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    Fundamental Research
  • Fundamental Research
    Study on Heat Storage Characteristics of Variable Proportion Phase Change Cascade Packed Bed
    CONG Yu, CAO Lihua, MENG Yuxin, ZHANG Zhongbin
    2023, 43(3): 283-291. https://doi.org/10.19805/j.cnkij.cspe.2023.03.001
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    To investigate the impacts of different phase change materials (PCM) ratios in the cascade packed bed on the thermal performance, seven kinds of physical models of phase change capsule thermal accumulation beds with different packing ratios were established. Via monitoring the heat exchange fluid and PCM temperature using numerical simulation, other indicators acquired from calculation were the heat storage, the exergy efficiency, the heat storage rate, and the heat storage rate density which were compared with relative indicators to characterize the thermal performance of the packed bed. Results show that with the increase of the proportion of high melting point PCM, the exergy efficiency of the packed bed increases. However, all other indicators increase with the increase of the proportion of low melting point PCM. In addition, the cascade packed bed with a stepped increase (or decrease) in the percentage of PCM from low to high melting point has a significant improvement in thermal storage quality (thermal storage efficiency) compared to the evenly divided cascade packed bed, which proves that the reasonable optimized ratio of PCM in the cascade packed bed can effectively improve its thermal performance.
  • Fundamental Research
    Flow and Heat Transfer of the 2DOF Cylinder Under Vortex-induced Vibration at Low Reynolds Number
    WANG Gang, WANG Zhiyun, ZHANG Lixin, SHANG Lixin, YANG Mo
    2023, 43(3): 292-299. https://doi.org/10.19805/j.cnkij.cspe.2023.03.002
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    The flow of fluid, vibration of the cylinder and heat transfer characteristics between the two at low Reynolds number were studied numerically when vortex induced vibration (VIV) occured. The Navier-Stokes equation was solved by the finite volume method to obtain flow field, and the fourth-order Runge-Kutta algorithm was used to solve motion characteristics of the cylinder, so as to analyze the effects of different Reynolds numbers and reduced velocity on vortex-induced vibration and heat transfer of the cylinder with two degrees of freedom(2DOF). Results show that vibration of the cylinder is in the "8" shape, and the vortex shedding mode is "2S" under different reduced velocities. The heat transfer is affected by vortex shedding frequency and vibration amplitude of the cylinder. For the 2DOF vortex-induced vibration cylinder, the vortex shedding frequency is closest to the natural frequency of the cylinder at reduced velocity of 4, leading to severe vibration of the cylinder and large vibration amplitude. Moreover, time average Nusselt number of 2DOF vortex-induced vibration cylinder is significantly higher than that of one-degree-of-freedom.
  • Fundamental Research
    Reaction Molecular Dynamics Study on the effect of H2O on HCN Oxidation in O2/H2O Atmosphere
    HONG Dikun, ZHAI Xiaoming, GUO Xin
    2023, 43(3): 300-306. https://doi.org/10.19805/j.cnkij.cspe.2023.03.003
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    The chemical effect of high concentration of H2O on HCN oxidation in O2/H2O atmosphere was studied by ReaxFF MD method, so as to compare the experimental results of HCN content with simulation results at different temperatures. Besides, HCN oxidation rate, the distribution of O and OH radicals, and the distribution of CO and CO2 products were analyzed in O2/N2 and O2/H2O atmospheres, the effect mechanism of H2O on NO generation was revealed by analyzing the evolution path and distribution of nitrogen-containing species. Results show that the HCN content distribution in the experimental temperature range of 1100-1350 K is consistent with the results in the simulated temperature range of 1500-2500 K. The concentration of OH radicals increases in O2/H2O atmosphere, thereby promoting the oxidation of HCN and the conversion of CO to CO2. Although the contribution of evolution path of HCNHOCNNH2HNONO to NO production can be enhanced by H2O, while it greatly weakens the contribution of the evolution path of HCNCNNNO, thus inhibiting the production of NO on the whole.
