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    Fundamental Research
  • Fundamental Research
    Experimental and Prediction Model of Flow Boiling Heat Exchange in a Vertical Narrow Rectangular Channel Heated by Steam
    ZHAO Xiefei, TAO Leren, JIN Cheng, JU Yiwei, HUANG Lihao
    2023, 43(8): 959-966. https://doi.org/10.19805/j.cnki.jcspe.2023.08.001
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    In order to study the heat transfer characteristics of flow boiling in narrow channels, the single-sided steam heating experiments were carried out in a vertical narrow rectangular channel. The influences of mass flow rate, inlet subcooling rate were analyzed, and the prediction equation of flow boiling heat transfer suitable for vertical narrow rectangular channels was established. Currently, most empirical formulas ignore the influence of inlet subcooling on bubble growth process, which results in low accuracy in predicting flow boiling heat transfer. Considering the size limitations of narrow rectangular channels and the influence of fluid surface tension, a new prediction model was established by introducing correlation coefficients. Results show that with the increase of mass flow rate or the decrease of inlet subcooling, the wall temperature increases first,then decreases and tends to be consistent finally. The decrease of the inlet subcooling will greatly improve the heat transfer coefficient, while the mass flow rate has little influence on the heat transfer coefficient. When the inlet subcooling is high, the influence of the mass flow rate is further weakened. The new predicted model could better predict the flow boiling heat transfer coefficient of narrow rectangular channel within the experimental conditions.
  • Fundamental Research
    Effects of Inflow Reynolds Number on Spray Characteristics of a Pressure Swirl Atomization Nozzle
    LUO Junwei, CHEN Yuxiao, ZHANG Zewu, LUO Cong, ZHANG Liqi
    2023, 43(8): 967-973. https://doi.org/10.19805/j.cnki.jcspe.2023.08.002
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    In order to reveal the mechanism of the medium flow and viscosity in the atomization process of pressure nozzle, a simulation approach combining large eddy simulation (LES) and volume of fluid (VOF) was adopted to explore the flow in the nozzle, and the effects of inflow Reynolds number (Re) on flow coefficient, atomization angle and particle size were analyzed. Results show that the flow coefficient of the nozzle and the liquid film thickness at the nozzle outlet decrease with the increase of Re. When Re is high, the effect of inflow Re on the flow coefficient is less.With the increase of Re, the atomization angle of the nozzle increases. When Re is less than 1 000, the increase of atomization angle is more obvious with the increase of Re. For a certain Re, the atomization angle is almost equal. When Re is higher, the Sauter mean diameters (dSMD) of atomized droplets are more uniform, and the distribution of the atomization particle size is closer to the characteristics of Rosin-Rammler (R-R) function.
  • Fundamental Research
    Effect of Turbulence and Non-uniform Particle Structure on Heat Storage Performance of Packed Bed Phase-change Thermal Storage Tank
    LIU Yun, ZHAO Xu, SHEN Wenran, XIE Lingtian
    2023, 43(8): 974-982. https://doi.org/10.19805/j.cnki.jcspe.2023.08.003
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    Taking the packed bed phase-change thermal storage tank as the research object, a local non-thermal equilibrium model of porous medium was established without mesh discretization of each encapsulated particle., by using the binary nitrate composing of 60%NaNO3 and 40%KNO3 as the heat transfer fluid, and the mixed molten salt of 59.98%MgCl2, 20.42%KCl and 19.6%NaCl as the phase-change material. The heat storage performance of packed bed phase-change thermal storage tank was numerically studied,and the influence of turbulence and particle structure on heat storage performance of the thermal storage tank was analyzed. To improve the heat storage performance of thermal storage tank, non-uniform particle distribution was adopted and compared with the uniform particle distribution. Results show that compared with the uniform particle diameter of 0.025 m and 0.015 m, the complete melting duration of phase-change material with the particle diameter of 0.025 m at the upper end and 0.015 m at the lower end decreases by 3.81% and 1.90%, respectively.
