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    Fundamental Research
  • Fundamental Research
    Numerical Study on Flow and Heat Transfer Characteristics of Supercritical CO2/R41 Mixtures in Spirally Fluted Tube
    LIN Zhibo, TAO Leren, QIU Han, DU Denggao, MA Yuyao
    2022, 42(9): 793-799. https://doi.org/10.19805/j.cnki.jcspe.2022.09.001
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    In order to reduce the working pressure of supercritical CO2 and enhance heat transfer, the flow and heat transfer process of CO2 and CO2/R41 mixtures under supercritical state in the spirally fluted tube was numerically simulated under constant heat flow cooling conditions, so as to analyze the effects of heat flux, mass flow rate and inclination angle on flow and heat transfer process. Results show that the maximum heat transfer coefficient of CO2/R41 is 7.7% higher than that of supercritical CO2 and the decay rate of heat transfer coefficient is lower, even its critical pressure difference is larger. The heat transfer coefficient of the spirally fluted tube is obviously improved in high temperature region than that in low temperature region, and the greater the heat flux is, the greater the heat transfer coefficient would be. Affected by the buoyancy force, the heat transfer coefficient is larger when the inclination angle is less than 0°, while heat transfer deterioration will occur when inclination angle varies from 45° to 90°, and vortices will be formed in the range of -45°-45°.
    • Power Equipment and System
  • Power Equipment and System
    Analysis of Sludge Blending Combustion on Wall Type Tangentially-fired Boiler
    YANG Kun, DING Shifa, ZHANG Tao
    2022, 42(9): 800-805. https://doi.org/10.19805/j.cnki.jcspe.2022.09.002
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    In order to verify the feasibility of blending high-water-content sludge in boilers, taking a 660 MW wall type tangential-fired boiler as an example, a numerical simulation model was established based on the field test data to analyze the influence of sludge on boiler combustion characteristics under different ratios and modes. Results show that with the increase of the sludge blending ratio, the velocity of the central flow field in the furnace decrease and the overall temperature in the furnace decrease, which will affect the combustion effect in the furnace and reduced the boiler efficiency. With the mixing ratio of 11%, the NOx concentration at the outlet is reduced by 22%. Under the same sludge mixing ratio, the combustion characteristics in the furnace can be effectively optimized by appropriately increasing the number of blending mills and reducing the sludge mixing ratio of single-layer burners.
  • Power Equipment and System
    Numerical Simulation of Particle Deposition on Supercritical Heating Surface
    ZENG Zilun, WANG Chao, LI Hongyuan, LI Yuhang, XU Hong
    2022, 42(9): 806-811. https://doi.org/10.19805/j.cnki.jcspe.2022.09.003
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    In order to clarify the motion law of the sediment in the flow field on the vapor side, the slender smooth horizontal circular tube was numerically simulated via a discrete term model. The turbulence model for cross-critical flow was compared and analyzed based on experimental data. Combined with the discrete term model, the particle incident geometric surface was defined according to the crystallization kinetics. And the deposition law of particles on the wall surface was analyzed under two limiting conditions of total capture and total reflection of the wall. Results show that the Realizable k-ε model is applicable for the turbulence simulation of supercritical water, and the deposition pattern of particles on the wall is affected by the flow field and is closely be related to the particle size. Small particles are mainly affected by the flow field and the collision frequency with the wall is higher , while the large particles are mainly affected by their own gravity which is benificial to the concentrated deposition of particles.The effect of thermophoresis force on small particle size is more obvious.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Comparative Study on Jacket and Monopile Foundation Response Under Seismic and Wind-Wave Loads of a 10 MW Offshore Wind Turbine
    YAN Yangtian, YUE Minnan, LI Chun, NIU Kailun
    2022, 42(9): 812-820. https://doi.org/10.19805/j.cnki.jcspe.2022.09.004
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    Taking a 10 MW offshore wind turbine with jacket foundation as an example, the interaction between flexible soil and pile foundation was described by p-y curves and Q-z curves. The finite element models of jacket and monopile wind turbine were established to study the structural dynamic response and bearing characteristics of two stuctures under seismic and wind-wave loads. Results show that both structures do eccentric reciprocating motion on the top of the tower under seismic and wind-wave loads. The seismic effect makes the lateral disturbance eccentricity more serious of monopile structure, but the disturbance amplitude of jacket structure is larger and the stress unloading is faster. The jacket structure is more stable than the monopile, but the partial load bearing pressure of certain part need to be reduced.
