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Effects of Imposing Contact Angle Schemes and Constructing a Special Ghost Fluid Layer on the heated Substrate in Pseudopotential Lattice Boltzmann Simulation of Sessile Droplet Evaporation

SSRN

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SSRN 2022年

作者： Wang, Dongmin Cheng, Ping Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China School of Mechanical Engineering Shanghai Jiao Tong University Shanghai200240 China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application Suzhou University of Science and Technology Suzhou215009 China

The primitive pseudopotential-based scheme (PP scheme), the modified pseudopotential-based scheme (MP scheme) and the improved virtual-density scheme (IVD scheme) are the three most widely used contact angle schemes to simulate wall wetting characteristics in the pseudopotential lattice Boltzmann (LB) model under isothermal conditions. In this paper, these three widely used contact angle schemes are applied to simulate the problem of sessile droplet evaporation on a heated substrate, which is a non-isothermal phase-change process where temperature varies spatially and temporally. It is found that (i) using the PP scheme (primitive pseudopotential-based scheme) and the MP scheme (modified pseudopotential-based scheme) may lead to algorithmic instability problems in certain ranges of contact angles, deformation of droplet interface shape or Marangoni vortices shape, generation of unphysical vortices near the heated substrate, or result in erroneous temperature distributions near droplet triple-phase line. (ii) The IVD scheme (improved virtual-density scheme) has better algorithmic stability than the PP scheme and MP scheme (primitive pseudopotential-based scheme and the modified pseudopotential-based scheme), where the droplet interface shape and Marangoni vortices shape are correct, the unphysical vortices and the erroneous temperature distribution near droplet triple-phase line disappear. (iii) If a special ghost fluid layer (as proposed in this paper) is constructed on the wall when the PP scheme or the MP scheme (primitive pseudopotential-based scheme or the modified pseudopotential-based scheme) is implemented, the instability of the numerical solution is improved, the deformation of droplet interface shape and the Marangoni vortices shape are corrected, and the unphysical vortices near the heated substrate and the erroneous temperature distribution near droplet triple-phase line disappear. The addition of such a special kind of ghost fluid layer at the heated wa

关键词： Vortex flow

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Influence of thiourea modification on the NH₃-SCR activity of CeO₂: Simultaneous tuning morphology and surface acidity

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JOURNAL OF THE ENERGY INSTITUTE 2021年 98卷 322-333页

作者： Wang, Wei Xiong, Zhibo He, Weifeng Lu, Wei Shi, Huancong 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 Zhejiang Univ Huzhou Inst Huzhou 313000 Zhejiang Peoples R China Univ Shanghai Sci & Technol Dept Environm Sci & Engn Shanghai 200093 Peoples R China

Herein, thiourea (TA) was firstly used as the structure-directing agent to simultaneously tune the morphology and surface acidity of CeO2(w/o) synthesized via one-pot hydrothermal treatment, and exhibits better enhancement on its NH3-SCR activity than urea (UA). In addition, CeO2-TA(10) obtained at the suitable TA/Ce molar ratio of 10 presents the superior NH3-SCR activity in a broad temperature window. The introduction of thiourea promotes the formation of cubic CeO2 nanocubes in catalyst, but not the nanoparticles formed in CeO2(w/o) and CeO2-UA(10). Furthermore, the cubic CeO2 nanocubes mainly expose the crystal faces of {100}, which is helpful to the formation of more oxygen vacancies on the surface of CeO2-TA(10). At the same time, the formation of the specific sulfate species (CeOSO4) is also promoted under the influence of thiourea, thus simultaneously tunes the surface acidity of CeO2(w/o) by enhancing the Bronsted acid sites, although its Lewis acid sites are significantly decreased due to the diminution of the BET surface area. Compared with urea, the using of thiourea as the structure-directing agent also adjusts the physical-chemical properties of CeO2(w/o) and promotes its chemisorbed oxygen concentration. The results presented herein give a new thought for the development of state-of-the-art cerium-based catalysts for the NH3-SCR reaction.