    • Power Equipment and System
  • Power Equipment and System
    A Comprehensive High Temperature Corrosion Model Based on Integrated Coupled Heat Transfer Model for Coal-fired Boiler
    LI Junjie, YAN Jingwen, JIN Donghao, LIU Xin, ZHANG Chaoqun, LI Chi, WANG Heyang
    2023, 43(8): 983-991. https://doi.org/10.19805/j.cnki.jcspe.2023.08.004
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    To accurately predict the high temperature corrosion of boiler water wall, a comprehensive high temperature corrosion model that incorporates the effects of both tube temperature and H2S concentration was proposed. The tube temperature depends on both the gas side heat transfer and the steam side heat transfer of the boiler, which is difficult to be simulated within a single model framework due to the great dimention difference between furnace and tube. Thus, a coupled heat transfer model was developed to provide accurate prediction of tube wall temperature. This model involved a three-dimensional CFD model and a one-dimensional hydrodynamic model to separately simulate the flow and heat transfer processes of the gas and the steam sides of the boiler. The corrosion model was applied to a 350 MW supercritical boiler. Results show that local high tube temperature zones can be formed on the water wall, leading to a substantial acceleration of wall corrosion rate despite the relatively low H2S concentration there.
  • Power Equipment and System
    Influence of Non-uniform Flow Jet on Tip Clearance Leakage Flow Under Oblique Blade Tip Shape
    LIAN Zhibo, DU Xuefei, XU Bin, HUANG Diangui
    2023, 43(8): 992-999. https://doi.org/10.19805/j.cnki.jcspe.2023.08.005
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    A control method of non-uniform flow jet was adopted, which meant that the flow rate of the tip jet hole was distributed in a quadratic curve along the axial chord length direction. Based on the LISA turbine, the influence of non-uniform flow jet on the tip clearance leakage flow under oblique blade tip shape was explored by numerical simulation.Results show that compared with the leading edge to trailing edge clearance from small to large, the non-uniform flow jet is more advantageous to control the gap flow in the tip gap with the leading edge to trailing edge clearance from large to small. Compared with no flow jet, the maximum increase of total isentropic efficiency of turbine can reach 2.20%, the maximum decrease of mass flow average total pressure loss coefficient on rotor outlet can reach 37.56%, and the maximum decrease of relative clearance leakage flow can reach 48.57%. When the jet flow ratio (the ratio of jet flow to main stream flow) is less than 1.0%, the distribution mode of large single-hole flow rate at the leading edge of the blade tip is adopted. When the jet flow ratio is larger than 1.0%, the single-hole flow rate in the middle of the blade tip is increased, and this non-uniform jet distribution pattern is more effective than the uniform flow distribution jet control.
  • Power Equipment and System
    Analysis and Experimental Research of Factors Influencing the Temperature of Journal Cross Section in Sliding Bearing
    FU Hao, SHEN Deming, YANG Jiangang, ZHOU Hao
    2023, 43(8): 1000-1005. https://doi.org/10.19805/j.cnki.jcspe.2023.08.006
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    To investigate the unstable vibration in synchronous whirl, a rotor test rig was established. The influence of rotary speed, whirl amplitude and static eccentricity on the temperature distribution of journal cross section in sliding bearing was experimentally studied, and a heat balance model was applied for the calculation and analysis. Results show that the difference of viscous shear stress between the thinnest and thickest parts of the oil film under journal whirl leads to temperature difference on journal cross section and rotor thermal deformation. The maximum temperature difference of journal surface increases approximately linearly with rotary speed and non-linearly with whirl amplitude. With increasing of static eccentricity, the temperature difference and oil film stiffness of the journal cross section both increase. And the effect of vibration suppression caused by the increasing of oil film stiffness is greater than that caused by the thermal deformation induced by temperature difference, which decreases the vibration.
