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Effects of Numerical Schemes of Contact Angle on Simulating Condensation heat transfer in a Subcooled Microcavity by Pseudopotential Lattice Boltzmann Model

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ENERGIES 2023年第6期16卷 2622-2622页

作者： Wang, Dongmin Lin, Gaoshuai Zhao, Yugang Gao, Ming Univ Shanghai Sci & Technol Sch Energy & Power Engn Key Lab Multiphase Flow & Heat Transfer Shanghai P Shanghai 200093 Peoples R China

Various numerical schemes of contact angle are widely used in pseudopotential lattice Boltzmann model to simulate substrate contact angle in condensation. In this study, effects of numerical schemes of contact angle on condensation nucleation and heat transfer simulation are clarified for the first time. The three numerical schemes are pseudopotential-based contact angle scheme, pseudopotential-based contact angle scheme with a ghost fluid layer constructed on the substrate with weighted average density of surrounding fluid nodes, and the geometric formulation scheme. It is found that the subcooling condition destabilizes algorithm of pseudopotential-based contact angle scheme. However, with a ghost fluid layer constructed on the substrate or using geometric formulation scheme, the algorithm becomes stable. The subcooling condition also decreases the simulated contact angle magnitude compared with that under an isothermal condition. The fluid density variation near a microcavity wall simulated by pseudopotential-based contact angle scheme plays the role of the condensation nucleus and triggers "condensation nucleation". However, with a ghost fluid layer constructed on the substrate or using geometric formulation scheme, the simulated fluid density distribution near the wall is uniform so that no condensation nucleus appears in the microcavity. Thus, "condensation nucleation" cannot occur spontaneously in the microcavity unless a thin liquid film is initialized as a nucleus in the microcavity. The heat flux at the microcavity wall is unphysical during the "condensation nucleation" process, but it becomes reasonable with a liquid film formed in the microcavity. As a whole, it is recommended to use pseudopotential-based contact angle scheme with a ghost fluid layer constructed on the substrate or use the geometric formulation scheme to simulate condensation under subcooling conditions. This study provides guidelines for choosing the desirable numerical schemes of conta

关键词： lattice Boltzmann method condensation contact angle ghost fluid layer fluid density variation near wall

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A Tabu-Matching Heuristic Algorithm Based on Temperature Feasibility for Efficient Synthesis of heat Exchanger Networks

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PROCESSES 2023年第9期11卷 2713页

作者： Huang, Xiaohuang Shen, Hao Yue, Wenhao Duan, Huanhuan Cui, Guomin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer P Shanghai 200093 Peoples R China

The non-structural model of heat exchanger networks (HENs) offers a wide solution space for optimization due to the random matching of hot and cold streams. However, this stochastic matching can sometimes result in infeasible structures, leading to inefficient optimization. To address this issue, a tabu matching based on a heuristic algorithm for HENs is proposed. The proposed tabu-matching method involves three main steps: First, the critical temperature levels-high, medium, and low-temperature intervals-are determined based on the inlet and outlet temperatures of streams. Second, the number of nodes is set according to the temperature intervals. Third, the nodes of streams are flexibly matched within the tabu rules: the low-temperature interval of hot streams with the high-temperature interval of cold streams;the streams crossing cannot be matched. The results revealed that by incorporating the tabu rules and adjusting the number of nodes, the ratio of the feasible zone in the whole solution domain increases, and the calculation efficiency is enhanced. To evaluate the effectiveness of the method, three benchmark problems were studied. The obtained total annual costs (TACs) of these case studies exhibited a decrease of USD 4290/yr (case 1), USD 1435/yr (case 2), and USD 11,232/yr (case 3) compared to the best published results. The results demonstrate that the proposed tabu-matching heuristic algorithm is effective and robust.

