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Design and heat transfer analysis of a compound multi-layer insulations for use in high temperature cylinder thermal protection systems

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Science China(Technological Sciences) 2018年第7期61卷 994-1002页

作者： chen mengjun ZHANG Ping LI Qiang MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power Engineering Nanjing University of Science & Technology School of Mechanical and Electrical Engineering Guilin University of Electronic Technology

Thermal protection systems are very essential for high temperature thermal conductivity measurement system to reduce the heat loss to environment at the range of 600-1800 K. A compound multi-layer insulations structure which composed of inner carbon fibrous materials and outer alternately arranged alumina fibrous materials and high reflectivity foils is proposed for use in high temperature cylinder thermal protection systems. A coupled conductive and radiation governing equations is presented for heat transfer analysis of the structure. The finite volume method and the discrete ordinate method are used to solve the goveming equations. The optimization structure of the compound multi-layer insulations is investigated by considering the pressure of the gas, the density of the carbon fibrous materials, the density of the alumina fibrous materials, the number of reflective foil layers and the emissivity of reflective foils. The results show that the compound structure has the best thermal insulation performance when the pressure of the gas is below 0.01 kPa, the density of carbon fibrous materials is 180 kg m^-3, the density of alumina fibrous materials is 256 kg m^-3 and the number of reflective foil layers is 39. In addition, the thermal insulation performance is much better when the emissivity of reflective foils is lower.

关键词： compound insulation heat transfer carbon fibrous alumina fibrous

Granular analyzing of weapon SoS demand description

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Journal of Systems Engineering and Electronics 2009年第3期20卷 565-570页

作者： Zhao Qingsong Yang Kewei chen Yingwu Li mengjun School of Information System and Management National Univ. of Defense Technology Changsha 410073 P. R. China

The systematism of weapon combat is the typical characteristic of a modern battlefield. The process of combat is complex and the demand description of weapon system of systems （SOS） is difficult. Granular analyzing is an important method for solving the complex problem in the world. Granular thinking is introduced into the demand description of weapon SoS. Granular computing and granular combination based on a relation of compatibility is proposed. Based on the level of degree and degree of detail, the granular resolution of weapon SoS is defined and an example is illustrated at the end.

关键词： weapon SoS demand description granular analyzing granular resolution.

Copper recovery from waste printed circuit boards concentrated metal scraps by electrolysis

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Frontiers of Environmental Science & Engineering 2017年第5期11卷 107-111页

作者： Xiaonan Liu Qiuxia Tan Yungui Li Zhonghui Xu mengjun chen State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials Southwest University of Science and Technology Mianyang 621010 China Key Laboratory of Solid Waste Treatment and Resource Recycle Ministry of Education Southwest University of Science and Technology Mianyang 621010 China

Copper recovery is the core of waste printed circuit boards （WPCBs） treatment. In this study, we proposed a feasible and efficient way to recover copper from WPCBs concentrated metal scraps by direct electrolysis and thctors that affect copper recovery rate and purity, mainly CuSO4.5H2O concentration, NaCI concentration, H2SO4 concentration and current density, were discussed in detail. The results indicated that copper recovery rate increased first with the increase ofCuSO4- 5H2O, NaCI, H2SO4 and current density and then decreased with further increasing these conditions. NaCI, H2SO4 and current density also showed a similar impact on copper purity, which also increased first and then decreased. Copper purity increased with the increase of CuSO4.5H2O. When the concentration of CuSO4-5H2O NaCI and H2oSO4 was respectively 90, 40 and 118 g/L and current density was 80 mA/cm-, copper recovery rate and purity was up to 97.32% and 99.86%, respectively. Thus, electrolysis proposes a feasible and prospective approach for waste printed circuit boards recycle, even for e-waste, though more researches are needed for industrial application.

关键词： Waste printed circuit boards (WPCBs)Copper Recovery rate Purity Electrolysis

Theoretical and experimental study on the rheological properties of WIS grout and the dispersion and sealing mechanism

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International Journal of Mining Science and Technology 2022年第4期32卷 669-684页

作者： Mengmeng Zhou Shucai Li Zhuo Zheng Rentai Liu mengjun chen chenyang Ma ARC Research Hub for Computational Particle Technology Department of Chemical EngineeringMonash UniversityClayton 3800Australia Geotechnical and Structural Engineering Research Center Shandong UniversityJinan 250061China

Recently a new grout material called water inflow sealing(WIS) was invented for sealing water inflow in tunneling and underground constructions. In this study, a special experimental method called intubated counter grouting(ICG) was proposed to investigate the influence of water dispersion on the rheological properties of the grout during the grouting process, and to testify the sealing performance of the grout,such as instant gelling ability(IGA) and anti-dispersion ability(ADA). In the experiment, dispersion was restricted in the downstream of the channel with a high turbulence intensity. The influences of ADA and IGA were therefore decoupled and evaluated separately. Experimental results revealed two distinctive sealing mechanisms of WIS. For a low initial velocity of water, WIS turned the shear flow of water into an overall movement of a plug by absorbing water into the particles. For a high initial velocity and the situation that the particles reached the outlet before sufficiently expanding, WIS modified the rheology of the water in the channel and reduced its velocity till the static state. The distinctive feature of WIS brings a reformation on the sealing mechanism and provides an effective way to control water inflow with high pressure and velocity.

