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Particuology 2020年第4期18卷 53-63页

作者： Xiangwen Guan Zhixing Zhou Jihong Li Shizhong Li Institute of New Energy Technology Tsinghua UniversityBeijing 100084China Beijing Engineering Research Center for Biofuels Institute of New Energy TechnologyTsinghua UniversityBeijing 100084China

The mixing of raw materials in a rotary drum bioreactor is important for advanced solid-state fermentation technology.However,the shape,size,and other properties of pulverized sweet sorghum stalk particles are more complicated than those of the spherical particles.In this study,a soft rod-shaped discrete particle model was established and verified to simulate the mixing behavior of sweet sorghum stalk particles in a rotary drum bioreactor.We were inspired by the particle shape and established a rod-shaped particle model by investigating the influence of the shape(length-diameter ratio)and size(diameter)on the particle packing(stack height and bed porosity).We used orthogonal simulations and extremum difference analysis to determine the main factors,optimum level,and groups of other parameters.Based on calibrated parameters,twelve sets of simulations of radial mixing in the drum were performed,and the results were compared with experiments conducted under identical operating conditions.The average relative error between the simulation and the experiment was 10.95%,which indicates that they agreed well and that the simulation could predict the mixing process well.

关键词： Sweet sorghum particles Radial mixing Discrete element method Rotary drum bioreactor Parameter determination

Enhancing mixing of cohesive particles by baffles in a rotary drum

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Particuology 2016年第2期14卷 104-110页

作者： Zhixing Zhou Jihong Li Jingzhi Zhou Shizhong Li Junxiao Feng Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China beijing engineering research Centre of biofuels China MOST-USDA Joint research center for biofuels beijing 100084 China Department of Thermal Science an-d Energy engineering School of Mechanical Engineering University of Science and Technology Beifing Beijing 100081 China

A soft-sphere discrete cohesive powder model was used to simulate the transverse mixing of particles in a rotary drum. Using this model, the effect of cohesion strength and baffle length was investigated. Mixing time （tR） and mixing entropy were used to characterize the mixing behavior. The results showed that increasing particle cohesiveness increases tR. Baffles enhanced transverse mixing, especially for high- cohesive particles. Moreover, the baffle length played a significant role on mixing. An optimized length of 0.50 （L/R） enhances transverse mixing for high-cohesive particles, Further increases in baffle length only decreases the mixing rate by impeding the surface flow layer. In contrast to high-cohesive particles, low-cohesive particles needed much shorter baffles.A soft-sphere discrete cohesive powder model was used to simulate the transverse mixing of particles in a rotary drum. Using this model, the effect of cohesion strength and baffle length was investigated. Mixing time （tR） and mixing entropy were used to characterize the mixing behavior. The results showed that increasing particle cohesiveness increases tR. Baffles enhanced transverse mixing, especially for high- cohesive particles. Moreover, the baffle length played a significant role on mixing. An optimized length of 0.50 （L/R） enhances transverse mixing for high-cohesive particles. Further increases in baffle length only decreases the mixing rate by impeding the surface flow layer. In contrast to high-cohesive particles, low-cohesive particles needed much shorter baffles.

关键词： Cohesive particles Mixing Baffles Rotary drum

Development of a whole-cell biosensor based on an ArsR-Pars regulatory circuit from Geobacter sulfurreducens

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Environmental Science and Ecotechnology 2021年第2期6卷 3-10页

作者： Pengsong Li Yumingzi Wang Xin Yuan Xinying Liu Chunmao Liu Xiaofen Fu Dezhi Sun Yan Dang Dawn E.Holmes beijing Key Laboratory for Source Control Technology of Water Pollution Engineering Research Center for Water Pollution Source Control and EcoremediationCollege of Environmental Science and EngineeringBeijing Forestry UniversityBeijing 100083China Key Laboratory of beijing Yanjing Beer Brewing Technology Beijing Yan Jing Brewery Company Ltd.Beijing 101300China MOST-USDA Joint research center for biofuels Beijing Engineering Research Center for BiofuelsInstitute of New Energy TechnologyTsinghua UniversityBeijing 100084China Department of Physical and Biological Sciences Western New England University1215 Wilbraham RdSpringfieldMA 01119USA

