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Recommendation for strut designs of vertical axis wind turbines: Effects of strut profiles and connecting configurations on the aerodynamic performance

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ENERGY CONVERSION AND MANAGEMENT 2023年 276卷

作者： Miao, Weipao Liu, Qingsong Zhang, Qiang Xu, Zifei Li, Chun Yue, Minnan Zhang, Wanfu Ye, Zhou Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Liverpool John Moores Univ Dept Maritime & Mech Engn Byrom St Liverpool L3 3AF Lancs England Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

The strut is a necessary support structure that connects the vertical axis wind turbine blade to the rotating shaft and transfers the torque, and is one of the key factors affecting the aerodynamic performance of the wind turbine. However, research on struts is limited and the appropriate strut design remain uncertain. Therefore, in this paper, the struts of a straight-bladed vertical axis wind turbine are investigated by a three-dimensional computational fluid dynamics approach, to find the appropriate strut design parameters that minimize the impact on the aerodynamic performance. Thirty strut profiles with different chord lengths, thicknesses, areas, and streamlined shapes were parametrically created and analyzed, including a novel strut-specific profile proposed in this paper. Furthermore, all strut connecting parameters, such as spanwise and chordwise positions, connecting angle and fairing were investigated. The results show that the power loss of a vertical axis wind turbine has a relatively linear relationship with the dimensionless absolute thickness of the strut within a certain range. The strut chord length is another important influencing factor. Equal chord lengths of the strut and the blade should be avoided as much as possible. The proposed novel olivary strut profile has lower drag characteristics and more favorable geometrical structural properties compared to the most used NACA airfoil. The influence of the spanwise connecting position (within the range around the blade quarter span) is minor. But the chordwise position has a significant effect, and special attention should be paid to avoid the strut maximum thickness position connecting with the blade aerodynamic center, which will result in the greatest performance degradation. Analysis of the connecting angles shows that inclined struts are suitable for small wind turbines. The fairing is effective when the strut chord length is equal to or longer than the blade chord length. With these results,

关键词： Strut effects H-type VAWT Aerodynamic drags Strut parameters CFD

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Simultaneous Absorption of NOx and SO2 into Water and Acids under High Pressures

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ENERGY & FUELS 2020年第8期34卷 9787-9795页

作者： Cheng, Qian Li, Wei Liu, Dunyu Chen, Jun Yang, Huinan Jin, Jing Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Scrubbing of SO2 and NOx from oxy-fuel combustion flue gas under a high pressure has been well recognized as an effective technique for flue gas purification. Experiments were performed in a bubbling column under high pressure to explore the absorption products and the SO2 selectivity during simultaneous absorption of SO2 and NOx. The main absorption product in liquid phase at pH > 1 was identified as hydroxylamine disulfonic acid (HADS), which was then quantified by the Raman spectroscopy. The N2O concentration in gas phase was estimated by the nitrogen mass balance across the system. Results showed that N2O and HADS were produced dominantly by the reaction between HNO2 and HSO3- at pH > 1, and this followed the Raschig mechanism. However, the absorption of SO2 was promoted while the absorption of NOx was inhibited, and this followed the lead chamber mechanism. Based on the quantification of the nitrogen and sulfur related products in both gas and liquid phase, about 48%-56% NQ and 14%-17% SO2 were consumed by the Raschig mechanism, and 15%-23% SO2 was consumed by the lead chamber mechanism in the pH range 1.09-1.72. For simultaneous absorption of NOx and SO2, SO2 was completely absorbed in different solutions except in the 18.4 mol/L H2SO4. A high concentration of H2SO4 suppressed the absorption of NOx but cannot achieve selective absorption of SO2 without absorbing NO. HNO3 concentration did not have appreciable effect on NOx absorption efficiency in the concentration range 0.1-1 mol/L. When the concentration of HNO3 was 15 mol/L, NQ was no longer absorbed into liquid solution. The mixed acids produced by the simultaneous absorption of NOx and SO2 can cause severe corrosion to a 316L stainless steel tube.

关键词： Electrochemistry Liquids Absorption Nitrogen Oxidation

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Design of Solar Dish/Stirling Rotation Control System with Dual Axis Solar Tracker 40

Design of Solar Dish/Stirling Rotation Control System with D...