关键词： WIS grout material Grouting treatment Water inflow Sealing mechanism Flow regularity

Enhanced recovery of high-purity Fe powder from iron-rich electrolytic manganese residue by slurry electrolysis

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International Journal of Minerals,Metallurgy and Materials 2024年第3期31卷 531-538页

作者： Wenxing Cao Jiancheng Shu Jiaming chen Zihan Li Songshan Zhou Shushu Liao mengjun chen Yong Yang Key Laboratory of Solid Waste Treatment and Resource Recycle(SWUST) Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China Daxin Manganese Mining Branch of South Manganese Group Limited Chongzuo 532315China

Iron-rich electrolytic manganese residue(IREMR)is an industrial waste produced during the processing of electrolytic metal manganese,and it contains certain amounts of Fe and Mn resources and other heavy *** this study,the slurry electrolysis technique was used to recover high-purity Fe powder from *** effects of IREMR and H2SO4 mass ratio,current density,reaction temper-ature,and electrolytic time on the leaching and current efficiencies of Fe were *** to the results,high-purity Fe powder can be recovered from the cathode plate,and the slurry electrolyte can be *** leaching efficiency,current efficiency,and purity of Fe reached 92.58%,80.65%,and 98.72wt%,respectively,at a 1:2.5 mass ratio of H2SO4 and IREMR,reaction temperature of 60℃,electric current density of 30 mA/cm^(2),and reaction time of 8 *** addition,vibrating sample magnetometer(VSM)analysis showed that the coercivity of electrolytic iron powder was 54.5 A/m,which reached the advanced magnetic grade of electrical pure-iron powder(DT4A coercivity standard).The slurry electrolytic method provides fundamental support for the industrial application of Fe resource recovery in IRMER.

关键词： iron-rich electrolytic manganese residue slurry electrolysis high-purity iron powder leaching efficiency current efficiency

Copper fractal growth during recycling from waste printed circuit boards by slurry electrolysis

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Frontiers of Environmental Science & Engineering 2021年第6期15卷 271-280页

作者： Jiqin Wang Xiaoxia Yi Xiangfei Zeng Shuyuan chen Rui Wang Jiancheng Shu mengjun chen Zhengxue Xiao Key Laboratory of Solid Waste Treatment and Resource Recycle Ministry of EducationSouthwest University of Science and TechnologyMianyang 621010China

Superfine copper particles could be directly prepared from waste printed circuit boards by slurry ***,copper fractal growth could be *** better understand this phenomenon,the factors that affect copper dendrites in a point-cathode system were discussed in *** results showed that the fractal degree of copper dendrites increased as the increase of applied voltage and the decrease of copper sulfate and gelatin *** lauryl sulfate and hydrochloric acid concentrations could not significantly impact the fractal degree of copper dendrites,while gelatin concentration *** minimum copper fractal dimension was 1.069 when gelatin and copper sulfate concentration was 120 mg/L and 0.1 mol/L,respectively with an applied voltage of 11 ***,the results diffusion-limited aggregation model demonstrated that particle translational speed,particle numbers and binding probability significantly affected copper dendrite *** scanning electron microscopy results indicated that the three additives greatly affected the refinement of the copper *** findings contribute to enrich the theoretical study on metals recovery from e-waste by slurry electrolysis.

关键词： Dendritic copper Fractal growth WPCBs Slurry electrolysis

Leaching Stability of Simulated Waste Forms for Immobilizing An^(3+) by Gd_2Zr_2O_7 with Nd^(3+)

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Journal of Wuhan University of Technology(Materials Science) 2014年第5期29卷 885-890页

作者：卢喜瑞 chen mengjun DONG Faqin WANG Xiaoli WU Yanlin XIAO Zhengxue Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security Southwest University of Science and Technology Key Laboratory of Radiation Physics and Technology (Sichuan University) Ministry of EducationInstitute of Nuclear Science and Technology Sichuan University Institute of Nuclear Physics and Chemistry China Academy of Engineering Physics School of High Energy Accelerator Science Graduate University for Advanced Studies

