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The Thermal Stratification Evaluation of Phase-Change Materials in a heat Storage Tank: Computational Fluid Dynamics and Experimental Study

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JOURNAL OF SOLAR ENERGY engineering-TRANSACTIONS OF THE ASME 2020年第2期142卷 1-13页

作者： Wang, Zilong Zhang, Hua Dou, Binlin Zhang, Guanhua Huang, Huajie Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The heat storage technology can improve the performance of a solar thermal utilization system effectively. This work studied the effect of phase-change materials (PCMs) on thermal stratification in a heat storage tank. A 60 l sodium acetate trihydrate heat storage tank with 331.15 K phase-change temperature was designed and fabricated. A mathematical model was built to simulate the discharge process in the water tank, and the temperature distribution during the discharge process was obtained. The computational fluid dynamics model was verified by the experimental data. Furthermore, the Ri, the fill efficiency, and the MIX number were adopted to extensively analyze the performance of a heat storage tank with different positions of PCMs with the variation of flow rates. The results indicated that the distance between the isothermal surfaces of 303.15 K and 348.15 K in PCM1, PCM2, PCM3, and PCM4 were 11.75 cm, 11.13 cm, 10.52 cm, and 9.28 cm, respectively, with 9 l/min of flow velocity when t*= 0.7, showing that the thermal stratification was improved as the position of the PCMs got closer to the inlet. The PCMs' half-life (the liquefaction rate reached 50%) was prolonged as the inlet flow rates increased. As the flow rate increased from 1 l/min to 5 l/min, the half-life of PCM4 delayed from a dimensionless time of 0.5 to a dimensionless time of 0.9. Moreover, when the flow velocity was 9 L/min, the liquefaction rate of PCM4 remained at 1. The calculated values of fill efficiency and Richardson number were higher than the experimental data slightly, while the MIX number was smaller than the experimental results. The experimental and calculated values of root mean square error (RMSE) increased with the increasing inlet flow velocity and the lowering of the positions of the PCMs.

关键词： thermal stratification phase-change materials fill efficiency heat storage tank CFD conservation energy renewable solar thermodynamics

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Adsorption of Dibenzofuran by Modified Biochar Derived from Microwave Gasification

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SSRN 2024年

作者： Ren, Jiyun Zhang, Yong Wang, Hui Huang, Xiaoming Jin, Xiaoling Zhang, Kai Li, Ruiyu Yang, Kaixuan Yue, Yang Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Yantai Longyuan Power Technology Co. Ltd Yantai264000 China West Pipeline Company of PipeChina Urumchi830000 China Jinggangshan Power Plant Huaneng Power International Inc Jiangxi 343009 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating and microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques including BET, X-ray CT, SEM-EDS, FTIR, and XPS are performed to identify the DBF adsorption mechanism on biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. Higher porosity (16.94%) and lower mineral content (1.75%) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11%) > KOH-modified CSC (77.14%) > unmodified CSC (49.11%) > unmodified OC (39.70%) > HNO3-modified CSC (36.09%). The adsorption mechanisms of DBF on the gasified biochar encompass pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously. © 2024, The Authors. All rights reserved.

关键词： Potassium hydroxide

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A Thermal Calculation Model for Tubular Condensing heat Exchanger

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SSRN 2023年

作者： Han, Lei Yang, Kaixuan Yang, Jiahui Li, Ruiyu Li, Yuhang Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Shanghai Power Equipment Research Institute Co. Ltd. Shanghai200240 China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and Research Foshan528300 China Xi’an Thermal Power Research Institute Co. Ltd. Xi’an710032 China

The condensing heat exchanger is commonly applied in various heat exchange systems. It can efficiently recover moisture and heat from the flue gas that contains water vapor. However, the convective-condensation heat transfer process is so complicated that no mature thermal calculation model is available. This study develops a thermal calculation model for the widely employed tubular condensing heat exchanger in industry. To characterize the degree of the heat and mass transfer, this study introduces two parameters, namely the sensible and latent heat transfer efficiencies of fin. The thermal calculations are conducted for the condensing heat exchangers reported in the literature to verify the proposed model by comparing it with the experimental data. The results show that the absolute error of the calculated sensible and latent heat transfer efficiencies is 0.0365 and 0.0268, respectively. A maximum difference of 5.2 K has been acquired between the measured and calculated values of the outlet temperature. The relative error of the condensate water flowrate is mostly within ±5.0% and ±10.0% under the bare-tube and finned-tube conditions, respectively, with a maximum deviation of 0.7 and 1.4 kg h-1. This study provides a general model for designing and optimizing various tubular condensing heat exchangers accurately. © 2023, The Authors. All rights reserved.