    • Power Equipment and System
  • Power Equipment and System
    Temperature Field Modeling and Thermal Stress Simulation in Vertical Water-wall Weld Staggered Region of the Ultra-supercritical Boiler
    QIAN Jun, YAN Zhenrong, WANG Huanan, CHEN Le, HE Xiang, MA Dafu
    2023, 43(3): 307-313. https://doi.org/10.19805/j.cnkij.cspe.2023.03.004
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    Taking a 660 MW ultra-supercritical boiler as research object, the temperature field model in vertical water-wall weld staggered region was constructed to study the effects of thermal stress on cracks. Results show that the temperature at the fire-facing side of the tube girth weld in the weld staggered region is higher than that of the straight tube wall, and it is easier to crack than that of the straight tube wall in case of overtemperature. The maximum axial tensile stress is located near the fire-facing side at the weld toe of the tube girth weld in the weld staggered region. It is more likely to cause alternating thermal stress under variable load operating conditions and transverse cracks would be formed extending along the weld toe of the tube girth weld. The equivalent stress at the stress concentration position in the weld staggered region is greater than that at the corresponding position of the straight tube section. The equivalent stress at the junction between the weld toe of the tube girth weld and the fin fillet weld on the back fire side is the largest, which exceeds the corresponding high-temperature yield strength, and cracks would be induced by alternating thermal stress, and the cracks extend along the weld toe of the tube girth weld to the tube wall on the back fire side.
  • Power Equipment and System
    Numerical Simulation of Flame Transfer Function of Swirl Premixed Flame Based on White Noise Signal
    REN Lilei, GUO Qingbo, WANG Kun, QIN Yupeng, YANG Yu
    2023, 43(3): 314-318. https://doi.org/10.19805/j.cnkij.cspe.2023.03.005
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    The vortex premixed flame was disturbed by two different broadband noise signals and their spectral characteristics were compared. The accuracy of the transfer function program was verified by the classical proportional control link. Meanwhile,the accuracy of the calculation results was verified by the transfer functions between the velocity pulsations at different positions and the flame transfer function between flame heat release and velocity pulsation. Results show that the flame transfer functions of the two signals basically coincide with each other and have obvious convective characteristics. The interaction between convective vortex and flame is the internal mechanism leading to heat release fluctuation. The amplitude-frequency characteristics show obvious low-pass characteristics, and the phase-frequency characteristics meet the proportional relationship. The research has important engineering application value for the combustion chamber design.
  • Power Equipment and System
    Effect of Inlet Condition on Film Cooling Performance of a Fan-shaped Hole
    LIU Pengmin, CUI Xiaofeng, LIN Chixiang, DAI Ren
    2023, 43(3): 319-325. https://doi.org/10.19805/j.cnkij.cspe.2023.03.006
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    Under the condition of cross-flow inlet, the effects of cross-flow ratios of 0,0.2 and 0.4 and inlet blockage (upstream and downstream sides of cross-flow) on the film cooling characteristics of fan-shaped holes under different blowing ratios were studied based on the film cooling plate experiment. Results show that when the crossflow ratio decreases from 0.4 to 0.2, the film deflection of the fan-shaped hole is reduced and the film performance is improved. But when the crossflow ratio approaches zero, the coolant deflects to the opposite side with performance decline. Blockage on the downstream side aggravates the film deflection and reduces the cooling effectiveness. Blockage on the upstream side reverses the coolant deflection direction and raises the coolant coverage. Effects of inlet blockage on film cooling effecive depend on the hole location and the coolant serving flow conditions.
  • Power Equipment and System
    Design and Verification of Submergence Test System for Qualification of Third-generation Nuclear Power Equipment
    GE Lei, CHEN Gongming, WU Danlei, CHEN Zhiqiang
    2023, 43(3): 326-331. https://doi.org/10.19805/j.cnkij.cspe.2023.03.007
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    In order to verify the functional characteristics of the nuclear grade equipment in the third generation nuclear power plant under immersion conditions, a set of immersion test system was designed and debugged by analyzing the required curve of immersion test and the key problems affecting the test results. Results show that the test curve obtained by the debugging system is consistent with the required test curve. The immersion test system can meet the needs of nuclear grade equipment identification and simulate the immersion state of equipment after an accident in a nuclear power plant.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Study on the Effect of Active Component V of SCR Catalyst on SO2 Oxidation
    YIN Zijun, SU Sheng, ZHONG Yuxiu, QING Mengxia, HUANG Jianxun, WANG Yi, HU Song, XIANG Jun
    2023, 43(3): 332-340. https://doi.org/10.19805/j.cnkij.cspe.2023.03.008
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    The V2O5-TiO2 catalyst produced by ultrasonic impregnation method was used to study the effects of different V loadings on the formation of SO3 at the catalyst surface. The samples were characterized by N2 adsorption, X-ray diffraction (XRD), Raman analysis (Raman), X-ray photoelectron spectroscopy (XPS), NH3 temperature programmed desorption (NH3-TPD), H2 temperature programmed reduction (H2-TPR) methods. Results show that with the increase of active component V loading, the content of V4+ and V3+ formed on the catalyst during the reaction also increases, and when the acidity of the catalyst surface increases, the amount of oxygen (Oα) adsorbed by the VO bond on the catalyst surface will increase as well. After introduction of SO2, it will react with VO on the surface of the catalyst. V5+ is reduced to V4+ and can provide more surface that allows adsorption of oxygen (Oα), so that SO2 can be oxidized to VOSO4. On the other hand, SO2 will also react with the [V5+]-OH groups on the catalyst surface and produce HSO-4, and simultaneously, V5+ is reduced to V4+. During the reaction, O2 dose not directly provide O atoms to oxidize SO2 but reacts with VOSO4 to regenerate VO, transforming V4+ oxidized to V5+ again.