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40th Chinese Control Conference (CCC)

作者： Zhou, Zhijie Chen, Jiaxing Hu, Zhuohuan Nie, Daolin Wen, Chulin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Jiehan Ind Automat Shanghai Co Ltd Shanghai 201800 Peoples R China

ISBN: (纸本)9789881563804

This paper presents a dual-axis tracking control system for a Small Dish/Stirling System (SDSS). The sun trajectory tracking algorithm was applied for all-weather accurate sun tracking. The rotating devices consist of two brushless DC motors, an encoder, an inclinator and slewing drivers. The dual-axis solar tracker was applied to improve the system's accuracy. Experimental results show that the system performance is reliable, and the average sun-tracking accuracy achieves 0.278 degrees and 0.321 degrees for azimuth and zenith respectively.

关键词： Dish/Stirling system Solar tracking Dual axis DC motor

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Fault diagnosis of rolling bearing using CNN and PCA fractal based feature extraction

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MEASUREMENT 2023年 223卷

作者： Zhao, Kaicheng Xiao, Junqing Li, Chun Xu, Zifei Yue, Minnan 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 Dept Maritime & Mech Engn Byrom St Liverpool L3 3AF England

A novel adaptive decomposition algorithm based on CEEMDAN and fractal dimension is proposed in this study to overcome limitations like redundancy and mode confusion in traditional EMD-based algorithms. An intelligent fault diagnosis model is developed using CNN and the proposed CEEMDAN to enhance rolling bearing state recognition. Sub-signals generated by CEEMDAN are selected and reconstructed using PCA and fractal dimension. In feature extraction and pattern recognition, the proposed Improve Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN), coupled with CNN, extracts advanced features from the reconstructed signal for intelligent diagnosis. The methodology is validated through empirical experiments involving rolling bearings, where its superiority and reliability are compared with approaches based on CNN. The accuracy of this method reaches 99.79%

关键词： Complete ensemble empirical mode decomposition with adaptive noise Convolutional neural network Rolling bearing Box dimension Fault diagnosis

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Ranking Oxygen Carriers for Elemental Mercury Oxidation in Coal-Fired Chemical-Looping Combustion: A Thermodynamic Approach

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ENERGY & FUELS 2020年第2期34卷 2355-2365页

作者： Ni, Mingguo Liu, Dunyu Jin, Jing Feng, Liang Liu, Zhuang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Oxygen carriers in coal-fired chemical looping combustion can oxidize elemental mercury, but there are still no specific criteria to rank the efficiencies of Hg-0 oxidation by classification of different oxygen carriers. Both an experimental approach and thermodynamic modeling were adopted to evaluate the Hg-0 oxidation efficiencies in the case of eight commonly used oxygen carriers, applying a temperature range from 800 to 1000 degrees C. The efficiency of the Hg-0 oxidation process in experiments within this temperature range was found to correspond well with the amounts of Cl/Cl-2 in the calculated reaction products. Results have shown that the sequence of the amounts of Cl/Cl-2 for different oxygen carriers was as follows: CaSO4 > Co3O4 (Mn2O3) > Fe2O3 > CuO (CeO2) > SiO2 (Al2O3). This sequence was in agreement with the simulations of the experiments investigating the efficiency of Hg-0 oxidation. According to thermodynamic calculations, the oxidation mechanism of Hg(0 )can be classified into two categories: MxOy- based mechanisms (Fe2O3 , CuO, Co3O4, Mn2O3, CeO2, Al2O3, and SiO2) and CaSO4-based processes. Hg-0 oxidation by MxOy follows three reaction pathways. In the first instance, Hg-0 can be oxidized by Cl-2 to form HgCl2;in the second reaction pathway, Hg-0 can be oxidized by Cl to form HgCl, which is oxidized afterward by Cl/Cl-2 to HgCl2. In the third reaction pathway, Hg-0 is oxidized by oxygen atoms to HgO, which is then oxidized by Cl2O to form HgCl2. In comparison, the oxidation of Hg-0 by CaSO4 is different from that of other oxygen carriers with existing additional reaction pathways. Hg-0 is converted first to HgS before being oxidized to HgCl2. The approach in this study may be used for choosing the optimum oxygen carriers for Hg-0 oxidation in coal-fired chemical-looping combustion processes.

