Pub Date : 2021-12-30DOI: 10.20998/2078-774x.2021.02.07
Olena Harashchenko, V. Dmytryk, T. Syrenko
The issues of research of structural changes as applied to welded joints of steam pipelines are considered. The results of metallographic analysis of structural changes in the metal of steam pipelines are presented. There was carried out the analysis for a number of samples cut from different sections of the steam line at different operating time under creep and low-cycle fatigue conditions. In the analyzing process of the images of micro sections, the relative content of the structural-phase components and their distribution in the metal were revealed. A comparative analysis of the statistical characteristics of the distribution and the relative content of structural components for different sections of the metal of welded joints with different operating time is carried out. A scientifically substantiated description of structural changes in the metal of various sections of samples of welded joints is given, as well as the possibility of extending the service life of elements of steam pipelines with a degraded structure and the presence of damageability. The most promising, in the opinion of the authors, directions of further research of samples to provide conditions for extending the service life of steam pipelines have been formulated and substantiated.
{"title":"Study of the Structural-Phase State of Pipeline Welded Metal","authors":"Olena Harashchenko, V. Dmytryk, T. Syrenko","doi":"10.20998/2078-774x.2021.02.07","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.02.07","url":null,"abstract":"The issues of research of structural changes as applied to welded joints of steam pipelines are considered. The results of metallographic analysis of structural changes in the metal of steam pipelines are presented. There was carried out the analysis for a number of samples cut from different sections of the steam line at different operating time under creep and low-cycle fatigue conditions. In the analyzing process of the images of micro sections, the relative content of the structural-phase components and their distribution in the metal were revealed. A comparative analysis of the statistical characteristics of the distribution and the relative content of structural components for different sections of the metal of welded joints with different operating time is carried out. A scientifically substantiated description of structural changes in the metal of various sections of samples of welded joints is given, as well as the possibility of extending the service life of elements of steam pipelines with a degraded structure and the presence of damageability. The most promising, in the opinion of the authors, directions of further research of samples to provide conditions for extending the service life of steam pipelines have been formulated and substantiated.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"78 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":"114432999","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.2021.03.01
A. Lapuzin, V. Subotovich, Y. Yudin, S. Naumenko, Ivan Malymon
The obtained research data are given for the nozzle cascade used by a small-size gas turbine of an average fanning in combination with the radial diffuser. Aerodynamic characteristics of the nozzle blade cascade were determined in a wide range of a change in the Reynolds number varying from 4∙105 to 106 and the reduced velocity varying in the range of 0.4 to 1.13. The flow rate coefficient of the nozzle cascade was derived for all modes using the integral methods and the drainages behind the cascade. The kinetic energy loss coefficient and the flow angles were calculated using the measurement data of flow parameters in three control modes that were obtained due to the use of orientable pneumometric probes. When the expansion degree of the convergent –divergent annular duct behind the cascade is equal to 1.43 the flow in the narrow section of this duct is “enlocked” in the mode when the reduced velocity behind the cascade is equal to 1.127. At such velocity the Reynolds number 106 is self-similar for the flow rate coefficient. At lower values of Reynolds number, the decrease of it is accompanied by an intensive decrease in the flow rate coefficient for all the values of the reduced velocity. For the Reynolds number lower than 7∙105 an increase in the velocity results in a decreased flow rate coefficient. When this number exceeds 8∙105 an increase in the velocity results in an increase of the flow coefficient up to the moment when the flow is “enlocked” in the nozzle cascade.