  • New Energy Resources and Energy Storage
    The Spatial-temporal Evolution of the Vertical Axis Wind Turbines Wake
    TIAN Tian, SUN Chong, ZHU Xiaocheng, DU Zhaohui
    2023, 43(3): 341-348. https://doi.org/10.19805/j.cnkij.cspe.2023.03.009
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    Aiming at analyzing the wake evolution features of 3-blade vertical axis wind turbines (VAWT), a dynamic mode decomposition (DMD) was used to evaluate statistics spatial-temporal features of the flow field under unsteady flow field computations, and spectrum analysis of the wake flow field of wind turbine was carried out at the tip speed ratio of 2.65. Results show that different frequency characteristics are observed respectively at the near wake, the transition region of the wake, and the far wake. The DMD decomposition results extract the flow modes corresponding to the above different characteristic frequencies, and successfully capture the flow structures of different scales in the downstream wake flow field. The first five main modes visually display the flow characteristic structures of three different regions in the wake flow field.
  • New Energy Resources and Energy Storage
    Performance Analysis of Semi-closed S-CO2 Brayton Cycle Based on Carbon Capture System
    TIAN Songfeng, LIU Yaxuan, LI Zhengkuan, LIU Shiyao, BAO Zhongxiang
    2023, 43(3): 349-358. https://doi.org/10.19805/j.cnkij.cspe.2023.03.010
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    Aiming at the problem of unused supercritical and large flow characteristics of CO2 in the recovery and storage process of high-temperature calcium-based carbon capture technology, the semi-closed supercritical carbon dioxide (S-CO2) Brayton cycle system was proposed to replace the conventional CO2 recovery and storage system to reduce the heat loss caused by the carbon capture system. Aspen Plus software was used to build a gas turbine power generation model coupled with calcium-cyclic carbon capture, which couples the S-CO2 Brayton cycle system and transcritical carbon dioxide (T-CO2) Brayton cycle system in the CO2 recovery system. REFPROR physical property method with higher precision was used to study the effects of main compressor outlet pressure, turbine inlet temperature, turbine inlet pressure and shunting coefficient on the net work of the circle system. Results show that through coupling the S-CO2 Brayton cycle system in the CO2 recovery system, the thermal efficiency of the plant can be increased by 1.7%, and the exergy efficiency is 26.98%. The method of diverting pure flue gas to generate a heat source for the S-CO2 Brayton cycle system can improve the thermal efficiency of the same residual heat by 6.7%.