In this study,an Escherichia coli(E.coli)whole-cell biosensor for the specific detection of bioavailable arsenic was developed by placing a green fluorescent protein(GFP)reporter gene under the control of the ArsR1(GSU2952)regulatory circuit from Geobacter sulfurreducens.E.coli cells only emitted green fluorescence in the presence of arsenite and were more sensitive to arsenite when they were grown in M9 supplemented medium compared to LB medium.Under optimal test conditions,the Geobacter arsR1 promoter had a detection limit of 0.01 mM arsenite and the GFP expression was linear within a range of 0.03-0.1 mM(2.25-7.5 mg/l).These values were well below World Health Organization’s drinking water quality standard,which is 10 mg/l.The feasibility of using this whole-cell biosensor to detect arsenic in water samples,such as arsenic polluted tap water and landfill leachate was verified.The biosensor was determined to be just as sensitive as atomic fluorescence spectrometry.This study examines the potential applications of biosensors constructed with Geobacter ArsR-Pars regulatory circuits and provides a rapid and cost-effective tool that can be used for arsenic detection in water samples.

关键词： Arsenic detection Whole-cell biosensor Geobacter sulfurreducens ars operon

Influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors

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Chinese Journal of Chemical engineering 2022年第4期35卷 51-71页

作者： He Yang Aqiang Chen Shujun Geng Jingcai Cheng Fei Gao Qingshan Huang Chao Yang Key Laboratory of biofuels Qingdao Institute of Bioenergy and Bioprocess Technology(QIBEBT)Chinese Academy of Sciences(CAS)Qingdao 266101China Dalian National Laboratory for Clean Energy(DNL) Dalian 116023China Synthetic Biology Technology Innovation center of Shandong Province Qingdao 266101China Key Laboratory of Green Process and engineering Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical engineering University of Chinese Academy of SciencesBeijing 100080China Petrochemical research Institute China National Petroleum Corporation(CNPC)Beijing 100083China

Slurry reactors are popular in many industrial processes,involved with numerous chemical and biological mixtures,solid particles with different concentrations and properties,and a wide range of operating conditions.These factors can significantly affect the hydrodynamic in the slurry reactors,having remarkable effects on the design,scale-up,and operation of the slurry reactors.This article reviews the influences of fluid physical properties,solid particles,and operating conditions on the hydrodynamics in slurry reactors.Firstly,the influence of fluid properties,including the density and viscosity of the individual liquid and gas phases and the interfacial tension,has been reviewed.Secondly,the solid particle properties(i.e.,concentration,density,size,wettability,and shape)on the hydrodynamics have been discussed in detail,and some vital but often ignored features,especially the influences of particle wettability and shape,as well as the variation of surface tension because of solid concentration alteration,are highlighted in this work.Thirdly,the variations of physical properties of fluids,hydrodynamics,and bubble behavior resulted from the temperature and pressure variations are also summarized,and the indirect influences of pressure on viscosity and surface tension are addressed systematically.Finally,conclusions and perspectives of these notable influences on the design and scale-up of industrial slurry reactors are presented.

关键词： Multiphase reactors Fluid physical properties Particle Operating conditions Bubble column Airlift loop reactor

MicroRNA528 Affects Lodging Resistance of Maize by Regulating Lignin Biosynthesis under Nitrogen-Luxury Conditions

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Molecular Plant 2018年第6期11卷 806-814页

作者： Qing Sun Xiaogang Liu Juan Yang Wenwen Liu Qingguo Du Hongqiu Wang Chunxiang Fu Wen-Xue Li National engineering Laboratory for Crop Molecular Breeding Institute of Crop Science Chinese Academy of Agricultural Sciences Beijing 100081 China Shandong Provincial Key Laboratory of Energy Genetics Qingdae Engineering Research Center of Biomass Resources and Environment and CAS Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences Qingdao 266101 China

Lodging under nitrogen （N）-Iuxury conditions substantially reduces crop yield and seed quality. However, the molecular mechanisms of plant lodging resistance remain largely unclear, especially in maize. We report here that the expression of ZmmiR528, a monocot-specific microRNA, is induced by N luxury but reduced by N deficiency. We show by the thioacidolysis and acetyl bromide analysis that N luxury signifi- cantly reduces the generation of H, G, and S monomers of the lignin as well as its total content in maize shoots. We further demonstrate that ZmLACCASE3 （ZmLAC3） and ZmLACCASE5 （ZmLAC5）, which encode the copper-containing laccases, are the targets of ZmmiR528. In situ hybridization showed that ZmmiR528 is mainly expressed in maize vascular tissues. Knockdown of ZmmiR528 or overexpression of ZmLAC3 significantly increased the lignin content and rind penetrometer resistance of maize stems. In contrast, transgenic maize plants overexpressing ZmmiR528 had reduced lignin content and rind penetrometer resistance and were prone to lodging under N-luxury conditions. RNA-sequencing analysis revealed that ZmPAL7 and ZmPAL8 are upregulated in transgenic maize lines downregulating ZmmiR528. Under N-lux- ury conditions, the expression levels of ZmPALs were much higher in ZmmiR528-knockdown lines than in the wild type and transgenic maize lines overexpressing ZmmiR528. Taken together, these results indicate that, by regulating the expression of ZmLAC3 and ZmLAC5, ZmmiR528 affects maize lodging resistance un- der N-luxury conditions.

