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SSRN 2023年

作者： Ni, Hu Fan, Rong Hu, Haihang Yang, Bin Wang, Zhixin Cao, Di Yang, Yang Shi, Zhiquan School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Space Propulsion Technology Research Institute Shanghai201109 China

To characterize solid propellant combustion, the measurement method of burning rate and combustion temperature of solid propellant specimen is developed that simultaneously combines shadow and radiation imaging methods. Shadow and radiation images of solid propellant specimen combustion are simultaneously captured by using light splitting and wavelength filtering imaging measurement system. Burning rate and combustion temperature of solid propellant specimen are synchronized obtained by burning surface identification and radiation image temperature measurement algorithm. Measurement accuracies of burning rate and combustion temperature of solid propellant specimen are validated by other independent measurement methods. Compared with target-line measurement method, the burning rate measurement relative deviation is less than 3.1%. Compared with thermocouple measurement, the temperature measurement relative deviation is less than 1.7%. On this basis, the synchronized measurements of burning rate and combustion temperature of different formulations of solid propellant specimens under different working conditions are carried out. The results show that burning rate and combustion temperature are important characterization parameters of solid propellant combustion performance. For a certain formula solid propellant specimen, the burning rate can be greatly increased by increasing the pressure, but the combustion temperature is not much increased. Therefore, the synchronized measurement of burning rate and combustion temperature can provide more direct data support for the evaluation of solid propellant combustion performance. © 2023, The Authors. All rights reserved.

关键词： Solid propellants

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Influence of Bi3+ Doping on the Electrochemical Properties of Ti/Sb-Sno2/Pbo2 Electrode for Zinc Electrowinning

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SSRN 2024年

作者： Wu, Jia Kang, Xuanqi Xu, Shuangwen Wei, Zhen Xu, Shangyuan Liu, Kang Feng, Qing Jia, Bo Wang, Yunhai Xían Taijin New Energy & Materials Sci-Tech CO. Ltd Xi’an710016 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao tong University Xi’an710049 China

Bi3+ doped Ti/Sb-SnO2/PbO2 electrode materials were fabricated by electrodeposition to improve its electrochemical performance in zinc electrowinning. The surface morphology, chemical composition and hydrophilicity of the as-prepared electrodes are characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and contact angle. The electrochemical measurement and the accelerate lifetime experiment are also conduct to investigate the electrocatalytic performance and stability of the electrodes. The results showed that Bi3+ modification electrode has an important effect on the coating morphology, crystal structure, surface hydrophilicity, electrocatalytic activity and stability. The electrode prepared from the solution containing 2 mmol·L-1 Bi(NO3)3 (marked as the Ti/Sb-SnO2/2Bi-PbO2 electrode) exhibits the best hydrophilicity performance (θ=21.6°) and the longest service life (1196 h). During the electrochemical characterization analysis, the Ti/Sb-SnO2/2Bi-PbO2 electrode showed the highest oxygen evolution activity, which can be attributed to the highest electroactive surface (qT*=21.20 C·cm-2) and the best charge transfer efficiency. DFT calculation demonstrate that the doping of Bi lead to the decrease in the OER reaction barrier and increase the DOS of the electrode, which further enhanced the catalytic activity and conductivity of the electrode. Moreover, the simulated zinc electrowinning experiment demonstrate that the Ti/Sb-SnO2/2Bi-PbO2 electrode consume less energy than other electrodes. Therefore, it is expected that the Bi modified electrodes may become a very promising electrode material for zinc electrowinning in the future. © 2024, The Authors. All rights reserved.

