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    Advanced Intelligent Control
  • Advanced Intelligent Control
    Dynamic Characteristics and Coordinate Control Optimization of Steam Temperatures for an Ultra-supercritical Double-reheat Boiler with Three Rear Ducts
    YE Qing, WANG Chaoyang, YI Guangzhou, MA Zhaozhao, LIU Ming, YAN Junjie
    2023, 43(2): 117-125,184. https://doi.org/10.19805/j.cnki.jcspe.2023.02.001
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    To improve the steam temperature control accuracy of a 660 MW ultra-supercritical (supercritical) double-reheat boiler with three rear ducts and ensure its operation safety during the transient operation processes, based on dynamic model, the dynamic characteristics of the main and reheat steam temperatures of the boiler were studied and obtained after changing the opening of the baffles fixed in the rear flue gas ducts. Then an adjustment control strategy of the baffles with synergistic main and reheat steam temperatures was proposed and coupled with the boiler dynamic model. The control effects of the original logic and the synergistic logic considering the main and reheat steam temperatures on the steam temperatures were studied when the load changed in the range of 50%-100% boiler maximum continuous rating (BMCR). Results show that after adopting the logic considering the coordination of the main and reheat steam temperatures, the control accuracy is significantly improved, and the steam temperature fluctuation during the transient operation processes is reduced. The cumulative deviation of steam temperatures decreases by 40.9% and 15.7% respectively during the loading up and down processes.
  • Advanced Intelligent Control
    Cooperative Control Strategy of Source and Storage for Improving Frequency Regulation Performance of Wind Power
    YAO Lujin, WANG Wei, CAI Wei, LIU Jizhen
    2023, 43(2): 126-135,193. https://doi.org/10.19805/j.cnki.jcspe.2023.02.002
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    In order to improve the frequency regulation performance of wind power, a cooperative control strategy of source and storage based on adaptive model predictive control (AMPC) was proposed to flexibly adjust the output of each frequency regulation unit. Taking the rate of change of frequency (ROCOF) as the output conversion characteristic, the frequency regulation model of wind farm and the adaptive primary frequency regulation (PFR) control strategy of battery energy storage system (BESS) were constructed. And the source-storage cooperative PFR strategy was designed with the optimization of the frequency control effect of grid and the frequency regulation performance of wind power. Based on step and continuous disturbance loads, the corresponding PFR evaluation indexes were proposed respectively. Results show that the proposed strategy significantly improves the PFR effect under different disturbance conditions, and the PFR output of wind power increases by 69.67% under continuous load disturbance condition.
  • Advanced Intelligent Control
    Parallel Control of Thermal Power Unit for Large-scale Renewable Energy Accommodation
    GONG Linjuan, WANG Wenyu, GAO Yaokui, WANG Lin, GAO Lin, HOU Guolian
    2023, 43(2): 136-142. https://doi.org/10.19805/j.cnki.jcspe.2023.02.003
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    To guarantee the safety, economy and environment friendliness of power system in large-scale renewable energy accommodation process, and further improve the intelligent level of the power plant, a parallel control system was designed for thermal power units based on the theory of digital twin and parallel intelligence. Firstly, based on several typical thermal power units, some critical technics such as the dynamics modeling and intelligent control were coordinated to develop the artificial control system. Then, through the computation experiment and evaluation of artificial control system, the optimal dynamics model and control algorithms were determined for guiding the operation of actual power generation process, which provided the performance optimation for system. Moreover, the flexible and intelligent regulating ability of thermal power unit was ensured via parallel execution and feedback modification between the constructed artificial system and actual system. Results show that based on the proposed parallel control scheme, the average modeling error of the plant is less than 0.5% under the wide load operation conditions of 30%-100%, and the maximum deviation during load regulation process is less than 1% of the rated value, so the operation flexibility is remarkable.