关键词： maize nitrogen ZmmiR528 ZmLACs lodging resistance

Enrichment of anammox biomass during mainstream wastewater treatment driven by achievement of partial denitrification through the addition of bio-carriers

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Journal of Environmental Sciences 2024年第3期137卷 181-194页

作者： Yuqing Ma Bo Wang Xiaodi Li Shuo Wang Wen Wang Yongzhen Peng National engineering Laboratory for Advanced Municipal Wastewater Treatment and Reuse Technology Engineering Research Center of BeijingBeijing University of TechnologyBeijing 100124China

Anammox is widely considered as the most cost-effective and sustainable process for nitrogen removal.However,how to achieve the enrichment of anammox biomass remains a challenge for its large-scale application,especially in mainstream wastewater treatment.In this study,the feasibility of enrichment of anammox biomass was explored through the realization of partial denitrification and the addition of bio-carriers.By using ordinary activated sludge,a sequencing batch reactor(SBR)followed by an up-fow anaerobic sludge bed(UASB)was operated at 25±2℃ for 214 days.The long-term operation was divided into five phases,in which SBR and UASB were started-up in Phases I and II,respectively.By eliminating oxygen and adjusting the infow ratios in Phases III-V,advanced nitrogen removal was achieved with the effuent total nitrogen being 4.7 mg/L and the nitrogen removal efficiency being 90.5%in Phase V.Both in-situ and ex-situ activity tests demonstrated the occurrence of partial denitrification and anammox.Moreover,16S rRNA high-throughput sequencing analysis revealed that Candidatus Brocadia was enriched from below the detection limit to in biofilms(0.4%in SBR,2.2%in UASB)and the foc sludge(0.2%in SBR,1.3%in UASB),while Thauera was mainly detected in the foc sludge(8.1%in SBR,8.8%in UASB),which might play a key role in partial denitrification.Overall,this study provides a novel strategy to enrich anammox biomass driven by rapid achievement of partial denitrification through the addition of bio-carriers,which will improve large-scale application of anammox processes in mainstream wastewater treatment.

关键词： Enrichment Anammox biomass Bio-carriers Partial denitrification Mainstream wastewater

Heat Leakage Numerical Investigation of a Compound Parabolic ConcentratorPulsating Heat Pipe Solar Collector

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Journal of Thermal Science 2022年第5期31卷 1318-1326页

作者： XU Rongji CHEN Jingyan ZHANG Xiaohui WANG Ruixiang XU Shuhui beijing engineering research center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing100044China

As a new type of equipment for solar medium temperature utilization, the compound parabolic concentrator-pulsating heat pipe solar collector(CPC-PHPSC) uses pulsating heat pipe(PHP) as an endotherm, which can realize efficient energy conversion. The design of proper concentration ratio of compound parabolic concentrator(CPC) ensures that the incident sunlight can be concentrated on the evaporator section surface of PHP without solar tracking system. The objective of the present work is to study the influence of solar radiation intensity, air speed, material thickness(glass and insulation board) and tilt angle on the thermal performance of the new collector, which is difficult to control in the experiment. The heat leakage process and characteristics of the CPC-PHPSC were numerically studied by establishing a 3D numerical model of the collector unit. The results show that the theoretical collector efficiency of CPC-PHPSC reaches 74.5%, which is consistent with the experimental results. During operation, the heat collection performance is the best when the tilt angle is 45° and the solar radiation intensity is 1000 W/m^(2), while the excessive air speed will increase the convective heat loss. Increasing the thickness of insulation board and glass has little effect on the collector efficiency.