  • Power Equipment and System
    Thermodynamic and Economic Analyses on Mixed Combustion Power System Integrating with Coal Slime Drying
    LIU Rongtang, WANG Yu, FAN Peipei, LIU Ming
    2023, 43(8): 1006-1014. https://doi.org/10.19805/j.cnki.jcspe.2023.08.007
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    In order to improve the comprehensive utilization efficiency of coal slime, the coal slime drying technology was coupled with the coal slime mixed combustion power system. Coal slime mixed combustion power systems integrating with steam/air drying were constructed. Based on the basic law of thermodynamics and the theory of technical economy, analysis models of thermo-economic and techno-economic for the system were established, respectively. Energy, exergy and economic analyses on the system of a 660 MW coal-fired unit were carried out. Results show that the coal saving capacity of the coal slime mixed combustion power systems integrating with steam/air drying is 2.07-9.44 g/(kW·h) and 1.19-5.43 g/(kW·h), respectively, when the coal slime ratio is 25%-90%. The energy saving essence of the system is that heat source in the drying process before coal slime furnace is low-grade energy rather than the high-grade energy, which reduces irreversible loss in combustion process and exergy loss in flue gas emissions. Payback periods of the coal slime mixed combustion power systems integrating with steam/air drying are 5.0 years and 3.1 years, and the maximum net present values in 20 years are 6.941 million yuan and 5.405 million yuan, respectively. From the perspective of thermodynamics/technology and economy, the performance of the coal slime mixed combustion power systems integrating with steam/air drying is better when the power plant remaining life is less than 8.9 years.
  • Power Equipment and System
    Influence Mechanism of Operating Parameters on Performance of Curved-arm Steam Water Separator
    YANG Xuelong, ZHU Chenbing, ZOU Daohang, MOU Jiegang
    2023, 43(8): 1015-1021. https://doi.org/10.19805/j.cnki.jcspe.2023.08.008
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    The effects of operating parameters, such as steam load, circulation ratio and water level, on the performance of curved-arm steam water separator for steam generator of CANDU6 reactor were calculated and analyzed by computational fluid dynamics (CFD) technology. Euler two fluid model and three sizes of the water droplets, which were 100 μm, 200 μm and 300 μm respectively, were used to simulate the two-phase flow of steam and water in the separator. Results show that the influential trend of operating parameters on separation performance is basically identical for all the three droplet sizes, the droplet size independence law applies. When the droplet size is 300 μm, more accurate separation efficiency and pressure loss value can be obtained. As the steam load is increased, the separation efficiency increases and the outlet humidity decreases, while the circulation ratio and the water level result an opposite influential trend. The pressure loss increases as steam load or circulation ratio increases, but the pressure loss coefficient decreases, the influence of water level on pressure loss and pressure loss coefficient can be ignored.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Aerodynamic Performance Investigation of Vertical Axis Wind Turbines with the Synergistic Effect of Blowing and Suction
    LIU Qingsong, MIAO Weipao, LUO Shuai, LI Chun
    2023, 43(8): 1022-1029. https://doi.org/10.19805/j.cnki.jcspe.2023.08.009
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    For the complex flow field characteristics of vertical axis wind turbine (VAWT), an active flow control method based on the synergistic effect of blowing and suction was proposed to suppress the dynamic stall phenomenon caused by periodic changes in the angle of attack. The effect on the aerodynamic performance of the VAWT was investigated by simultaneous suction and blowing at the leading edge of the airfoil suction surface and the trailing edge of the pressure surface using high-precision numerical simulations. Results show that the synergistic jet is most effective in improving the wind energy utilization at low to medium tip speed ratios, which can significantly slow down the dynamic stall of the blade, eliminate the negative torque of the whole machine, and then reduce the centrifugal force of the blade and increase the stability and safety of the wind turbine.
