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.03.10","url":null,"abstract":"The purpose of the research was to find a solution for a decrease in the cost price of the basic oxygen furnace steel. It is conditioned by an increase in the scrap metal portion due to an increase in the СО to CO2 afterburn degree in the basic oxygen furnace cavity according to the optimal model predictive control of the parameters of the blowing mode. The optimal parameter control system was synthesized for the blowing mode of the oxygen-converter melting on the basis of the feedback based on the model-predictive control using the linear-quadratic functional and it enabled a simultaneous control of the blowing intensity and the lance position when programmatically changing the task for the oxygen consumption and CO2 content improving also the control quality and energy saving during the melting process due to an increased afterburn degree during the CO to CO2 conversion that is a consequence of an increased portion of the scrap metal. Closed CO to CO2 afterburn degree control systems were improved by the synthesis of the model-predictive controller taking into consideration process limitations imposed on the shifting rate of controlling mechanisms, improving thus the process control quality in the case of the limitations. The suggested solution enables certain process control quality improvement under the conditions of process limitations. A comparative investigation of the operation of the model – predictive controller and combined control system with PID–controllers showed that the obtained transition processes of the automatic control of the blowing mode for the basic oxygen furnace melting using the automatic model-predictive controller provided ISE values for the oxygen consumption loop equal to 5577 and the CO2 content equal to 43 in basic oxygen furnace gases with a maximum dynamic deviation of the CO2 content in converter gases equal to 0.95 %. The use of the model-predictive controller allowed us to improve the control quality for the oxygen consumption loop by a factor of 1.63 CO2 and by a factor of 32.5 for the CO2 content control loop in converter gases. A maximum dynamic deviation of the CO2 content in converter gases was reduced by 16.55 % in comparison to that in the combined control system equipped with PID-controllers.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"235 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116327585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.01.04
Riza Sherfedinov, Oleksandr Usatyi, O. Avdieieva
The issues of improving the structural-topological formation of the information model of the flow path of a steam turbine with the aim of using it in the problems of optimal design of turbine blocks are considered. A new hierarchical level "Compartment" has been added, which made it possible to link in a single information space the parameters of the frequency converter and the rest of the equipment of the turbine unit and made it possible to set and solve the problems of optimal design of turbine blocks. An improved one-dimensional model of the processes in the frequency converter, which allows simulating the course of processes in the frequency converter of a turbine from compartment to compartment (sub-section modeling of processes in the frequency converter with given steam parameters between the compartments). The improved mathematical model of the processes in the frequency converter is coordinated with the improved information model of the frequency converter and is one of the components of the optimal design subsystem of the “Turboagregat” CAD system. The performed test comparative calculations of the FC of steam turbine cylinders were carried out using algorithms created on the basis of two mathematical models: the original and the improved one. Good agreement was confirmed. Insignificant differences in thermogasdynamic parameters in the cross-sections between the rims of the inverter, obtained according to the original and improved models, are noted. Small deviations in the results are mainly caused by the need to use in the improved model the formulation of the problem with the given steam parameters in front of each compartment and the value of the mass flow rate to the head of each compartment. The fulfillment of the boundary conditions was ensured by a corresponding change in the effective angle of the nozzle grate of the first stage of each compartment.
{"title":"Information and Mathematical Models of the Flow Part in the Problems of Optimal Design of a Turboblock","authors":"Riza Sherfedinov, Oleksandr Usatyi, O. Avdieieva","doi":"10.20998/2078-774x.2022.01.04","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.01.04","url":null,"abstract":"The issues of improving the structural-topological formation of the information model of the flow path of a steam turbine with the aim of using it in the problems of optimal design of turbine blocks are considered. A new hierarchical level \"Compartment\" has been added, which made it possible to link in a single information space the parameters of the frequency converter and the rest of the equipment of the turbine unit and made it possible to set and solve the problems of optimal design of turbine blocks. An improved one-dimensional model of the processes in the frequency converter, which allows simulating the course of processes in the frequency converter of a turbine from compartment to compartment (sub-section modeling of processes in the frequency converter with given steam parameters between the compartments). The improved mathematical model of the processes in the frequency converter is coordinated with the improved information model of the frequency converter and is one of the components of the optimal design subsystem of the “Turboagregat” CAD system. The performed test comparative calculations of the FC of steam turbine cylinders were carried out using algorithms created on the basis of two mathematical models: the original and the improved one. Good agreement was confirmed. Insignificant differences in thermogasdynamic parameters in the cross-sections between the rims of the inverter, obtained according to the original and improved models, are noted. Small deviations in the results are mainly caused by the need to use in the improved model the formulation of the problem with the given steam parameters in front of each compartment and the value of the mass flow rate to the head of each compartment. The fulfillment of the boundary conditions was ensured by a corresponding change in the effective angle of the nozzle grate of the first stage of each compartment.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126248744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.03.08