  • Advanced Intelligent Control
    Combustion Optimization and Adaptive Coordination Control Based on Online Detection of Coal Quality
    WANG Wenyu, GONG Linjuan, WANG Lin, GAO Yaokui, ZHAO Zhangming, GAO Lin, XIE Beibei, TANG Yongfeng
    2023, 43(2): 143-150. https://doi.org/10.19805/j.cnki.jcspe.2023.02.004
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    To improve the adaptive ability of coal-fired units to the variation of coal quality, an on-line analysis system of coal quality was developed with a combination of laser-induced breakdown spectroscopy and soft sensing model. Based on the coal quality, the optimization control strategies of oxygen, secondary air, and over-fire air were proposed. An advanced coordination control method including fuzzy control and multi-quadrant interval division was proposed by using the calorific value of coal as an input. The accurate control of steam temperature, steam pressure and variation rate of load in a 1 000 MW unit was realized. Results show that the NOx concentration in the unit decreases, and the main output becomes more stable after the in-operation of combustion optimization control. After the in-operation of coordination control, the maximum pressure deviation in the steady state maintains at 0.13 MPa in the load range of 550 to 900 MW. And the main parameters keep stable without the swing phenomenon. In variable load operation mode, the maximum deviation of the main steam pressure maintains at about 0.5 MPa during the load increase or decrease,and the fluctuation of the superheat degree keeps at about 6 K, the water wall run well without the over temperature phenomenon.
    • Deep Peak Shaving and Energy Saving
  • Deep Peak Shaving and Energy Saving
    Design and Operation Optimization of Water Recovery System from Flue Gas for Coal-fired Power Plants
    JIA Chenhui, LIU Pei, LI Zheng
    2023, 43(2): 151-157,213. https://doi.org/10.19805/j.cnki.jcspe.2023.02.005
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    Ceramic composite membrane condensers can be used for water recovery from flue gas in coal-fired units, there exists a large range of power generation load fluctuation of coal-fired units. Therefore, a scenario-based two-stage design and operation optimization method was proposed. By considering the charateristics of load fluctuation, a group of scenarios with proability was generated, and the optimal design and operation scheme of ceramic composite membrane condenser was obtained with the lowest total investment and operation cost in the whole lifespan cycle as the objective function. Finally, a 330 MW coal-fired unit was taken as an example for calculation. Results show that compared with the reference scheme based on rated condition, the proposed scheme can reduce the membrane area by 3% and the total cost by 8%, the investment cost and the operation and maintenance cost are reduced by 3% and 12% respectively.
  • Deep Peak Shaving and Energy Saving
    Real-time Energy Consumption Analysis of Coal-fired Power Units During Load Change Transient Processes
    HE Ning, XIE Tian, YIN Junjie, WANG Wenbin, CUI Qingru, ZHAO Yongliang
    2023, 43(2): 158-164. https://doi.org/10.19805/j.cnki.jcspe.2023.02.006
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    Based on the calculation method of the energy consumption in the steady-state conditions and the operating characteristics during the transient processes of coal-fired power units, considering the change of boiler heat storage during the transient processes and the influence of steam thermodynamic parameters on the turbine efficiency, a more general energy consumption analysis model was established, which makes some simplification to meet engineering application requirements. The real-time energy consumption calculation of coal-fired units could be realized under the whole operating condition with the model. The energy consumption analysis model was applied to a 660 MW ultra-supercritical coal-fired power unit to verify the reliability, and the calculated coal consumption was compared with that of thermal system simulation model during the selected typical load change processes. Results show that the calculated energy consumption results are consistent with the trend of the measured coal consumption. Furthermore, the maximum deviation between the calculated values of the standard coal consumption rate with these two models is less than 1%.
  • Deep Peak Shaving and Energy Saving
    Optimal Design of Residual Pressure Cascade Utilization Heat Supply System with Absorption Heat Pump
    ZHOU Jiahui, DENG Genggeng, WANG Rukang, XU Gang, LIU Wenyi, WANG Yongxu
    2023, 43(2): 165-173. https://doi.org/10.19805/j.cnki.jcspe.2023.02.007
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    In view of the large exergy loss of steam extraction during the process of temperature and pressure reduction, a residual pressure cascade utilization heat supply system was proposed, in which two back-pressure small steam turbines were used to recover the residual energy of the extracted steam after temperature and pressure reduction before entering the heat pump and the peak heater. Taking a 600 MW cogeneration unit coupled with absorption heat pump as the research object, the off-design model of the heating system was established using EBSILON software, so as to analyze the energy, exergy, economy and sensitivity. Results show that under the benchmark heating condition, standard coal consumption rate of the new residual pressure cascade utilization heat supply system is 10.02 g/(kW·h) lower than that of the case system, and the exergy loss in the two temperature and pressure reducers before the heat pump and the peak heater is reduced by 77.77% and 78.99%, respectively. The net present value in the whole life cycle is expected to reach 139.242 2 million yuan, and the dynamic recovery period is 3.27 a. With the reduction of the unit power supply load and the increase of the supply and return water temperature of the heat network, the energy saving effect of the new residual pressure cascade utilization heat supply system can be improved.