  • New Energy Resources and Energy Storage
    Study on Dynamic Stall Characteristics of the Airfoil with Locally Moving Surface
    ZHANG Xinyi, SUN Xiaojing
    2022, 42(9): 821-828. https://doi.org/10.19805/j.cnki.jcspe.2022.09.005
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    The effects of the length (l), velocity ratio (k), notch depth (h) and dimensionless position (s) of the moving surface on the dynamic stall characteristics of NACA0012 airfoil with locally moving surface were studied by numerical simulation. The control effects of the airfoils with surface jet and by moving surface boundary-layer control (MSBC) method on dynamic stall were compared. Results show that the dynamic stall characteristics of the airfoil are significantly improved by MSBC method. Under the optimum combination of parameters (s=0.4、l=0.4、k=1和h=0.25 mm), compared with the original airfoil, the equivalent lift-to-drag ratio of MSBC airfoil increases by 57.10%. When the energy dissipation coefficient is small, MSBC airfoil can achieve the purpose of improving the aerodynamic efficiency through less locally energy input compared with the airfoil with surface jet.
  • New Energy Resources and Energy Storage
    Effect of the Numbers of Partitions in the Collector System of a Parabolic Trough Concentrated Solar Power Station on System Performance
    HAN Jianguo, WANG Qiang, LIU Xiangmin, WANG Xingping, DU Yuhang, JIANG Zhihao
    2022, 42(9): 829-834. https://doi.org/10.19805/j.cnki.jcspe.2022.09.006
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    Taking a 50 MW parabolic trough concentrated solar power (CSP) station as the simulation object, according to the main parameters of the power station, a model of the parabolic trough solar thermal power generation system was established to analyze the effects of the numbers of partitions and loops in the collector system and heat storage time on the annual net power generation and the levelized cost of energy (LCOE). Results show that for 50 MW parabolic trough CSP station, the optimal number of the collectors in a single loop is four, the optimal number of partitions of the collector system is six, and the optimal heat storage time is 16 h.
  • New Energy Resources and Energy Storage
    Performance Analysis of Compressed Air Energy Storage System Coupled with Coal-fired Power Plant
    XUE Xiaojun, LI Yunfei, TIAN Yukun, PENG Cheng, CHEN Heng, XU Gang, CHEN Honggang, WANG Xiuyan
    2022, 42(9): 835-842. https://doi.org/10.19805/j.cnki.jcspe.2022.09.007
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    To improve the overall performance of the compressed air energy storage (CAES) system, based on the heat regenerative system of a coal-fired power plant, a scheme of CAES system coupled with the coal-fired power plant was proposed. In the energy storage process, the feedwater from the heat regenerative system in the coal-fired power plant was used to cool the compressed air at the outlet of the compressor. In the energy release process, the compressed air at the inlet of the expander was heated by the feedwater from the heat regenerative system. At the same time, the feedwater was used to recover the heat from the exhaust of the expander. Taking a 630 MW coal-fired power plant as a research object, the energy analysis, exergy analysis and economic analysis of the proposed system were carried out. Results show that the system integration can not only improve the performance of CAES system, but also remove the heat storage equipment of the conventional CAES system, showing that the proposed system is extremely feasible. For the proposed system, the circulation efficiency and exergy efficiency are 63.28% and 79.02%, respectively; the dynamic payback period is 7.06 years, and the net present value can reach 14 496.5 thousand yuan.
