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CoCx-induced interfacial octahedral Co2+sites of NiCo-LDH electrode with improved faradic reactivity toward high-performance supercapacitor

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JOURNAL OF COLLOID AND INTERFACE SCIENCE 2023年第1期651卷 602-611页

作者： Yin, Baoyi Hao, Liang Li, Xiaogan Yang, Qiguo Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Dalian Univ Technol Sch Microelect Dalian 116024 Peoples R China

Battery-like electrode materials are characterized by large theoretical capacitance but suffer from poor surface reactivity and insufficient electroactive sites thus limiting their practical charge storage capacity. To overcome this challenge, an effective strategy for vacancy modulation on battery-like electrode materials is necessary. Herein, we report for the first time an elaborately designed three-dimensional (3D) hierarchical heterostructure consisting of CoCx@NiCo-LDH on conductive nickel foam as a freestanding supercapacitor electrode. Benefiting from the weakening of the coordination of Co-O bonds, the CoCx structure induces in-situ reconstruction of the NiCo-LDH lattice, resulting in the formation of abundant oxygen vacancies (interfacial octahedral Co2+ sites) that lower the OH- adsorption energy as determined by the density functional theory (DFT) calculation. The resulting CoCx@NiCo-LDH/NF electrode exhibits an ultrahigh rate capability (2330 mF cm-2 at 0.3 mA cm-2, with capacitance retention of 51.5 % at 30 mA cm-2) and remarkable cycling performance (capacitance retention of 81.6 % after 10,000 cycles). Additionally, the assembled asymmetric devices deliver an extremely high energy density of 246 & mu;Wh cm-2 at the power density of 798 & mu;W cm-2, with 87.8 % capacitance retention after 10,000 cycles at 8 mA cm-2. Overall, this study presents a simple yet effective strategy to construct high-performance battery-like electrodes for potential applications in energy storage, transportation, and communication.

关键词： Battery-like electrode Supercapacitor Vacancy modulation Ultrahigh rate capability

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Pore-Scale Simulation of Tortuosity in the Catalyst Layer of Proton Exchange Membrane Fuel Cells

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JOURNAL OF ENERGY engineering 2024年第4期150卷 04024015-04024015页

作者： He, Yusong Hao, Liang Bai, Minli Dalian Univ Technol Sch Energy & Power Engn Key Lab Ocean Energy Utilizat & Energy Conservat Minist Educ Dalian 116024 Liaoning Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

The porous structures of the catalyst layer (CL) for proton exchange membrane (PEM) fuel cells were reconstructed using the sphere-based simulated annealing (SA) method, in which different carbon sphere diameters, carbon phase fractions, ionomer loadings, and porosities were achieved to simulate different samples. The pore-scale simulation model based on the random walk algorithm was developed to evaluate the tortuosity in the CL. The results show that the carbon phase fraction, particularly the carbon sphere diameter, significantly influences the tortuosities in both pores and ionomer. Larger carbon spheres contribute to tightening the solid phase and enlarging the pore size within the CL, thereby affecting the pore structure and the ionomer distribution. The tortuosity obtained from the random walk algorithm aligns well with those from pore-scale diffusion and flow simulations using the Lattice-Boltzmann method (LBM). The random walk algorithm has the highest efficiency of the three methods in calculating the tortuosity of the CL when the porosity is less than 0.2, demonstrating its wider applicability. This study further proposes formulas for predicting the tortuosities in both pores and ionomer, which are closer to actual CLs than empirical equations. In addition, the present work confirms that the structural randomness resulting from the reconstruction method used in this work has little effect on the tortuosity, indicating that a small number of reconstructed samples suffice for investigating transport processes in the CL. Overall, our research contributes to the prediction of the properties of real porous media in energy engineering. This manuscript reports on the reconstruction of the catalyst layer in proton exchange membrane fuel cells using the simulated annealing method under some appropriate assumptions. A pore-scale simulation using a random walk algorithm was performed to compute the tortuosity both in the pores and in the ionomer, which is compared w

关键词： Pore-scale simulation Proton exchange membrane (PEM) fuel cells Catalyst layer (CL) Tortuosity

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A New Structure of Cooling Wall Tube for Supercritical CO_(2)Coal-Fired power Plants

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Journal of Thermal Science 2023年第3期32卷 1239-1250页

作者： WANG Yanjuan GAO Shuo JIANG Qiongqiong LI Yi LIU Qibin XU Jinliang The Beijing Key Laboratory of Multiphase Flow and Heat Transfer North China Electric Power UniversityBeijing 102206China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