G. Gorbenko, Edem Reshytov, R. Turna, Artem M. Hodunov, Yevhen Rohovyi
The subject of this article is the heat transfer of ammonia in the channels of thermal sink evaporators. The objective was to determine a sufficiently simple correlation acceptable for engineering practice, which could be used to calculate the heat transfer in cylindrical channels of a thermal sink, designed for two-phase systems of thermal control systems of uncrewed spacecraft. For this purpose, experiments were performed on two thermal sink having an evaporator channel of ~7 mm diameter made of aluminum alloy and stainless steel, with channel surface roughness Ra 3.33 µm and 0.12 µm. The experiments were carried out with a subcooled liquid or two-phase flow at the channel inlet. The results of the experiments were compared with Kupriyanova's formula obtained under markedly different conditions: with ammonia boiling in a large volume on the external surface of 5...6 mm diameter tubes at –40 °C...+20 °C. It is shown that Kupriyanova's formula can be used on the ground and in microgravity conditions to calculate heat transfer coefficients during the developed boiling of ammonia in the range of flow parameters: saturation temperature +35 °C...+75 °C; mass velocity 27...200 kg/(sec-m²); liquid subcooling to saturation temperature at thermal sink inlet 0 °C...30 °С; mass vapor quality at the inlet 0...0.7. Difference of calculated and experimental values of heat transfer coefficients did not exceed 30 %.
{"title":"Heat Transfer Coefficient Calculation for Developed Ammonia Boiling in the Evaporator Channel of a Thermal Sink","authors":"G. Gorbenko, Edem Reshytov, R. Turna, Artem M. Hodunov, Yevhen Rohovyi","doi":"10.20998/2078-774x.2022.03.08","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.03.08","url":null,"abstract":"The subject of this article is the heat transfer of ammonia in the channels of thermal sink evaporators. The objective was to determine a sufficiently simple correlation acceptable for engineering practice, which could be used to calculate the heat transfer in cylindrical channels of a thermal sink, designed for two-phase systems of thermal control systems of uncrewed spacecraft. For this purpose, experiments were performed on two thermal sink having an evaporator channel of ~7 mm diameter made of aluminum alloy and stainless steel, with channel surface roughness Ra 3.33 µm and 0.12 µm. The experiments were carried out with a subcooled liquid or two-phase flow at the channel inlet. The results of the experiments were compared with Kupriyanova's formula obtained under markedly different conditions: with ammonia boiling in a large volume on the external surface of 5...6 mm diameter tubes at –40 °C...+20 °C. It is shown that Kupriyanova's formula can be used on the ground and in microgravity conditions to calculate heat transfer coefficients during the developed boiling of ammonia in the range of flow parameters: saturation temperature +35 °C...+75 °C; mass velocity 27...200 kg/(sec-m²); liquid subcooling to saturation temperature at thermal sink inlet 0 °C...30 °С; mass vapor quality at the inlet 0...0.7. Difference of calculated and experimental values of heat transfer coefficients did not exceed 30 %.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133018236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.03.02
O. Krasnikov, Yu P Kukhtin
Consideration was given to the design methods available in practice for an increase in the vibration reliability of the blades of axial compressor. The problem was formulated to show the possibility of the reduction of the strain in the blade nib by the control of the exciting aerodynamic forces. When it is impossible to eliminate the resonance completely and the measures taken to increase structural damping fail to give positive effect it is reasonable to make use of the possibility of the strain reduction by the control of the excitation source. Consideration was given to the aerodynamic aspect of the problem relating to an increase of the vibration reliability of the blades of axial compressor. The aerodynamic loads affecting the axial compressor blades ranging from the trace to potential effects of adjacent shrouds were determined numerically. The program package SUnFlow with the realized in it numerical integration of the Reynolds-averaged Naiver-Stocks equations was used as an investigation tool. The high-pressure compressor stage containing 120 blades of the input guide unit, 83 operating blades and 104 blades of the guide system was used as a test object. The computations were done for the initial structure of the compressor stage and for the stage structure with embedded measures in the form of the variable- pitch input guide unit. Nonstationary computations of the options were done by including the three stage rings into the computation domain of total circumferences. Based on the obtained computation data, the integral and distributed loads onto operating blade were analyzed for comparable stage options. For the obtained distributed loads, the bend strains were calculated using the rod theory. Based on the obtained experimental data, the conclusion was made that the strains can be reduced in the blade nib by the control of the exciting aerodynamic forces.