关键词： heat exchanger network heuristic method temperature interval tabu matching

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Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number

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Journal of Hydrodynamics 2020年第5期32卷 807-819页

作者： Yan-ang Guo Xiang-rui Dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering Shanghai 200093China

The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Reθ=97-194 is experimentally *** this study,a moving single-frame and long-exposure(MSFLE)imaging method and a moving particle image velocimetry/particle tracing velocimetry(M-PIV/PTV)are designed and implemented for measuring the temporal and spatial evolution of vortex cores in both qualitative and quantitative ways,*** the other hand,the Liutex vector,which is a new mathematical definition and identification of the vortex core proposed by Liu’s group,is first applied in the experiment for the structural visualization and quantitative analysis of the local fluid *** results show that an intuitional process of vortex evolution can be clearly observed by tracking the vortex using MSFLE and verify that the roll-up of the shear layer induced by shear instability is the origin of vortex formation in ***,a quantitative investigation in terms of the critical vortex core boundary(size)and its accurate rotation strength is carried out based on the Liutex vector field analysis by M-PIV/*** to statistics of the relation between vortex core size and the rotation strength during the whole process,the physical mechanism of vortex generation and evolution in a turbulent boundary layer of low Reynolds number can be summarized as a four-dominant-state course consisting of the“synchronous linear segment(SL)-absolute enhancement segment(AE)-absolute diffusion segment(AD)-skewing dissipation segment(SD)”.

关键词： Turbulent boundary layer high-and low-speed fluid vortex generation moving single-frame and long-exposure moving particle image velocimetry/particle tracing velocimetry Liutex vector

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Investigation on the Mechanism of Co2 Hydrate Formation by Synergistic Action of Kinetic Promoters

SSRN

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SSRN 2023年

作者： Liu, Ni Leng, Jing Cui, Mengxue Yang, Liang School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

CO2 hydrate technology has a promising application in carbon neutralization through carbon capture. In this paper, the effect of different mass concentrations of fullerene C60 and sodium lignosulfonate (SL) on the gas storage performance of CO2 hydrate was investigated. C60 can promote the best results at the concentration of 0.01 wt%. The induction time was 168 minutes, and the gas storage capacity was 56.60 V/V, which is 112.22% higher than that of pure water. This is due to the large specific surface area of C60 nanoparticles, which reduces the surface tension of the solution and increases the gas-liquid mass transfer rate. SL can promote the best results at the concentration of 0.1 wt%. The induction time was 1,908 minutes, and the gas storage capacity was 89.98 V/V, which is 2.37 times higher than that in the pure water system. This is because SL molecules possess abundant functional groups, high chemical reactivity, high elasticity and surface activity. The best compounding pair was in the experimental group of 0.01 wt% C60 with 0.1 wt% SL. The induction time was 60 minutes, and the gas storage capacity was 108.87 V/V. Therefore, both C60 and SL have a positive effect on CO2 hydrate formation. © 2023, The Authors. All rights reserved.

关键词： Carbon dioxide

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Study on the Aerodynamic Characteristics of Vertical Axis Wind Turbines Based on Omnidirectional Guide Grids

SSRN

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SSRN 2023年

作者： Zhou, Ye Xiandong, Li Hao, Yu Renhao, Ruan School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai200093 China

In order to analyze the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine, a combination of the inclination angle, relative distance, and thickness of the blade grid was designed to compare the influence of the structural parameters of the omnidirectional deflector on the aerodynamic performance of the vertical axis wind turbine under various tip speed ratio conditions. The results show that the wind power utilization rate and moment coefficient of the wind turbine under the effect of the omnidirectional deflector grille tend to increase and then decrease as the inclination angle increases, and the best effect on the wind turbine aerodynamic performance is achieved when the inclination angle is 0°, the wind turbine moment is greatly increased, and the range of effective operating conditions is expanded. When the inclination angle is 0° at all relative distances, the omnidirectional deflector grid can improve the pressure distribution of wind turbine blades, and the corresponding pneumatic performance improvement increases with the relative distance. When the relative distance is 2.6, the best effect on the wind turbine's aerodynamic performance is achieved. By changing the number of deflector blades and chord length to adjust the grid consistency, the vertical axis wind turbine aerodynamic performance curve under the action of the omnidirectional deflector shifts toward the direction of the large tip speed ratio as the grid consistency increases, and the corresponding wind energy utilization rate and torque coefficient peak are increasing and then decreasing when the chord length is 374mm (grid consistency is 0.267). When the chord length is 374mm (the blade thickness is 0.267), the best effect on the aerodynamic performance of the vertical axis wind turbine is achieved. © 2023, The Authors. All rights reserved.