In order to investigate the anti-leaching capability of pyrochlore Gd2Zr2O7 immobilized An3＋, trivalent neodymium was used as the simulacrums for radioactive wastes with trivalence, Gd2-xNdxZr2O7（0.0 ≤ x≤2.0） series samples were successfully synthesized by high temperature solid reaction and using Gd2O3, ZrO2 powders as starting materials. The experiments of long-term chemical stability were conducted in synthetic seawater at 40 and 70 ℃. The XRD diffractive data and extraction ratio of as-received samples were collected with the help of X-ray diffraction （XRD） instrument and inductively coupled plasma mass spectrometry （ICP- Mass）. The results indicate that the phases of as-received compounds keep the single phase of pyrochlore. The extraction ratio of Gd3＋, Zr4＋ and Nd3＋ in waste forms is increasing with the increase of immersion time in synthetic seawater. The extraction ratio of waste forms at 70 ℃ is higher than at 40 ℃. The highest extraction ratio of Gd3＋, Zr4＋ and Nd3＋ after 42 days is near 0.025 8, 0.003 8 and 0.045 2 μ***-1, respectively.

关键词： pyrochlore radioactive waste with trivalence waste forms anti-leaching capability

Enhanced Mn^(2+)solidification and NH_(4)^(+)-N removal from electrolytic manganese metal residue via surfactants

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Chinese Journal of Chemical Engineering 2022年第9期35卷 205-212页

作者： Jiancheng Shu Xiangfei Zeng Danyang Sun Yong Yang Zuohua Liu mengjun chen Daoyong Tan School of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China

Electrolytic manganese metal residue(EMMR)harmless treatment has always lacked a low-cost and quick processing *** this study,surfactants,namely tetradecyl trimethylammonium chloride(TTC),sodium dodecyl benzene sulfonate(SDBS),sodium lignin sulfonate(SLS),and octadecyl trimethylammonium chloride(OTC),were used in the solidification of Mn^(2+)and removal of NH_(4)^(+)-N from *** Mn^(2+)and NH_(4)^(+)-N concentrations under different reaction conditions,Mn^(2+)solidification and NH_(4)^(+)-N removal mechanisms,and leaching behavior were *** results revealed that the surfactants could enhance the Mn^(2+)solidification and NH_(4)^(+)-N removal from EMMR,and the order of enhancement was as follows:TTC>SDBS>OTC>*** NH_(4)^(+)-N and Mn^(2+)concentrations were 12.3 and 0.05 mg·L^(-1)with the use of 60.0 mg·kg^(-1)TTC under optimum conditions(solid–liquid ratio of 1.5:1,EMMR to BRM mass ratio of 100:8,temperature of 20℃,and reaction duration of 12 h),which met the integrated wastewater discharge standard(GB8978-1996).Mn^(2+)was mainly solidified as Mn(OH)_(2),MnOOH and MnSiO_(3),and NH_(4)^(+)-N in EMMR was mostly removed in the form of *** results of this study could provide a new idea for cost-effective EMMR harmless treatment.

关键词： Electrolytic manganese metal residue Mn^(2+)solidification NH_(4)^(+)-N removal Surfactants

Super-absorbent swellable polymer as grouting material for treatment of karst water inrush

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International Journal of Mining Science and Technology 2021年第5期31卷 753-763页

作者： Shucai Li chenyang Ma Rentai Liu mengjun chen Jia Yan Zhenjun Wang Shaolong Duan Huasheng Zhang School of Civil Engineering Shandong UniversityJinan 250061China Geotechnical and Structural Engineering Research Centre Shandong UniversityJinan 250061China School of Qilu Transportation Shandong UniversityJinan 250002 China

Grouting is the most commonly used method to control water inrush in underground *** cement-based materials are easy to dilute and hard to coagulate under the influence of large flow and high-velocity water *** address these deficiencies,a new type of polymer grouting material with an excellent expansion ratio was *** material quickly absorbs water and has an expansion ratio of 1:*** material is composed of a superabsorbent polymer(SAP),glycerol,and *** effects of water quality on the expansion ratio and expansion rate of the material were examined,and the best solid–liquid ratio for the slurry was determined by fluidity measurements.A karst specially designed pipeline water inrush test device showed that 800 g of SAP can achieve 0.6 m/s water flow blockage in the smooth pipeline,demonstrating that the ability of the SAP slurry to block water inrush is superior to those of other *** study provides a reference for water inrush plugging,and has important implications for the reduction and control of karst pipeline-type water inrush disasters,ensuring the safety of construction sites and preventing loss of life and damage to property.

关键词： Karst Water inrush Model test Grouting material Superabsorbent polymer