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Overview of in-situ oxygen production technologies for lunar resources

International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 233-255页

作者： Youpeng Xu Sheng Pang Liangwei Cong Guoyu Qian Dong Wang Laishi Li Yusheng Wu Zhi Wang College of Materials Science and engineering Shenyang University of TechnologyShenyang 110870China CAS Key Laboratory of Green process and engineering National Engineering Research Center for Green Recycling of Strategic Metal ResourcesInstitute of Process EngineeringChinese Academy of SciencesBeijing 100190China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China School of Chemical engineering University of Chinese Academy of SciencesBeijing 100049China

The rich resources and unique environment of the Moon make it an ideal location for human expansion and the utilization of extraterrestrial ***,crucial for supporting human life on the Moon,can be extracted from lunar regolith,which is highly rich in oxygen and contains polymetallic *** oxygen and metal extraction can be achieved using existing metallurgical ***,the ample reserves of water ice on the Moon offer another means for oxygen *** paper offers a detailed overview of the leading technologies for achieving oxygen production on the Moon,drawing from an analysis of lunar resources and environmental *** delves into the principles,processes,advantages,and drawbacks of water-ice electrolysis,two-step oxygen production from lunar regolith,and one-step oxygen production from lunar *** two-step methods involve hydrogen reduction,carbothermal reduction,and hydrometallurgy,while the one-step methods encompass fluorination/chlorination,high-temperature decomposition,molten salt electrolysis,and molten regolith electrolysis(MOE).Following a thorough comparison of raw materials,equipment,technology,and economic viability,MOE is identified as the most promising approach for future in-situ oxygen production on the *** the corrosion characteristics of molten lunar regolith at high temperatures,along with the Moon's low-gravity environment,the development of inexpensive and stable inert anodes and electrolysis devices that can easily collect oxygen is critical for promoting MOE technology on the *** review significantly contributes to our understanding of in-situ oxygen production technologies on the Moon and supports upcoming lunar exploration initiatives.

关键词： lunar resources in-situ oxygen production space metallurgy molten lunar regolith electrolysis

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Unsteady flow structures in centrifugal pump under two types of stall conditions

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Journal of Hydrodynamics 2018年第6期30卷 1038-1044页

作者： Pei-jian Zhou Jia-cheng Dai Ya-fei Li Ting Chen Jie-gang Mou College of Mechanical engineering Zhejiang University of Technology engineering research center of process equipment and remanufacturing Ministry of Education School of Science Wuhan Institute of Technology

The stall is an unsteady flow phenomenon that always causes instabilities and low efficiency for pumps. This paper focuses on the unsteady flow structures and evolutions under two types of stall conditions in centrifugal pump impellers. Two centrifugal pump impellers, one with 6 and another with 5 blades, are considered and a developed large-eddy simulation method is adopted. The results show that the alternative stall occurs in the impeller with 6 blades, while, the rotating stall is observed in that with 5 blades. The flow structure and the pressure fluctuation characteristics are further analyzed. For the alternative stall, the stall cells are fixed relative to the impeller, but a large vortex in the stalled passage is always swaying. The outlet vortex is generated from it, and then develops and sheds periodically. For the rotating stall, the stall cells first occur in the suction side of the blade. With the growth of the stall cells, the block area gradually increases until the inlet region is almost blocked, then moves to the pressure side with a continuous decay. When the rotating stall occurs, the amplitude of the pressure fluctuation is much larger than that under the alternative stall condition. The propagation of the stall cells has a significant effect on the pressure fluctuations in the impeller.

关键词： Centrifugal pump flow structures rotating stall alternative stall large-eddy simulation

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Multi-level DEM study on silo discharge behaviors of non-spherical particles

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Particuology 2023年第11期82卷 179-191页

作者： Lei Xu Xiukai Wu Jingyin Liang Shuai Wang Shiyi Bao Institute of process equipment and Control engineering College of Mechanical EngineeringZhejiang University of TechnologyHangzhou310032China engineering research center of process equipment and remanufacturing Ministry of EducationChina State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou310027China

