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    Fundamental Research
  • Fundamental Research
    Study on Engineering Application of Fretting Fatigue Life Prediction Based on Critical Surface Method
    DENG Guojian, SHI Weichao, LIU Yang
    2024, 44(1): 1-6. https://doi.org/10.19805/j.cnki.jcspe.2024.220756
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    Fretting fatigue life prediction analysis for compressor material TC11 specimens was conducted to study its potential engineering application. The basic flow of fretting fatigue life prediction method based on critical surface method was combed, and the experimental results and prediction results were compared. Results show that the smaller radian of the tenon working surface will reduce the SWT critical interface parameter value of the contact area, which is conducive to the improvement of fretting fatigue life. The error dispersion band between the predicted results based on SWT critical interface parameters and the experimental values is within 2 times of the factor, which has reference significance for the prediction of fretting fatigue life of actual components of aeroengines and gas turbines.
  • Fundamental Research
    Study on Oxidation Behavior of TP347H and Sanicro25 in Water Vapor at 700 ℃
    WANG Miaomiao, NI Yifan, ZHANG Zuogui, WANG Yanfeng
    2024, 44(1): 7-14. https://doi.org/10.19805/j.cnki.jcspe.2024.230018
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    The oxidation behavior of austenitic stainless steel TP347H and Sanicro25 in high temperature steam environment at 700 ℃/5 MPa was studied. After oxidation for 1 000 h, the oxidation kinetics of two alloys were obtained by weight gain method and thickness method. The morphology and element distribution of the oxides were analyzed by scanning electron microscope and energy dispersive spectrometer, and the phase analysis of the oxides on the surface of the samples was carried out by X-ray diffractometer. Results show that the oxidation kinetic behavior of two alloys basically conforms to the parabolic law, and the formation and exfoliation of oxides are divided into six stages. The steam oxidation resistance of Sanicro25 is better than that of TP347H.The outer layer of TP347H oxide film consists of Fe2O3 and Fe3O4 mainly, and the inner layer is (Fe, Cr)3O4 mainly. The outer layer of Sanicro25 oxide film consists of Fe2O3 and Fe3O4 mainly, and the inner layer is (Fe, Cr)3O4 and Cr2O3 mainly.
  • Fundamental Research
    Analysis of Steam-Water Density Wave Instability Among Parallel Multiple Channels Under Low Parameter Conditions
    LIU Jialun, ZHANG Yonghai, CHEN Yongqiang
    2024, 44(1): 15-24. https://doi.org/10.19805/j.cnki.jcspe.2024.230020
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    A time-domain calculation model was developed to study the density wave instability of steam-water two phase flow in parallel multiple channel system. Based on the collocated mesh method, the flow domain along each channel was split into a series of sections, and the discretized mass, momentum, and energy equations were established for each section with consideration of the property variation. According to relevant parameters of boiler water wall under low load conditions during deep peak shaving, the model was used to study the density wave oscillation characteristics among parallel multiple channels under low system pressure (p=8-10 MPa) and low system mass flow rate (G=300-500 kg/(m2·s)). The axial heat flux distribution on the pipe wall was simplified, and it followed a linear distribution law that increases first and then decreases along the pipe. Results show that the stability of the system is gradually weakened with the decrease of system pressure and system mass flow rate. With the increase in the non-uniformity of the axial heat flux distribution, the density wave oscillation of the flow rate tends to diverge, and the corresponding threshold heat power gradually decreases, indicating that the system tends to be unstable. The change trend of the threshold heat power with the non-uniformity of the axial heat flux distribution is nonlinear.