关键词： Hydrophilicity

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Efficient Water Recovery and power Generation System Based on Air-Cooled Fuel Cell with Semi-Closed Cathode Circulation Mode

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SSRN 2024年

作者： Yang, Yuchen Wu, Zhen Yao, Jing Wang, Bofei Yang, Fusheng Zhang, Zaoxiao Ren, Jianwei School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering Science University of Johannesburg Johannesburg2092 South Africa

Air-cooled proton exchange membrane hydrogen fuel cell with on-line hydrogen production by hydrolysis has potential for portable applications due to its high volumetric power density and self-humidification. However, plenty of reserve water significantly reduces the power density of fuel cell system. Moreover, water recovery from fuel cell tail gas is difficult, because the tail gas humidity is very low due to excess cathode air as coolant. In this work, the dead-ended anode and semi-closed cathode proton exchange membrane fuel cell is proposed to achieve efficient water recovery and energy conversion via semi-closed cathode circulation mode. In this mode, cathode O2-poor tail gas is recycled as coolant instead of fresh air, which helps to enlarge the tail gas humidity by reducing the stoichiometric ratio of cathode to anode gas. The system lumped model with detailed component description is developed for optimization. More than 96% water production can be recycled under atmosphere temperature. The demand of fresh air is greatly reduced from 56 to 2 times of the consumption. Besides, the multi-objective optimization between water recovery and electrochemical performance shows high-efficiency water recovery of 94.70% and high energy conversion efficiency of 54.82%. © 2024, The Authors. All rights reserved.

关键词： Cathodes

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Effects of Combustor Wall Temperature on the Outer Recirculation Zone Combustion Modes Transition in Lean Premixed Dme/Air Swirl Flames

SSRN

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SSRN 2024年

作者： Lin, Wenjun Zhang, Weijie An, Zhenhua Wang, Jinhua Huang, Zuohua Zhang, Huangwei State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering National University of Singapore 9 Engineering Drive 1 Singapore117576 Singapore Department of Mechanical Engineering and Science Kyoto University Kyoto daigakuKatsura Nishikyo-ku Kyoto615-8540 Japan

In this study, the effects of wall thermal conditions on the ORZ combustion modes transition in the DME/air swirl flames are investigated using the Large Eddy Simulation (LES) and Flamelet Generated Manifold (FGM) method. The results show that the ORZ chemistry and temperature are highly sensitive to the wall thermal condition. Based on the correlation between the temperature and species observed in the time-averaged numerical results, the relation between the combustion mode and temperature in the ORZ is discovered. Through temporal analysis of species and heat release rate in the ORZ, the stable Mode II and Mode IV as well as the unstable Mode III are identified. The chemical reaction pathway analysis for typical probe in the ORZ reveals that different combustion modes undergo distinct (lowtemperature or high-temperature) chemical reaction pathways. Afterwards, the definition of combustion modes used in experiments is refined by utilizing the chemical reaction data from the simulations. And it is applied to identify the combustion mode across the entire computational domain. The results confirm the consistency between the combustion modes determined in experiments based on OH and CH2O and those determined in simulations using chemical reaction rates. Finally, this explains the mechanism of the flickering flame in Mode III is the competition between the low-temperature and high-temperature reaction in the ORZ. Whereas the unstable Mode III can be stabilized by changing the wall temperature to reach the Mode II or Mode IV. © 2024, The Authors. All rights reserved.

关键词： Temperature

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Pani Grafted Onto Waste Poros Polyurethane for Co-Adsorption of Multiple Pollutants in Industrial Wastewater

SSRN

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SSRN 2023年

作者： Wang, Ning Guo, Yirui Song, Yi Yan, Wei Gong, Xuesong Li, Yunfeng Mu, Ruihua Liu, Yonghong Zhang, Luohong School of Environmental and Chemical Engineering Xi'an Polytechnic University Xi'An710048 China Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China