  • New Energy Resources and Energy Storage
    Performance Analysis and Optimization of AA-CAES System Under Different Operation Schemes
    LI Peng, LI Guoneng, SU Hang, SHEN Mingxuan, HU Qingya, HAN Zhonghe
    2022, 42(9): 843-851. https://doi.org/10.19805/j.cnki.jcspe.2022.09.008
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    Aiming at the problems of single storage mode, single output mode and low exergic efficiency of the advanced adiabatic compressed air energy storage (AA-CAES) system, four combination schemes of different output mode and storage mode were proposed, and system parameters were optimized under different operation schemes. The effects of energy storage power, maximum pressure ratio of gas storage chamber and compressor inlet temperature on the system performance under the four schemes were discussed from thermodynamic and economic point of view. Using the NSGA-Ⅱ algorithm, multi-objective optimization of the system was carried out with exergic density and annual interest rate as the objective function. Results show that exergic efficiency and annual interest rate are the highest in scheme 3, while exergic density is the biggest in scheme 4. With the increase of energy storage power, exergic efficiency and annual interest rate of the four schemes increase, while exergic density decreases. As maximum pressure ratio of gas storage chamber increases, exergic efficiency and annual interest rate of the system decrease, while exergic density increases. As compressor inlet temperature increases, annual interest rate and exergic efficiency of the system decrease, and exergic density of the system increases in scheme 3 and scheme 4, while decreases in scheme 1 and scheme 2. The optimal exergic densities of the four schemes are 5.92 MJ/m3, 6.73 MJ/m3, 9.00 MJ/m3 and 9.84 MJ/m3, respectively, and the optimal annual interest rates are 19.19%, 16.04%, 25.40% and 21.25%, respectively.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Cold State Experimental Study on Water-drop-shaped Tubular Rod-grid Desulfurization Synergistic Device
    LI Luming, LI Jun
    2022, 42(9): 852-856. https://doi.org/10.19805/j.cnki.jcspe.2022.09.009
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    A novel water-drop-shaped tubular rod-grid desulfurization device was proposed and a cold test was carried out on the desulfurization test bench. The variation laws of the resistance of the device with the gas velocity in the tower, the liquid-gas ratio and the gap between the pipe and grid were studied. Results show that the resistance of the water-drop-shaped tubular rod-grid desulfurization device increases with the increase of the gas velocity and the liquid-gas ratio, and decreases with the increase of the gap between the pipe and grid. Furthermore, under the fixed gas velocity and the liquid-gas ratio, the resistance of the water-drop-shaped tubular rod-grid desulfurization synergistic device can be controlled within the range of 500-800 Pa by selecting the appropriate grid gap.
  • Green Energy and Low-carbon Technology
    Simulation of Flue Gas Dechlorination in a Coal-fired Power Plant Based on CPFD Method
    LI Hengfan, JIAO Shiquan, LI Yulong, ZHENG Zipan, HAN Zhonghe
    2022, 42(9): 857-864. https://doi.org/10.19805/j.cnki.jcspe.2022.09.010
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    To reduce the concentration of HCl gas in the tail flue and the generation of desulfurization wastewater, Ca(OH)2 atomized slurry was injected into the tail flue. Aiming at the dechlorination process of removing HCl from the flue gas in the tail flue of a 330 MW boiler by Ca(OH)2 atomized slurry, the heat and mass transfer model and chemical reaction model between flue gas and Ca(OH)2 atomized slurry were established based on CPFD method. The effects of calcium chloride ratio (SR), flue gas velocity and temperature, droplet temperature and size, slurry concentration, and HCl and SO2 concentration on dechlorination efficiency were analyzed. Results show that with the increase of SR, dechlorination efficiency increases gradually,but the growth rate slows down gradually. At the same SR, flue gas velocity, droplet temperature and SO2 concentration in the flue gas have little effect on dechlorination efficiency, and the change of dechlorination efficiency is less than 3.65%. The increase of flue gas temperature and slurry concentration and the decrease of HCl concentration will reduce dechlorination efficiency. The dechlorination efficiency first increases and then decreases with the increase of the average droplet size,when the average droplet size is equal to 80 μm,the dechlorination efficiency is the highest.In practical application,reasonable calcium chloride ratio,droplet size and slurry concentration must be selected to prevent adverse effects on tail flue and subsequent equipment and improve dechlorination efficiency.