    • Power Equipment and System
  • Power Equipment and System
    Heat Transfer Coefficient Calculation Model and Method for Steam Pipe and Valve as well as Outside Surface of Steam Turbine Outer Casing
    SHI Jinyuan, XIE Yuesheng, XU Jiamin
    2024, 44(1): 25-37. https://doi.org/10.19805/j.cnki.jcspe.2024.230048
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    The heat transfer coefficient calculation models and methods for outer surface of steam pipe, main stop valve, control valve and outer casing of steam turbines were established. The heat transfer coefficient calculation formulas for inner surface of steam pipe, main stop valve, control valve, high pressure (HP) outer casing, intermediate pressure (IP) outer casing and low pressure (LP) outer casing of steam turbine, and the composite heat transfer coefficient of the outer surface of the insulation structure and the outer surface of the LP outer casing were given. The calculation model of the heat transfer process of the steam pipe, the metal inner wall of the HP outer casing and the IP outer casing and the double-layer casing wall of the outer wall of the thermal insulation structure, the metal inner wall of the main stop valve, control valve and the double-layer spherical wall of the outer wall of the thermal insulation structure, and the single-layer cylinder wall of the LP outer casing of steam turbine were established. Considering that the inner surface temperature and outer surface temperature of the inner metal wall and the outer surface temperature of the outer wall of the thermal insulation structure were both undetermined, the iterative method was used to determine the surface temperature of these steam turbine components, the heat transfer coefficient and the heat flow density of the heat transfer process. The calculation and analysis of the external surface heat transfer coefficient of the steam pipes, main stop valve, control valve, HP outer casing, IP outer casing and LP outer casing of the steam turbine were completed. The calculation results of the heat transfer coefficient, heat flux density and equivalent surface heat transfer coefficient of the metal inner wall outer surface of these steam turbine components during the heat transfer process were obtained, providing heat transfer boundary conditions for finite element numerical calculation of temperature field and stress field of these steam turbine components.
  • Power Equipment and System
    Analysis of Unstable Vibration Caused by Shear Flow of Lube Oil in Micro-gap
    XIA Tian, YANG Jiangang
    2024, 44(1): 38-44. https://doi.org/10.19805/j.cnki.jcspe.2024.230024
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    Aiming at the unstable vibration phenomenon caused by the shear flow of lube oil in micro-gap, solving models of journal section temperature difference, rotor thermal bending and rotor vibration were established. Taking the periodic vibration fluctuation of two generator units as research object, the influence of lube oil temperature and unbalanced force on the vibration of turbo-generator was analyzed. Results show that the thermal bending effect caused by the shear flow of lube oil in the bearing micro-gap may cause the unstable vibration of the unit under certain conditions. Properly increasing the oil inlet temperature and sealing pad clearance can reduce the thermal bending deformation of the rotor and reduce the vibration fluctuation. Unbalanced force will excite large whirl track. By using dynamic balancing methods, the difference between the maximum and minimum oil film thickness of the bearing can be reduced, the temperature difference in the journal section can be reduced, and the vibration state can be stabilized.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Modeling and Optimal Control for Nitrogen Oxide Emissions from Biomass Circulating Fluidized Bed
    GUO Jiongnan, GAO Mingming, LÜ Junfu, YUE Guangxi
    2024, 44(1): 45-55. https://doi.org/10.19805/j.cnki.jcspe.2024.230200
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    Considering the combustion instability of the biomass circulating fluidized bed (CFB), the oxygen content model and the immediate combustion carbon model were established from the combustion mechanism of the boiler to realize the dynamic prediction of NOx in the process of load fluctuation. The self-generation and self-reduction mechanism of NOx in the furnace were analyzed, and the NOx dynamic emission model was established by mathematical modeling methods. The open-loop step tests for the feed rate and the secondary air flow were carried out. The coupling between NOx emission and oxygen content was analyzed, and the simplified diagonal decoupling and feedforward compensation decoupling method were used for decoupling. The simulation experiment was carried out using the actual operation data of a 130 t/h biomass CFB.Results show that the model has a good prediction effect. The dynamic characteristics of oxygen content and NOx emission process can be reflected, and the single-loop control for NOx emission by the feed rate and oxygen content by the secondary air flow can be realized. The designed NOx emission concentration model and decoupling control methods can provide reference for the biomass CFB unit to adapt to dynamic operation and intelligent control strategy designs in the future.
  • New Energy Resources and Energy Storage
    Study on Cu-based Chemical-looping Reforming of Biomass for Syngas Production
    GUO Lei, DONG Weiru, LIU Ting'an, WU Xiaoqin, WANG Liang, WU Wei
    2024, 44(1): 56-61. https://doi.org/10.19805/j.cnki.jcspe.2024.230322
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    Chemical-looping reforming of biomass using Cu-based oxygen carriers was analyzed in a thermogravimetric analyzer (TGA) and a small fluidized bed reactor respectively, and the influence of oxygen carriers and reactor temperature was studied. Results show that, compared with Fe-based oxygen carriers and quartz sand, the use of Cu-based oxygen carriers results in larger weight loss and weight loss rate, since Cu-based oxygen carriers can release oxygen at high-temperature and thus accelerate the pyrolysis and gasification of biomass. Meanwhile, higher temperature leads to higher gasification efficiency, gas yield, conversion efficiency and gasification rate. The Cu-based oxygen carriers appear good redox ability, anti sintering ability and high reactivity.