{"title":"Aerodynamic Aspect of the Problem Relating to the Reduction of the Vibration Strain in the Axial Compressor Blades of the Gas Turbine Engine","authors":"O. Krasnikov, Yu P Kukhtin","doi":"10.20998/2078-774x.2022.03.02","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.03.02","url":null,"abstract":"Consideration was given to the design methods available in practice for an increase in the vibration reliability of the blades of axial compressor. The problem was formulated to show the possibility of the reduction of the strain in the blade nib by the control of the exciting aerodynamic forces. When it is impossible to eliminate the resonance completely and the measures taken to increase structural damping fail to give positive effect it is reasonable to make use of the possibility of the strain reduction by the control of the excitation source. Consideration was given to the aerodynamic aspect of the problem relating to an increase of the vibration reliability of the blades of axial compressor. The aerodynamic loads affecting the axial compressor blades ranging from the trace to potential effects of adjacent shrouds were determined numerically. The program package SUnFlow with the realized in it numerical integration of the Reynolds-averaged Naiver-Stocks equations was used as an investigation tool. The high-pressure compressor stage containing 120 blades of the input guide unit, 83 operating blades and 104 blades of the guide system was used as a test object. The computations were done for the initial structure of the compressor stage and for the stage structure with embedded measures in the form of the variable- pitch input guide unit. Nonstationary computations of the options were done by including the three stage rings into the computation domain of total circumferences. Based on the obtained computation data, the integral and distributed loads onto operating blade were analyzed for comparable stage options. For the obtained distributed loads, the bend strains were calculated using the rod theory. Based on the obtained experimental data, the conclusion was made that the strains can be reduced in the blade nib by the control of the exciting aerodynamic forces.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"47 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134598881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-12-28DOI: 10.20998/2078-774x.2022.01.06
O. Yefimov, L. Tiutiunyk, T. Harkusha, Tetyana Yesipenko, A. Motovilnik
The materials of the article consider the design characteristics of horizontal steam generators PGV-1000 for WWER NPPs. The NPP steam generator, in particular the PGV-1000 steam generator, is a specific heat exchange unit. This unit, together with a nuclear reactor and a steam turbine, is one of the main equipment of multi-circuit (double-circuit) steam turbine NPPs. The steam generator produces working steam using heat dissipated from the reactor core by the cooling medium and sent to the heat exchange surface of the steam generator. NPP steam generators, connecting the contours of the coolant and the working substance, equally belong to each of them. The heat-absorbing medium in the steam generator is the working substance (water, steam). PGV-1000 type NPP steam generators with pressurized water reactors produce dry saturated steam. The requirement to maintain high purity of the coolant is due to the heat transfer surfaces of such steam generators made of austenitic stainless steel with electropolished surfaces. The design characteristics of modern horizontal steam generators such as PGV-1000 of various modifications provide high technical and economic performance of NPP units with WWER-1000 and high maintainability, which allows to extend the service life of domestic NPPs.
{"title":"Mathematical model of the horizontal steam generator PGV-1000","authors":"O. Yefimov, L. Tiutiunyk, T. Harkusha, Tetyana Yesipenko, A. Motovilnik","doi":"10.20998/2078-774x.2022.01.06","DOIUrl":"https://doi.org/10.20998/2078-774x.2022.01.06","url":null,"abstract":"The materials of the article consider the design characteristics of horizontal steam generators PGV-1000 for WWER NPPs. The NPP steam generator, in particular the PGV-1000 steam generator, is a specific heat exchange unit. This unit, together with a nuclear reactor and a steam turbine, is one of the main equipment of multi-circuit (double-circuit) steam turbine NPPs. The steam generator produces working steam using heat dissipated from the reactor core by the cooling medium and sent to the heat exchange surface of the steam generator. NPP steam generators, connecting the contours of the coolant and the working substance, equally belong to each of them. The heat-absorbing medium in the steam generator is the working substance (water, steam). PGV-1000 type NPP steam generators with pressurized water reactors produce dry saturated steam. The requirement to maintain high purity of the coolant is due to the heat transfer surfaces of such steam generators made of austenitic stainless steel with electropolished surfaces. The design characteristics of modern horizontal steam generators such as PGV-1000 of various modifications provide high technical and economic performance of NPP units with WWER-1000 and high maintainability, which allows to extend the service life of domestic NPPs.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129326960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.20998/2078-774x.2021.03.07
T. Rymar
Heating the air in the boiler air heater with the heat of fuel combustion products performs the functions of increasing the fuel combustion temperature, increasing the temperature level of gases in convective heating surfaces, improving ignition and fuel combustion conditions, increasing boiler efficiency by utilizing waste gas heat, improving fuel quality due to its preliminary supply, etc. However, the peculiarities of the process of heating the air in the air heaters do not allow to achieve a decrease in the temperature of the exhaust gases. This is due to the unfavorable ratio of heat capacities of flue gases and air, as well as corrosion and contamination of the heating surfaces of air heaters. The research of heat transfer processes and hydraulic resistance of unified package of cold layer of RAH is depicted at this work. The graphic dependence of the change in the coefficient of hydraulic resistance and Nu number for unified packages with single line of sheets and simplified profile with corrosion resistance enamel from the Reynolds number for different values of the length of the replaced areas was constructed. The unified packing of the simplified profile has increased by 1.17 times equivalent diameter and is characterized by good operational parameters and takes into account the risk of contamination of heating surfaces due to the enamel coating.
