Pub Date : 2024-05-04DOI: 10.1134/s0040601524040013
M. Gong, C. Han, J. Sun, Y. Zhao, S. Li, W. Xu
Abstract
Heat load prediction is crucial to the heat regulation of district heating systems (DHS). In heat load forecasting tasks, deep learning can frequently achieve more accurate model building. A deep learning algorithm, the temporal convolutional network (TCN), has been used for DHS heat load prediction. However, there are many hyperparameters for TCN. Manually tuning the TCN parameters cannot make the model have good performance. This study presents a hybrid method based on sand cat swarm optimization (SCSO) and TCN. The SCSO is used to optimize the hyperparameters (number of filters, filter size, dropout rate, and batch size) of TCN. To verify the effectiveness of SCSO-TCN, another two hybrid models, particle swarm optimization with TCN and the sparrow search algorithm with TCN, are established for comparison. The historical heat load data of three heat exchange stations in Tianjin is utilized for the testing experiments. The findings demonstrate that SCSO-TCN has higher predictive accuracy and better generalization ability than the PSO-TCN and SSA-TCN models.
{"title":"Heat Load Prediction of District Heating Systems Based on SCSO-TCN","authors":"M. Gong, C. Han, J. Sun, Y. Zhao, S. Li, W. Xu","doi":"10.1134/s0040601524040013","DOIUrl":"https://doi.org/10.1134/s0040601524040013","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Heat load prediction is crucial to the heat regulation of district heating systems (DHS). In heat load forecasting tasks, deep learning can frequently achieve more accurate model building. A deep learning algorithm, the temporal convolutional network (TCN), has been used for DHS heat load prediction. However, there are many hyperparameters for TCN. Manually tuning the TCN parameters cannot make the model have good performance. This study presents a hybrid method based on sand cat swarm optimization (SCSO) and TCN. The SCSO is used to optimize the hyperparameters (number of filters, filter size, dropout rate, and batch size) of TCN. To verify the effectiveness of SCSO-TCN, another two hybrid models, particle swarm optimization with TCN and the sparrow search algorithm with TCN, are established for comparison. The historical heat load data of three heat exchange stations in Tianjin is utilized for the testing experiments. The findings demonstrate that SCSO-TCN has higher predictive accuracy and better generalization ability than the PSO-TCN and SSA-TCN models.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884561","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 : 2024-05-04DOI: 10.1134/s0040601524040037
A. V. Kiryukhin, O. O. Mil’man, L. N. Serezkin, E. A. Loskareva, P. Yu. Dneprovskaya
Abstract
The results of experimental studies on the creation of highly efficient designs of vibration-isolating compensators for pipelines with liquid are considered. It is noted that the only way to evaluate the effectiveness of various compensators in reducing vibration at different frequencies currently is to compare their transient vibration stiffness or transient mechanical impedance, which were measured on special stands at a given frequency. The stiffness of the compensator increases significantly with increasing frequency vibrations. Hazardous frequencies may vary between piping systems. For this reason, it is impossible to set an integral criterion for the effectiveness of a vibration-isolating compensator, similar to static stiffness. The results of measurements carried out on a special stand on the transitional vibration stiffness of a new design compensator with thin-layer rubber-metal elements (TRME) are presented. The rigidity decreased by 10 or 100 times or more in the frequency range from 50 to 800 Hz relative to the rigidity of a serial compensator based on rubber cord casing (RCC), including in the presence of water inside it. It has been experimentally shown that the vibration-isolating ability of the same compensator as part of a pipeline system, determined by the value of the dynamic force transmitted by the compensator to the pipeline from the pump, significantly depends on the presence of water in them and its flow, which is not taken into account in known methods. The results of testing compensators with RCC and TRME with a bore diameter of 80 mm as part of a stand with a ring pipeline system, a pump, systems for monitoring the flow of the working fluid, vibrations, pressure pulsations, and dynamic (vibration) forces transmitted by the compensators to the pipeline are presented. In a stand with pipelines, the efficiency of vibration-isolating compensators with TRME is still 10 and 100 times higher than compensators with RCC in the absence of water and decreases by an order of magnitude in the presence of water without its flow when the pump is vibrated by a vibrator. Efficiency decreases even further if water flows through expansion joints and pipelines while the pump is running.