  • New Energy Resources and Energy Storage
    Numerical Simulation of Supercritical Carbon Dioxide Solar Cavity Receiver
    XIONG Lie, YANG Kai, HUANG Xiaohong, ZHANG Yanping, LI Li
    2023, 43(8): 1030-1038. https://doi.org/10.19805/j.cnki.jcspe.2023.08.010
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    A type of supercritical carbon dioxide truncated cone cavity heat receiver was designed and developed for the solar energy disk concentrator. The optic-thermal model of the cavity heat receiver was established, and the optic-thermal characteristics of the cavity heat receiver were analyzed by Monte Carlo ray tracing method. Based on the related theory, the thermal boundary conditions were introduced as the input parameters to import into Ansys Fluent software. CFD simulation was carried out to study the optical characteristics and flow heat transfer characteristics of the cavity heat receiver. The outlet temperature, pressure drop, optical efficiency, thermal efficiency and losses of heat convection, radiation and conduction were obtained under different inlet temperatures (100-200℃) and different solar radiation intensities (400-1 200 W/m2). Results show that the optical efficiency of the cavity heat receiver remains basically unchanged under different solar radiation intensities. The influence of solar radiation intensity on the thermal efficiency of cavity heat receiver is not significant. The higher the inlet temperature of the working fluid is, the lower the thermal efficiency of the cavity heat receiver is. In the heat losses of cavity heat receiver, natural convection heat loss is the largest, followed by radiation heat loss and heat conduction heat loss.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Damage Identification of Wind Turbine Pitch Bearing Based on OVME and SMHD
    TANG Guiji, XUE Gui, WANG Xiaolong
    2023, 43(8): 1039-1046. https://doi.org/10.19805/j.cnki.jcspe.2023.08.011
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    Aiming at the problem of damage identification of the wind turbine pitch bearings, a novel damage identification method based on optimal variational mode extraction(OVME) combined with sparse maximum harmonic-to-noise ratio deconvolution (SMHD) was proposed, aiming to extract specific signal components from composite signals. Firstly, the energy characteristic index was taken as the fitness function, and the white shark optimization algorithm was used to search for the optimal combination of influencing parameters of the variational mode extraction algorithm, so that the optimal values of the balance factor and the center frequency of the variational mode extraction were determined. Then, the variational mode extraction was used to extract the specific signal components from the vibration signals, and the extracted signal components were further deconvolved by sparse maximum harmonic-to-noise ratio to improve the signal-to-noise ratio of the signal and obtain the deconvolved signal. Finally, the envelope spectrum of the deconvolved signal was analyzed to extract the bearing damage characteristic frequency. Results show that the proposed method can accurately identify the damage characteristics of the wind turbine pitch bearings, which has a certain reference value for practical engineering.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Research on the Influence of Rotary Kiln Air Inlet Modes on Hazardous Waste Combustion
    LIU Wenhui, DENG Dandan, ZHANG Rui, ZOU Liangdong, WANG Fei
    2023, 43(8): 1047-1053. https://doi.org/10.19805/j.cnki.jcspe.2023.08.012
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    To explore the influence of rotary kiln air inlet modes on hazardous waste combustion, Fluent software was adopted to study the combustion process in a rotary kiln. The effects of three air inlet modes including double-channel swirl air inlet mode, single-channel swirl air inlet mode and annular air inlet mode on temperature field, component field, velocity field and burnout rate were simulated. Results show that under the double-channel swirl air inlet mode, the average temperature of the cross section of the rotary kiln is the highest, O2 concentration at the tail of the kiln is the lowest, and CO2 concentration is the highest while the concentration of CO is reduced to 0. In this condition, the gas turbulence in the kiln and the speed of hazardous waste are both the highest, the materials are completely burned out, and the coke conversion rate is the highest. Under the annular air inlet mode, average temperature of rotary kiln is the lowest while O2 concentration is the highest at the tail of the kiln, CO2 concentration is the lowest and CO is not fully converted. In this condition, the gas turbulent intensity and hazardous waste velocity are both the minimal. Therefore, the material burnout rate and coke conversion rate are both the lowest.The parameters under the single channel swirl inlet mode are between the above two.