Up-taking the pollutants simultaneously from industrial wastewater is an urgent in the advanced treatment. In this work, the polyaniline (PANI)-based efficient adsorbent supported by the waste polyurethane(PU) was designed for synchronous adsorption of pollutants (acid red G (ARG), methylene blue (MB), hexavalent chromium Cr(VI), phosphorus (TP), NH4+-N (ammonia nitrogen), NO3-N (nitrate nitrogen) and COD (chemical oxygen demand)). The results showed that the synchronous removal efficiency of ARG, MB, Cr(VI), TP, NH4+-N, NO3-N and COD in simulated wastewater reached 88%, 40%, 90%, 58%, 42%, 30% and 63%, respectively. The adsorption lasted for 1800 min (144 columns) before saturation, and no significant decrease was observed after 5 cycles of regeneration. Combined with the XPS (X-ray photoelectron spectroscopy) and EEM (excitation-emission matrix spectroscopy) analysis, ARG, Cr(VI), NO3-N and TP competed for the same adsorption sites, and the adsorption affinity order was ARG>Cr(Ⅵ)>TP>NO3-. During the adsorption process, Cr(VI) and =N- in PANI chain underwent redox reaction to form Cr(III) and -NH+-, which further promoted the adsorption of anionic pollutants, like H2PO4-. Redox reactions also occurred between Cr(VI) and MB before adsorption forming Cr(III) and small organic fragments. These conclusions prove the feasibility and effectiveness of PU-P/T as a potential engineering adsorbent for co-adsorption of a variety of pollutants. © 2023, The Authors. All rights reserved.

关键词： Adsorption

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Effect of Fuel System on the Heat Releasing Method and flow-Path Design of Rocket-Based Combined Cycle Engine

Effect of Fuel System on the Heat Releasing Method and Flow-...

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International Conference on Mechanical and Aerospace engineering (ICMAE)

作者： Xiao Liu Yinhu Wang Yiyan Yang Lei Shi Dekun Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Beijing Institute of Long March Vehicle Beijing China Science and Technology on Combustion Internal Flow and Thermal-structure Laboratory Northwestern Polytechnical University Xi’an China

Multi-components rocket-based combined cycle (RBCC) engine is widely applied in most two-stage-to-orbit program due to stable operation performance under variable flight conditions. Present researches numerically compared RBCC’s performance under ramjet mode and scramjet mode, respectively, by using two fuel system, hydrogen and kerosene together with a $\mathrm{k}-\omega$ SST turbulence model. Researches showed that the combustor area ratio should be increased to keep stable pressure difference balance between inflow and flame because of higher caloric value using hydrogen. Distributed heat addition method is benifit for overall performance improvement when using hydrogen. Different from using kerosene, head should be delayedly added in combustor downtream under scramjet mode. Moreover, the advanced heat addition amount should be decreased under ramjet mode to ensure effective isolator operation.

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Rate-limiting factors in thin-film evaporative heat transfer processes

arXiv

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arXiv 2024年

作者： Zhao, H. Poole, R. Zhou, Z. Wolfson School of Mechanical Electrical and Manufacturing Engineering Loughborough University Loughborough LeicestershireLE11 3TU United Kingdom State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

In this paper, we present a theoretical study aimed at investigating the rate-limiting factors in thin-film evaporative heat transfer processes, considering the finite-rate evaporation kinetics. The problems of evaporation of a flat thin-film in either pure vapours or vapour-inert-gas mixtures are analysed based on the non-dimensionalised macroscopic transport equations for continuum fluids, coupled with out-of-equilibrium kinetic boundary conditions. Both the full numerical solutions and asymptotic analytical solutions at slow evaporation limit are provided and applied to analyse thin water film evaporation. Existing solutions, assuming negligible heat transfer in the gas domain, or negligible temperature jump across the non-equilibrium kinetic layer, or more boldly a thermodynamically equilibrial interface (i.e. its temperature is at the saturation temperature), can be fully recovered from the more general solutions presented here. Our results show that while these assumptions hold in special cases, they can lead to significant errors in many conditions, especially when the film thickness δ is reduced to a few micrometers or thinner. We show that the conventional views that the rate-limiting factors in thin-film evaporative heat transfer is either the heat diffusion through the liquid film or the mass transfer in the gas domain only apply to thick film (i.e. δ λ where λ is the mean free path in the vapour phase). As δ decreases to a few micrometer or smaller (more precisely when the Knudsen number Kn increases beyond O(1) in an pure vapour environment or when the kinetic Peclet number Pe is reduced below O(1) in inert gases), the interfacial thermal resistance due to the evaporation kinetics can be on the same orders of magnitude as the thermal resistance in the liquid film. The analysis also allow us to compare the heat transfer processes during the evaporation of a thin-film in pure vapours to those in inert gases, providing deeper insight into the effectiveness