{"title":"Flow Characteristics of the Nozzle Blade Cascade in the Mode of the Joint Operation with the Radial Diffuser","authors":"A. Lapuzin, V. Subotovich, Y. Yudin, S. Naumenko, Ivan Malymon","doi":"10.20998/2078-774x.2021.03.01","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.03.01","url":null,"abstract":"The obtained research data are given for the nozzle cascade used by a small-size gas turbine of an average fanning in combination with the radial diffuser. Aerodynamic characteristics of the nozzle blade cascade were determined in a wide range of a change in the Reynolds number varying from 4∙105 to 106 and the reduced velocity varying in the range of 0.4 to 1.13. The flow rate coefficient of the nozzle cascade was derived for all modes using the integral methods and the drainages behind the cascade. The kinetic energy loss coefficient and the flow angles were calculated using the measurement data of flow parameters in three control modes that were obtained due to the use of orientable pneumometric probes. When the expansion degree of the convergent –divergent annular duct behind the cascade is equal to 1.43 the flow in the narrow section of this duct is “enlocked” in the mode when the reduced velocity behind the cascade is equal to 1.127. At such velocity the Reynolds number 106 is self-similar for the flow rate coefficient. At lower values of Reynolds number, the decrease of it is accompanied by an intensive decrease in the flow rate coefficient for all the values of the reduced velocity. For the Reynolds number lower than 7∙105 an increase in the velocity results in a decreased flow rate coefficient. When this number exceeds 8∙105 an increase in the velocity results in an increase of the flow coefficient up to the moment when the flow is “enlocked” in the nozzle cascade.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"7 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":"116834024","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.2021.03.04
V. Kravchenko, O. Lymarenko, Z. Xiaolong, Kiril Khromiy, Yehor Buchka
Today, the world oversees an explosive development of the nuclear power stations (NPS) of a low power. Most projects deal with pressurized water reactors and as a matter of fact with steam generators (SG). Ukraine has a well-developed engineering industry backbone that can be used for the production of the equipment required for the nuclear power plants of a low power. This scientific paper delves into the computations of the strength of elements used for the monotube steam generator with cylindrical coils that is the most presentable of all the projects in question in IAEA materials. Appropriate methods were developed to perform structural computations and steam generator strength computations. The mathematical model was developed that allows us to perform strength computations of the SG elements making use of the analytical method with reference to the Regulations and do simulations using the ANSYS software code. The specified elements include the body elements, in particular the cylindrical part, the flange, the bottom and the cover, including the heat carrier branch pipe and heat exchange tubes. The comparison of the data obtained by both methods showed their similarity and accordingly, the accuracy of the data that are indicative of the need for an increase in the wall thickness of the cylindrical part of the external branch pipe intended for the heat carrier. The body bottom strain for calculated dimensions exceeds the permissible value by 1.56 %. Since this value is 5 % lower than permissible values it is deemed that the strength condition is passed through. The simulation proved that the strength conditions are met for heat exchange tubes, for the body, the body cover, the body flange, the conical part of the external branch pipe intended for the heat carrier. Based on the analysis done, we would like to recommend performing strength computations using the normative method with the subsequent check out by the simulation using the computer code.
{"title":"Steam Generator Strength Computation for Nuclear Electric Power Plants of a Low Power","authors":"V. Kravchenko, O. Lymarenko, Z. Xiaolong, Kiril Khromiy, Yehor Buchka","doi":"10.20998/2078-774x.2021.03.04","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.03.04","url":null,"abstract":"Today, the world oversees an explosive development of the nuclear power stations (NPS) of a low power. Most projects deal with pressurized water reactors and as a matter of fact with steam generators (SG). Ukraine has a well-developed engineering industry backbone that can be used for the production of the equipment required for the nuclear power plants of a low power. This scientific paper delves into the computations of the strength of elements used for the monotube steam generator with cylindrical coils that is the most presentable of all the projects in question in IAEA materials. Appropriate methods were developed to perform structural computations and steam generator strength computations. The mathematical model was developed that allows us to perform strength computations of the SG elements making use of the analytical method with reference to the Regulations and do simulations using the ANSYS software code. The specified elements include the body elements, in particular the cylindrical part, the flange, the bottom and the cover, including the heat carrier branch pipe and heat exchange tubes. The comparison of the data obtained by both methods showed their similarity and accordingly, the accuracy of the data that are indicative of the need for an increase in the wall thickness of the cylindrical part of the external branch pipe intended for the heat carrier. The body bottom strain for calculated dimensions exceeds the permissible value by 1.56 %. Since this value is 5 % lower than permissible values it is deemed that the strength condition is passed through. The simulation proved that the strength conditions are met for heat exchange tubes, for the body, the body cover, the body flange, the conical part of the external branch pipe intended for the heat carrier. Based on the analysis done, we would like to recommend performing strength computations using the normative method with the subsequent check out by the simulation using the computer code.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"25 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":"117017125","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.2021.02.04
A. Tarasov, Oksana Lytvynenko, Irina Myhaylova
Modern CFD methods for calculating combustion processes make it possible to take into account changes in temperatures, heat loads, rates of coolants, as well as further changes in fuel quality. To develop the skills of CFD design and understanding of combustion processes among future specialists in thermophysical specialties, work was carried out to simulate the burner device of a waste heat boiler. For the study, the design of the gas burner of the waste heat boiler RB-70-4.0-440, which operates as a part of the power unit at the LLC “Rubezhansky Cardboard and Container Plant” in the city of Rubezhnoe, was selected. When constructing a geometric model, the hydraulic resistance to the flow of the supply and distribution manifolds was taken into account. To simplify the calculations, the problem was carried out in a two-dimensional, axisymmetric formulation. Analyzing the computational combustion models, the Non-Premixe Combustion model was chosen, which made it possible to take into account the entry of fuel and oxidizer into the reaction zone by two different flows, as well as turbulent diffusion flame propagation. Six variants of models were investigated: the first three variants with a flame tube with a solid disc with diameters of 32, 48, 56 mm, the next three variants, had a burner with a discontinuous disk 32 mm in diameter at a distance of 6, 16, 32 mm from the flame tube. As a result of the research, the optimal shape of the burner was chosen, which corresponds to model 4, and provides a high-quality combustion process, as evidenced by the high temperature of the torch and the lowest temperature at the disk. The conducted research gives future masters the skills of modeling combustion processes in power equipment.