  • New Energy Resources and Energy Storage
    Research on Cross-domain Fault Diagnosis of Bearings Based on Deep Conditional Subdomain Adaptive Network
    FAN Yongsheng, DING Xue, DENG Aidong
    2024, 44(1): 62-67. https://doi.org/10.19805/j.cnki.jcspe.2024.220789
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    A new deep conditional subdomain adaptive network (DCSAN) was proposed for the problems of insufficient labeled data and low diagnostic accuracy in the unsupervised cross-domain fault diagnosis field. The network mapped the confidence predicted by the classifier to the features extracted by the shared feature extractor to obtain the multimodal mapping features. And then the multi-kernel local maximum mean difference (MK-LMMD) was used to measure the distance between the multimodal mapping features in different domains. By minimizing the MK-LMMD and the loss functions of the classifier, the alignment of the corresponding sub-domain distributions in the source and target domains was achieved. The feasibility of the proposed method was verified on the bearing dataset of Jiangnan University. Results show that in six migration tasks under variable work conditions, the average diagnostic accuracy of the DCSAN model are 9.5%, 8.0% and 13.6% higher respectively than that of DAN, D-CORAL and DANN model. The proposed DCSAN model has certain effectiveness and superiority in sub-domain alignment and cross-domain adaptive fault diagnosis.
  • New Energy Resources and Energy Storage
    Screening of Working Material for ORC Power Generation System Based on Vapor-Liquid Two-phase Geothermal Heat Source
    ZHAO Bin, WEN Rou, BIAN Jichao, LIU Rui, GONG Yulie, WANG Shanmin
    2024, 44(1): 68-75. https://doi.org/10.19805/j.cnki.jcspe.2024.230011
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    In order to select the optimal working fluid for the organic Rankine cycle (ORC)power generation system driven by a vapor-liquid two-phase hybrid geothermal fluid with the heat source temperature of 140 ℃, six dry working materials were selected and a system model was built in MATLAB. The influence of each working fluid evaporation temperature on the system thermodynamic performance was analyzed. The variation of the optimal evaporation temperature with the heat source temperature under different steam mass fractions was compared. The influence of heat source mass flow rate on the system net output power and the influence of evaporation temperature on the recharge temperature were studied. Results show that considering the effect of thermodynamic performance, physical and chemical stability, thermal source matching and system recharge temperature on geothermal ORC power generation system, R601a (isopentane) is the best suitable material for ORC power generation system driven by 140 ℃ vapor-liquid two-phase hybrid geothermal fluid as heat source.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Feedforward Control of Superheated Steam Temperature with Wide Load Model for Coal-fired Units
    CHEN Yifan, CAO Yue, SI Fengqi
    2024, 44(1): 76-83. https://doi.org/10.19805/j.cnki.jcspe.2024.230042
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    In order to achieve more accurate feedforward control for the superheated steam temperature with wide load operation, a predictive feedforward signal model based on physical guided neural network (PGNN) was proposed, and the load segment allocation of multiple models was determined based on gap measurement. The PGNN prediction method of multi-model gap measurement adopted the multi-model gap measurement method to reasonably divide the load section. Combined with the long short term memory neural network guided by the superheater mechanism, the strong coupling and large inertia superheated steam temperature wide load feedforward signal can be accurately predicted. Results show that when in the wide load of the unit, the nonlinear degree of the control object gradually increases with the load reduction, and more models are needed. The multi-model gap measurement PGNN feedforward control method can adopt feedforward signals suitable for the current working conditions under different working conditions, and improve the adjustment accuracy and stability of superheated steam temperature.
  • Digitalization and Intelligentization
    Cascaded Self-coupling PID Control of SCR Denitration System
    ZENG Peng, ZENG Zhezhao, HUANG Lirong
    2024, 44(1): 84-90. https://doi.org/10.19805/j.cnki.jcspe.2024.230017
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    Aiming at the complex characteristics of selective catalytic reduction (SCR) denitration system with multiple disturbances, large inertia and model uncertainty, a control method based on self-coupling PID (SCPID) control theory was proposed. This method defines all complex factors such as internal disturbance, external disturbance and model uncertainty in the SCR denitration system as total disturbance, and then maps the system to a linear disturbance system. Based on this, a controlled error system under the inverse excitation of the total disturbance was constructed. Then, two separated self-coupling PID controllers were designed for the inner and outer loops of the SCR denitration system, so that the dimension of the control force matched the controlled system. Finally, three simulation experiments were conducted to verify the effectiveness of the proposed method. Results show that the proposed SCPID control method in this paper has fast response, small overshoot, strong anti-interference ability and good robustness.