关键词： NH3-SCR CeO2 Structure-directing agent Thiourea Specific sulfate species

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Mesoscale simulations of saturated flow boiling heat transfer in a horizontal microchannel

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NUMERICAL heat transfer PART A-APPLICATIONS 2020年第4期78卷 107-124页

作者： Wang, Haoyuan Lou, Qin Li, Ling 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 Peoples R China

The bubble dynamics and their effects on flow boiling heat transfer in a horizontal channel are investigated under constant wall temperature and constant wall heat flux conditions. It is found that both the bubble departure time and departure diameter decrease with increasing the inertial force for all the considered heating modes. Moreover, the bubble departs from the heater with a residual for the constant wall temperature condition so the heat transfer efficiency for the constant wall temperature condition depends mainly on the bubble growth rate and the vapor thickness. While for the constant heat flux condition, the bubble slides away from the heater accompany with waiting periods. So the heat transfer performance for this condition is mainly affected by the growth and waiting times. Besides, the results also show there were two contradictory trends of heat transfer efficiency under different wettabilities for the considered heat modes.

关键词： Efficiency

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Review on high ice packing factor (IPF) ice slurry: Fabrication, characterization, flow characteristics and applications

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JOURNAL OF ENERGY STORAGE 2024年 81卷

作者： Zhou, Zhijie Zhang, Guanhua Lu, Wei Luo, Maohui Wu, Zhigen 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 Mech Engn Shanghai 201804 Peoples R China Tongji Univ State Key Lab Pollut Control & Resource Reuse Shanghai 200092 Peoples R China Shanghai Inst Pollut Control & Ecol Secur Shanghai 200092 Peoples R China

Ice slurry has been widely used in various cold storage scenarios because of its environmental friendliness, pumpability, high cold storage density and fast load response time. As one of the important parameters of ice slurry, ice packing factor (IPF) has a great influence on its heat transfer efficiency and flow characteristics. High IPF ice slurry has great potential for cold chain logistics and pipe cleaning due to its high cold storage capacity and wall shear stress. However, the practical applications of high IPF ice slurry are greatly limited by the problems of difficult preparation as well as unclear flow and heat transfer characteristics. Therefore, it comprehensively reviews the latest research about high IPF ice slurry, including the preparation, properties, flow characteristics and applications. The production methods and influencing factors of high IPF ice slurry are elaborated in this paper. The measurement methods of key thermo-physical properties and flow characteristics of high IPF ice slurry are discussed. Moreover, the latest status and application prospects of high IPF ice slurry in cold chain logistics and pipe cleaning are introduced. Finally, it summarizes the future challenges and opportunities for the rapid development of high IPF ice slurry.

关键词： Ice slurry High ice packing factor Fabrication flow characteristics Applications

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Anti-coking performance of Cr/CeO₂ coating prepared by high velocity oxygen fuel spraying

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FUEL PROCESSING TECHNOLOGY 2022年 225卷 107043-107043页

作者： Sun, Yilun Huang, Meng Li, Jingpeng Wang, Zhiyuan Zhou, Jianxin Nanjing Tech Univ Sch Mech & Power Engn Nanjing 211816 Jiangsu Peoples R China Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The coke in the coils has a serious impact on the long-term and stable operation of the ethylene plant. Inhibiting coking of the cracking furnace is an important issue. In this paper, the Cr/CeO2 coatings were prepared on the surface of 310S stainless steel by high-velocity oxygen-fuel (HVOF) spraying. The anti-coking performances of the bare 310S specimen and the Cr/CeO2 coatings were tested by using the pyrolysis of naphtha. The results show that the coating with the thickness of 10-15 mu m and a very small number of pores was built up by the obviously deformed splats and the coating/substrate interface is jagged bond. The white area on the surface of Cr/CeO2 coatings mainly includes CeO2. However, the gray area is made of Cr or Cr2O3. Compared with the bare 310S specimen, the coking inhibition rates of coatings are 48.7%, 58.9%, 76.1% and 88.9% when the ratio of Cr and CeO2 powder is 19:1, 9:1, 4:1 and 3:2, respectively. With increasing the relative ratio of CeO2, more white areas without coke are exposed. The CeO2 surface can not only inhibit catalytic coking, but also promote the reaction of water vapor and coke.