关键词： Vertical axis wind turbine

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Estimation of particle depth from two defocused images using the Fourier transform

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Particuology 2020年第2期18卷 48-54页

作者： Wu Zhou Xu Luo Benting Chen Yukun Zhang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Depth from defocus is one technology for depth *** estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging *** images are processed with the Fourier transform to obtain the characteristic parameter(i.e.,the standard deviation of the relative blur kernel of these two defocused images).First,we theoretically analyze the functional relationship between the object depth and the standard deviation or variation of the relative blur ***,we verify the relationship *** analyze the influence of particle size,window size and image noise on the calibration curves using both numerical simulations and *** obtain the depth range and accuracy of this measurement system *** the verification experiments,we use a sample of glass microbeads and the irregularly-shaped dust particles on a microscope *** of these experiments present a suitable depth measurement ***,we apply the measuring system to the depth estimation of drops from a small anti-fogging *** results show that our system and image processing algorithm are robust for different types of particles,facilitating the in-line three-dimensional positioning of particles.

关键词： Depth from two defocused images Fourier transform Standard deviation of relative blur kernel Drops depth measurement Sensitivity and accuracy analysis

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Experimental study on improvement of freeze-drying process for porcine aorta

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DRYING TECHNOLOGY 2022年第2期40卷 401-415页

作者： Gui, Chao Tao, Leren Zhang, Yaqi Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Xinxiang Univ Sch Civil Engn & Architecture Xinxiang Henan Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai Peoples R China

Freeze-drying is an effective method for preservation of aortas. In order to maintain the original properties of aortas, the sublimation drying process requires accurate monitoring. In this study, we used a contactless mass measurement device to monitor drying process, porcine aortic segments were divided into four series for freeze-drying, then relevant experiments and calculations were carried out to evaluate the quality of lyophilized samples. The study found that the sublimation process could not be accurately monitored by measured temperature, however, the real-time weighing could do it well, and was suitable to judge the endpoint of primary drying. Meanwhile, the change law of sublimation temperature was obtained by quasi-steady heat transfer equations. The removal ratio of free water during the primary drying greatly affected the properties of lyophilized samples, thorough sublimation had contributed to better performance of products, especially in mechanical properties. In addition, compared with annular aortic segments, the flaky samples had better heat transfer and performed better in histological scanning.

关键词： Freeze-drying dehydration rate sublimation rehydration capacity mechanical properties histological scanning

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Sensitively Detection of Ascorbic Acid in Orange Samples with Ionic Liquid Functionalized Carbon Dots and Lanthanide Complexes

SSRN

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SSRN 2024年

作者： Li, Ying Xia, Ji-Ji Lu, Jia-Zhen Wang, Zi-Long Wang, Mi-Tang School of Materials and Chemistry University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

In the food industry, ascorbic acid (AA) is widely used as an antioxidant. However, the concentration of AA is influenced by various factors, including temperature, time, and pH value during food preparation and storage, leading to its instability in content. This makes the accurate detection of AA content particularly important. Precise determination of AA content in food and pharmaceuticals is crucial for ensuring the adequate intake of essential vitamins and maintaining good health. Herein, we have developed a successful preparation method of an imidazole-based ionic liquid functionalized CDs hybrids APM-CDs. A novel photo functional hybrid probe Eu3+@APM-CDs was obtained via an ion-exchange reaction between APM-CDs and lanthanide complex Eu(DPA)3. The obtained hybrid probe was extensively characterized in detail. What’s more, the results show that the FL intensity of Eu3+@APM-CDs has a good linear response to AA concentrations in the range of 0-500 μM (R2 = 0.99), with a detection limit of 80 nM. The fluorescence probe demonstrates good selectivity and sensitivity toward AA and has the potential for significant application in AA detection by simplifying procedures and reducing interference from impurities. © 2024, The Authors. All rights reserved.