In terms of developing supercritical CO_(2)(sCO_(2))coal-fired power plants,enhancing cooling wall performance is one of significant factors to improve system *** this paper,a new cooling wall tube structure is proposed to match the non-uniform heat flux(NUH)with the thermal resistance by changing the cooling wall tube eccentricity.A three-dimensional multi-physical coupling model of cooling wall is constructed to compare the novel structure to the conventional *** properties of fluid dynamics,thermal stress,coupled heat transfer and cooling wall deformation are *** contrast to the traditional structure,the maximum temperature and circumferential temperature difference(CTD)of the proposed structure can be reduced by 2%and 27.4%,*** essential working parameters related to the performances of the cooling wall tube are *** maximum temperature of the new structure is reduced by 8-13 K and the maximum thermal stress is reduced by about 10%-15%under all the simulated working conditions when the eccentricity changes from 0 to *** proposed structure can effectively reduce the maximum temperature and circumferential temperature gradient under ***,a novel insight is put out for the design and optimization of the cooling wall tube in coal-fired power plants.

关键词： supercritical carbon dioxide cooling wall tube thermal-hydraulic structural coupling supereritical heat transfer

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Clathrate Hydrate Framework Construction Enhanced by Waste Bio-Shavings for Efficient Methane Storage

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ACS SUSTAINABLE CHEMISTRY & engineering 2022年第37期10卷 12127-12138页

作者： Yang, Liang Liu, Daoping Wang, Jiajie Liu, Ni Xie, Yingming Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

Improving the hydrate formation rate as well as gas storage capacity is significant for gas hydrate technology applications. Porous woodshavings with different liquid-solid ratios (R-L/S) were prepared to capture methane in the form of hydrate. The kinetics of methane hydrate formation in wet shavings were studied using an unstirring reactor at pressures ranging from 5.0 to 8.0 MPa and a temperature of 274.2 K. The results demonstrated that the liquid water spread well on the surface of the shavings and permeated into their interior micropores. Wet multi-stack shaving beds could provide abundant channels for gas diffusing to the film water coated on the surface of the shavings. The rough and irregular wooden surface was capable of contributing a considerable number of nucleation sites for hydrate formation. The skeletons of wet shavings aided in the construction of a three-dimensional hydrate bridge and framework, which accelerated the upward migration of pore water and gravity water to form a hydrate crown. Compared with bulk water, the water dispersed by shavings greatly accelerated hydrate nucleation and growth. The R-L/S ceilings of wet samples that allowed for a significant quantity of methane hydrate formation were 11.0 (8.0 MPa), 9.0 (7.0 MPa), 8.0 (6.0 MPa), and 7.0 (5.0 MPa). The wet beds with the R-L/S of 8.0 exhibited the best gas storage performance at all pressures except 5.0 MPa. Furthermore, 10 cycles of repeated tests showed that wet shavings could store gas extremely stably, with cyclic peak gas uptakes ranging from 146.0 to 154.1 cm(3).cm(-3). A hypothesis of "hydrate shell-bridge-framework construction enhanced by bio-shavings" was proposed to illustrate the fast hydrate formation in the porous shavings.

关键词： methane storage clathrate hydrate formation kinetics waste bio-shavings enhancement

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Configuration Strategy and Performance Analysis of Combined heat and power System Integrated with Biomass Gasification, Solid Oxide Fuel Cell, and Steam power System

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PROCESSES 2024年第3期12卷 446页

作者： Zhu, Xinyao Li, Zeqiu Tian, Ying Huang, Xiuhui 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 Univ Shanghai Sci & Technol Sch Opt Elect & Comp Engn Shanghai 200093 Peoples R China

Renewable energy integration is a crucial approach for achieving a low-carbon energy supply in industrial utility systems. However, the uncertainty of user demand often leads to a mismatch between the system's real operating conditions and the optimal operating points, resulting in energy wastage and high emissions. This study presents a multi-source heat and power system that integrates biomass gasification, solar collecting, solid oxide fuel cell (SOFC), gas turbine, and steam power systems. A scheduling strategy that varies the heat-to-power ratio is proposed to accommodate changes in user requirements. A simulation model of this multi-source system is established and validated. The influence of three key parameters on system performance under different configurations is explored. Energy and economic evaluations are conducted for three different configurations, and the system's energy production and adjustable range are determined. The analysis reveals that, under the optimal configuration, the system can achieve an energy efficiency of 64.51%, and it is economically feasible with the levelized cost of electricity (LCOE) of USD 0.16/kWh. The system is capable of producing an output power ranging from 11.52 to 355.53 MW by implementing different configuration strategies. The heat-to-power ratio can be adjusted from 0.91 to 28.09.