  • Deep Peak Shaving and Energy Saving
    Effect of Boiler Operation Oxygen on Combustion Stability and NOx Emission Characteristics of a Tangentially Fired Boiler Under Ultra-low Load
    MA Dafu, LIU Pingyuan, ZHANG Shouyu, HE Xiang, WU Yuxin
    2023, 43(2): 174-184. https://doi.org/10.19805/j.cnki.jcspe.2023.02.008
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    Numerical simulation was used to investigate the distribution rules of temperature, oxygen, CO and NOx in a 300 MW tangential combustion boiler under ultra-low load and different oxygen operating conditions, to analyze the effect on combustion stability and NOx emission characteristics. Results show that compared with medium and high load, under 90 MW and 60 MW ultra-low load conditions with high boiler operation oxygen, the imaginary tangent circle is difficult to form and the combustion stability is weakened. The de-NOx effectiveness of the deep-air-staging combustion system gets worse. When the auxiliary air is completely turned off, the overall temperature of the furnace increases, the ignition distance is shorter. Meanwhile the imaginary tangent circle is easier to form, the burning-out distance increases, and the combustion stability is improved, and the average mass concentration of NOx is reduced by 29% and 24% respectively. Continuing to reduce the exhaust air volume until the operating oxygen volume reaches 3.5%, temperature of the separated over-fire air (SOFA) zone increases slightly, and the NOx emission decreases by 9% and 10% respectively. In addition, most of the total NOx at ultra-low load is fuel-NOx, and the reduction of oxygen has a significant effect on the reduction of NOx emission. Therefore, it is recommended to reduce the auxiliary air in the main combustion area under ultra-low load and keep the burnout air constant. The recommended oxygen values under 90 MW and 60 MW load are 6.5% and 8.5% respectively.
  • Deep Peak Shaving and Energy Saving
    Optimization of Plant-level Thermal and Power Load Distribution Under the Back-ground of Deep Peak Shaving
    WANG Rukang, ZHOU Jiahui, XU Gang, CHEN Honggang, WANG Yongxu
    2023, 43(2): 185-193. https://doi.org/10.19805/j.cnki.jcspe.2023.02.009
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    In order to solve the thermal power scheduling problem of cogeneration units with different capacity in the peak shaving auxiliary service market, the peak shaving scheduling model of multiple cogeneration units was established. The maximum profit of the whole plant was taken as the objective function, the piecewise cubic Hermite interpolation method was used to calculate the coal-fired cost.Moreover, considering the thermal power output constraints of the unit, the particle swarm optimization algorithm was used to solve the thermal power scheduling problem between units.Finally, the typical daily thermal power load of the thermal power plant was taken as an example.Results show that the peak shaving scheduling model can significantly improve total income of the plant, and the total income decreases with the increase of peak shaving allocation amount. When the thermal load increases, the total income also increases. When the power load of the whole plant is about 60% of the total rated capacity of the unit, the total income reaches the maximum.
    • CHP and Multi-energy Cogeneration
  • CHP and Multi-energy Cogeneration
    Optimal Scheduling of Combined Heat and Power-Virtual Power Plant Considering High-dimensional Uncertainty
    YUAN Zhiwei, YU Songyuan, FANG Fang, LIU Jizhen
    2023, 43(2): 194-204. https://doi.org/10.19805/j.cnki.jcspe.2023.02.010
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    Based on the Dirichlet process mixture model and the variational inference algorithm, a high-dimensional data-driven uncertain fuzzy set of wind power, solar power, electric load and heat load was established. On this basis, a two-stage stochastic robust optimization scheduling strategy for combined heat and power-virtual power plant (CHP-VPP) was proposed considering high-dimensional uncertainty. In the first and second stage, taking the maximum daily and real-time market revenue as the objective function, considering various constraints such as unit operation, power balance, market transactions and network structure, the accelerated column and constraint generation (AC&CG) algorithm was developed to solve the optimal scheduling problem. Results show that the proposed stochastic robust optimization method achieves the balance between the economy and robustness of CHP-VPP. The uncertain boundary value of the fuzzy set is negatively correlated with total revenue of the system. With the increase of uncertain boundary value, total revenue of the system decreases and the robustness increases.