关键词： Mass transfer

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Novel in-situ synthesis of metal nanoparticles-supported bulk photocatalyst and its application in 4-nitrophenol reduction

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APPLIED SURFACE SCIENCE 2022年 598卷

作者： Sun, Li Diao, Yuanyuan Shan, Yuejin Zhi, Yuan Zhang, Hua Dou, Binlin Huang, Weijia Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Jun Gong Rd 516 Shanghai 200093 Peoples R China Utsunomiya Univ Dept Mat & Environm Chem Res Div Funct Mat Design Yoto 7-1-2 Utsunomiya 3218585 Japan Shanghai Minrula Biotechnol Co Ltd R&D Dept Bldg 15 Haji Sixth Rd 218 Shanghai 201306 Peoples R China

Based on a normal copper wire, an effective photocatalyst (ACW) for the 4-nitrophenol (4-NP) reduction is successfully synthesized by an in-situ redox method. The constitution of ACW is similar to "ants on a tree ", i.e., dense Au and Cu nanoparticles (NPs) are loaded on the copper wire surface covered by submicro-sized Cu cubes. Employing ACW as photocatalyst, the conversion efficiency of 4-NP can achieve to 100% at 2.5 min and the rate constant for the 4-NP reduction can reach up to 1.45 min-1. Moreover, ACW exhibits satisfactory reusability for 25 cycles and stability in 12 months. These excellent performance can be attributed to the synergistic effect of Au NPs, Cu NPs and the Cu wire surface covered with submicro-sized cubes. Clearly, the above in-situ redox method provides a facile route to prepare metal NPs-supported bulk photocatalysts. Meanwhile, as-synthesized ACW can be a promising photocatalyst candidate for the practical treatment of 4-NP.

关键词： In-situ redox reaction Bulk photocatalyst 4-Nitrophenol reduction Au nanoparticles Cu nanoparticles

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Control of two-phase flow around a cylinder with a cylindrical attachment: A numerical study

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Ocean engineering 2025年 334卷

作者： Wang, Ziqing Hu, Yu Huang, Shengxian Zhang, Yongxing Moghtaderi, Behdad Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China National Engineering Laboratory for Pipeline Safety/MOE Key Laboratory of Petroleum Engineering/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum – Beijing Beijing102249 China Centre for Innovative Energy Technologies The University of Newcastle CallaghanNSW2308 Australia

Mitigating flow separation, vortex shedding and sediment-induced erosion around cylindrical structures is critical for enhancing marine engineering safety. This study investigates the hydrodynamic performance of a two-phase flow around a cylinder equipped with an auxiliary cylinder under realistic ocean conditions. key parameters include the clearance ratio (G/D), particle characteristics (size and concentration), and vibration modes of the auxiliary body. This study investigates real ocean conditions, focusing on the influence of clearance ratio (G/D) and an auxiliary cylinder on flow field changes with varying particle characteristics. The results demonstrate that: (1) A clearance ratio G/D = 0.1 yields the optimal drag reduction (57.18 %) for the primary cylinder in single-phase flow;(2) Larger particles weaken vortex-particle interactions, while higher particle concentrations exacerbate uneven deposition near the cylinder;(3) Transverse vibration of the auxiliary body (amplitude ratio = 0.025, frequency ratio = 0.65) reduces drag by 18.7 % compared to stationary configurations. These findings provide insights into flow control strategies for offshore structures subjected to sediment-laden flows. © 2025 Elsevier Ltd

关键词： Marine safety

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Experimental research on thermal deviation of high temperature reheater in the single tangential Π type boiler based on radiation spectroscopy analysis 7

Experimental research on thermal deviation of high temperatu...

