检索结果-内蒙古大学图书馆

Analyzing convective Heat Transfer in combined Solar chimneys: A Theoretical and Numerical Study of key Influencing Parameters

学校读者我要写书评

暂无评论

SSRN 2024年

combined solar chimneys represent a potent mechanism for harnessing solar energy to bolster natural ventilation in green building designs. This study focuses on the impact of structural parameters and external conditions on the ventilation and heat transfer performance of such systems. Through scaling analysis and numerical simulations, we investigate the flow dynamics and heat transfer mechanisms. We examine the influence of five critical control parameters: inclination angle (α), inlet size ratio (h/H), ratio of inclined to vertical section lengths (L/H), Rayleigh number (Ra), and the temperature difference between indoor and outdoor environments (Δθ). Our findings indicate that ventilation intensity escalates with increasing inclination angle, particularly within the range of 15°to 75°, achieving standard requirements at angles of 30° or greater. Ventilation and heat exchange performance exhibit an initial increase followed by a decline as the inlet size ratio expands from 0.10 to 0.40. Optimal ventilation efficiency is observed at a Rayleigh number of 1.98×1014 with an inlet size ratio of 0.15. conversely, a low ratio of inclined to vertical section lengths (L/H=0.20) correlates with suboptimal ventilation performance. Both ventilation intensity and efficiency are positively correlated with increases in Ra and Δθ. This research quantitatively delineates these relationships, providing a theoretical foundation for the design of natural ventilation systems in sustainable buildings using combined solar chimneys. © 2024, The Authors. All rights reserved.

关键词： computational fluid dynamics

Enhancing Solar chimney Performance with Novel Passive Optimization Strategies for Dual carbon Goals

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Han, Mengjiao cui, Huimin Han, Zhiming Liu, Qingkuan School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China

The development of green buildings plays a pivotal role in achieving "dual carbon" goals. This study focuses on the combined Solar chimney (cSc) as an effective method for utilizing solar energy to enhance building ventilation and heat exchange, thereby reducing air-conditioning energy consumption. We introduce two innovative passive optimization measures: deflectors and segmented heat-absorbing walls. Using numerical simulations, we analyze the impact of five control parameters—the angle and length of the straight deflector, the central angle of the curved deflector, the number of heat-absorbing wall segments, and the Rayleigh number (Ra)—on cSc performance. Our findings detail the temperature distribution and the vertical vortex dimensions to elucidate underlying mechanisms. Results indicate that air changes per hour (AcH) can be significantly improved with the implementation of deflectors and segmented walls. Optimal deflector configurations are identified as a 25° angle, a 0.375 length-to-width ratio (l/W), and a 60° central angle. The study recommends using two heat-absorbing wall segments for practical applications. When both measures are applied, ventilation performance can be enhanced by up to 25.71%. Additionally, this research establishes quantitative relationships between the control parameters, AcH, and heat exchange efficiencies, providing a theoretical foundation for practical engineering designs. © 2024, The Authors. All rights reserved.

关键词： Solar chimneys

Experimental Investigations on the Wind Load Interference Effects of Single-Axis Solar Tracker Arrays

学校读者我要写书评

暂无评论

SSRN 2022年

作者： Ma, Wenyong Zhang, Weida Zhang, Xiaobin chen, Wei Tan, Qiang School of Civil Engineering Shijiazhuang Tiedao University Hebei 050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Hebei 050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Mechanical Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China Jiangsu Guoqiang Singsun Energy Co. Ltd 213300 China

Aiming at the interference effect of wind loads on single-axis solar tracker arrays, this study conducts rigid-model pressure measurement wind tunnel tests on a single-row solar tracker and solar tracker arrays. The effects of the tilt angle and wind direction on aerodynamic characteristics are examined. The basic characteristics of the wind-induced interference effects of a single-axis solar tracker array are clarified. The results reveal that when the tilt angle is small, the interference effect is small, the tilt angle increases, the interference effect becomes stronger. From the mean pressure and torque coefficients, the interference effect is mainly manifested as a shielding effect. Based on the fluctuating pressure and torque coefficients, the interference effect appears as a shielding effect and an amplification effect in small- and large-tilt angle ranges, respectively. The wind load power spectrum of the solar modules in the rear-row of the solar tracker arrays presents remarkable frequency peaks, and experiences stronger wind-induced vibrations than the front-row modules. The influence of the wind direction results in nonuniform distributions of wind loads along the length of the solar tracker. Thus, the enhancement in wind loads on the edge areas of solar arrays caused by the wind direction should be considered. © 2022, The Authors. All rights reserved.