  • Green Energy and Low-carbon Technology
    Influence of CuO Oxygen Carrier on Mercury Migration in Coal Chemical Looping Combustion
    LIU Qiuqi, LIU Dunyu, WANG Jingjie, FAN Yunpei, XU Kailong
    2023, 43(8): 1054-1059. https://doi.org/10.19805/j.cnki.jcspe.2023.08.013
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    The combustion and mercury migration patterns in "CuO+coal", "SiO2+coal" and "coal" experiments were studied. Results show that after the reaction between the oxygen carrier and coal in the chemical looping combustion reduction reactor, the main gas component is CO2, with a small amount of volatile substances such as CO, CH4 and H2, etc. Mercury is mainly released in the form of elemental mercury (Hg0) in the reduction reactor. In the "CuO+coal" experiment, released amount of Hg0 accounted for 22.6% of the total mercury released amount, which is much lower than the reference group. CuO promotes the migration of mercury to the oxygen carrier during the combustion process, forming particulate mercury (HgP). The Oα on the surface of CuO oxygen carrier is conducive to the conversion and adsorption of mercury onto the surface of the oxygen carriers, resulting in the formation of adsorbed HgO. When CuO is partially reduced, more adsorption sites are exposed, which is conducive to the oxidation of Hg0.
  • Green Energy and Low-carbon Technology
    Study on Environmental Footprint of Hardwood-like Biomass Used in Direct Combustion Power Generation
    ZHU Guangyan, TIAN Yajun, LI Junjie, XIE Kechang
    2023, 43(8): 1060-1067. https://doi.org/10.19805/j.cnki.jcspe.2023.08.014
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    Based on the life cycle assessment method, inventory data of hardwood used in direct combustion power generation was established. The ILCD Midpoint+ method was used to evaluate six environmental impact types, and the main pollutants causing various environmental impacts were analyzed. At the same time, multiple power generation methods were compared in terms of six environmental impact types. Results show that the environmental impact of the direct combustion of hardwood for power generation mainly comes from the planting process and power generation process, with global warming mainly coming from the power generation process, and the other five types of environmental impact mainly coming from the planting process. Nitrogen oxide, sulfur oxide, ammonia and greenhouse gas are the main factors causing environmental impact of each unit process. In terms of environmental impact, compared with hydropower, wind power, and photovoltaic power generation methods, hardwood direct combustion power generation has certain disadvantages, but its environmental impact is much lower than traditional fossil energy power generation methods.
    • Integrated Energy System
  • Integrated Energy System
    Performance Analysis of Combined Heat and Power System Coupling Fuel Cell and Organic Rankine Cycle Based on Methanol Reforming
    ZHANG Zhong, AN Jizhen, PAN Peiyuan, CHEN Heng, XU Gang
    2023, 43(8): 1068-1076. https://doi.org/10.19805/j.cnki.jcspe.2023.08.015
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    To solve the issue of difficult hydrogen storage and transportation, and to achieve efficient and clean utilization of methanol fuel, a combined heat and power system coupling fuel cell and organic Rankine cycle based on methanol reforming was proposed. In the proposed system, the reforming reaction of methanol with water under mid-low temperature condition yielded hydrogen-rich syngas. The chemical energy contained in hydrogen-rich syngas was converted to electricity in the fuel cell. The high temperature exhaust gas from the fuel cell could be used to heat the air and as a heat source for the organic Rankine cycle, and energy cascade utilization was achieved. Under the system steady operation condition, energy, exergy and economic analyses were carried out for the new system. Results show that the total output power of the new system is 147.372 kW, the system efficiency is 51.29%, and the system exergy efficiency is 40.56%. The dynamic payback period of the new system is 4.97 years. With a 15-year life span, the net present value is 1.279 4 million yuan.