{"title":"Heat Exchange and Hydrodynamic Characteristics of Unified Package of Cold Layer of RAH","authors":"T. Rymar","doi":"10.20998/2078-774x.2021.03.07","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.03.07","url":null,"abstract":"Heating the air in the boiler air heater with the heat of fuel combustion products performs the functions of increasing the fuel combustion temperature, increasing the temperature level of gases in convective heating surfaces, improving ignition and fuel combustion conditions, increasing boiler efficiency by utilizing waste gas heat, improving fuel quality due to its preliminary supply, etc. However, the peculiarities of the process of heating the air in the air heaters do not allow to achieve a decrease in the temperature of the exhaust gases. This is due to the unfavorable ratio of heat capacities of flue gases and air, as well as corrosion and contamination of the heating surfaces of air heaters. The research of heat transfer processes and hydraulic resistance of unified package of cold layer of RAH is depicted at this work. The graphic dependence of the change in the coefficient of hydraulic resistance and Nu number for unified packages with single line of sheets and simplified profile with corrosion resistance enamel from the Reynolds number for different values of the length of the replaced areas was constructed. The unified packing of the simplified profile has increased by 1.17 times equivalent diameter and is characterized by good operational parameters and takes into account the risk of contamination of heating surfaces due to the enamel coating.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"100 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123019452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.20998/2078-774x.2021.04.06
Alexander Pereselkov, O. Kruglyakova
When the casting roller is cooled or heated in the preconditioning chamber the water is supplied to its surface by flat-jet nozzles. The visual inspection of the model of the casting roller showed that a considerable part of it can be covered with the water film spreading from sprinkling zones. It was established that the heat conductivity in the roller body is considered to be a crucial thermal preparation factor in the conjugate heat-exchange problem for the roller of a large diameter at Bio criterion values exceeding 20. Hence, it is sufficient to provide an essential level of the heat transfer that corresponds to the heat transfer coefficient of 2000 W/(m2∙K) to provide appropriate operating conditions for the thermal preparation of the roller. The conditions are also met in sprinkling zones. Due to this fact this scientific paper studies the heat exchange conditions under the water film that spreads between the adjacent sprinkling zones. A range of changes in the flow rate of the spreading water film was determined experimentally. The conditions of heat exchange between the surface of alpha-calorimeter and the water film were analyzed depending on its flow rate and the heat meter surface temperature. A generalized correlation equation was derived. It was established that the heat exchange intensity in sprinkling zones and under the spreading water film meets technological roller treatment conditions in the preconditioning chambers. The obtained research data can be used for the rational arrangement of the collectors and flat-jet nozzles in casting roller preconditioning chambers to reduce the cold and hot water consumption and cut down operating costs.
{"title":"Experimental Studies of the Heat Exchange Between the Water Film and the Casting Roller in the Thermal Preconditioning Chamber","authors":"Alexander Pereselkov, O. Kruglyakova","doi":"10.20998/2078-774x.2021.04.06","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.04.06","url":null,"abstract":"When the casting roller is cooled or heated in the preconditioning chamber the water is supplied to its surface by flat-jet nozzles. The visual inspection of the model of the casting roller showed that a considerable part of it can be covered with the water film spreading from sprinkling zones. It was established that the heat conductivity in the roller body is considered to be a crucial thermal preparation factor in the conjugate heat-exchange problem for the roller of a large diameter at Bio criterion values exceeding 20. Hence, it is sufficient to provide an essential level of the heat transfer that corresponds to the heat transfer coefficient of 2000 W/(m2∙K) to provide appropriate operating conditions for the thermal preparation of the roller. The conditions are also met in sprinkling zones. Due to this fact this scientific paper studies the heat exchange conditions under the water film that spreads between the adjacent sprinkling zones. A range of changes in the flow rate of the spreading water film was determined experimentally. The conditions of heat exchange between the surface of alpha-calorimeter and the water film were analyzed depending on its flow rate and the heat meter surface temperature. A generalized correlation equation was derived. It was established that the heat exchange intensity in sprinkling zones and under the spreading water film meets technological roller treatment conditions in the preconditioning chambers. The obtained research data can be used for the rational arrangement of the collectors and flat-jet nozzles in casting roller preconditioning chambers to reduce the cold and hot water consumption and cut down operating costs.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"192 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124219781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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