关键词： Ethylene High-velocity oxygen-fuel spraying Inhibiting coking Cr CeO2 coating

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Numerical and experimental investigation on the air flow characteristics of heating, ventilation, and air-conditioning module for a small electric vehicle

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE engineering 2020年第6期234卷 1597-1609页

作者： Li, Kang Gao, Hao Jia, Peng Su, Lin Fang, Yidong Zhang, Hua Liu, Ni 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 Peoples R China

In electrical vehicles, replacing positive temperature coefficient heater as heat source with an air source heat pump could improve the driving range and decrease energy consumption in cold climate. Design of the heating, ventilation, and air-conditioning module for heat pump system has a significant influence on its performance in each working mode. A newly designed heat pump heating, ventilation, and air-conditioning module was introduced in this paper. The air flow characteristics of the heat pump heating, ventilation, and air-conditioning module in four working modes were analyzed, and the air flow rate and wind resistance were obtained by numerical simulation. Experiments were also conducted for validating its airflow rate in each working mode. Results of these experiments show that some unfavorable phenomena such as flow maldistribution and vortex inside the heat pump heating, ventilation, and air-conditioning module exist, which could lead to insufficient utilization of the heat exchange area of heat exchangers and the generation of aerodynamic noise. Furthermore, the air flow rate of the original heating, ventilation, and air-conditioning module was also measured for comparison, and the designed heat pump heating, ventilation, and air-conditioning module shows nearly 15-20% decrease in each working mode.

关键词： Air-conditioning heat pump system heat pump HVAC module airflow rate and wind resistance airflow distribution electrical vehicle

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EXPERIMENTAL INVESTIGATIONS ON THE COMBINED EFFECT OF NANOFLUID AND ULTRASONIC FIELD ON AMMONIA BUBBLE ABSORPTION

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JOURNAL OF ENHANCED heat transfer 2020年第2期27卷 159-171页

作者： Yang, Yingying Wu, Weidong Tang, Hengbo Lu, Jian Univ Shanghai Sci & Technol Sch Energy & Power Engn 516 Jungong Rd Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

This article investigates the enhancement effect of nanofluid and ultrasonic fields separately and simultaneously on ammonia bubble absorption in the absorber for improving the efficiency of the absorption refrigeration system. Ammonia bubble absorption experiments are carried out in a visualized absorber. Three nanofluids (Al2O3, Fe2O3, and multiwalled carbon nanotubes LMWNTs]) at different concentrations and ultrasonic fields of single frequency (20 kHz, 28 kHz, and 40 kHz) and mixed frequency (20-28 kHz, 20-40 kHz, 28-40 kHz, and 20-28-40 kHz) are studied as enhancement factors. The absorption amount of ammonia and the effective absorption ratio, with and without enhancement factors, are obtained during the experiments. The bubble behaviors during the absorption process are observed: occurs, grows, detaches, diffuses, transforms, and vanishes. The results show that the addition of nanofluids enhances the heat and mass transfer process in the absorber. This enhancement ability follows Fe2O3 > Al2O3 > MWNTs. The effective absorption ratio achieves 1.16 enhanced by Fe2O3 nanofluid of 0.020 wt%. For the ultrasonic field of single frequency, the higher the frequency, the higher the effective absorption ratio. The mixed ultrasonic field results in better effects than the single ultrasonic field. Under the mixed ultrasonic field of 20-28-40 kHz, the effective absorption ratio reaches 1.11. Finally, the effect of combined actions of nanofluid and ultrasonic field are tested. The effective absorption ratio is 1.22 with the ultrasonic field of 20-28-40 kHz and nanofluid of 0.020 wt% Fe2O3.

关键词： heat transfer enhancement ammonia bubble absorption ultrasonic field nanofluid bubble behaviors

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Bionic microchannels for step lifting transpiration

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International Journal of Extreme Manufacturing 2023年第2期5卷 244-252页

作者： Zhaolong Wang Qiu Yin Ziheng Zhan Wenhao Li Mingzhu Xie Huigao Duan Ping Cheng Ce Zhang Yongping Chen Zhichao Dong Interdisciplinary Research Center of Low-carbon Technology and Equipment College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082People’s Republic of China MOE Key Laboratory for Power Machinery and Engineering School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Qian Xuesen Laboratory of Space Technology China Academy of Space Technology(CAST)Beijing 100094People’s Republic of China Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Environmental Science and EngineeringSuzhou University of Science and TechnologySuzhouJiangsu 215009People’s Republic of China Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education School of Energy and EnvironmentSoutheast UniversityNanjing 210096People’s Republic of China Chinese Academy of Sciences Key Laboratory of Bio-inspired Materials and Interface Sciences Technical Institute of Physics and ChemistryChinese Academy of Sciences100190 BeijingPeople’s Republic of China