  • CHP and Multi-energy Cogeneration
    Thermodynamics and Flexibility Analysis of a Novel Coal-fired CHP-CAES System
    LI Jiajia, LI Xingshuo, ZHOU Guowen, YAN Peigang, LIU Jinfu, YU Daren
    2023, 43(2): 205-213. https://doi.org/10.19805/j.cnki.jcspe.2023.02.011
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    To enchance operation flexibility, a novel integrated system of combined heat and power (CHP) unit, advanced adiabatic compressed air energy storage (AA-CAES) system, and district heating system was proposed. Energy flow analysis and system performance study based on a 350 MW CHP unit and a 30 MW AA-CAES system were carried out. The energy comprehensive utilization level and regulation range under the two modes of independent operation and coupled operation were analyzed. Results show that for the same heating load ratio of 80%, the energy utilization efficiency is enhanced by 1.10%. The minimum load rate is reduced by 11.69%, and the maximum power generation capacity is increased by 22.24 MW which is about 6.35% of the rated power. 27.26 tons of coal is saved for one cycle. The results are similar for other heating conditions. The advantages of the proposed system in heat-power decoupling, enhancing operation flexibility, clean heating, as well as energy utilization are demonstrated.
  • CHP and Multi-energy Cogeneration
    Thermal Performance and Flexibility Analysis of a Supercritical Carbon Dioxide Coal-fired Cogeneration System
    CHEN Dongxu, HAN Zhonghe, GUO Dongyang, BAI Yaping, LI Peng
    2023, 43(2): 214-221,236. https://doi.org/10.19805/j.cnki.jcspe.2023.02.012
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    To study the performance characteristic of a supercritical carbon dioxide (SCO2) coal-fired cogeneration system and point out the direction of system performance improvement, the simulated model of the SCO2 coal-fired cogeneration system was established by Ebsilon software. The thermal performance and flexibility of the system were analyzed, and the effects of design conditions on system performance were studied. Results show that under the design condition, the energy efficiency and exergy efficiency of the system are 89.74% and 44.03%, respectively. The operating domain area of the system is 11.40 m2, which is 93.55% higher than that of the traditional system. When the compressor inlet pressure is selected at 7.6 MPa, the system has higher exergy efficiency and better flexibility. When the compressor inlet pressure is selected at 11.2 MPa, the system has higher energy efficiency and better flexibility. Under the off-design condition that the heat supply split coefficient is less than 1, the thermal performance of the system could be improved by decreasing the precooler outlet temperature. To improve the system flexibility, the scheme to increase the maximum permissible flow rate of the system is preferred.
  • CHP and Multi-energy Cogeneration
    A New Type of Coupled Multistage Steam Ejector Heating System for Small Steam Turbine and Its Performance Analysis
    DENG Genggeng, ZHOU Jiahui, ZHOU Tianyu, XU Gang, LIU Wenyi, WANG Yongxu
    2023, 43(2): 222-230. https://doi.org/10.19805/j.cnki.jcspe.2023.02.013
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    A new heating system of small steam turbine coupled multistage steam ejector for cogeneration units was proposed to realize the cascade utilization of heating extraction steam energy, and to reduce the waste of steam quality and the loss of cold end caused by direct extraction heating of cogeneration units. Part of the heating extraction steam ejected the exhaust steam of the unit through the parallel steam ejector system. After the mixing of the heating extraction steam and the exhaust steam, the water of the heat network was heated in two stages. While the other part of steam entered the back pressure small steam turbine to do work, then entered the coupled heat network heater to heat the heat network backwater, so that it reached the specified heat network water supply temperature. Taking a 330 MW cogeneration unit as the research object, EBSILON 15.0 software was used for accurate modeling calculation of the system, and the detailed thermal performance and economic analyses of the system were carried out. Results show that compared with the case system, the overall standard coal consumption and the power generation coal consumption of the new system were reduced by 4.18 t/h and 15.84 g/(kW·h) respectively, and the total cogeneration efficiency is increased by 3.22%. The annualized new gains of the new system can reach 5.700 2 million yuan, indicating that the new system has good economic gains.