  • Integrated Energy System
    Thermodynamic Analysis on Flash-type Waste Heat Power Generation System Coupled with Carbon Capture Unit in Cement Kilns
    JIAO Wenting, CHENG Weiliang
    2023, 43(8): 1077-1084. https://doi.org/10.19805/j.cnki.jcspe.2023.08.016
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    To achieve the cascade utilization of low-temperature waste heat from cement kilns and the carbon capture of flue gas, a novel flash-type waste heat power generation system integrated with carbon capture unit was proposed. The primary saturated flash steam of the waste heat power generation system was used as the heat source for the carbon capture unit. Then, the saturated water generated steam through the secondary flash, and the generated steam was sent to the steam turbine as supplementary steam to generate power. The Aspen Plus and Ebsilon software were used to simulate the carbon capture unit and the waste heat power generation system, respectively. The thermal integration of the system was optimized, and the technology of the carbon capture unit was further improved to reduce carbon capture energy consumption. Meanwhile, from perspectives of energy and exergy, the thermal performance variation of the system after integrated with the carbon capture unit was deeply analyzed. On this basis, the influence of carbon capture energy consumption on the performance of the novel system was further analyzed. Results show that the proposed system has a generating capacity of 7.452 MW, and captures about 110 000 tons of CO2 annually. The carbon capture energy consumption rate decreases from 3.58 GJ/t to 3.08 GJ/t, and the cycle efficiency and net power generation efficiency can be increased by 0.51 and 0.9 percentage points, respectively.
  • Integrated Energy System
    Performance Study of an Efficient and Flexible Heating System Based on Cascade Use of Energy
    ZHANG Yichen, YANG Yongping, GE Zhihua, YANG Zhiping, ZHENG Lijun
    2023, 43(8): 1085-1094. https://doi.org/10.19805/j.cnki.jcspe.2023.08.017
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    An efficient and flexible heating system coupled with low-grade waste heat and extraction steam was constructed to balance efficiency and flexibility. The performance indexes of heating and peak shaving were determined and the thermal model was established by Ebsilon. The thermal performance of the system under design and off-design conditions in the case area was studied. The adjustable range of electric load under different heating loads was obtained. The flexible operation and control strategy and the energy consumption characteristics of the system were analyzed in case of simultaneously meeting heat and electric demand.Results show that the system achieves low energy consumption heating by matching energy and quality, reducing specific equivalent electricity consumption. The specific coal consumption for heat supply is 13.3 kg/GJ under the design condition. The maximum peaking capacity ratio is 48.1%, which is 24.3% higher than the back-extracting mode. When the electric and heat load change, the operation mode switches among back-extracting-cutting modes, and the specific coal consumption for heat supply ranges from 8 to 14.7 kg/GJ. The specific coal consumption for heat supply increases with the decrease of electric load. The system develops the energy-saving advantage of supplying heat by waste heat and realizes heat and power decoupling in a certain range. Both "efficient" and "flexible" operation are taken into account.
  • Integrated Energy System
    Optimal Operation Strategy of Multi-source Cogeneration System for
    Industrial Park Considering Carbon Trading
    JIA Xiaoqiang, LI Dezhi, CHEN Hongyin
    2023, 43(8): 1095-1102. https://doi.org/10.19805/j.cnki.jcspe.2023.08.018
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    In order to study the impact of participating in carbon trading on the operation strategy of multi-source cogeneration system combined cooling heating and power, taking an industrial park as the research object, a multi-source cogeneration system including energy storage was constructed. Taking the electrothermal characteristics, climbing power limit of combined heating and power (CHP) and supply-demand balance as constraints and the annual comprehensive cost including operation cost and carbon transaction cost as optimization objectives, the effects of parameters including the proportion of photovoltaic utilization area (x) and the heat distribution coefficient of waste heat boiler input absorption chiller (μ) on the comprehensive cost and carbon emission of the system were studied. Results show that photovoltaic equipment has a greater impact on the system economy than solar boiler. The best economy is obtained when x is 90%. The ranges of μ in four seasons are[0,1],[0.74,1],[0,1],[0,0.21], which should be valued reasonably according to season and demand.