{"title":"Development of Compensators to Improve Vibration Isolation of Equipment of Thermal Plants through Pipelines and the Influence of Liquid Flow on the Effectiveness of Vibration-Isolating Compensators","authors":"A. V. Kiryukhin, O. O. Mil’man, L. N. Serezkin, E. A. Loskareva, P. Yu. Dneprovskaya","doi":"10.1134/s0040601524040037","DOIUrl":"https://doi.org/10.1134/s0040601524040037","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of experimental studies on the creation of highly efficient designs of vibration-isolating compensators for pipelines with liquid are considered. It is noted that the only way to evaluate the effectiveness of various compensators in reducing vibration at different frequencies currently is to compare their transient vibration stiffness or transient mechanical impedance, which were measured on special stands at a given frequency. The stiffness of the compensator increases significantly with increasing frequency vibrations. Hazardous frequencies may vary between piping systems. For this reason, it is impossible to set an integral criterion for the effectiveness of a vibration-isolating compensator, similar to static stiffness. The results of measurements carried out on a special stand on the transitional vibration stiffness of a new design compensator with thin-layer rubber-metal elements (TRME) are presented. The rigidity decreased by 10 or 100 times or more in the frequency range from 50 to 800 Hz relative to the rigidity of a serial compensator based on rubber cord casing (RCC), including in the presence of water inside it. It has been experimentally shown that the vibration-isolating ability of the same compensator as part of a pipeline system, determined by the value of the dynamic force transmitted by the compensator to the pipeline from the pump, significantly depends on the presence of water in them and its flow, which is not taken into account in known methods. The results of testing compensators with RCC and TRME with a bore diameter of 80 mm as part of a stand with a ring pipeline system, a pump, systems for monitoring the flow of the working fluid, vibrations, pressure pulsations, and dynamic (vibration) forces transmitted by the compensators to the pipeline are presented. In a stand with pipelines, the efficiency of vibration-isolating compensators with TRME is still 10 and 100 times higher than compensators with RCC in the absence of water and decreases by an order of magnitude in the presence of water without its flow when the pump is vibrated by a vibrator. Efficiency decreases even further if water flows through expansion joints and pipelines while the pump is running.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884504","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 : 2024-05-04DOI: 10.1134/s0040601524040074
Yu. V. Yudov, I. G. Danilov
Abstract
A noniterative implicit method for solving the discrete conservation equations of the KORSAR/GP computer code (hereinafter referred to as KORSAR) two-fluid model is presented. The KORSAR/GP code has been developed jointly by specialists of the Federal State Unitary Enterprise Aleksandrov Research Institute of Technology (NITI) and the special design bureau OKB Gidropress. In 2009, the code was certified at the Federal Service for Environmental, Technological, and Nuclear Supervision (Rostekhnadzor) as applied to numerical safety assessment of VVER-type power reactor plants. The code uses the semi-implicit numerical scheme, which limits the integration time step by the Courant condition with respect to the velocity of a two-phase flow. To cut down the time it takes to calculate prolonged transients in reactor plants, an implicit numerical method, which does not limit the time step by the Courant condition, has been developed on the basis of the SETS (stability-enhancing two-step) method. It is based on the semi-implicit scheme. Prior to its application, discrete phase momentum conservation equations with the convective terms written in implicit form are solved at each time step. After the semi-implicit step, the specific (per unit volume) mass and energy of the phases, which are donor quantities in the convective terms of the transport equations, are calculated at the new time layer. Unlike the SETS method, the implicit method developed for the KORSAR code employs a semi-implicit scheme with linearization of unsteady terms describing the change in the specific mass and energy of a two-phase flow. This approach enables us to solve discrete equations in a noniterative manner. However, the implementation of this procedure requires that the unknown scalar variables, such as the phase specific enthalpies, the vapor volume fraction, and the pressure, be determined in the computational cells. Therefore, the semi-implicit scheme with linearization of unsteady terms with recalculated donor quantities at the end of the time step is reused. The performance and effectiveness of the developed implicit method have been confirmed by solving, using the KORSAR code, a test problem of a two-phase flow in a heated horizontal tube driven by a pressure difference.