    • Flexibility Transformation and Fault Diagnosis
  • Flexibility Transformation and Fault Diagnosis
    Study on Dielectric Properties of Primary Air Powder Mixture in the Boiler
    GAO Manda, WU Zhen, HE Ning, WANG Yinan, LI Gengda, WANG Wenbin, GAO Xing, HE Xujie, QIAN Jiangbo
    2023, 43(2): 231-236. https://doi.org/10.19805/j.cnki.jcspe.2023.02.014
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    Theoretical study on dielectric properties of wind coal were carried out, and a new calculation model of complex dielectric constant of heterogeneous dielectric was established based on integral modification of Maxwell-Wagner heterogeneous dielectric model. The dielectric parameters of air and coal were measured experimentally, so as to obtain the variation of complex dielectric constant of wind coal with electric field frequency at different temperatures and pulverized coal concentrations. Results show that real part of the complex dielectric constant of wind coal increases with the increase of temperature and pulverized coal concentration, while decreases with the increase of electric field frequency. The imaginary part of the complex dielectric constant increases with the increase of temperature and pulverized coal concentration, and increases first and then decreases with the increase of electric field frequency.
  • Flexibility Transformation and Fault Diagnosis
    Fault Diagnosis of Main Steam Temperature System Based on Multi-graph Convolutional Neural Network
    WU Zheng, ZHANG Yue, DONG Ze
    2023, 43(2): 237-245. https://doi.org/10.19805/j.cnki.jcspe.2023.02.015
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    In view of the characteristics of the main steam temperature system with large delay, large inertia, nonlinearity and time-varying, a fault diagnosis method based on multi-graph fusion convolutional neural network was proposed. The adjacency graph and correlation graph were established to expand the historical operation data of the unit into non-Euclidean space graph data, and feature weights and truncation parameters were introduced to constrain the correlation between nodes. At the same time, the adjacency matrix was used to establish the topology information between the operating data, and information of the adjacent nodes was fused through the depth graph convolution structure to establish the mapping relationship between the system data and the operating state. Results show that compared with probabilistic neural network (PNN), long short-term memory (LTSM) and least squares support vector machine (LSSVM), fault diagnosis accuracy of the proposed MG-GCN model has been improved by 11%, 7% and 16% respectively, the model has lower false detection rate and missing detection rate, which can accurately identify various system fault types, and has good fault diagnosis performance.
    • Pollution and Carbon Reduction
  • Pollution and Carbon Reduction
    Research on Distributed Predictive Control of Carbon Capture System in Coal-fired Power Plant
    WU Quan, YANG Jinning, WANG Zhiyong, XU Dong, YANG Yang, TANG Zihan, WU Xiao
    2023, 43(2): 246-252,274. https://doi.org/10.19805/j.cnki.jcspe.2023.02.016
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    An optimal control method for CO2 capture system in coal-fired power plant based on distributed predictive control was proposed. Based on the dynamic matrix control principle, local predictive controllers were designed for the coal-fired power plant and the CO2 capture system respectively. Finally, the proposed control method was simulated and tested on a 660 MW supercritical coal-fired power plant coupled with a monoethanolamine based carbon capture system. Results show that the distributed predictive control method achieves global optimal control effect on both sides of electric and carbon with high computational efficiency, and the control effect is significantly better than the conventional decentralized predictive control method.