The silo discharge of non-spherical particles has been widely practiced in engineering processes, yet the understanding of multi-level mechanisms during solid transportation is still lacking. In this study, a high-fidelity super-ellipsoid Discrete Element Method (DEM) model is established to investigate the discharge behaviors of non-spherical particles with different size distributions. After the comprehensive model validations, we investigated the effects of particle shape (aspect ratio and particle sharpness) on the particle level discharge behaviors. The discharge rates of the ellipsoid particles used in the current work are larger than the spherical particles due to the larger solid fraction. The discharge rates of the cuboid-like particles are determined by the combined effect of the solid fraction and the contact force. Parcel level data show that the translational movements of the ellipsoid particles are more ordered, which is supported by the global level data. Strong correlations exist between the particle level and parcel level data, especially the ellipsoid particles and the large particles in the polydispersed cases.

关键词： Multi-level study Non-spherical particle Numerical simulation Silo discharge Granular flow

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Investigation of CFD Calculation Method of a Centrifugal Pump with Unshrouded Impeller

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Chinese Journal of Mechanical engineering 2014年第2期27卷 376-384页

作者： WU Dazhuan YANG Shuai XU Binjie LIU Qiaoling WU Peng WANG Leqin Institute of process equipment Zhejiang University engineering research center of High Pressure process equipment and Safety of Ministry of Education Zhejiang University

Currently, relatively large errors are found in numerical results in some low-specific-speed centrifugal pumps with unshrouded impeller because the effect of clearances and holes are not accurately modeled. Establishing an accurate analytical model to improve performance prediction accuracy is therefore necessary. In this paper, a three-dimensional numerical simulation is conducted to predict the performance of a low-specific-speed centrifugal pump, and the modeling, numerical scheme, and turbulent selection methods are discussed. The pump performance is tested in a model pump test bench, and flow rate, head, power and efficiency of the pump are obtained. The effect of taking into consideration the back-out vane passage, clearance, and balance holes is analyzed by comparing it with experimental results, and the performance prediction methods are validated by experiments. The analysis results show that the pump performance can be accurately predicted by the improved method. Ignoring the back-out vane passage in the calculation model of unshrouded impeller is found to generate better numerical results. Further, the calculation model with the clearances and balance holes can obviously enhance the numerical accuracy. The application of disconnect interface can reduce meshing difficulty but increase the calculation error at the off-design operating point at the same time. Compared with the standard k-ε, renormalization group k-ε, and Spalart-Allmars models, the Realizable k-ε model demonstrates the fastest convergent speed and the highest precision for the unshrouded impeller flow simulation. The proposed modeling and numerical simulation methods can improve the performance prediction accuracy of the low-specific-speed centrifugal pumps, and the modeling method is especially suitable for the centrifugal pump with unshrouded impeller.

关键词： centrifugal pump unshrouded impeller numerical simulation clearance turbulence model

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High Velocity Electric Arc Sprayed Fe-Al-Nb-B Composite Coating and Its Wear Behavior

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Acta Metallurgica Sinica(English Letters) 2013年第3期26卷 313-320页

作者： Yongxiong CHEN Xiubing LIANG Jinyuan BAI Binshi XU National engineering research center for Mechanical Product remanufacturing Academy of Armored Forces Engineering National Key Laboratory for remanufacturing Academy of Armored Forces Engineering

A type of Fe-Al-Nb-B cored wire was designed and the coating was prepared using a robot-based electric wire arc spraying process. The Fe-Al binary cored wire and coating were also prepared as comparison. The phase composition and structure of the coatings were investigated using X-ray diffraction （XRD）, scanning electron microscopy （SEM） coupled with energy dispersive X-ray spectroscopy （EDS） and transmission electron microscopy （TEM）. The coating tribological properties were evaluated with the micromotion wear tester under different conditions. The results show that, although typical lamellar structure was performed for both the arc sprayed Fe-Al-Nb-B coating and Fe-Al coating, the structure composition, mechanical and wear properties of the former are quite different from those of latter. The Fe-Al-Nb-B coating is a typical composite coating, which is distributed inhomogeneously with α-Fe crystalline, FeAl and Fe3Al intermetallics, amorphous and nanocrystallines as well as locally existed oxide phases. As a result, the mircrohardness and wear resistance of the Fe-Al-Nb-B composite coating increased significantly. Finally the mechanism of the coating wear resistant behavior was discussed based on the experimental results such as friction coefficient, two dimensional and three dimensional worn surface profiles.