关键词： biomass gasification configuration strategy solid oxide fuel cell (SOFC) steam power system (SPS)

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Theoretical model of electromagnetic flowmeter under annular conductivity distribution based on annular domain weight function

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MEASUREMENT 2025年 253卷

作者： Yang, Yang Yang, Biaohu Wang, Gaoyun Chen, Tianqiu Zhang, Chao Yang, Bin Zhang, Linli Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Sinopec Shengli Oilfield Co Tech Inspection Ctr Dongying 257000 Peoples R China

Electromagnetic flowmeter has advantages such as non-invasiveness, no moving parts and high reliability. And they are not affected by physical parameters like fluid density, temperature, pressure, and viscosity. However, they can be influenced by non-uniform distribution of medium conductivity. In this paper, the theoretical model of electromagnetic flowmeter under annular conductivity distribution was established based on the fundamental control equation and the annular domain weight function. To verify the effectiveness of the theoretical model, COMSOL Multiphysics numerical simulation and experimental validation study were both conducted. The relative deviations between the theoretical value and the numerical simulation, as well as the experimental result, are +/- 4 % and +/- 1 %, respectively. This study provides a theoretical basis for expanding the application of electromagnetic flowmeter to annular conductivity distribution.

关键词： Electromagnetic flowmeter Annular weight function Annular conductivity distribution Multiphysics coupling

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Thermodynamic analysis of combined cycle system based on supercritical CO2 cycle and gas turbine with reheat and recuperation

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ENERGY SOURCES PART A-RECOVERY UTILIZATION AND ENVIRONMENTAL EFFECTS 2023年第1期45卷 1443-1463页

作者： Lian, Zhibo Qi, Yinke Huang, Diangui Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China

The gas turbine combined cycle (GTCC) system has the advantages of high power density, high efficiency, and fast start-stop control, which will occupy an important position in the next-generation power system. In this paper, two groups of reheat cycle gas turbines with different thermal parameters are compared and the reheat and recuperative cycle is constructed by adding a recuperator to the recommended reheat cycle. Two typical sCO(2) cycles are selected to construct a combined cycle system with simple cycle, reheat cycle, reheat, and recuperative cycle, respectively. In the range of gas turbine pressure ratio of 32-56, the parameters of GTCC with turbine inlet temperature of 1750 degrees C are optimized based on the system calculation method of total physical properties, and the thermodynamic performance of the GTCC system was evaluated. The research shows that the reheat cycle with a TRIT (inlet temperature of the turbine after reheat) of 1250 degrees C has higher efficiency and lower specific net work than the reheat cycle with a TRIT of 1750 degrees C, and the relatively low exhaust temperature is more suitable for the sCO(2) bottoming cycle. In addition, compared with the simple cycle, the optimal topping cycle thermal efficiency of the reheat and regenerative cycle is only reduced by 0.1%, but the exhaust temperature is higher. Under the same sCO(2) cycle form, the combined cycle efficiency is improved by 1.5-2.0%. The thermal efficiency of the reheat and regenerative cycle gas turbine combined cycle (RCRHCC) studied in this paper can reach up to 67.53%, which has the potential to become the next generation of GTCC units.

关键词： GTCC reheating recuperative sCO(2) cycle thermodynamic analysis

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Experimental study on the relationship between the flow pattern and heat transfer characteristics of flow boiling in a vertical upward rectangular narrow channel

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INTERNATIONAL JOURNAL OF heat AND MASS transfer 2025年 242卷

作者： Sun, Chen Dai, Ren Tao, Leren Huang, Lihao Gu, Shengjie Zhang, Yuxin Gu, Zhipan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Jiaxing Univ Sch Architecture & Civil Engn Jiaxing 314001 Zhejiang Peoples R China