关键词： Thin films

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Numerical Simulation of Unsteady flow Control Mechanism of Attached Stationary Or Vibrating Small Cylinder On a Main Cylinder

SSRN

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SSRN 2022年

作者： Huang, Shengxian Hu, Yu 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 Key Laboratory of Science and Technology on Aerodynamic Design and Research Xi’an710072 China

The phenomena of flow separation and vortex shedding after bluff body are the key to the safety of offshore engineering. To deepen the understanding of the relevant physical mechanism of wake vortex control of the non-equal diameter double cylinder model, simulation was conducted when Re=200 using the SST k-ω turbulence model. The effects of different diameter ratios, position angle, and gap ratio between the double cylinder model on the flow pattern, surface pressure, and wake characteristics of the main cylinder are investigated. Four different forced vibration forms are applied to the small cylinder with the optimum arrangement area, and their influence on the hydrodynamic characteristics of the main cylinder is analyzed. The results show that the main cylinder's vortex shedding and aerodynamic characteristics can be effectively improved by the small auxiliary cylinder arranged in the near wake region of the main cylinder, and there is an optimal position for the small cylinder. In addition, the vibration of the small auxiliary cylinder in the wake area will cause the locking area of the main cylinder and the side vortex shedding on the main cylinder can be better suppressed by using the auxiliary vibration small cylinder with a suitable frequency ratio. © 2022, The Authors. All rights reserved.

关键词： Vortex shedding

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Understanding Copper Corrosion in Bentonite-Enriched Environments: Insights from the Point Defect Model

SSRN

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SSRN 2024年

作者： Ning, Zhiyuan Zhou, Qulan Li, Na Macdonald, Digby D. Zhou, Jie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Departments of Nuclear Engineering and Materials Science and Engineering University of California at Berkeley BerkeleyCA94720 United States Xi’an Aerospace Propulsion Institution Xi’an China

The laboratory simulated copper corrosion in a bentonite/groundwater solution, analyzing the kinetics of metal passivation through potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy experiments. Corrosion development patterns were inferred from morphological characterization, and the mechanisms by which bentonite affects copper corrosion were comprehensively elucidated based on the point defect model. The research revealed that bentonite affects copper corrosion resistance through Donnan exclusion, cation adsorption, and hydrolysis of salts. Based on the point defect model, the study elucidated the microscopic mechanism of pitting corrosion induced by bentonite hydrolysis salts, calculating the polarizability of the passive layer/outer layer interface as α = 0.1. The reliability of the cation adsorption and adsorption-desorption mechanisms was confirmed through experimental data fitting, point defect model fitting, and theoretical analysis. © 2024, The Authors. All rights reserved.

关键词： Hydrolysis

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Experimental Study on the flow Characteristics of a Plate with a Mechanically Choked Orifice

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Fluid Dynamics & Materials Processing 2021年第1期17卷 97-107页

作者： Ming Liu Xingkai Zhang Dong Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Petroleum Engineering Technology Research Institute of Shengli Oilfield Company SINOPECDongying257000China Shandong Key Laboratory of Heavy Oil Production Technology Shengli Oilfield CompanySINOPECDongying257000China Petroleum Engineering College Yangtze UniversityWuhan430100China

The mechanically choked orifice plate (MCOP) is a new type of device for flow control by which choking conditionsfor incompressible fluids can be obtained with relatively small pressure losses. Given the lack of relevant results anddata in the literature, in the present study, we concentrate on the experimental determination of the flow coefficientfor the annular orifice, the pressure distribution in the MCOP, and the characteristics of the choked flow itself. Asconfirmed by the experimental results, the Reynolds number, the orifice plate thickness, the plug taper, and theeccentricity have an obvious influence on the aforementioned flow coefficient. The pressure drop in the MCOPis mainly generated near the orifice plate, and the pressure upstream of the orifice plate is slightly reduced in theflow direction, while the pressure downstream of the orifice plate displays a recovery trend. The choked flow rateof the MCOP can be adjusted by replacing the spring with a maximum flow control deviation of 4.91%.

关键词： Mechanical choked orifice plate flow control flow coefficient flow characteristics

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