  • Digitalization and Intelligentization
    Photovoltaic Power Prediction by Weight Parameter Optimization-based Parallel Deep Learning
    DONG Kun, RAN Peng, LIU Xu, FAN Qinyang, LI Zheng, ZENG Qinghua, LI Weiqi
    2024, 44(1): 91-98. https://doi.org/10.19805/j.cnki.jcspe.2024.230021
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    A parallel deep learning framework with adaptive optimization of weight parameters was proposed to address the accuracy and adaptability short comings of existing photovoltaic (PV) power prediction models when the data fluctuation patterns varied greatly in different application scenarios. The framework contained two parallel deep learning algorithm units such as Attention-Seq2Seq unit and Transformer unit and a weight parameter adaptive optimization unit. Based on the proposed parallel deep learning framework, the prediction of PV power generation was carried out and compared with the prediction results by Attention-Seq2Seq and Transformer models. Results show that the proposed framework not only can offset the lack of prediction accuracy and adaptability of single algorithm under different data fluctuation patterns, but also can effectively solve the long-distance dependence problem in time series prediction, which results in higher forecasting accuracy. The maximum reduction of average absolute error (EMAE) and root mean square error (ERMSE) is 41.18% and 45.59% in a typical day of summer, respectively,while the maximum reduction of EMAE and ERMSE arrives at 81.13% and 82.86%, respectively in a typical day of winter.
  • Digitalization and Intelligentization
    Zonal Control of Reactive Power and Voltage in Wind Farms Considering Fuzzy Multi-objective Optimization
    WANG Wei, YANG Jian, REN Guorui, REN Xin, WANG Hua
    2024, 44(1): 99-108. https://doi.org/10.19805/j.cnki.jcspe.2024.230028
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    To improve the reactive power compensation and voltage stability of doubly-fed wind farms, a zonal control method of reactive power and voltage in wind farms considering fuzzy multi-objective optimization was proposed. Based on the active power data, the wind farm was partitioned and dimensionality was reduced, and the reactive power optimization limits for each zone were calculated. The zonal reactive power margin index was defined to describe the safety margin of wind farm voltage operation. Taking into account both operation safety and stability, a fuzzy multi-objective optimization model for wind farm reactive power voltage was established. A self-adaptive genetic taboo algorithm that can quickly and globally optimize on a large scale has been proposed. the global timeliness of optimization was improved by redefining the crossover and mutation, and the accuracy of optimization was improved by introducing taboo algorithm. Finally, simulation verification was conducted using a doubly fed wind farm as an example. Results show that the proposed method can reserve sufficient reactive power margin for wind farms and significantly reduce voltage fluctuations within the system.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Experimental Study on Simultaneous Removal of HCl and SO2 from Waste Incineration Flue Gas by Dry Process with NaHCO3
    MA Rushuang, DING Delong, GE Chunliang, WU Zhepeng, WEI Tingfan, ZHANG Yiqin, DAI Shangfang, YANG Jianguo
    2024, 44(1): 109-117. https://doi.org/10.19805/j.cnki.jcspe.2024.230014
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    The removal of acidic pollutants in waste incineration flue gas by NaHCO3-based dry process was performed. For complex flue gas components, effects of various important factors on simultaneous removal of HCl and SO2 were investigated. Results show that temperature has minor influence on the deacidification efficiency by NaHCO3-based dry process. The removal efficiency of HCl and SO2 can reach more than 95% and 90% within the temperature range of 130 to 250 ℃, respectively. The deacidification efficiency can be improved significantly with the increase of reaction time. With the comprehensive consideration of environmental protection and economy, the residence time of above 1.25 s in ducts and the designed filtration velocity of 0.60 m/min in fabric filters are suitable at the stoichiometric ratio of NaHCO3 to HCl and SO2 (SR) of 1.1. At the water fraction in flue gas<15%, the steam can obviously promote the removal of SO2. At SR≤1.0, the removal of HCl is preferred. At SR=1.1, the removal efficiency of SO2 decreases by about 1.1% with the increase of HCl concentration by 100 mg/m3, while the emission concentration of SO2 increases by about 4 mg/m3. However, SO2 concentration in flue gas has no effect on the removal efficiency of HCl.
