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The noise spectral characteristics and noise reduction schemes of screw air-source heat pump:A case study

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building Simulation 2024年第1期17卷 53-70页

作者： Dongsheng Liu Yaohan Feng Jikang Jia Pengfei Si Ya Feng China Southwest Architecture Design and research institute co.Ltd. Chengdu 610041China CSCEC Green construction Engineering research Center Chengdu 610041China

The screw air-source heat pump can cause incessant high noise levels during operation,which might hinder adoption of this energy-efficient heat pump.First,aco.stic measurements and co.parison testing were performed in this research.The measurements revealed that the co.pressor is the main noise source of the heat pump,and it shows a multipeak frequency distribution and a wide frequency spectrum under different work co.ditions,with multiple peaks at 63,250,and 1000 Hz.Then,a co.pressor sound insulation co.er with broadband absorption was proposed,and it was experimentally proven that the insulation co.er can reduce the maximum sound pressure level of one unit from 89.8 dBA to 79.1 dBA.Third,we proposed several noise reduction strategies and co.pared their noise reduction effects using co.puter simulation.The results showed that the noise problem can be effectively improved through the rational design of the sound barrier and the layout and opening options of heat pump.The distance between the sound barrier and heat pump and the sound attenuation due to diffraction ALa exhibit a U-shaped relation.For buildings of different heights,the optimal heights of noise barrier are proposed.The 5.5-meter is the optimal height of the sound barrier for single-story buildings.The co.clusions can be applied to other building projects for heat pump noise reduction.

关键词： aco.stic simulation broadband noise noise reduction air-source heat pump sound barrier

Optimal scheduling of a township integrated-energy system using the adjustable heat-electricity ratio model

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Global Energy Interco.nection 2024年第1期7卷 48-60页

作者： Quan Chen Jingyi Wang Min Cang Xiaomeng Zhai Xi Cheng Shuang Wu Dongwei Li Eco.omic and Technology research institute of State Grid Jiangsu Electric Power co. LtdNanjing210008P.R.China Power construction Technical and Eco.omic co.sulting Center of China Electricity co.ncil Beijing100053P.R.China

With the expansion and implementation of rural revitalization strategies,there is a co.stant need for new energy sources for the construction of new townships.co.sequently,integrated energy systems with the interco.nection and interaction of multiple energy sources are developing rapidly.Biomass energy,a renewable green energy source with low pollution and wide distribution,has significant application potential in integrated energy systems.co.sidering the application of biomass energy in townships,this study established an integrated biomass energy system and proposed a model to optimize its operation.Lowest eco.omic co.t and highest clean energy utilization rate were co.sidered as the objective functions.In addition,a plan was suggested to adjust the heat-electricity ratio based on the characteristics of the co.bined heat and power of the biomass.Finally,a simulation analysis co.ducted for a town in China was discussed,demonstrating that the construction of a township integrated-energy system and the use of biomass can significantly reduce operating co.ts and improve the energy utilization rate.Moreover,by adjusting the heat-electricity ratio,the eco.omic co.t was further reduced by 6.70%,whereas the clean energy utilization rate was increased by 5.14%.

关键词： Biomass energy Integrated-energy system Afterburning device Heat-electricity ratio Operation optimization

Seasonal thermal energy storage using natural structures:GIS-based potential assessment for northern China

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building Simulation 2024年第4期17卷 561-574页

作者： Yichi Zhang Jianjun Xia Midea HVAC Heating&Ventilation Equipment co. LtdFoshan528311China building Energy research Center Tsinghua UniversityBeijing100084China

Seasonal thermal energy storage(STES)allows storing heat for long-term and thus promotes the shifting of waste heat resources from summer to winter to decarbonize the district heating(DH)systems.Despite being a promising solution for sustainable energy system,large-scale STES for urban regions is lacking due to the relatively high initial investment and extensive land use.To close the gap,this study assesses the potentials of using two naturally available structures for STES,namely valley and ground pit sites.Based on geographical information system(GIS)methods,the available locations are searched from digital elevation model and selected co.sidering several criteria from land uses and construction difficulties.The co.ts of dams to impound the reservoir and the yielded storage capacities are then quantified to guide the choice of suitable sites.The assessment is co.ducted for the northern China where DH systems and significant seasonal differences of energy demand exist.In total,2,273 valley sites and 75 ground pit sites are finally identified with the energy storage capacity of 15.2 billion GJ,which is much larger than the existing DH demand in northern China.The results also prove that 682 valley sites can be achieved with a dam co.t lower than 20 CNY/m^(3).By co.ducting sensitivity analysis on the design dam wall height and elevations,the choices of available natural structures are expanded but practical issues about water pressures and constructions are also found.Furthermore,the identified sites are geographically mapped with nearest urban regions to reveal their roles in the DH systems.In general,560 urban regions are found with potential STES units and most of them have STES storage capacities larger than their own DH demand.The novel planning methodology of this study and publicly available datasets create possibilities for the implementations of large-scale STES in urban DH systems.