This study investigated the evolution of flow patterns and heat transfer characteristics of flow boiling within vertical upward rectangular narrow channels. The channel, visualized and heated to simulate compact heat exchangers and the fuel channels of small modular reactors (SMRs), has geometric dimensions of 720 mm x 240 mm x 2.75 mm (l x w x s) and employs deionized water as the working fluid. Experimental conditions include inlet temperature in the range of 50 - 90 degrees C, mass flux between 4.04-24.24 kg/(m2 & sdot;s), and heat flux between 3.32-64.12 kW/m2. Images acquired via high-speed camera are presented to elucidate the flow regime physics. Different types of flow pattern maps were drawn and compared with other researchers' data under adiabatic and steam heating conditions. A new type of dimensionless correlative flow pattern transition criterion for vertical rectangular narrow channels was obtained and showed good accuracy in predicting the critical vapor quality of flow pattern transition. The results indicated that thermo-hydraulic parameters influence the positions and length of flow patterns, and the overall trend of the local heat transfer coefficient (HTC) remains consistent during flow pattern transition. Peak HTC values occurred during the later processes of restricted bubbly flow and annular flow. Critical heat flux (CHF) exhibited a positive correlation with mass flux but showed minimal sensitivity to inlet temperature. Specially, due to the intermittent wetting behavior of the tidal flow, heat transfer deterioration demonstrated a delayed response, and the heat flux of optimal average HTC was higher than the CHF.

关键词： flow boiling Narrow channel flow pattern CHF Two-phase flow heat transfer

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An improved model on the evaporation kinetics of the single aerosol droplet and its application for the droplet composed of ammonium sulfate or sucrose solution

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POWDER TECHNOLOGY 2025年 453卷

作者： Zhang, Chao Lu, Miaoran Bao, Han Ma, Nan Yu, Dandan Yang, Yang Wang, Yueshe Wiedensohler, Alfred Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China Jinan Univ Inst Environm & Climate Res Guangzhou 511443 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Leibniz Inst Tropospher Res D-04318 Leipzig Germany

An improved model is proposed to investigate effects of gas phase temperature, relative humidity and initial solute concentration on the evaporation rate of the aerosol droplet consisted of ammonium sulfate (AS) or sucrose (SC) solution and the water diffusion coefficient in bulk phase. Results show that the new model is more accurate than the traditional model ignoring the bulk phase mass diffusion. Effect of the bulk phase mass diffusion on the evaporation rate of the AS-water droplet is almost unaffected by factors studied here due to the predominance of the mass transfer in gas phase and gas-droplet interface. However, effect of the bulk phase mass diffusion on the evaporation rate of the SC-water droplet is negatively correlated with the gas phase temperature and the relative humidity, but it is positively correlated with the initial solute concentration. Furthermore, influence mechanisms of the water diffusion coefficient in AS (SC)-water droplets are revealed.

关键词： Aerosol droplets Evaporation Theoretical model Mass diffusion

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Experimental investigation on flow boiling heat transfer of R1233zd(E) in parallel microchannel heat sink with variable channel widths

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INTERNATIONAL JOURNAL OF heat AND MASS transfer 2025年 244卷

作者： Jiang, Chen-han Lu, Di Yu, Wen-long Fang, Yi-dong Zhao, Jia-yi Yang, Hui-nan Chen, Shuo 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 Tongji Univ Sch Aerosp Engn & Appl Mech Shanghai 200092 Peoples R China

In this study, a novel parallel microchannel heat sink with variable channel widths was proposed to confront the issue of flow maldistribution. With R1233zd(E) as the working fluid, subcooled flow boiling experiments were conducted in the microchannel heat sink with variable and uniform widths under the inlet subcooling of 5-8 degrees C and the mass flux and heat flux ranges of 500-2000 kg/m2 s, 0-180 kW/m2, respectively. The results indicated that the two-phase flow pattern in the microchannel with variable channel widths (VWMC) showed a better distribution uniformity than the one with uniform channel width (CWMC). The boiling curve in the two test sections showed that the onset of nucleate boiling (ONB) is incipient earlier in VWMC due to the improved flow uniformity, meanwhile it had lower wall superheat with the increase of heat flux. The deviation of boiling curves at local positions was also smaller in VWMC. Furthermore, the overall heat transfer coefficients (HTCs) in VWMC were consistently higher than those in CWMC across all operating conditions, with a maximum improvement of up to 60%. The improvements of HTC were also observed at various locations in different channels of VWMC along the flow direction. The pressure drop of VWMC, however, was generally higher than that in the CWMC, with the maximum penalty of 39%. Meanwhile, the pressure drop fluctuations maintained at a low level of +/- 0.6 kPa under most conditions, presenting optimal two-phase flow stability.

关键词： flow boiling Parallel microchannel Variable channel widths flow pattern heat transfer

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