Those various cross-sectional vessels in trees transfer water to as high as 100 meters,but the traditional fabrication methods limit the manufacturing of those vessels,resulting in the non-availability of those bionic ***,we fabricate those bionic microchannels with various cross-sections by employing projection micro-stereolithography(PμSL)based 3D printing *** circumradius of bionic microchannels(pentagonal,square,triangle,and five-pointed star)can be as small as 100μm with precisely fabricated sharp ***'s more,those bionic microchannels demonstrate marvelous microfluidic performance with strong precursor effects enabled by their sharp *** significantly,those special properties of our bionic microchannels enable them outstanding step lifting performance to transport water to tens of millimeters,though the water can only be transported to at most 20 mm for a single bionic *** mimicked transpiration based on the step lifting of water from bionic microchannels is also *** precisely fabricated,low-cost,various cross-sectional bionic microchannels promise applications as microfluidic chips,long-distance unpowered water transportation,step lifting,mimicked transpiration,and so on.

关键词： bionic microchannel microfluidics water transportation step lifting 3D printing

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Hydrogen and syngas co-production by coupling of chemical looping water splitting and glycerol oxidation reforming using Ce-Ni modified Fe-based oxygen carriers

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JOURNAL OF CLEANER PRODUCTION 2022年 335卷

作者： Luo, Chuanqi Dou, Binlin Zhang, Hua Zhao, Longfei Zeng, Pingchao Gao, Daoxing Wang, Yadong Chen, Haisheng Xu, Yujie Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Sch Energy & Power Engn Shanghai 200093 Peoples R China Chinese Acad Sci Inst Engn Thermophys Beijing 100190 Peoples R China

In this study, renewable hydrogen production was achieved by coupling of water splitting and glycerol oxidation reforming by chemical looping technology (CLWS-GOR) using the novel Ce-Ni modified Fe-based oxygen carriers (OCs). The OCs were developed by combining metal chelating sol-gel and isometric impregnation method, which exhibited anti-sintering characteristic and lattice oxygen migration ability in CLWS-GOR. The amount of hydrogen between 12.49 and 12.96 mmol in the steam stage was produced from all the OCs with different ratios of Fe, Ce and Ni. However, with the increase of Ce and Ni doping, the production of H-2 and CO in the fuel stage increased, as well as the probability of carbon deposits released in the subsequent steam stage. The H-2/CO ratio in syngas were easily adjusted by steam to carbon molar ratio (S/C) in chemical looping steam reforming (CLSR), but the effects of steam introducing led to gradual deterioration of OCs. The results proved the OCs prepared by the combination method has high activity and stability for renewable hydrogen production from coupling of CLWS-GOR.

关键词： Chemical looping water splitting (CLWS) Glycerol oxidation reforming (GOR) Chemical looping steam reforming (CLSR) Ce-Ni modified Fe-Based oxygen carriers (OCs) Combination of metal chelating sol-gel and isometric impregnation method

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Preparation of a novel diatomite-based PCM gypsum board for temperature-humidity control of buildings

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BUILDING AND ENVIRONMENT 2022年 226卷

作者： Yang, Yingying Shen, Zhonghua Wu, Weidong Zhang, Hua Ren, Yan Yang, Qiguo 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 516 Jungong Rd Shanghai Peoples R China

Building envelopes with excellent performance in thermal storage and humidity control are effective in reducing the heat and humidity load burdens of the electrical facilities, thus achieving energy conservation. However, thermal and hygroscopic properties have typically been examined separately in most studies. This study aims to develop a novel composite gypsum board by integrating modified diatomite and a binary phase-change material (PCM) to simultaneously control the temperature and humidity of buildings. Raw diatomite was first modified by acid and salt treatments and then used to prepare a diatomite-based shape-stabilised composite PCM (D/PCM), which was applied to fabricate the proposed functional gypsum board. The physicochemical and hygrothermal properties of the proposed D/PCM gypsum board were studied experimentally. The results show that the D/PCM gypsum board demonstrates satisfactory performance in terms of heat storage and temperature delay, mitigating temperature fluctuations indoors. Moreover, the moisture adsorption capability was significantly improved compared with that of the normal gypsum board. The proposed D/PCM gypsum board is a promising composite building material that can be widely applied to promote energy conservation in buildings.

关键词： Temperature -humidity control Phase change material Diatomite Gypsum board Building energy conservation

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