关键词： Fe-Al-Nb-B coating Structure High velocity electric arc spraying Wear resistance

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Simulations of the Transient Flow Generated from a Started Flat Plate

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Chinese Journal of Mechanical engineering 2012年第6期25卷 1190-1197页

作者： WANG Leqin MA Xudan LI Zhifeng WU Peng WU Dazhuan Institute of process equipment Zhejiang UniversityHangzhou 310027China engineering research center of High Pressure process equipment and Safety Ministry of EducationHangzhou 310027China

Transient operations are commonly founded in fluid machineries such as the starting, stopping, and variations of rotor speeds, etc. Flow generated from a started fiat plate is of fundamental importance. Experiments have been done to observe the flow evolution in current researches. And in order to explore the flow in more detailed scale, some vortex methods with high resolution and other numerical methods were developed to solve various related problems by some researchers. But the promotion of vortex method to engineering application is rare due to its complexity and difficulty in specifying the boundary conditions. In order to build up a method of numerical study for such problems, a simplified model is built up with a flat plate. The development of two-dimensional viscous incompressible flow generated from an impulsively started and uniformly accelerated infinitesimally thin flat plate is simulated numerically. A dynamic mesh（DM） method based on the spring analogue and local remeshing is applied to realize the mesh motion caused by the started plate. researches show that the mesh quality will decline under large grid shear force during the updating process. To conquer this problem, a region near the plate is separated to guarantee the mesh quality at location of interest which is the innovation of the present paper. All computations at least cover a period during which the plate translates 6 times its length. The simulated instantaneous velocity profiles, flow structures and drag coefficients under several Reynolds numbers （20 ≤ Re ≤ 126） and accelerations （20 m/s2≤ a ≤ 152 m/s2） are presented and compared with existing results in literatures. Comparisons are found to be satisfactory, confirming the validity of the current proposed method（region separated DM）. The proposed DM method is firstly used to study the transient flow generated from a started flat plate and can be used in further study of transient characteristics during transient operations of turbo mach

关键词： numerical simulation flat plate start transient flow region separated dynamic mesh

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Leakage and Stiffness Characteristics of Bionic Cluster Spiral Groove Dry Gas Seal

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Chinese Journal of Mechanical engineering 2018年第2期31卷 148-158页

作者： Jin-Bo Jiang Xu-Dong Peng Ji-Yun Li Yuan Chen engineering research center of process equipment and Its Re-manufacturing of Ministry of Education Zhejiang University of Technology

Spiral groove dry gas seal(S?DGS), the most widely used DGS in the world, encounters the problem of high leakage rate and inferior film stability when used in high?speed machinery equipment, which could not be well solved by optimization of geometrical parameters and molded line of spiral groove. A new type of bionic cluster spiral groove DGS(CS?DGS) is proved to have superior film stability than S?DGS at the condition of high?speed and low?pressure numerically. A bionic CS?DGS is experimentally investigated and compared with common S?DGS in order to provide evidence for theoretical study. The film thickness and leakage rate of both bionic spiral groove and common spiral groove DGS are measured and compared with each other and with theoretical values under different closing force at the condition of static pressure, high?speed and low?pressure, and the film stiffness and stiffness?leakage ratio of these two face seals are derived by the relationship between closing force and film thickness at the steady state. Experimental results agree well with the theory that the leakage and stiffness of bionic CS?DGS are superior to that of common S?DGS under the condition of high?speed and low?pressure, with the decreasing amplitude of 20% to 40% and the growth amplitude of 20%, respectively. The opening performance and stiffness characteristics of bionic CS?DGS are inferior to that of common S?DGS when rotation speed equals to 0 r/min. The proposed research provides a new method to measure the axis film stiffness of DGS, and validates the superior performance of bionic CS?DGS at the condition of high?speed and low?pressure experimentally.