关键词： seasonal thermal energy storage geographical information system district heating water reservoir

Technical innovation in the “Beishan No. 1” hard rock tunnel boring machine for high-gradient spiral tunnels

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Frontiers of Engineering Management 2024年第1期11卷 175-179页

作者： Ju WANG Mengxue QI Bin LONG Hongsu MA Beijing research institute of Uranium Geology Beijing 100029China China Railway 18th Bureau Group Tunnel Engineering co. Ltd.Chongqing 400700China China Railway construction Heavy Industry co. Ltd.Changsha 410100China

1 Project overview The“Beishan No.1”,the world’s first-ever hard rock Tunnel Boring Machine(TBM)tailored for high-gradient spiral tunnels,co.stitutes a pivotal element within the Beishan Underground research Laboratory(URL)initiative in China.Beishan URL,the first URL for geological disposal of high level radioactive waste(HLW)in China,is a national key construction project listed in the“13th Five-Year Plan”.In 2019,subsequent to receiving approval from the China Atomic Energy Authority,the Beijing research institute of Uranium Geology(BRIUG),serving as the project’s owner,initiated its construction.This underground facility,categorized as a“third generation”URL for HLW disposal,i.e.,area-specific URL,was located in Beishan,Jiuquan City,Gansu Province,China,following more than three decades of rigorous research on site selection.

关键词： tunnel boring machine extremely hard rock co.tinuous small-radius curves high gradient equipment technology innovation

co.rdinated Voltage co.trol of Distribution Network co.sideringMultiple Types of Electric Vehicles

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Energy Engineering 2024年第2期121卷 377-404页

作者： Liang Liu Guangda Xu Yuan Zhao Yi Lu Yu Li Jing Gao State Grid Jibei Electric Power research institute(North China Electric Power research institute co. Ltd.)Beijing100045China

The co.ple between the power network and the transportation network(TN)is deepening gradually with the increasing penetration rate of electric vehicles(EV),which also poses a great challenge to the traditional voltage co.trol scheme.In this paper,we propose a co.rdinated voltage co.trol strategy for the active distribution networks co.sidering multiple types of EV.In the first stage,the action of on-load tap changer and capacitor banks,etc.,are determined by optimal power flow calculation,and the node electricity price is also determined based on dynamic time-of-use tariff mechanism.In the seco.d stage,multiple operating scenarios of multiple types of EVs such as cabs,private cars and buses are co.sidered,and the scheduling results of each EV are solved by building an optimization model based on co.straints such as queuing theory,Floyd-Warshall algorithm and traffic flow information.In the third stage,the output power of photovoltaic and energy storage systems is fine-tuned in the normal co.trol mode.The charging power of EVs is also regulated in the emergency co.trol mode to reduce the voltage deviation,and the amount of regulation is calculated based on the fair voltage co.trol mode of EVs.Finally,we test the modified IEEE 33-bus distribution system co.pled with the 24-bus Beijing TN.The simulation results show that the proposed scheme can mitigate voltage violations well.

关键词： Electric vehicle transportation network voltage co.trol queuing theory

Disco.tinuity development patterns and the challenges for 3D discrete fracture network modeling on co.plicated exposed rock surfaces

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2154-2171页

作者： Wen Zhang Ming Wei Ying Zhang Tengyue Li Qing Wang Chen Cao Chun Zhu Zhengwei Li Zhenbang Nie Shuonan Wang Han Yin co.lege of construction Engineering Jilin UniversityChangchun130026China Liaoning Nonferrous Geological Exploration and research institute co. Shenyang110013China School of Earth Sciences and Engineering Hohai UniversityNanjing210098China Northeastern University Shenyang110819China

Natural slopes usually display co.plicated exposed rock surfaces that are characterized by co.plex and substantial terrain undulation and ubiquitous undesirable phenomena such as vegetation co.er and rockfalls.This study presents a systematic outcrop research of fracture pattern variations in a co.plicated rock slope,and the qualitative and quantitative study of the co.plex phenomena impact on threedimensional(3D)discrete fracture network(DFN)modeling.As the studies of the outcrop fracture pattern have been so far focused on local variations,thus,we put forward a statistical analysis of global variations.The entire outcrop is partitioned into several subzones,and the subzone-scale variability of fracture geometric properties is analyzed(including the orientation,the density,and the trace length).The results reveal significant variations in fracture characteristics(such as the co.centrative degree,the average orientation,the density,and the trace length)among different subzones.Moreover,the density of fracture sets,which is approximately parallel to the slope surface,exhibits a notably higher value co.pared to other fracture sets across all subzones.To improve the accuracy of the DFN modeling,the effects of three co.mon phenomena resulting from vegetation and rockfalls are qualitatively analyzed and the co.responding quantitative data processing solutions are proposed.Subsequently,the 3D fracture geometric parameters are determined for different areas of the high-steep rock slope in terms of the subzone dimensions.The results show significant variations in the same set of 3D fracture parameters across different regions with density differing by up to tenfold and mean trace length exhibiting differences of 3e4 times.The study results present precise geological structural information,improve modeling accuracy,and provide practical solutions for addressing co.plex outcrop issues.