关键词： Oxygen Chemical reactions Mercury Oxidation Metals

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Experimental investigation of the comprehensive heat transfer performance of PCMs filled with CMF in a heat storage device

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INTERNATIONAL JOURNAL OF heat AND MASS transfer 2022年 188卷 122582-122582页

作者： Zhu, Mengshuai Wang, Zilong Zhang, Hua Sun, Xiangxin Dou, Binlin Wu, Weidong Zhang, Guanhua Jiang, Long Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Zhejiang Univ Coll Energy Engn Hangzhou 310027 Zhejiang Peoples R China

Phase-change materials (PCMs) can overcome the low energy density and utilization efficiency of solar energy. However, the low thermal conductivity of PCMs significantly affects the thermal efficiency of solar devices;thus, improving the thermal conductivity of PCMs has been the focus of many recent studies. In this study, copper metal foam (CMF) composite PCMs were prepared using paraffin wax and highpore-density CMF. The effect of the CMF proportion on heat transfer enhancement in the PCM melting process was analyzed using experimental equipment for heat storage visualization. Comprehensive heat transfer coefficients of CMF composite PCMs were obtained. The experimental results showed that as the CMF proportion increased from 0 to 2.15%, the melting time of the CMF composite PCMs and their heat storage capacity first increased and then decreased, whereas the heat storage rate and comprehensive heat transfer coefficient first decreased and then increased. The minimum temperature gradient of 8.09 K was reached when the CMF proportion was 2.15%. More importantly, as the proportion of CMF increased from 0.43 to 2.15%, the proportion of natural convection decreased from 87.90 to 17.69%, and natural convection was the major heat transfer mechanism in the melting process of composite PCMs with a low CMF proportion. The composite PCMs with a CMF proportion of 0.86% has the best heat storage performance when the heat storage capacity and heat storage rate were both considered. (c) 2022 Elsevier Ltd. All rights reserved.

关键词： Phase-change heat storage Copper metal foam Phase-change materials heat transfer enhancement Comprehensive heat transfer coefficient

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Aqueous phase reforming of biodiesel byproduct glycerol over mesoporous Ni-Cu/CeO2 for renewable hydrogen production

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FUEL 2022年 308卷 122014-122014页

作者： Wu, Kai Dou, Binlin Zhang, Hua Liu, Dashuai Chen, Haisheng Xu, Yujie Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Chinese Acad Sci Inst Engn Thermophys Beijing 100190 Peoples R China

Aqueous phase reforming (APR), regarded as one method for inexpensive H-2 production, was widely studied due to lower temperature and unnecessary to vaporize water and fuels. In this study, the mesoporous CeO2, regarded as a metal oxide carrier, was first prepared by colloidal solution combustion, and then the Ni-Cu bimetallic supported on mesoporous CeO2 was successfully synthesized to investigate the catalytic performance in APR of biodiesel byproduct glycerol. The results show that the Cu element in the catalysts can effectively improve water-gas shift (WGS) reaction and inhibit the formation of methane, which increases the H-2 production rate from 125.08 to 195.57 mu ***(-1).g cat(-1). The higher reaction temperature is beneficial to the H-2 production rate, but not to H-2 selectivity. Kinetics analysis indicates that catalyst of 1Ni2Cu/CeO2 + 0.2gCaO has the lowest apparent activation energy (29.86 ***(-1)). CaO is introduced as an absorbent to improve WGS reaction and reduce methanation reactions through in-situ CO2 removal and capture. The reaction path and mechanism of APR of glycerol are also discussed in this paper.

关键词： Hydrogen production Aqueous phase reforming of biodiesel byproduct glycerol Mesoporous Ni-Cu/CeO2 catalyst In-situ CO2 capture

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Accelerated methane storage in clathrate hydrates using the natural tobacco

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ENERGY 2022年第0期241卷 122549-122549页

作者： Li, Chunxiao Yang, Liang Liu, Daoping Liu, Ni Xie, Yingming Cui, Guomin Zhang, Lixin Gao, Ming Zhao, Yugang Wang, Juan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Shanghai Univ Elect Power Sch Environm & Chem Engn Shanghai 200090 Peoples R China