关键词： Wind stress

Evolution of Pore-Fracture and Permeability During co2+O2 In-Situ Leaching Process of Fractured Sandstone

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Niu, Qinghe He, Jiabin Yuan, Wei chang, Jiangfang Wang, Wei Yuan, Junhong Wang, Qizhi Zheng, Yongxiang Shang, Songhua Key Laboratory of Roads and Railway Engineering Safety Control Shijiazhuang Tiedao University Ministry of Education Shijiazhuang050043 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Hebei Technology and Innovation Center on Safe and Efficient Mining of Metal Mines Shijiazhuang050043 China State Key Laboratory of Nuclear Resources and Environment East China University of Technology Nanchang330013 China School of Transportation Inner Mongolia University Hohhot010021 China School of Civil Engineering Hebei University of Science and Technology Shijiazhuang050018 China

This work is organized to reveal the influence mechanism and law of cO2+O2 in situ leaching on pore permeability characteristics of stimulated deposits. Results show that geochemical reactions during the cO2+O2 ISL process are complex, the dolomite and potassium feldspar are dissolved, while the clay mineral precipitates are formed. The response characteristics and mechanisms of pore-fracture structures differ between the single and multi-fractured samples during the cO2+O2 ISL process. The pore number density of the single-fractured sample increases while porosity decreases, causing larger pores to evolve into smaller ones. While the porosity and fracture volume of the multi-fractured sample increase significantly. The permeability characteristics of fractured samples are consistent with the evolution of pore-fracture structures. The multi-fractured sample possesses a higher fracture compression coefficient and lower PLR due to the larger compressive space, the self-supporting effect of fracture network and the scouring effect of leaching solution. Although creating a single fracture in reservoir stimulation can enhance the original deposit permeability, the conductivity will gradually decline during the subsequent cO2+O2 ISL process. Optimizing reservoir stimulation techniques to create complex fracture networks within deposits can enhance overall permeability and weaken the permeability reduction effect, ensuring the efficient extraction of uranium resources. © 2024, The Authors. All rights reserved.

关键词： Fracture

Model Test and Numerical Simulation Study on Soil Arching Effect Evolution Of Pile - Supported Reinforced Embankment

学校读者我要写书评

暂无评论

SSRN 2024年

作者： Wang, Xin Yang, Guang-Qing Li, Hao-Ran Hebei GEO University Hebei Shijiazhuang050030 China The 6410th Factory of the People's Liberation Army of China Hebei Shijiazhuang050307 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China Shijiazhuang Tiedao University Hebei Shijiazhuang050043 China

The mechanical behavior of pile-supported reinforced embankment is complex, and the shape of soil arch has not been unified. It is of great scientific value to further study the mechanism of soil arch effect. Through three-dimensional model test, this paper studies the influence of embankment filling properties, pile spacing and horizontal reinforcement on soil arching effect. Based on the stress monitoring results of foundation surface and embankment internal, the formation process and evolution mechanism of soil arching effect in cohesive soil embankment were studied. The arch axis expressions of the central area between four piles and the strip area between two piles were proposed by numerical simulation. The results show: The differential settlement of pile-soil has a great influence on the degree of soil arching effect. The increase of pile spacing promotes the soil arching effect to a certain extent, but too large pile spacing will increase the settlement of roadbed;The cohesion of embankment has a certain promoting effect on load transfer. With the increase of cohesion, the differential settlement of pile-soil decreases gradually;Under the action of the reinforcement, the internal structure of the soil arch changes;The height of soil arch is related to the net spacing of pile cap. The maximum height of soil arch in the strip area between two piles is 1.10(s-a), and the maximum height of soil arch in the central area between four piles is 1.64(s-a). © 2024, The Authors. All rights reserved.

关键词： Piles

Simplified calculation method for the critical load bearing of market-based profile emergency steel pier

学校读者我要写书评

暂无评论

Heliyon 2024年第22期10卷 e38808页

作者： Liu, Zi-yu chen, Shi-tong Zhi, Mo-mo Zhang, Kai Zhang, Hong-tao Collaborative Innovation Center for Performance and Security of Large-scale Infrastructure Shijiazhuang Tiedao University Shijiazhuang China Hebei Eng. Innovation Center for Traffic Emergency and Guarantee Shijiazhuang Tiedao University Shijiazhuang China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang China

A novel emergency steel pier, assembled from market-available profiles, has been developed to address the challenges associated with the “regular stockpiling and rapid emergency deployment” of bridge pier repair equipment. These challenges often involve significant labor and financial costs for manufacturing and maintenance. The buckling modes of the columns and pier-girder connections were considered. Using energy methods and plate-shell theory, an analytical formula for the critical load-bearing capacity of the steel pier under emergency conditions was derived. Numerical simulations were conducted for comparison and validation, resulting in an optimized and simplified method for calculating the critical load capacity, which is suitable for engineering applications. The study shows that the critical load-bearing capacity of the emergency steel pier exhibits distinct patterns under the influence of column buckling modes and pier-girder connection methods. In cases where the column is fixed at one end and hinged at the other, or fixed at both ends, the critical load for axisymmetric buckling is affected by factors such as elastic modulus, Poisson's ratio, height, radius, wall thickness, and the number of buckling waves. When considering non-axisymmetric buckling, the number of circumferential buckling waves becomes an additional factor. A simplified method for calculating the critical load-bearing capacity was developed. The simplified formula depends only on a correction factor, modified buckling stress, the number of columns, and cross-sectional area. This makes it highly practical for emergency engineering applications. © 2024

关键词： critical bearing capacity Emergency Energy method Rush-repair steel pier Standard market profiles Temporary-permanent conversion