关键词： Probes

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Mercury transformation and removal in chemical looping combustion of coal: A review

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FUEL 2023年第1期347卷

作者： Liu, Dunyu Wang, Chaoran Fan, Yunpei Liu, Qiuqi Wang, Xudong Xu, Kailong Jin, Jing Ma, Jingjing Ma, Jinchen 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 Ningxia Univ Coll Chem & Chem Engn State Key Lab High Efficiency Utilizat Coal & Gree Yinchuan 750021 Ningxia Peoples R China Huazhong Univ Sci & Technol State Key Lab Coal Combust Wuhan 430074 Peoples R China

Chemical looping combustion (CLC) of coal for carbon capture utilization and storage is an effective technology to reduce carbon emission due to smaller energy penalty and inherent low emission of pollutants. However, a large uncertainty exists in mercury emission from both air and fuel reactor for coal-fired chemical looping combustion. This paper attempts to reveal the underlining mechanisms for the transformation of mercury-related species both in combustion and post-combustion process. Mercury in coal, temperature, and water vapor pro-mote the release of mercury in fuel reactor. Oxygen carriers (OCs) promote the conversion of Hg0 to Hg2+ and HgP. Both oxygen release and adsorption ability of reduced OCs contributes to the mercury removal efficiency. HCl is the dominant species for Hg0 oxidation. NO, SO2, CO, and H2 have negative impacts on Hg0 oxidation;while O2 promotes Hg0 oxidation;the influence of H2O on Hg0 oxidation depends on concentration. H2S may promotes Hg0 removal by formation metal sulfides. In the post combustion mercury removal by adsorption and catalytic oxidation process, O2, HCl, NO, and CO2 promote the oxidation of Hg0, whereas SO2, CO, and H2 inhibit the oxidation of Hg0. The impacts of H2S and H2O on Hg0 oxidation depends on their concentrations. Simul-taneous removal of SO2, NO, and Hg0 by green oxidation-based absorption using free radicals or in the compression process have a good prospect due to potential low cost. This work will encourage wider discussion on flue gas treatment possibilities to reduce the cost of future CLC power plant.

关键词： Chemical looping combustion Mercury transformation Oxygen carrier

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Experimental investigation on heat transfer characteristics of upward flow boiling in a vertical narrow rectangular channel

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EXPERIMENTAL heat transfer 2024年第7期37卷 1037-1066页

作者： Jin, Cheng Tao, Leren Ju, Yiwei Zhao, Xiefei Gu, Shengjie Huang, Lihao 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 Peoples R China

heat transfer experiment on water flow boiling was carried out in the upward direction under atmospheric pressure through a narrow rectangular channel heated on one-side by vapor having a gap of 2.75 mm, a width of 250 mm, and length of 1400 mm. The heat transfer coefficient and thermal hydraulic thresholds of the flow boiling in forced convective flow, such as the onset of nucleate boiling (ONB) and onset of fully developed nucleate boiling (OFDB) were investigated. The experiment was performed over a wide range of inlet temperature (75-95 & DEG;C), mass flow rate (2-9 g/m), and heat fluxes (5-16 kW/m2). The effects of the parameters on the heat transfer coefficients have been discussed in detail. A series of ONB, FDB and heat transfer correlations were evaluated using the experimental data, and most of the correlations did not adequately fit the experimental results. A modified Hong et al. correlation and modified Zhu et al. correlation were used to predict the wall superheat at ONB and FDB respectively. The average errors (AEs) of the two correlations were 2.36% and -0.68%, and the root mean square errors (RMSEs) of them were both 14.00%. A modified Li and Wu correlation was used to predict heat transfer coefficients with the average error (AE) of 1.46% and the root mean square errors (RMSE) of 11.88%.

关键词： flow boiling narrow rectangular channel ONB FDB heat transfer

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