{"title":"CFD Design of Waste Heat Boiler Burner in the Education System of Masters Heat Engineering Specialties","authors":"A. Tarasov, Oksana Lytvynenko, Irina Myhaylova","doi":"10.20998/2078-774x.2021.02.04","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.02.04","url":null,"abstract":"Modern CFD methods for calculating combustion processes make it possible to take into account changes in temperatures, heat loads, rates of coolants, as well as further changes in fuel quality. To develop the skills of CFD design and understanding of combustion processes among future specialists in thermophysical specialties, work was carried out to simulate the burner device of a waste heat boiler. For the study, the design of the gas burner of the waste heat boiler RB-70-4.0-440, which operates as a part of the power unit at the LLC “Rubezhansky Cardboard and Container Plant” in the city of Rubezhnoe, was selected. When constructing a geometric model, the hydraulic resistance to the flow of the supply and distribution manifolds was taken into account. To simplify the calculations, the problem was carried out in a two-dimensional, axisymmetric formulation. Analyzing the computational combustion models, the Non-Premixe Combustion model was chosen, which made it possible to take into account the entry of fuel and oxidizer into the reaction zone by two different flows, as well as turbulent diffusion flame propagation. Six variants of models were investigated: the first three variants with a flame tube with a solid disc with diameters of 32, 48, 56 mm, the next three variants, had a burner with a discontinuous disk 32 mm in diameter at a distance of 6, 16, 32 mm from the flame tube. As a result of the research, the optimal shape of the burner was chosen, which corresponds to model 4, and provides a high-quality combustion process, as evidenced by the high temperature of the torch and the lowest temperature at the disk. The conducted research gives future masters the skills of modeling combustion processes in power equipment.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"5 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":"128542299","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.2021.04.04
Oksana Lytvynenko, Irina Myhaylova
Due to the importance of the problems of implementing energy-saving technologies in modern conditions, one of the promising areas is the use of gas turbines for combined heat and power generation. One of the areas of effective development and technical re-equipment is the widespread use of highly economical combined steam and gas plants and gas turbines. The operation of the gas turbine unit “Aquarius” SE NPCG “Zorya-Mashproekt” with the injection of steam into the combustion chamber, which operates on the advanced cycle A-STIG and has in its circuit equipment for water regeneration, condensed from a vapor-gas mixture is considered. For condensation of steam from the vapor-gas mixture, a contact condenser-gas cooler is used, which is a mixing heat exchanger of complex design. The efficiency of heat transfer is determined by the design of the nozzle, namely, the developed heat transfer surface, small hydraulic supports, high heat transfer coefficients. An important aspect is the overall dimensions, which must be within certain limits. In the work it is offered to execute a design of the condenser in the form of a packed column. Different types of nozzles are considered to choose the best option. As a result of thermal design calculation of the contact capacitor, it is proposed to use Rashiga rings (15152) as a nozzle, which provide the lowest height of the nozzle at the required diameter of the device.