关键词： solar collector CPC(Compound Parabolic Concentrator) pulsating heat pipe solar irradiation intensity glass thickness

Homogenization Function of Microchannel on Heat Absorber with Compound Parabolic Concentrator

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Journal of Thermal Science 2022年第6期31卷 2022-2031页

作者： WANG Xueqing WU Haifeng MA Yusen WANG Suilin XU Rongji beijing engineering research center of Sustainable Energy and Buildings Beijing University of Civil Engineering and ArchitectureBeijing 100044China

Microchannels offer unique advantages on heat transfer performance. In this paper, microchannels are applied to the compound parabolic concentrator(CPC) system. A multi-physical field coupling model based on Finite Element Method is proposed to investigate the homogenization effect of the microchannel heat absorber on the CPC non-uniform concentration. The energy conversion process from optics to heat is simulated using TracePro software, and the heat transfer processes in the microchannel are computed by Fluent using user defined functions(UDF). It is found that the microchannels behave well on weakening the influence of the nonuniformity solar heat flux on the performance of the CPC. The temperature nonuniformity of the outlet section is less than 10^(-3) in the direction of fluid flow caused by the microchannel, although the maximum surface heat flux inhomogeneity of the microchannel reaches 2.3. The peak value of the heat flux on the surface of the absorber changes from double peak to single peak, and moves to the edge, resulting in more uneven heat flux distribution with the increase of the incident angle within the acceptance semi-angle of the CPC. The result of TracePro clearly shows that when the concentration ratio is less than 5, the heat flux nonuniformity on the surface of the absorber decreases with the increase in concentration ratio. It was interestingly found that the temperature distribution of the heat transfer fluid has weak sensitivity to the changes of truncation ratio. This work provides a way to design a CPC solar collector.

关键词： solar energy microchannel compound parabolic concentrator multi-physical field

Design and Implementation of a Battery Big Data Platform Through Intelligent Connected Electric Vehicles

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Chinese Journal of Mechanical engineering 2023年第2期36卷 291-301页

作者： Rui Xiong Baoqiang Zhu Kui Zhang Yanzhou Duan Fengchun Sun National engineering research center for Electric Vehicles School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China

The development of a battery management algorithm is highly dependent on high-quality battery operation data,especially the data in extreme conditions such as low temperatures.The data in faults are also essential for failure and safety management research.This study developed a battery big data platform to realize vehicle operation,energy interaction and data management.First,we developed an electric vehicle with vehicle navigation and position detection and designed an environmental cabin that allows the vehicle to operate autonomously.Second,charging and heating systems based on wireless energy transfer were developed and equipped on the vehicle to investigate optimal charging and heating methods of the batteries in the vehicle.Third,the data transmission network was designed,a real-time monitoring interface was developed,and the self-developed battery management system was used to measure,collect,upload,and store battery operation data in real time.Finally,experimental validation was performed on the platform.Results demonstrate the efficiency and reliability of the platform.Battery state of charge estimation is used as an example to illustrate the availability of battery operation data.

关键词： Intelligent connected electric vehicle Battery Operation data State estimation Wireless energy transfer

Mechanical Properties and Energy Absorption of Integrated AlSi10Mg Shell Structures with BCC Lattice Infill

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Chinese Journal of Mechanical engineering 2023年第6期36卷 159-171页

作者： Yingchun Bai Jiayu Gao Chengxiang Huang Yue Li National engineering research center of Electric Vehicles School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 100081China

Shell-infill structures comprise an exterior solid shell and an interior lattice infill,whose closed features yield superior comprehensive mechanical performance and light weight.Additive manufacturing(AM)can ensure the fabrica-tion of complex structures.Although the mechanical behaviors of lattice structures have been extensively studied,the corresponding mechanical performances of integrated-manufactured shell structures with lattice infills should be systematically investigated due to the coupling effect of the exterior shell and lattice infill.This study investigated the mechanical properties and energy absorption of AlSi10Mg shell structures with a body-centered cubic lattice infill fabricated by AM.Quasi-static compressive experiments and corresponding finite element analysis were conducted to investigate the mechanical behavior.In addition,two different finite element modeling methods were compared to determine the appropriate modeling strategy in terms of deformation behavior.A study of different parameters,including lattice diameters and shell thicknesses,was conducted to identify their effect on mechanical performance.The results demonstrate the mechanical advantages of shell-infill structures,in which the exterior shell strengthens the lattice infill by up to 2.3 times in terms of the effective Young’s modulus.Increasing the infill strut diameter can improve the specific energy absorption by up to 1.6 times.

关键词： Shell-infill structure Body center cubic(BCC) Additive manufacturing Compression properties Energy absorption