  • Green Energy and Low-carbon Technology
    System Integration Design and Optimization of Double-reheat Coal-fired Power Unit with CO2 Capture and Methanol Production
    FU Wenfeng, DOU Yanbin, WANG Lanjing, CUI Qingwei
    2024, 44(1): 118-127. https://doi.org/10.19805/j.cnki.jcspe.2024.230065
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    Aiming at high energy consumption and subsequent CO2 utilization in power plants with carbon capture, an integration system of double-reheat coal-fired power unit with CO2 capture and methanol production was designed. Taking a 1 000 MW double-reheat ultra-supercritical power generation unit as an example, the optimization of this proposed system was performed using dynamic adaptive particle swarm optimization algorithm. Then the influence of carbon capture rate and photoelectric hydrogen production cost on its performance was analyzed. Results show that at the carbon capture rate of 90%, the thermal efficiency and net benefit of this proposed system increase by 6.62% and 3.342 billion yuan, respectively, while the CO2 emission intensity reduces by 4.45 g/(kW·h) compared with the coal-fired unit with CO2 capture. The thermal efficiency of this integrated system can be maintained at above 49% when the carbon capture rate changes within the range of 40%~90%. As the cost of photovoltaic hydrogen production decreases, the net benefit of this integrated system will be significantly improved in the future.
    • Integrated Energy System
  • Integrated Energy System
    A New Dynamic Constraint Working Point Design Method for Multi-energy Complementary Distributed Energy System
    ZHANG Ruifang, CUI Guomin, XU Yue, XIAO Yuan, YI Zhikang, GUO Jia
    2024, 44(1): 128-137. https://doi.org/10.19805/j.cnki.jcspe.2024.230001
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    A new dynamic constriant working point design method was proposed, which can enhance the advantages of peak shaving and valley filling by adjusting the capacity of some devices and synchronously optimizing the capacity of energy storage devices. With the goal of optimizing economic efficiency and the capacity of each device in the system as the optimization variable, the capacity configuration optimization model was combined with the forced evolution random walk algorithm, which was applied to specific examples. Results show that compared to the other three schemes, the dynamic constraint working point design method reduces the annual comprehensive cost by 11.3%, 8.8% and 4.1%, respectively, further improving the economy of the system.
  • Integrated Energy System
    Optimization and Performance Analysis of Integrated Energy System Considering AA-CAES and PTC Integration
    WU Di, LIU Ao, GONG Dixin, MA Fanfan, MA Li, HAN Zhonghe, LIU Shuhua
    2024, 44(1): 138-147. https://doi.org/10.19805/j.cnki.jcspe.2024.230039
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    In order to further exert the multi-energy complementary advantages of the integrated energy system (IES), an optimized operation strategy of integrated energy system (IES-PTC-CAES) integrating with advanced-adiabatic compressed air energy storage system (AA-CAES) and parabolic trough solar collector (PTC) was proposed. Firstly, the AA-CAES, PTC and other equipment in the system were analyzed and the corresponding models were established. Then, economy, environmental protection and energy efficiency were treated as the optimization objectives, and the key parameters of equipment operation were treated as the optimization variables, a collaborative optimization strategy was established based on time-of-use electricity price. The simulated typical annual load was clustered into typical daily load by K-means algorithm. Finally, the optimal operation strategies of IES-PTC-CAES under different objectives were obtained by the parallel genetic algorithm. Results show that compared with the reference system, the cost under the economic target is reduced by 146 100 yuan, and the carbon dioxide emission under the environmental protection target is reduced by 6 194.38 kg.
  • Integrated Energy System
    Multi-parameter and Collaborative Operation Optimization of Waste Heat Recovery System of Pre-heater of Coal-fired Unit
    CHEN Xun, FENG Youlin, YANG Kaixuan, LIU Ming, YAN Junjie
    2024, 44(1): 148-156. https://doi.org/10.19805/j.cnki.jcspe.2024.220785
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    The calculation model of the multi-parameter design optimization and variable working conditions was developed for the waste heat recovery system of the pre-heater of coal-fired unit. The multi-parameter optimization for the system was performed. The control strategy of operating parameters was proposed. Results show that the coal-saving rate of the optimized system under the design condition is 3.67 g/(kW·h). Although the multi-parameter optimized system can maintain a high coal-saving rate under off-design working conditions, the safety is seriously restricted by the ambient temperature and unit load. The proposed control strategy can extend the lower limit of environmental temperature for safe operation of the system from 24 ℃ to -3 ℃ at 100% rated load, which significantly improves the comprehensive effect of system optimization.