  • New Energy Resources and Energy Storage
    Effect of Cathode Baffle Arrangement on PEMFC Reactant Transport and Performance
    CHU Xu, GUO Xueyan
    2023, 43(3): 359-364. https://doi.org/10.19805/j.cnkij.cspe.2023.03.011
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    To improve the performance of the proton exchange membrane fuel cell (PEMFC), the baffles were installed in the gas channels to enhance the species transport from the reaction gas to the catalytic layer. A three-dimensional, two-phase and steady PEMFC numerical model was established and three baffle arrangements were selected, which were "high to low" arrangement, "low to high to low" arrangement and "low to high" arrangement. The effects of three different baffle arrangements in the cathode side flow channel on the performance of PEMFC were studied and compared with those of the unbaffled flow channel case. Then based on the optimum arrangement of baffles, the effects of three baffle shapes (rectangular, trapezoidal and semicircular) on the performance of PEMFC were studied. Results show that the "low to high" arrangement in the cathode side flow channel has the best performance because its net power is increased by 14.3% when compared with the flow field of the unbaffled channel. Among three simulated baffle shapes, the performance of the trapezoidal baffle is the best, achieving an increase of 16.4% in net power compared with that of the unbaffled channel case.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Macrokinetics of Simultaneous Desulfurization and Denitration by NaClO2 Solution in a Double Stirred Reactor
    ZANG Yao, QIAN Xin, LIANG Zian, JIN Quanzhi, LIU Feng, QI Liqiang
    2023, 43(3): 365-371. https://doi.org/10.19805/j.cnkij.cspe.2023.03.012
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    The macrokinetics of simultaneous desulfurization and denitration from flue gas by NaClO2 solution was studied in a self-designed double-stirred reactor with fixed gas-liquid mass transfer interface. The effects of solution pH, reaction temperature, initial concentration of SO2, NO and NaClO2 on SO2, NO and NO<i>x reaction rate were studied, so as to calculate reaction order and the constant of reaction rate. Results show that increasing reaction temperature and decreasing pH within a certain range are conducive to the increase of NO<i>x reaction rate.The initial concentration of NO has no significant effect on SO2 reaction rate,but with the increase of initial mass concentration of NO, the reaction rate of NO and NO<i>x increases. With the increase of initial mass concentration of SO2, the reaction rate of SO2 increases, while the reaction rate of NO<i>x increases first and then decreases. The reaction orders of NO and SO2 are 0.699 and 0.843 respectively, the reaction rate constants of NO and SO2 are 6.30 mg0.301/(m2.903·s) and 2.20 mg0.157/(m2.471·s) respectively.
  • Green Energy and Low-carbon Technology
    Numerical Study on Gas-Liquid Distribution and Mixing Characteristics of Spray Drying Desulfurization Tower Under Swirling Flue Gas
    CHEN Hong, TANG Qiang, KUANG Zenghui, MI Hui, DING Baizhong
    2023, 43(3): 372-379. https://doi.org/10.19805/j.cnkij.cspe.2023.03.013
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    Focusing on the mixing problem in the spray drying desulfurization tower, the discrete phase model (DPM) was used to numerically analyze the radial displacement of the droplet group, the droplet group dispersion, and the gas-liquid mixing, and the effects of the flue gas swirl intensity (S) and the average droplet size (d) were particularly studied. Results show that with the flue gas swirl intensity increasing from 0 to 0.5, the radial displacement of the droplet group decreases slowly at first then increases rapidly. The radial displacement of the droplet group presents a linear augment with an increase of average droplet size from 65 μm to 150 μm. The droplet group dispersion increases at the beginning and then decreases with the increase of flue gas swirl intensity and average droplet size. The appropriate flue gas swirl intensity and average droplet size can effectively reduce the gas-liquid mixing variance and thus significantly improve gas-liquid mixing. When the swirl intensity is 0.3, the radial displacement of the droplet group and the gas-liquid mixing variance are the smallest. Compared with the absence of a swirl scenario, the radial displacement of the droplet group is reduced by about 20% on average, and the gas-liquid mixing variance is reduced by about 34.45% on average. When the average droplet size is 150 μm, the droplet group dispersion degree reaches the maximum, while the gas-liquid mixing variance is the smallest. Compared with the average droplet size of 65 μm, the gas-liquid mixing variance decreases by about 51.85% on average.
    • Integrated Energy System
  • Integrated Energy System
    Performance Analysis of the Cogeneration Waste Heat Heating System Integrated with a Steam Ejector Under Full Conditions
    ZHANG Youjun, GE Zhihua, PANG Jingshuai, XU Lei, YANG Zhiping, DU Xiaoze
    2023, 43(3): 380-390. https://doi.org/10.19805/j.cnkij.cspe.2023.03.014
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    To improve the utilization rate of industrial waste heat, a novel cogeneration waste heat recovery heating system coupled with a steam ejector was proposed. This model allowed part of the low-temperature exhaust steam to be injected into the extraction steam and used as an intermediate heat source to cascade heating water in the heating network. Considering the energy matching characteristics of the steam ejector, taking a 350 MW cogeneration unit as a case, the operation parameters of the ejector were determined through variable calculated working conditions and the cascade heating system integration was completed. Based on this simulation, the thermodynamic system model was established and the research on the thermodynamic performances and applicability of variable working conditions was analyzed. Results show that compared with the case system, the new system has acquired an extra 12.15% of exhaust steam utilization rate under designed heating condition, an increase of 4.64% in the average power generation thermal efficiency, and a reduction of 8.50 g/(kW·h) in the standard coal consumption rate. The flexibility of load regulation is also improved, when the heating load rate reaches 80%, the peak capacity ratio of the new system can be increased to 27.26%, which is 5.78% higher than that of the case system.