关键词： co.plicated exposed rock surfaces Disco.tinuity characteristic variation Three-dimensional discrete fracture network modeling Outcrop study Vegetation co.er and rockfalls

Preparation of high-purity fluorite and nanoscale calcium carbonate from low-grade fluorite

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1198-1207页

作者： Qianqian Lu Haisheng Han Wenjuan Sun Xingfei Zhang Weiwei Wang Bilan Zhang Wensheng Chen Qin Zou School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Hunan Nonferrous Chenzhou Fluoride Chemical co. Ltd.Chenzhou 423000China State Key Laboratory of Baiyunobo Rare Earth Resource researches and co.prehensive Utilization Baotou Research Institute of Rare EarthsBaotou 014030China Hunan Shizhuyuan Nonferrous Metal co. Ltd.Chenzhou 423000China

Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the reco.ery and purity of fluorite co.centrate.A new acid leaching–flotation process for fluorite is proposed in this work.This innovative process raised the fluor-ite’s grade to 97.26wt%while producing nanoscale calcium carbonate from its leachate,which co.tained plenty of calcium ions.On the production of nanoscale calcium carbonate,the impacts of co.centration,temperature,and titration rate were examined.By modifying the process co.ditions and utilizing crystal co.ditioning agents,calcite-type and amorphous calcium carbonates with co.responding particle sizes of 1.823 and 1.511μm were produced.The influence of the impurity ions Mn^(2+),Mg^(2+),and Fe^(3+)was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system co.pared with the calcium chloride solution.The co.bination of the acid leaching–flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while reco.ering calcite resources,thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.

关键词： fluorite calcite nanoscale calcium carbonate waste reco.ery

co.pled heat and moisture transfer in walls featuring moisture-buffering materials and ventilating layers:An Experimental study

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Energy and Built Environment

Energy and Built Environment 2024年第1期5卷 97-109页

作者： Xueqiong He Chi Feng Huibo Zhang School of Design Shanghai Jiao Tong UniversityShanghai 200240China Shanghai research institute of building Sciences Group co. LtdShanghai 200032China School of Architecture and Urban Planning Chongqing UniversityChongqing 400045China

The moisture performance of building envelopes largely depends on the building materials,construction tech-niques,and exposure loads from the indoor and outdoor regions.A ventilated air interlayer placed in a wall can help dehumidify the wall and indoor air.This paper presents an experimental study of the heat,air,and moisture variations within the envelope wall of a chamber featuring different air interlayer settings under real outdoor air co.ditions during the summer of 2020 in Shanghai,China.Self-developed humidity-co.trolling building mate-rials were applied to the inner building envelope.Temperature,humidity,wind velocity,and heat-flow sensors were placed at different positions in the middle of the wall.These parameters were measured and reco.ded in real-time under three working co.ditions:humidification,dehumidification,and ventilation.The experimental results show that under the ventilation working co.ditions,moisture co.tent of 0.52 kg can be removed after a 2-h air layer ventilation,which can benefit the design strategy for the humidification and ventilation of dehu-midification walls.

关键词： Ventilated wall Heat and humidity co.pling transfer Moisture-buffering materials Experimental research

Investigation of mechanical failure performance of a large-diameter shield tunnel segmental ring

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第5期25卷 411-428页

作者： Binyong GAO Renpeng CHEN Huaina WU Chengcheng ZHANG Meng FAN Chao XIAO research Center of Underground Space Advanced Technology Hunan UniversityChangsha 410082China Key Laboratory of building Safety and Energy Eficiency of the Ministry of Education Hunan UniversityChangsha 410082China Department of Civil Engineering Hunan UniversityChangsha 410082China China construction No.5 Civil Engineering co. Ltd.Changsha 410004China

The co.trol criteria for structural deformation and the evaluation of operational safety performance for large-diameter shield tunnel segments are not yet clearly defined.To address this issue,a refined 3D finite element model was established to analyze the transverse deformation response of a large-diameter segmental ring.By analyzing the stress,deformation,and crack distribution of large-diameter segments under overload co.ditions,the transverse deformation of the segmental ring co.ld be divided into four stages.The main reasons for the decrease in segmental ring stiffness were found to be the extensive development of cracks and the co.plete formation of four plastic hinges.The deformation co.trol value for the large-diameter shield tunnel segment is chosen as 8%o of the segment's outer diameter,representing the transverse deformation during the formation of the first semi-plastic hinge(i.e.,the first yield point)in the structure.This co.trol value can serve as a reinforcement standard for preventing the failure of large-diameter shield tunnel segments.The flexural bearing capacity characteristic curve of segments was used to evaluate the structural strength of a large-diameter segmental ring.It was disco.ered that the maximum internal force co.bination of the segment did not exceed the segment ultimate bearing capacity curve(SUBC).However,the co.bination of internal force at 9°,85°,and 161°of the joints,and their symmetrical locations about the 0°-180°axis exceeded the joint ultimate bearing capacity curve(JUBC).The results indicate that the failure of the large-diameter segment lining was mainly due to insufficient joint strength,leading to an instability failure.The findings from this study can be used to develop more effective maintenance strategies for large-diameter shield tunnel segments to ensure their long-term performance.

关键词： Finite element model Transverse deformation response Upper overload Plastic hinges Flexural bearing capacity