{"title":"An Implicit Numerical Method for Integration of the Conservation Equations Incorporated into the KORSAR Code Two-Fluid Model","authors":"Yu. V. Yudov, I. G. Danilov","doi":"10.1134/s0040601524040074","DOIUrl":"https://doi.org/10.1134/s0040601524040074","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A noniterative implicit method for solving the discrete conservation equations of the KORSAR/GP computer code (hereinafter referred to as KORSAR) two-fluid model is presented. The KORSAR/GP code has been developed jointly by specialists of the Federal State Unitary Enterprise Aleksandrov Research Institute of Technology (NITI) and the special design bureau OKB Gidropress. In 2009, the code was certified at the Federal Service for Environmental, Technological, and Nuclear Supervision (Rostekhnadzor) as applied to numerical safety assessment of VVER-type power reactor plants. The code uses the semi-implicit numerical scheme, which limits the integration time step by the Courant condition with respect to the velocity of a two-phase flow. To cut down the time it takes to calculate prolonged transients in reactor plants, an implicit numerical method, which does not limit the time step by the Courant condition, has been developed on the basis of the SETS (stability-enhancing two-step) method. It is based on the semi-implicit scheme. Prior to its application, discrete phase momentum conservation equations with the convective terms written in implicit form are solved at each time step. After the semi-implicit step, the specific (per unit volume) mass and energy of the phases, which are donor quantities in the convective terms of the transport equations, are calculated at the new time layer. Unlike the SETS method, the implicit method developed for the KORSAR code employs a semi-implicit scheme with linearization of unsteady terms describing the change in the specific mass and energy of a two-phase flow. This approach enables us to solve discrete equations in a noniterative manner. However, the implementation of this procedure requires that the unknown scalar variables, such as the phase specific enthalpies, the vapor volume fraction, and the pressure, be determined in the computational cells. Therefore, the semi-implicit scheme with linearization of unsteady terms with recalculated donor quantities at the end of the time step is reused. The performance and effectiveness of the developed implicit method have been confirmed by solving, using the KORSAR code, a test problem of a two-phase flow in a heated horizontal tube driven by a pressure difference.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884505","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 : 2024-05-04DOI: 10.1134/s0040601524040062
A. P. Solodov
Abstract
The problem of friction and heat transfer in a laminar, transition, or turbulent flow along solid permeable surfaces has been solved using a numerical simulation technique. To derive a compact mathematical description intended for engineering applications in the power industry and other thermal processes, a modern version of the Kolmogorov–Prandtl model with one differential equation (namely, the turbulent kinetic energy conservation equation) was employed. The mathematical model is represented by a system of first-order nonlinear ordinary differential equations for the distributions of flow velocity, friction stress, temperature, turbulent energy, and turbulent energy flux density across the film thickness. The problem of singularity of the mathematical description on a solid wall is discussed. The integral hydrodynamic and thermal characteristics of film flows currently receiving a lot of interest, such as the film Reynolds number and the Stanton number, were obtained. Functional correlations among dimensionless parameters that are relevant for engineering applications, including those for special regimes of film flows with recirculation and mass crossflow on permeable surfaces of structural materials, have been established. The film Reynolds and Stanton numbers are defined as functions of dimensionless parameters at which the relative values of the film thickness, acting forces, and mass crossflow are specified. The obtained correlations can be used in the design and optimization of condensation and steam-generating facilities in the power industry, for elaboration of evaporative coolers for high-stress structural elements in gas turbine and rocket equipment, simulation of hydraulic roughness, and in thin-film materials technologies.