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7th International Conference on power engineering, ICOPE 2019

作者： Xie, Jianwen Wen, Wubin Yang, Bin Yang, Fei Ping, Li Zhang, Fei Zhang, Jianwen Electric Power Research Institute Co. Ltd. Beijing100025 China Jiangsu Guohua Chenjiagang Power Generation Co. Ltd. Jiangsu Yancheng224631 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Boiler Works Ltd. Shanghai200245 China

The superimposed phenomenon of thermal deviation of low and high temperature reheaters was found under the high load condition in a 660MW ultra super-critical Π type boiler. And the discharge temperature deviation between the two sides of steam were more than 15℃ in high temperature reheater. In order to reveal the thermal deviation of high temperature reheater in this boiler, a probe was designed and developed to measure the visible radiation spectrums of coal dust in the high temperature reheater zone by using the servo mechanism of soot blower. The particle concentration and temperature of coal dust were obtained by the parameter fitting method based on Planck's radiation law. The measurement result shows that the burning delay of pulverized coal caused by originally equipped one-level air staged combustion system and enrichment of coal dust under the action of inertia are the main reasons of thermal deviation of high temperature reheater. And the momentum of SOFA to eliminate the rotation is insufficient in this boiler. In order to improve the thermal balance of both sides, a new type of the two-level air staged combustion system was proposed as principle of retrofit scheme. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Coal combustion

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Research on the Noise Reduction and Efficiency Increase for Axial Fan with Wave Leading Edge Blades

Research Square

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Research Square 2020年

作者： Li, Bo Wu, Yu-Jing Guo, Dan-Ge Luo, Dan Huang, Dian-Gui School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai China

This paper imitates the raised structure of the leading edge of the humpback whale fin limbs, designed six bionic blades. The aerodynamic analysis show that: the wave leading edge blade can improve the total pressure efficiency of the axial flow fan, and under off-design conditions, the aerodynamic performance of bionic fan is better than that of prototype fan. The noise analysis shows that: under the condition of constant wave number, increasing wave amplitude can reduce the overall sound pressure level at the monitoring point, in the middle and high frequency range, the sound pressure level of the bionic fan at the monitoring point is significantly lower than that of the prototype fan, and the noise reduction effect increases with the increase of wave amplitude;under the condition of constant wave amplitude, increasing the wave number can reduce the fan noise. At a certain wave number and amplitude, the overall sound pressure level of the bionic fan at the monitoring point is at most 2.91 dB lower than that of the prototype fan. In this paper, the noise reduction effect of increasing wave number is more obvious than that of increasing wave amplitude. © 2020, CC BY.

关键词： Noise abatement

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Aerodynamic and aeroacoustic performance assessment of a vertical axis wind turbine by synergistic effect of blowing and suction

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ENERGY CONVERSION AND MANAGEMENT 2022年 271卷

作者： Liu, Qingsong Miao, Weipao Bashir, Musa Xu, Zifei Yu, Nanting Luo, Shuai Li, Chun Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Liverpool John Moores Univ Liverpool Logist Offshore & Marine LOOM Res Inst Byrom St Liverpool L3 3AF England Univ Plymouth Sch Engn Comp & Math SECaM Plymouth PL48 AA England

The power efficiency of Darrieus wind turbines significantly deteriorates during rotation caused by periodic dynamic stall at low tip speed ratios. This leads to a strong fluctuation in torque and a reduction in energy acquisition. This paper aims to improve the aerodynamic performance of an H-type Darrieus wind turbine using an innovative fluidic flow control technique based on the synergistic effect of blowing and suction. The aero-acoustic noise emissions accomplished with this enhancement are evaluated. The Improved Delayed Detached Eddy Simulation turbulence model and the Ffowcs Williams-Hawkings acoustic analogy method are adopted to simulate the instantaneous flow field and predict the far field noise. Following validation of the numerical approach using wind tunnel experimental data on a static airfoil, an orthogonal experimental design method was used to analyze and optimize the operating factors. The factors include suction position relative to leading-edge (Ls), blowing position relative to trailing-edge (Lb) and jet coefficient (C mu). The results indicate that C mu plays crucial role in determining the airfoil performance, while the role of Lb is almost negligible. Furthermore, the impact of optimal combination of these factors was analyzed based on three different control strategies. It is found that appropriate application of the active control solution can eliminate the wind turbine's negative torque, avoid excessive alternating load on the rotor and improve the energy extraction efficiency. The aero-acoustic noise estimation shows that the active device can reduce the noise emission by moderating pressure fluctuation, stabilizing the flow field and influencing the vortex shedding. Similarly, the proposed active control solution can reduce the wind turbine noise level by up to 6.56 dB by modifying the sound pressure spectra at frequencies between 100 and 1000 Hz.