Studies of Turbulent Heat Transfer Properties in combined Solar chimneys and Their engineering Applications

学校读者我要写书评

暂无评论

SSRN 2023年

作者： cui, Huimin Han, Mengjiao Zhang, Jitao Han, Zhiming Xu, Feng Liu, Qingkuan State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang050043 China Department of Mathematics and Physics Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang050043 China School of Physical Science and Engineering Beijing Jiaotong University Beijing100044 China

Solar chimneys can induce natural ventilation through solar radiation. However, sufficient theoretical studies are needed as a basis in order to fully exploit passive design in practical green building design. In this study, the heat transfer properties of turbulent natural convective flows in a combined solar chimney with a thermal flux at the absorption wall are investigated by theoretical analysis and numerical simulations. Two different flow patterns have been discovered, one with an obvious thermal boundary layer flow pattern and the other without, based on the high Rayleigh number. For the flow development in these two flow regimes, the transient scaling analysis is performed separately and the control mechanism for each phase is presented. Scaling correlations of air flow speed, temperature, and mass flow rate have been established to describe the ventilation properties of solar chimneys. The corresponding numerical simulation data is used for scaling verification. Ventilation times are calculated for a solar chimney with aspect ratio A=7.5 to provide a basis for the devise of a solar chimney. © 2023, The Authors. All rights reserved.

关键词： Boundary layers

The Effects of Row Spacing and Ground clearance On the Wind Load of Photovoltaic (Pv) Arrays

学校读者我要写书评

暂无评论

SSRN 2023年

作者： Xu, Ang Ma, Wenyong Yuan, Huanxin Lu, Lihe State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Shijiazhuang050043 China School of Civil Engineering Shijiazhuang Tiedao University Shijiazhuang051132 China Key Laboratory of Road and Railway Engineering Safety Ministry of Education Shijiazhuang Tiedao University Shijiazhuang Hebei050043 China Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Hebei050043 China School of Civil Engineering Wuhan University Wuhan430072 China Inner Mongolia Electric Power Survey & Design Istitute Co. Ltd. Huhehot Inner Mongolia 010011 China

Row spacing and ground clearance have a significant effect on the wind load of a photovoltaic (PV) array. Based on wind tunnel tests and numerical simulations with the self-sustainable equilibrium atmospheric boundary layer, the influences of row spacing and ground clearance on the wind load of PV arrays are analysed, and the mechanism of the wind-induced interference effect is determined by flow field analysis. The results show that the ground clearance affects the wind load distribution on the PV module, and this effect has an inconsiderable impact on the net wind pressure on the PV modules. The effect of row spacing on the wind load of PV arrays is more significant, and this effect is mainly manifested in the shielding effect. The tilt angle is the main factor that affects the size of the vortex scale which significantly influences the wind load. The ground clearance, row spacing and tilt angle all affect the torque coefficient on the PV module. The larger the ground clearance is, the larger the torque coefficient. Finally, the wind load coefficients and reduction factors are presented as a recommendation for wind resistance design of PV arrays. © 2023, The Authors. All rights reserved.

关键词： Atmospheric boundary layer

curing Stress Effect on Stability, Microstructure, Matric Suction and Electrical conductivity of cementitious Tailings Backfills

学校读者我要写书评

暂无评论

SSRN 2022年

作者： chen, Shunman Yilmaz, Erol Wang, Wei Wang, Yi-Ming School of Civil Engineering and Architecture East China Jiaotong University Jiangxi Nanchang330013 China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao University Hebei Province Shijiazhuang050043 China Jiangxi Key Laboratory of Disaster Prevention-mitigation and Emergency Management East China Jiaotong University Jiangxi Nanchang330013 China Department of Civil Engineering Geotechnical Division Recep Tayyip Erdogan University Fener RizeTR53100 Turkey School of Civil and Resources Engineering University of Science and Technology Beijing Beijing100083 China

cementitious tailings backfill (cTB) is a regularly used technique for most mines at home and aboard since it has a significant meaning for the recycling of total tailings and enhances the safety of underground mines. Thus, studying the behavior of the cTB materials exposed to diverse curing stresses is fairly vital to guarantee the whole stability and long-term ageing of underground mining structures. This paper inspects the effect of diverse curing stresses (0 kPa – witness, 180 kPa, 360 kPa and 540 kPa) on physico-mechanical characteristics of cTB materials subjected to a curing age of up to 28 days. Based on lab tests, uniaxial compression and microstructure analyses are performed for all the specimens. To well characterize the self-desiccation behavior of cTB specimens, suction and electrical conductivity are also scrutinized during their curing processes. Results indicate that curing of cTBs under stress ranging from 0 to 540 kPa can improve their strength gains to some extent. Irrespective of curing stress, cTB’s suction is enlarged while its porosity is dropped once increased with curing age and stress, respectively. There exists a robust power function between suction and strength while there is a linear link between electrical conductivity and strength. One can state from this study that curing stress must be significantly taken into account during the backfill mixture proportions’ design. © 2022, The Authors. All rights reserved.

关键词： Pore structure