{"title":"A One-Dimensional Model of Hydrodynamics and Heat Transfer in a Film Flow on a Permeable Surface","authors":"A. P. Solodov","doi":"10.1134/s0040601524040062","DOIUrl":"https://doi.org/10.1134/s0040601524040062","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The problem of friction and heat transfer in a laminar, transition, or turbulent flow along solid permeable surfaces has been solved using a numerical simulation technique. To derive a compact mathematical description intended for engineering applications in the power industry and other thermal processes, a modern version of the Kolmogorov–Prandtl model with one differential equation (namely, the turbulent kinetic energy conservation equation) was employed. The mathematical model is represented by a system of first-order nonlinear ordinary differential equations for the distributions of flow velocity, friction stress, temperature, turbulent energy, and turbulent energy flux density across the film thickness. The problem of singularity of the mathematical description on a solid wall is discussed. The integral hydrodynamic and thermal characteristics of film flows currently receiving a lot of interest, such as the film Reynolds number and the Stanton number, were obtained. Functional correlations among dimensionless parameters that are relevant for engineering applications, including those for special regimes of film flows with recirculation and mass crossflow on permeable surfaces of structural materials, have been established. The film Reynolds and Stanton numbers are defined as functions of dimensionless parameters at which the relative values of the film thickness, acting forces, and mass crossflow are specified. The obtained correlations can be used in the design and optimization of condensation and steam-generating facilities in the power industry, for elaboration of evaporative coolers for high-stress structural elements in gas turbine and rocket equipment, simulation of hydraulic roughness, and in thin-film materials technologies.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884563","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 : 2024-05-04DOI: 10.1134/s0040601524040049
A. A. Kudinov, S. K. Ziganshina
Abstract—
The use of condensing heat exchangers (CHEs) in gas-fired boiler units helps cool the flue gases below the dew point. One of the issues that has to be settled in the case of CHEs installed downstream of boilers is to ensure that the flue gas removal stacks will operate without steam condensation on their inner surfaces. To protect smoke stacks against hydrate corrosion, bypassing of part of combustion products not cooled in the CHE is mainly used in practice. The article presents the results obtained from computations of the heat-transfer processes in the combustion products cooled in a CHE as they move in a reinforced concrete smoke stack fitted with clamped lining, which is protected against hydrate corrosion by bypassing. The computations are carried out for three operation modes of the 180-m high smoke stack, through which flue gases are removed from three power-generating boilers of the BKZ-420-140 NGM type installed at the Samara combined heat and power plant (CHPP), a branch of Samara PAO T Plus. The peculiarity and complexity of the computations are connected with the fact that that the flue gas’s thermophysical parameters and motion velocity in the smoke stack vary during the flue gas cooling process. The parameters’ variation pattern depends essentially on the fraction of gases directed in bypass of the CHE. A mathematical model and computer program are developed for computing the heat-transfer processes in flue gases moving in the smoke stack with CHEs installed downstream of the boilers and with the smoke stack protected against hydrate corrosion by the bypassing method. It has been determined that, for a 180-m high three-layer reinforced concrete smoke stack operating at an outdoor air temperature of –30°С and boilers operating at the nominal load, the fraction of bypassed gases makes 30–35%. With the boilers operating at partial loads equal to 75 and 60% of the nominal value, the fraction of bypassed gases makes 35–40 and 40–45%, respectively. The use of condensing heat exchangers in boiler units results in that the levels of temperature difference, free temperature deformation, and thermal stresses in the smoke stack’s structural elements are reduced by a factor of 1.33–2.80 depending on the fraction of gases passed through the CHEs, thereby enhancing the flue gas removing smoke stack performance reliability.
摘要--在燃气锅炉机组中使用冷凝式热交换器（CHE）有助于将烟气冷却到露点以下。在锅炉下游安装冷凝式热交换器时，必须解决的一个问题是确保烟气排放烟囱在运行时不会在其内表面产生蒸汽冷凝。为了保护烟囱免受水合物腐蚀，在实践中主要采用了旁通 CHE 中未冷却的部分燃烧产物的方法。文章介绍了通过旁路保护防止水合物腐蚀的钢筋混凝土烟囱中，在 CHE 中冷却的燃烧产物在移动过程中的传热过程的计算结果。计算针对 180 米高烟囱的三种运行模式进行，从萨马拉热电联产厂（CHPP）（萨马拉 PAO T Plus 的分公司）安装的三台 BKZ-420-140 NGM 型发电锅炉排出的烟气通过烟囱排出。计算的特殊性和复杂性与烟气的热物理参数和烟道中的运动速度在烟气冷却过程中的变化有关。参数的变化模式主要取决于进入燃烧器旁路的气体比例。我们开发了一个数学模型和计算机程序，用于计算烟气在烟道中移动时的传热过程，CHE 安装在锅炉下游，烟道采用旁路方法防止水合物腐蚀。据测定，在室外空气温度为 -30°С、锅炉以额定负荷运行的情况下，180 米高的三层钢筋混凝土烟囱的旁路气体比例为 30-35%。当锅炉的部分负荷为额定值的 75% 和 60% 时，旁路气体的比例分别为 35-40% 和 40-45%。在锅炉机组中使用冷凝式热交换器的结果是，烟囱结构部件中的温差、自由温度变形和热应力水平降低了 1.33-2.80 倍，这取决于通过冷凝式热交换器的气体比例，从而提高了烟气除烟囱性能的可靠性。