  • Pollution and Carbon Reduction
    Study on Output Variation of a 660 MW Coal-fired Power Plant with Solar-assisted Carbon Capture
    LIU Jun, CHEN Heng, ZHAO Shuyuan, LI Bo, PAN Peiyuan, XU Gang
    2023, 43(2): 253-261. https://doi.org/10.19805/j.cnki.jcspe.2023.02.017
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    To study the effect of carbon capture on the output, a simulation model was established to analyze the performance change of a coal-fired unit after carbon capture device retrofit. The system was divided into two schemes, which are the conventional scheme and the solar-assisted scheme. The conventional scheme extracted steam from the unit intermediate-pressure turbine to supply energy to the carbon capture device, while solar-assisted scheme used solar energy to completely replace the extracted vapor to improve the performance of the coal-fired power plant. Taking a 660 MW coal-fired unit as the research object, the impact of carbon capture retrofit on the performance of the unit was analyzed, and the effect of solar assist on unit performance enhancement was compared with the conventional scheme. Results show that compared with the original coal-fired unit, the unit's maximum output in the conventional scheme is reduced from 666.70 MW to 466.31 MW, and the power supply efficiency is reduced from 42.79% to 30.69%. The unit output in the solar-assisted scheme can reach 604.30-608.06 MW, which indicates that carbon capture can significantly impact the maximum output of the coal-fired power plant and using solar-assisted carbon capture can primarily restore the work capacity of the unit.
  • Pollution and Carbon Reduction
    Study on Optimization of Flue Gas Bypass Heating Technology Based on Multi-pipe and Multi-point Mixing
    LU Lianxiang, YANG Zhenli, ZHANG Yize, MA Weiwei, ZHU Yifan, ZHOU Hao
    2023, 43(2): 262-268. https://doi.org/10.19805/j.cnki.jcspe.2023.02.018
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    In order to solve the problem of low denitrification efficiency due to temperature reduction under the low load of thermal power units, the main flue of a 350 MW supercritical unit boiler was used as the research object, and a multi-pipe and multi-point mixing scheme was proposed to verify its thermal mixing effect through numerical simulation. Then the scheme was applied to industrial production. Results show that the problem of uneven longitudinal temperature distribution in the flue after the original single-strand jet thermal mixing is effectively improved in the proposed scheme, and the horizontal temperature deviation caused by uneven flow distribution is further eliminated by adding the main flue baffles.The temperature distribution unevenness coefficient of the three schemes was reduced from 0.502 to 0.138, the reduction of which is 72.51%. The even temperature distribution of high and low temperature flue gas mixing can be realized in the proposed scheme. The optimized scheme will make the inlet flue gas temperature of selective catalytic reduction (SCR) achieve a rise of 26.3 K at 40% load, effectively solving the problem of low load SCR inlet flue gas temperature leading to excessive pollutant emissions.
    • New Energy
  • New Energy
    Comparative Analysis of Thermal Performance of Compressed Gas Energy Storage Systems Using Different Working Fluids
    LI Yanghai, MEI Xin, XU Wanbing, WANG Yuanjing, YANG Tao, ZHANG Yanping
    2023, 43(2): 269-274. https://doi.org/10.19805/j.cnki.jcspe.2023.02.019
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    By improving the structure of compressed gas energy storage(CGES) systems at high, medium and low temperatures, air and CO2 were used for simulation respectively, and the system cycle efficiency, energy storage density and exergy analysis were analyzed and compared when different working fluids were used. Results show that the cycle efficiency of the high and medium temperature systems using air as working fluid is higher, while that of the low temperature system is opposite. The exergy efficiency of the system using air is higher. The system using CO2 as working fluid has higher energy storage density and lower overall exergy input, exergy output and exergy loss.
  • New Energy
    Heat Transfer Performance Optimization of Enhanced Shell-Tube Thermal Storage Units Based on S-CO2
    FANG Minghui, CAO Lihua, CONG Yu
    2023, 43(2): 275-282. https://doi.org/10.19805/j.cnki.jcspe.2023.02.020
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    In order to understand the heat transfer performance of shell-tube thermal storage units, an optimization method to improve the thermal storage performance of shell-tube phase change thermal storage units was proposed. First, a high-quality selection of different HTFs was performed and the structural parameters of the shell-tube phase change thermal storage units were optimized based on regression orthogonal tests. Results show that the regressed equation satisfies the significance and lack-of-fit test, and the validation results are within 1% error of the equation calculation.A combination of supercritical CO2 (S-CO2) at 800 ℃ and 20 MPa and a tube diameter ratio of 0.666 3 is optimal.The optimized thermal storage unit obtains a maximum heat storage capacity of 2 674.52 kJ with an increase of about 39.5% compared to the pre-optimization, and the heat transfer rate decreases from 1.76 kW to 0.007 kW.