{"title":"Selection of the Design of a Contact Condenser of a Gas-Steam Plant with Steam Injection into the Combustion Chamber","authors":"Oksana Lytvynenko, Irina Myhaylova","doi":"10.20998/2078-774x.2021.04.04","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.04.04","url":null,"abstract":"Due to the importance of the problems of implementing energy-saving technologies in modern conditions, one of the promising areas is the use of gas turbines for combined heat and power generation. One of the areas of effective development and technical re-equipment is the widespread use of highly economical combined steam and gas plants and gas turbines. The operation of the gas turbine unit “Aquarius” SE NPCG “Zorya-Mashproekt” with the injection of steam into the combustion chamber, which operates on the advanced cycle A-STIG and has in its circuit equipment for water regeneration, condensed from a vapor-gas mixture is considered. For condensation of steam from the vapor-gas mixture, a contact condenser-gas cooler is used, which is a mixing heat exchanger of complex design. The efficiency of heat transfer is determined by the design of the nozzle, namely, the developed heat transfer surface, small hydraulic supports, high heat transfer coefficients. An important aspect is the overall dimensions, which must be within certain limits. In the work it is offered to execute a design of the condenser in the form of a packed column. Different types of nozzles are considered to choose the best option. As a result of thermal design calculation of the contact capacitor, it is proposed to use Rashiga rings (15152) as a nozzle, which provide the lowest height of the nozzle at the required diameter of the device.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"56 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":"124517537","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.2021.03.05
V. Konshin, Mikola Zaiats
Extending the life of nuclear power plants in Ukraine during in the super-project period, as in most countries operating nuclear power units, is an accepted strategy and is being implemented practically. In this regard, there is a need for verification calculation of the main elements The calculated analysis of the stress-strain state of the heat exchanger is carried out using the finite element method of power equipment that determine the resource characteristics. The technical condition of the emergency cooling heat exchanger for the power unit no. 3 of the SUNPP has been evaluated. The analysis of design, technical and operational documentation in the amount of preliminary evaluation of technical condition was performed. Potential mechanisms of wear of heat exchanger elements were determined. The technique of carrying out verification calculations for static, cyclic and seismic stability was described. The emergency cooling heat exchanger calculation model is made in the APM Structure 3D calculation code. The tense-deformed state of the heat exchanger is calculated using the finite-element method of resampling the design region. The results of the verification calculation of the emergency cooling heat exchanger in the calculated states corresponding to normal operating conditions, hydrotests and under seismic impacts in conditions of the maximum design earthquake were presented. The correspondence of the actual stresses in the calculation zones of the heat exchanger to the permissible values, specified in the current regulatory documentation was established. The amount of damageability to the heat exchanger elements was determined for the permissible number of load cycles. The cyclical strength of the elements of the emergency cooling heat exchanger, taking into account the period of application equal to 60 years inclusive, is ensured in accordance with the requirements.
{"title":"Assessment of the Technical Condition of the Emergency Heat Exchanger for the Reactor Plant of the B-320 Type in Order to Extend Its Service Life","authors":"V. Konshin, Mikola Zaiats","doi":"10.20998/2078-774x.2021.03.05","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.03.05","url":null,"abstract":"Extending the life of nuclear power plants in Ukraine during in the super-project period, as in most countries operating nuclear power units, is an accepted strategy and is being implemented practically. In this regard, there is a need for verification calculation of the main elements The calculated analysis of the stress-strain state of the heat exchanger is carried out using the finite element method of power equipment that determine the resource characteristics. The technical condition of the emergency cooling heat exchanger for the power unit no. 3 of the SUNPP has been evaluated. The analysis of design, technical and operational documentation in the amount of preliminary evaluation of technical condition was performed. Potential mechanisms of wear of heat exchanger elements were determined. The technique of carrying out verification calculations for static, cyclic and seismic stability was described. The emergency cooling heat exchanger calculation model is made in the APM Structure 3D calculation code. The tense-deformed state of the heat exchanger is calculated using the finite-element method of resampling the design region. The results of the verification calculation of the emergency cooling heat exchanger in the calculated states corresponding to normal operating conditions, hydrotests and under seismic impacts in conditions of the maximum design earthquake were presented. The correspondence of the actual stresses in the calculation zones of the heat exchanger to the permissible values, specified in the current regulatory documentation was established. The amount of damageability to the heat exchanger elements was determined for the permissible number of load cycles. The cyclical strength of the elements of the emergency cooling heat exchanger, taking into account the period of application equal to 60 years inclusive, is ensured in accordance with the requirements.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"54 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":"123629713","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.2021.02.02
K. Horban, O. Siryi, Myhailo Abdulin
The Power engineering is an inseparable part of the contemporary world that has a negative influence on the ecology; in particular it provokes the pollution of atmosphere with such harmful emissions as nitrogen and carbon oxides. Different methods are used to reduce the emission of harmful substances. The efficiency of such methods is increased when these are used in combination and not separately. The recirculation of flue gases and the use of contemporary technologies for municipal boilers, in particular jet-niche technology (JNT) enabled the reduction of NOx and СО emissions to the levels that meet the requirements of European standards simultaneously improving the efficiency of the operation of the fire-engineering facility. The principle of operation of the JNT is based on the formation of the compact stable self-controlled vortex structure and on the interaction system of flammable and oncoming oxidizer flows. This technology enables the operation at minimum recirculation values and it means that all boiler parameters can be retained, in particular starting characteristic, combustion stability and unavailability of vibration modes including a high level of fuel burnout. The obtained research data showed that NОх values were in the range of 80 to 140 mg/m3 when the oxygen content at the furnace inlet was 20% and lower for different boiler systems (DKBR-10, KVGM-6.5, PTVM-50) at CO values close to 50 mg/m2. Hence, the use of the burners of a JNT type enables the reduction of NОхemissions and retains the combustion process efficiency.