{"title":"Assessing the Smoke-Stack Performance with Boiler Unit Flue Gases Cooled below the Dew Point","authors":"A. A. Kudinov, S. K. Ziganshina","doi":"10.1134/s0040601524040049","DOIUrl":"https://doi.org/10.1134/s0040601524040049","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract—</h3><p>The use of condensing heat exchangers (CHEs) in gas-fired boiler units helps cool the flue gases below the dew point. One of the issues that has to be settled in the case of CHEs installed downstream of boilers is to ensure that the flue gas removal stacks will operate without steam condensation on their inner surfaces. To protect smoke stacks against hydrate corrosion, bypassing of part of combustion products not cooled in the CHE is mainly used in practice. The article presents the results obtained from computations of the heat-transfer processes in the combustion products cooled in a CHE as they move in a reinforced concrete smoke stack fitted with clamped lining, which is protected against hydrate corrosion by bypassing. The computations are carried out for three operation modes of the 180-m high smoke stack, through which flue gases are removed from three power-generating boilers of the BKZ-420-140 NGM type installed at the Samara combined heat and power plant (CHPP), a branch of Samara PAO T Plus. The peculiarity and complexity of the computations are connected with the fact that that the flue gas’s thermophysical parameters and motion velocity in the smoke stack vary during the flue gas cooling process. The parameters’ variation pattern depends essentially on the fraction of gases directed in bypass of the CHE. A mathematical model and computer program are developed for computing the heat-transfer processes in flue gases moving in the smoke stack with CHEs installed downstream of the boilers and with the smoke stack protected against hydrate corrosion by the bypassing method. It has been determined that, for a 180-m high three-layer reinforced concrete smoke stack operating at an outdoor air temperature of –30°С and boilers operating at the nominal load, the fraction of bypassed gases makes 30–35%. With the boilers operating at partial loads equal to 75 and 60% of the nominal value, the fraction of bypassed gases makes 35–40 and 40–45%, respectively. The use of condensing heat exchangers in boiler units results in that the levels of temperature difference, free temperature deformation, and thermal stresses in the smoke stack’s structural elements are reduced by a factor of 1.33–2.80 depending on the fraction of gases passed through the CHEs, thereby enhancing the flue gas removing smoke stack performance reliability.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884567","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 : 2024-05-04DOI: 10.1134/s0040601524040025
V. O. Kindra, I. A. Maksimov, I. I. Komarov, S. K. Osipov, O. V. Zlyvko
Abstract
The active development of the Arctic and the Northern Sea Route determines the importance of the rapid development of energy-supply systems for remote regions. A key component of isolated power systems are low-power energy sources. The high cost of fossil fuels in remote regions, coupled with tightening environmental regulations, brings to the fore the challenge of implementing carbon-neutral energy generation technologies. Promising power plants, the performance of which is little dependent on weather conditions, and whose operation is not associated with the generation of greenhouse gas emissions, are low-power nuclear power plants. Currently, some countries are developing and implementing new types of reactor plants whose electrical power does not exceed 300 MW: according to the IAEA, there are more than 70 different projects. Modularity, versatility (in addition to power generation, many projects also provide for the production of thermal energy and hydrogen), increased compactness, and lower capital costs for construction compared to traditional high-power power units make it promising to create low-power reactor plants. This review presents an analysis of the current state of the problems in the design and implementation of such power plants. The technical level of domestic and foreign projects of small modular reactors (SMR) was assessed. Promising areas for the use of thermal energy from small modular installations have been identified, taking into account current trends in energy, including low-carbon and nuclear-hydrogen areas. Possible circuit solutions for the production of electricity based on advanced cycles, including the use of nontraditional working fluids, have been studied. The potential for commercialization of low-power nuclear power plant projects has been considered; the question of successful business implementation of power plants of this type remains open.