关键词： Vertical axis wind turbine Active flow control Aerodynamic Aeroacoustic Computational fluid dynamics Noise

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An ANN-based method for predicting Zhundong and other Chinese coal slagging potential

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FUEL 2021年 293卷 120271-120271页

作者： Yang, Haoran Jin, Jing Hou, Fengxiao He, Xiang Hang, Yixuan Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer 516 Jungong Rd Shanghai 200093 Peoples R China Lehigh Univ 27 Mem Dr West Bethlehem PA 18015 USA

Conventional ash-component-based slagging indices and ash fusion temperatures (AFTs) successfully predict the slagging behavior of steam coals. However, these methods fail to tell the ZDc slagging potential accurately. In this paper, a back propagation artificial neural network (BP-ANN) is proposed to predict the slagging potential for both ZDc and other steam coals. Python is used for the training, verification and test of the BP-ANN. In training and verification, 12 ZDc, 2 lignite, 3 blend coal samples are analyzed and other 63 coals are collected as data. The result shows that the accuracy rate of the network based on ash components is 62.5%, close to the value of conventional slagging indices. It can only predict the slagging potential of certain coals. In contrast, modifying the network with coal properties can greatly increase the accuracy rate to 87.5%. The verification results of 14 samples are completely consistent with the actual slagging behavior, and that of 2 samples shows the slagging tendency. After that, 30 samples are collected from other papers for test. The results of 25 samples are completely consistent with the actual slagging behavior and that of 3 samples shows the slagging tendency, only 2 samples telling the wrong results.

关键词： Zhundong coal Slagging potential Artificial neural network High calcium coal

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Defect engineering on sea-urchin-like transition-metal oxides for high-performance supercapacitors

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JOURNAL OF power SOURCES 2022年 533卷 231409-231409页

作者： Yin, Baoyi Hao, Liang Wei, Tao Wang, Chen Zhu, Bao Li, Xiaogan Yang, Qiguo Dalian Univ Technol Sch Microelect Dalian 116024 Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Univ Jinan Sch Mat Sci & Engn 336 Nanxinzhuang West Rd Jinan 250022 Shandong Peoples R China Fudan Univ Sch Microelect State Key Lab ASIC & Syst Shanghai 200433 Peoples R China Natl Integrated Circuit Innovat Ctr Shanghai 201203 Peoples R China

Reasonable design of nanostructures and application of Defect engineering have been proved to be essential for the construction of high-performance electrochemical energy storage devices. Herein, a defect engineering strategy is developed to fabricate a 3D multi-layered sea urchin-like structure assembled by 1D nanowire, which shows a high specific surface area for electrochemical active sites. More significantly, the phosphate-doping treatment introduces N/P elements in P-NiCo2O4, thus generates Co/Ni-P and Co/Ni-N bonds to create more oxygen vacancies. Vacancy defects manipulate the electronic structure of the electrode materials to obtain good physical and electrochemical properties. The prepared sea urchin-like P-NiCo2O4 electrode in this work exhibits exceptionally excellent charge storage capability in aqueous solutions with high specific capacitance (467 C g 1 at 1 A g 1), good rate capability, and ultra-high cycling stability at 20 A g 1 (87.2% capacitance retention over 10,000 cycles). Furthermore, the assembled asymmetric supercapacitor using P-NiCo2O4 cathode and AC anode shows a high energy density of 31.25 Wh kg 1 at a much large power density of 7500 W kg 1, and an outstanding cycling performance at 10 A g 1 (83.4% capacitance retention over 10,000 cycles). The prepared P-NiCo2O4 electrode materials are expected to be used in high-performance supercapacitors.

关键词： Defect engineering Oxygen vacancy High-power density Band generation

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