{"title":"Jet-Niche Technology Influence Potential on the Economic and Operating Parameters of the Fire-Engineering Equipment","authors":"K. Horban, O. Siryi, Myhailo Abdulin","doi":"10.20998/2078-774x.2021.02.02","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.02.02","url":null,"abstract":"The Power engineering is an inseparable part of the contemporary world that has a negative influence on the ecology; in particular it provokes the pollution of atmosphere with such harmful emissions as nitrogen and carbon oxides. Different methods are used to reduce the emission of harmful substances. The efficiency of such methods is increased when these are used in combination and not separately. The recirculation of flue gases and the use of contemporary technologies for municipal boilers, in particular jet-niche technology (JNT) enabled the reduction of NOx and СО emissions to the levels that meet the requirements of European standards simultaneously improving the efficiency of the operation of the fire-engineering facility. The principle of operation of the JNT is based on the formation of the compact stable self-controlled vortex structure and on the interaction system of flammable and oncoming oxidizer flows. This technology enables the operation at minimum recirculation values and it means that all boiler parameters can be retained, in particular starting characteristic, combustion stability and unavailability of vibration modes including a high level of fuel burnout. The obtained research data showed that NОх values were in the range of 80 to 140 mg/m3 when the oxygen content at the furnace inlet was 20% and lower for different boiler systems (DKBR-10, KVGM-6.5, PTVM-50) at CO values close to 50 mg/m2. Hence, the use of the burners of a JNT type enables the reduction of NОхemissions and retains the combustion process efficiency.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"41 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":"123880783","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.2021.03.02
V. Tuz, N. Lebed, M. Lytvynenko
Perfecting the existing technologies and developing new ones require to rethink the processes in order to obtain qualitatively new results. Widespread use of cryogenic engineering in the chemical industry and medicine calls for a thorough analysis of both the efficiency of thermodynamic cycles and the hardware design of appropriate equipment. The power necessary to obtain low working medium temperatures is distributed between the cooling of the object and the losses in the various elements of the cryogenic setup. One of the best ways to increase the efficiency of the setup is to use the cold energy recovery. This is done by using various designs of recuperative heat exchangers, such as twisted heat exchangers. Existing methods of calculating the parameters of power equipment are based on empirical dependencies, which require some justification and clarification in order to be used for calculating cryogenic equipment parameters. The article describes the experimental setup, presents the research methods applied and analyses the results of the study on convective heat transfer in external flow past the tubular surface of the twisted heat exchanger. The obtained results for the laminar gas flow mode at Re < 2300 allowed determining the length of the initial heat section depending on the regime parameters of the contact phases and the geometric specifications of the twisted heat exchanger. The obtained dependence will make it possible to refine the method of calculating the parameters of the twisted heat exchanger in the annular channel.