{"title":"Small Power Nuclear Plants: Technical Level and Prospects for Commercialization (Review)","authors":"V. O. Kindra, I. A. Maksimov, I. I. Komarov, S. K. Osipov, O. V. Zlyvko","doi":"10.1134/s0040601524040025","DOIUrl":"https://doi.org/10.1134/s0040601524040025","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The active development of the Arctic and the Northern Sea Route determines the importance of the rapid development of energy-supply systems for remote regions. A key component of isolated power systems are low-power energy sources. The high cost of fossil fuels in remote regions, coupled with tightening environmental regulations, brings to the fore the challenge of implementing carbon-neutral energy generation technologies. Promising power plants, the performance of which is little dependent on weather conditions, and whose operation is not associated with the generation of greenhouse gas emissions, are low-power nuclear power plants. Currently, some countries are developing and implementing new types of reactor plants whose electrical power does not exceed 300 MW: according to the IAEA, there are more than 70 different projects. Modularity, versatility (in addition to power generation, many projects also provide for the production of thermal energy and hydrogen), increased compactness, and lower capital costs for construction compared to traditional high-power power units make it promising to create low-power reactor plants. This review presents an analysis of the current state of the problems in the design and implementation of such power plants. The technical level of domestic and foreign projects of small modular reactors (SMR) was assessed. Promising areas for the use of thermal energy from small modular installations have been identified, taking into account current trends in energy, including low-carbon and nuclear-hydrogen areas. Possible circuit solutions for the production of electricity based on advanced cycles, including the use of nontraditional working fluids, have been studied. The potential for commercialization of low-power nuclear power plant projects has been considered; the question of successful business implementation of power plants of this type remains open.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884740","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 : 2024-05-04DOI: 10.1134/s0040601524040086
Bingwen Zhao, Hanyu Zheng, Ruxue Yan
Abstract
District heating system is the main way of heating in cities and towns in China. The development of district heating system still has the problems of low intelligence and low control accuracy, and there is the imbalance of heat supply and demand in heat distribution. Resulting in the energy consumed by the district heating system can account for more than half of the total energy consumption of the building. In order to alleviate this imbalance, this paper studies the control of heat distribution of each heat exchange station in the primary network. The heat model of primary network is established by recurrent neural network (RNN), and the data set used for modeling is the operation data of heat exchange station in reality. Combined with the heat load prediction model, a heat distribution strategy was proposed to optimize the primary flow of the heat exchange station. According to the predicted value, chaotic particle swarm optimization (CPSO) algorithm is used to optimize the primary flow sequence of each heat exchange station, and then the primary flow is adjusted to control the heat distribution of the secondary network. Finally, Simulink simulation model is used to simulate the water supply temperature of the secondary side of the heat exchange station. And analyze the operation status of the secondary side, the results verify the effectiveness of the strategy. The model simulation results show that the heat distribution scheme proposed in this paper can effectively distribute the heat of the heat exchange station according to the heat demand.
AbstractDistrict heating system is the main way of heating in cities and towns in China.区域供热系统的发展仍存在智能化程度低、控制精度低、供热供需不平衡等问题。导致区域供热系统的能耗占建筑总能耗的一半以上。为了缓解这种不平衡，本文研究了一次网中各换热站的热量分配控制。采用递归神经网络（RNN）建立一次网热量模型，建模数据集为现实中换热站的运行数据。结合热负荷预测模型，提出了优化换热站一次流量的热分配策略。根据预测值，采用混沌粒子群优化算法（CPSO）优化各换热站的一次流量顺序，然后通过调整一次流量来控制二次网的热量分配。最后，利用 Simulink 仿真模型模拟换热站二次侧的供水温度。并分析二次侧的运行状态，结果验证了该策略的有效性。模型仿真结果表明，本文提出的热量分配方案能根据热量需求有效分配换热站的热量。
{"title":"Heat Distribution of Heat Exchange Station in District Heating System based on Load Forecasting","authors":"Bingwen Zhao, Hanyu Zheng, Ruxue Yan","doi":"10.1134/s0040601524040086","DOIUrl":"https://doi.org/10.1134/s0040601524040086","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>District heating system is the main way of heating in cities and towns in China. The development of district heating system still has the problems of low intelligence and low control accuracy, and there is the imbalance of heat supply and demand in heat distribution. Resulting in the energy consumed by the district heating system can account for more than half of the total energy consumption of the building. In order to alleviate this imbalance, this paper studies the control of heat distribution of each heat exchange station in the primary network. The heat model of primary network is established by recurrent neural network (RNN), and the data set used for modeling is the operation data of heat exchange station in reality. Combined with the heat load prediction model, a heat distribution strategy was proposed to optimize the primary flow of the heat exchange station. According to the predicted value, chaotic particle swarm optimization (CPSO) algorithm is used to optimize the primary flow sequence of each heat exchange station, and then the primary flow is adjusted to control the heat distribution of the secondary network. Finally, Simulink simulation model is used to simulate the water supply temperature of the secondary side of the heat exchange station. And analyze the operation status of the secondary side, the results verify the effectiveness of the strategy. The model simulation results show that the heat distribution scheme proposed in this paper can effectively distribute the heat of the heat exchange station according to the heat demand.</p>","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140884581","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 : 2024-05-04DOI: 10.1134/s0040601524030108