The rapid formation rate and high storage capacity of clathrate hydrates are crucial for natural gas storage and transportation. In this study, a series of wet tobacco samples prepared by soaking different masses of tobacco shred/granules in water were used to store methane in the hydrate. Gas consumption experiments were conducted in an unstirred reactor to investigate the hydrate formation kinetics in the tobacco/water mixtures and their filtrates at 274.15 K and 8.0 MPa. The results demonstrated that the tobacco solutions with surfactivity played a promoting role in the hydrate formation. The wet loose biomass materials provided abundant nucleation sites for gas to solid hydrates. Compared to pure water, the tobacco-water mixtures significantly shorten the induction time of nucleation and accelerate hy-drate growth. The amount of methane stored in tobacco granule systems ranged from 112.3 to 160.3 cm(3) cm(-3), and the storage rates reached 2.06-5.58 cm(3) cm(-3)center dot min(-1). The wet tobacco shreds exhibited higher gas uptakes (132.6-171.6 cm(3) cm(-3)) than the tobacco granule systems and tobacco shreds filtrates at the same liquid-solid ratio. The use of green wet tobacco samples to enhance of hydration should be helpful for the extension of hydrate-based technology. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Methane hydrate Formation Kinetics Promotion Natural tobacco Surfactivity

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A Study of Optimal Refrigerant Charge Amount Determination for Air-Conditioning heat Pump System in Electric Vehicles

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ENERGIES 2020年第3期13卷 657-657页

作者： Li, Kang Yu, Jun Liu, Mingkang Xu, Dan Su, Lin Fang, Yidong Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai 200093 Peoples R China

With regard to concerns about an electric vehicle's driving range extension in a cold climate, an air-conditioning heat pump (ACHP) shows considerable advantage over thermoelectric heaters for battery energy conservation. The effect of refrigerant charge amount for cooling and heating performance of the ACHP system is significant. The optimal charge, realizing the optimal system performance, is usually determined by experiments of cooling and heating performance. In this paper, the optimal charge determination process based on a newly designed ACHP applied in electric vehicles was introduced. Relationships of characteristics with charge in two modes were investigated by experimental and theoretical methods. Firstly, the performance of the ACHP system was respectively investigated at different charge amounts in cooling and heating operating conditions according to key parameters of system cycles. Secondly, the intersection platforms of subcooling and superheat variation curves with refrigerant charge amount were obtained for determining optimal charge amount of the system further by comprehensive analysis. Finally, the theoretical calculation of charge with three instructive and classical void friction correlation models were applied for better comparisons. It was found that charge amount calculated by the Hughmark model proved to be most consistent with the comprehensive experimental results.

关键词： cooling and heating performance optimum refrigerant charge charge determination modelling void fraction correlation

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Mercury Removal Based on Adsorption and Oxidation by Fly Ash: A Review

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ENERGY & FUELS 2020年第10期34卷 11840-11866页

作者： Liu, Zhuang Liu, Dunyu Zhao, Bingtao Feng, Liang Ni, Mingguo Jin, Jing Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Mercury (Hg), in particular elemental mercury (Hg-0) captured from coal-fired power plants, has attracted much attention because of its severe harm to human health and environment. Hg-0 can be removed using the technology of adsorbent injection, and one of the promising adsorbents is fly ash. To evaluate the effect of complex multifactors of fly ash on Hg-0 removal performance, this review summarizes, analyzes, and evaluates the quantitative effects of fly ash compositions, physical parameters, flue gas components, and modification reagents. The effects of electric field (EF), magnetic field (MF), and ultraviolet (UV) light on Hg-0 removal using fly ash are also introduced. Unburned carbon (UBC) and Fe2O3 are two reactive components in fly ash for Hg-0 oxidation. Physical parameters including higher specific surface area, larger total pore volume, and wider distribution of pores with well-developed micropores are beneficial for Hg-0 retention, and no consistent relationship between particle size and Hg-0 retention using fly ash has been obtained. While gas phase components including HCl, NO, and O-2 promote the removal of Hg-0 using fly ash, no agreement about the effects of SO2 and H2O vapor on Hg-0 removal has been reached. The promotion of halogen-modified fly ash on Hg-0 removal may be explained by the Langmuir-Hinshelwood mechanism, the Mars-Maessen mechanism, as well as the Eley-Ridel mechanism. The contribution of metal-modified fly ash to Hg-0 removal is attributed to the oxidation ability of metal oxides as well as metal positive ions. EF, MF, and UV light enhance the oxidation of Hg-0 using fly ash to different degrees. The promotion of EF may be attributed to the formation of more Cl, O, and OH radicals by a series of electron-induced reactions. The enhancement of MF is simultaneously attributed to the energy-level splitting of Hg-0 as well as the magnetochemistry effect of magnetic materials in fly ash. The function of fly ash on the photocatalytic oxida

关键词： Particle size Mercury Oxidation Reaction products Adsorption

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