{"title":"Particularity of Heat Exchange of Twisted Heat Exchangers in External Flow","authors":"V. Tuz, N. Lebed, M. Lytvynenko","doi":"10.20998/2078-774x.2021.03.02","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.03.02","url":null,"abstract":"Perfecting the existing technologies and developing new ones require to rethink the processes in order to obtain qualitatively new results. Widespread use of cryogenic engineering in the chemical industry and medicine calls for a thorough analysis of both the efficiency of thermodynamic cycles and the hardware design of appropriate equipment. The power necessary to obtain low working medium temperatures is distributed between the cooling of the object and the losses in the various elements of the cryogenic setup. One of the best ways to increase the efficiency of the setup is to use the cold energy recovery. This is done by using various designs of recuperative heat exchangers, such as twisted heat exchangers. Existing methods of calculating the parameters of power equipment are based on empirical dependencies, which require some justification and clarification in order to be used for calculating cryogenic equipment parameters. The article describes the experimental setup, presents the research methods applied and analyses the results of the study on convective heat transfer in external flow past the tubular surface of the twisted heat exchanger. The obtained results for the laminar gas flow mode at Re < 2300 allowed determining the length of the initial heat section depending on the regime parameters of the contact phases and the geometric specifications of the twisted heat exchanger. The obtained dependence will make it possible to refine the method of calculating the parameters of the twisted heat exchanger in the annular channel.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"44 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":"116039311","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.2021.02.01
M. Vorobiov, Volodymyr Zgurskyi, A. Prokofiev, Ruslan Gubatyk
The high efficient design of the radiation-convective recuperator with secondary emitters have been proposed, in which due to the rational arrangement of heating surfaces, as well as due to the installation of secondary emitters in flues, an increase in heat perception is transmitted to the secondary heat carrier – preheating air. High efficiency of air preheating is provided by two-stage heating: 1st stage of heating – the internal air ring channel with bilateral heating which is washed by combustion products from the parties of the central cylindrical and peripheral ring channels of combustion products; 2nd stage of heating – the external air ring channel in which unilateral heating by products of combustion from the peripheral ring channel of products of combustion is organized. Inner and outer annular air ducts (tanks), interconnected by bypass pipes. To increase the efficiency of heat transfer in the considered recuperator in the central channel of combustion products is placed emitter, which consisting of intersecting radial plates, and in the annular channel of combustion products are placed auxiliary emitters, which made in the form of flat radial edges. These emitters provide an increasing in total heat flux to the walls of the channels of the recuperator. On the basis of the conducted theoretical researches, engineering calculations and CFD – modelling the characteristics of operation of the recuperator for its installation on the furnace of secondary smelting of aluminium are defined. The main advantages of the new design of recuperator are high thermo-hydraulic efficiency, compactness and low metal consumption, ease of installation on the furnace and no need for placement in separate chimneys. It is established that the recuperator provides air heating ta,ex ~ 400 °C at an acceptable aerodynamic drag (pressure drop) on the air track (∆pa ~ 1000 Pa). Appropriate design documentation has been developed for the manufacture of the recuperator, which is installed on a pilot furnace of secondary aluminium smelting by California Die Casting (USA).
{"title":"Development of Highly Efficient Radiation-Convective Recuperator for Furnace of Secondary Aluminum Melting","authors":"M. Vorobiov, Volodymyr Zgurskyi, A. Prokofiev, Ruslan Gubatyk","doi":"10.20998/2078-774x.2021.02.01","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.02.01","url":null,"abstract":"The high efficient design of the radiation-convective recuperator with secondary emitters have been proposed, in which due to the rational arrangement of heating surfaces, as well as due to the installation of secondary emitters in flues, an increase in heat perception is transmitted to the secondary heat carrier – preheating air. High efficiency of air preheating is provided by two-stage heating: 1st stage of heating – the internal air ring channel with bilateral heating which is washed by combustion products from the parties of the central cylindrical and peripheral ring channels of combustion products; 2nd stage of heating – the external air ring channel in which unilateral heating by products of combustion from the peripheral ring channel of products of combustion is organized. Inner and outer annular air ducts (tanks), interconnected by bypass pipes. To increase the efficiency of heat transfer in the considered recuperator in the central channel of combustion products is placed emitter, which consisting of intersecting radial plates, and in the annular channel of combustion products are placed auxiliary emitters, which made in the form of flat radial edges. These emitters provide an increasing in total heat flux to the walls of the channels of the recuperator. On the basis of the conducted theoretical researches, engineering calculations and CFD – modelling the characteristics of operation of the recuperator for its installation on the furnace of secondary smelting of aluminium are defined. The main advantages of the new design of recuperator are high thermo-hydraulic efficiency, compactness and low metal consumption, ease of installation on the furnace and no need for placement in separate chimneys. It is established that the recuperator provides air heating ta,ex ~ 400 °C at an acceptable aerodynamic drag (pressure drop) on the air track (∆pa ~ 1000 Pa). Appropriate design documentation has been developed for the manufacture of the recuperator, which is installed on a pilot furnace of secondary aluminium smelting by California Die Casting (USA).","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"11 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":"128664600","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.2021.04.09