关键词： Bionic cluster spiral groove Film stiffness Dry gas seal Leakage rate

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Multi-level coarse-grained discrete element method modeling of cylinder particle flow in a rotating drum

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Particuology 2024年第5期88卷 218-238页

作者： Lei Xu Xiukai Wu Shuai Wang Shiyi Bao Institute of process equipment and Control engineering Zhejiang University of TechnologyHangzhou 310023China engineering research center of process equipment and remanufacturing Ministry of EducationZhejiang University of TechnologyHangzhou 310023China College of Mechanical engineering Zhejiang University of TechnologyHangzhou 310023China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027China

The coarse-grained discrete element method(DEM)is probably a feasible option for simulating an actual drum-type biomass boiler,which contains over 10 million cylinder particles.A multi-level study was conducted based on particle and coarse-grained level data to evaluate the adequacy of the coarse-grained approach in terms of geometrical characteristics,kinematic features,and dynamic *** scaling laws for contact parameters were used and compared during the *** results show that the coarse-grained approach can accurately predict the positions of the free surface and active-passive interface,the mixing index,and the orientation *** in the velocity fields may occur due to the worse flowability of coarse-grained particles near the free *** efficiency is significantly improved by the coarse-grained model compared with the corresponding original case(the same DEM code without a coarse-grained model was used for the original simulations).

关键词： Coarse-grained method Discrete element method(DEM) Cylinder particle Rotating drum Granular flow

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Analysis on Pseudo Excitation of Random Vibration for Structure of Time Flight Counter

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Chinese Journal of Mechanical engineering 2015年第2期28卷 325-330页

作者： WU Qiong LI Dapeng Beijing engineering Technological research center of High-efficient & Green CNC Machining process and equipment Beihang University

Traditional computing method is inefficient for getting key dynamical parameters of complicated *** Excitation Method（PEM）is an effective method for calculation of random *** to complicated and coupling random vibration in rocket or shuttle launching,the new staging white noise mathematical model is deduced according to the practical launch *** deduced model is applied for PEM to calculate the specific structure of Time of Flight Counter（ToFC）.The responses of power spectral density and the relevant dynamic characteristic parameters of ToFC are obtained in terms of the flight acceptance test *** stiffness of fixture structure,the random vibration experiments are conducted in three directions to compare with the revised *** experimental results show the structure can bear the random vibration caused by launch without any damage and key dynamical parameters of ToFC are *** revised PEM is similar with random vibration experiment in dynamical parameters and responses are proved by comparative *** maximum error is within 9%.The reasons of errors are analyzed to improve reliability of *** research provides an effective method for solutions of computing dynamical characteristic parameters of complicated structure in the process of rocket or shuttle launching.

关键词： pseudo excitation method power spectral density random processes dynamic response vibration

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Experiment on Wear Behavior of High Pressure Gas Seal Faces

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Chinese Journal of Mechanical engineering 2014年第6期27卷 1287-1293页

作者： XU Jing PENG Xudong BAI Shaoxian MENG Xiangkai LI Jiyun MOE engineering research center of process equipment and Its Remanufacture Zhejiang University of Technology School of Mechanical engineering Hangzhou Dianzi University

Current researches show that mechanical deformation of seal ring face makes fluid film clearance decrease at high pressure side, thus a divergent clearance is formed and face wear occurs more seriously at the high pressure side than that on the low pressure side. However, there is still lack of published experimental works enough to prove the theoretical results. In this paper, a spiral groove dry gas seal at high pressures is experimentally investigated so as to prove the face wear happened at the high pressure side of seal faces due to the face mechanical deformation, and the wear behavior affected by seal ring structure is also studied. The experimental results show that face wear would occur at the high pressure side of seal faces due to the deformation, thus the leakage and face temperature increase, which all satisfies the theoretical predictions. When sealed pressure is not less than 5 MPa, the pressure can provide enough opening force to separate the seal faces. The seal ring sizes have obvious influence on face wear. Face wear, leakage and face temperature of a dry gas seal with the smaller cross sectional area of seal ring are less than that of a dry gas seal with bigger one, and the difference of leakage rate between these two sizes of seal face width is in the range of 24%–25%. Compared with the effect of seal ring sizes, the effect of secondary O-ring seal position on face deformation and face wear is less. The differences between these two types of dry gas seals with different secondary O-ring seal positions are less than 5.9% when the rotational speed varies from 0 to 600 r/min. By linking face wear and sealing performance changes to the shift in mechanical deformation of seal ring, this research presents an important experimental method to study face deformation of a dry gas seal at high pressures.

关键词： dry gas seal structures face wear high pressure mechanical deformation

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