E. V. Somova
Abstract
The modern structure of energy consumption enhances the nonuniformity of electrical load curves. With the more pronounced nonuniformity of daily and weekly electrical energy consumption, the requirements for the maneuverable characteristics of power units, which include the control range of the power unit load (technological minimum) and the minimum safe load of the power unit (technical minimum), become more demanding. Due to the problem of maintenance and adequate passing of the minimum of electrical loads during nighttime periods and nonworking days, large supercritical pressure (SCP) condensing power units had to be engaged in controlling the loads. This situation is topical for the Russian power industry in the absence of semipeak power units. For SCP power units, it is advisable to perform unloading under sliding pressure conditions throughout the entire steam-water path. The depth of unloading depends mainly on the reliability of the boilers, the hydraulic design of whose heating surfaces had been performed without considering operation at subcritical pressure. The possibility of application of sliding pressure unloading for SCP units was determined by ensuring reliable temperature and hydraulic conditions of the boiler heating surfaces, in which the state of the working fluid changed from subcooled water to slightly superheated steam. Unloading of drum boilers requires maintenance of reliable circulation in the furnace waterwalls and safe temperature conditions of the steam superheating surfaces. The results of the tests of various types of gas-and-oil fired once-through and drum boilers with unloading at sliding or rated subcritical pressures are presented. The reliability indicators of the hydraulic paths of the boilers and the factors limiting deep unloading of power units have been analyzed. The minimum safe loads were determined. Technical solutions for deep unloading were proposed for the hydraulic circuits of the steam-generating part of the flow path of SCP boilers.
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Pub Date : 2024-05-04DOI: 10.1134/s0040601524040050
I. A. Ryzhii, A. V. Shtegman, D. V. Sosin, A. S. Natal’in
Abstract—
Automating the operation of equipment at modern thermal power plants to the maximal possible extent is becoming an increasingly more urgent problem. For coal-fired boilers, the development of furnace operation mode control systems is of special importance. A significant scatter in the characteristics of the coal delivered for combustion have a strong influence on the boiler’s operation mode and its technical and economic indicators. Essential changes in the combustion mode frequently give rise to problems connected with gas temperature fluctuations at the furnace outlet, with maintaining a stable superheated steam temperature, slagging of heating surfaces, degraded combustion efficiency, etc. For estimating the influence of coal properties on the operation mode of the E-210-13.8KT boiler (the factory designation is BKZ-210-140) at the Tomsk GRES-2 thermal power plant, computational studies of gas temperature at the furnace outlet were carried out using the Boiler Designer software package. With an essential variation in the coal characteristics, the calculated values of temperature varied from 1103 to 1150°С at 100% load and from 910 to 948°С at 50% load. The adjustment of fireball direction at the burner outlet by ±15° made it possible to change the gas temperature at the furnace outlet by approximately 90°С. In the case of introducing a fireball direction adjustment system, it would be possible to solve, to a significant extent, the boiler-operation problems mentioned above. An algorithm for automatically adjusting the combustion mode has been developed, which, in case of having been implemented, would make it possible to achieve more reliable operation of boiler unit components, decrease the risk of the heating surfaces becoming intensely fouled with slag, and maintain a stable superheated steam temperature in different boiler-operation modes. A swirl movable burner able to vary the fireball direction at the burner outlet by ±15° should become the combustion system’s key component.
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Pub Date : 2024-05-01DOI: 10.1134/s0040601524050033
V. Blinov, I. Zubkov, G. Deryabin
{"title":"Estimating the Influence of Compressor Blade Erosion Wear on the Compressor’s Integral and Local Characteristics","authors":"V. Blinov, I. Zubkov, G. Deryabin","doi":"10.1134/s0040601524050033","DOIUrl":"https://doi.org/10.1134/s0040601524050033","url":null,"abstract":"","PeriodicalId":799,"journal":{"name":"Thermal Engineering","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141144550","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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