V. Dmitrik, I. Kasyanenko, Alexandr Krakhmalyov
The authors studied the interrelation between the type of structure and the damage rate of the welded joints of steam pipelines made of the heat-resistant pearlitic steels that were operated for a long time, i.e. more than 270 thousand hours in the conditions of creepage and low-cycle fatigue. The purpose of this research was to establish the interrelation between the structural-&-phase condition of the metal used for welded joints of the elements of steam systems and their damageability rate for the service life of welded joints exceeding 270 thousand hours. During the studies, the methods of optical and electron microscopy were used according to the requirements of the guideline documentation and also the methods that are used for the determination of mechanical properties. The level of their reliability has been substantiated and the residual life has been determined. To impart functional performances to welded joints we used well-known methods that were appropriately emended according to the structural changes of above joints. Such changes condition the conversion of the original structure of welded joints into the ferrite-carbide mixture. The availability of the conversion process of the initial structure on the thermal action zone sections (TAZ) of welded joints has essential distinctions due to a different disposition of metal to its own damageability. On the whole, the welded joints are damaged more intensively in comparison to the basic metal of steam pipelines. The analysis of the structural state of welded joints in the steam pipelines of thermal power plants as for the extension of their service life results in a considerable economic effect. Understanding the fact that the metal deterioration in welded joints adheres mainly to the fragile mechanism we managed to establish the level of their damageability that demands the renewal of damaged welded joints. We believe that the damageability level of welded joints that tots up to 0.25 or 0.35 of the volume of their TAZ section should be considered as critical for the service life exceeding 270 thousand hours. The damaged welded joints should be renewed throughout the time period of 15 to 20 thousand hours as soon as the specified damageability level is attained.
{"title":"Structural-&-Phase Condition and the Damageability of the Welded Joints of Steam Pipelines at Thermal Power Plants","authors":"V. Dmitrik, I. Kasyanenko, Alexandr Krakhmalyov","doi":"10.20998/2078-774x.2021.04.09","DOIUrl":"https://doi.org/10.20998/2078-774x.2021.04.09","url":null,"abstract":"The authors studied the interrelation between the type of structure and the damage rate of the welded joints of steam pipelines made of the heat-resistant pearlitic steels that were operated for a long time, i.e. more than 270 thousand hours in the conditions of creepage and low-cycle fatigue. The purpose of this research was to establish the interrelation between the structural-&-phase condition of the metal used for welded joints of the elements of steam systems and their damageability rate for the service life of welded joints exceeding 270 thousand hours. During the studies, the methods of optical and electron microscopy were used according to the requirements of the guideline documentation and also the methods that are used for the determination of mechanical properties. The level of their reliability has been substantiated and the residual life has been determined. To impart functional performances to welded joints we used well-known methods that were appropriately emended according to the structural changes of above joints. Such changes condition the conversion of the original structure of welded joints into the ferrite-carbide mixture. The availability of the conversion process of the initial structure on the thermal action zone sections (TAZ) of welded joints has essential distinctions due to a different disposition of metal to its own damageability. On the whole, the welded joints are damaged more intensively in comparison to the basic metal of steam pipelines. The analysis of the structural state of welded joints in the steam pipelines of thermal power plants as for the extension of their service life results in a considerable economic effect. Understanding the fact that the metal deterioration in welded joints adheres mainly to the fragile mechanism we managed to establish the level of their damageability that demands the renewal of damaged welded joints. We believe that the damageability level of welded joints that tots up to 0.25 or 0.35 of the volume of their TAZ section should be considered as critical for the service life exceeding 270 thousand hours. The damaged welded joints should be renewed throughout the time period of 15 to 20 thousand hours as soon as the specified damageability level is attained.","PeriodicalId":416126,"journal":{"name":"NTU \"KhPI\" Bulletin: Power and heat engineering processes and equipment","volume":"1 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":"130874513","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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