    • Integrated Energy System
  • Integrated Energy System
    Energy Efficiency Analysis and Evaluation Methods for Complex Thermal Systems Under Multiple Efficiency Perturbations
    CHEN Haiping, XUE Kaili, ZHANG Heng
    2022, 42(9): 865-872. https://doi.org/10.19805/j.cnki.jcspe.2022.09.011
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    Thermal system of thermal power units was taken as the object to exploring the influence law of simultaneous changes in sub-system efficiencies on total system thermal efficiency and the size of their weights.Based on the first law of thermodynamics, a computational model for analysis and evaluation of energy efficiency of complex thermal systems under multiple efficiency change modes was derived through rigorous theoretical deduction. Results show that when sub-efficiencies of multiple sub-systems or thermal equipments change simultaneously, the relative rate of change in whole plant thermal efficiency is equal to the sum of the relative rates of change in relevant sub-systems or thermal equipment sub-efficiencies.Through the error analysis under different boundary conditions, it is verified that the model fully meets actual engineering requirements.
  • Integrated Energy System
    Study on Optimization of Wind, Solar, Fuel and Storage Integrated Energy System Taking into Account the Cost of Carbon Emissions
    HAN Xu, ZHOU Junyi, LI Qi, WU Di, LI Peng, HAN Zhonghe
    2022, 42(9): 873-880. https://doi.org/10.19805/j.cnki.jcspe.2022.09.012
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    A set of integrated energy system coupled with wind, solar, fuel, storage and network was constructed.With the optimization objectives of system economy and environmental benefits, the equipment and parameters of the system were optimized to obtain the optimal system configuration under current constraints. Results show that among the five systems, the annual CO2 emission and total system cost of the wind, photo, combustion, storage and network system are the lowest. The wind, light, storage and network system has the best ability to absorb renewable energy, and the penetration rate of renewable energy is 69.93%, but the total cost is 159% of the wind, light, combustion, storage and network system. Photovoltaic prices and carbon tax prices are inversely proportional to annual CO2 emissions, and when the photovoltaic price reduction ratio reaches 40%, its limiting effect on annual CO2 emissions is no longer prominent.
  • Integrated Energy System
    Performance Analysis and Optimization of Two-stage Composite Source Heat Pump for Natural Gas Expansion Power Generation System
    XU Xiao, ZHANG Xiao, WU Zhengyong, ZOU Lei, FANG Chao, LU Dinghao
    2022, 42(9): 881-888. https://doi.org/10.19805/j.cnki.jcspe.2022.09.013
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    In order to reduce the excessive preheating energy consumption in natural gas expansion power generation process, a novel natural gas multi-stage expansion power generation system was proposed based on an air-soil composite source two-stage heat pump. Thermodynamic and exergy models of the system were established by Matlab and Aspen Plus. The optimal allocation strategy of expansion ratio and compression ratio under different working conditions was explored. Finally, the performance differences between the new and traditional systems were compared by taking a pressure regulating station in Yangzhou city as an example. Results show that compared with the single stage air-source and ground-source heat pump systems, the annual average net output power ratio of the new system is 0.799, which is incresed by 6.55% and 7.14% respectively; the annual average performance coefficient of heat pump is 5.46, increased by 20.31% and 27.76% respectively; the annual average exergy efficiency is 48.9%, increased by 7.35% and 7.93% respectively.