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- MakaleYalnız künye2023Scopus SJRQ1Analysis of the mechanical behavior and prediction of the plastic zone of a large-diameter buried gas pipeline under ground overload
Xu, Qian; Zhong, Liqiong; Shu, Mengjie; Zou, Zhenwei; Yang, Gang; Zheng, Qiang; Chen, Xingli; Akkurt, Nevzat; Zhang, Hui; Qiang, Yujie
Plastic failure of pipelines caused by ground overload is increasing. The one-dimensional model based on mechanical nodal parameters cannot predict the plastic failure characteristics of the three-dimensional structure of the pipeline. In order to predict the evolution of the plastic failure of the pipeline with the yield strength as the evaluation criterion, a multidimensional model is needed to consider the changes in the external loads and the changes in the mechanical properties of the pipeline along the circumferential and axial directions. In this study, a finite element calculation model for a large-diameter gas pipeline underground overload was established to investigate the law of stress change in the plastic zone. The nonlinear surface fitting method was used to establish the angle fitting model of the plastic zone and the depth fitting model of the plastic zone. The variation of the area of the plastic zone was described, and the reliability of the results was verified. In addition, the accuracy of the fitting model and the cost of the finite element calculation were evaluated. The results showed that the pipeline entered plasticity at a ground load of P = 25 MPa, and the plastic zone developed continuously in the axial and circumferential directions as the ground load increased. The angle and depth increased to 36° and 1.8 m, respectively, at P = 50 MPa. The average absolute errors for the plastic zone depth fitting model and the plastic zone angle fitting model were 6.42% and 6.64%, respectively, both of which can provide an accurate description of the plastic zone. The calculation results of the plastic zone angle fitting model could meet requirements of data processing and analysis. The plastic zone depth fitting model could be used to obtain solutions with higher accuracy, but it increases the cost of finite element simulation.
AtıfScopus6OpenAlex6
İncele - MakaleYalnız künye2023Scopus SJRQ1Analysis of the mechanical characteristics and plasticity-hazardous zones development of natural gas pipeline under overload
Zheng, Qiang; Shu, Zekai; Yang, Gang; Zhang, Hui; AKKURT, Nevzat; Guan, Ben; Chen, Weiwang; Xu, Qian; Zang, Yong; Ding, Yulong
The problem of natural gas pipeline overload failure is of great significance, and the development law of critical mechanical properties of pipelines is of great importance to the safety design of natural gas pipelines. This study establishes a three-dimensional finite element computational model of the pipeline that integrates the changes in axial and circumferential mechanical characteristics, and uses the yield strength, safety factor and ellipticity indexes as criteria to dimensionless the axial depth and circumferential angle of the plastic zone to explore the characteristics of the plastic damage stage of the pipeline. By solving the plastic hazardous zones based on the safety factor, the applicability of the dimensionless parameters is extended to investigate the development laws of the hazardous zones and the correlation mechanism between failure criteria and hazardous zones. The results show that as the ground load increases, the pipeline deformation gradually develops into the plastic stage (P = 16 MPa) and then goes through three deformation stages. With the increase of safety factor, the change trend of the proportion of stage I in the whole loading process decreases to 4 %, the change trend of the proportion of stage III increases significantly to 52 %, while the proportion of stage II shows a change trend of decreasing and then increasing, the proportion of this stage ranges from 30 % to 38 %. Based on the law of variation of axial ellipticity of pipeline section, a high-risk section of pipeline was identified in the range of 0–2 m from the point of maximum local compression strain. The results of the study can serve as a basis for accurate evaluation of the safety status of natural gas pipelines under overload.
AtıfScopus3WoS3OpenAlex3İncele - Derleme MakaleYalnız künye2023Scopus SJRQ1A review of advances in mechanical behaviors of the underground energy transmission pipeline network under loads
Zheng, Qiang; Xu, Qian; Shu, Zekai; Yang, Di; Chen, Weiwang; Akkurt, Nevzat; Zhang, Hui; Lin, Lin; Zhang, Xinxin; Ding, Yulong
The safety of underground energy transmission pipeline network is threatened by traffic, earthquakes, explosions, and other stresses. To solve the problem of damage to the underground energy transmission pipeline networks by external loads, this study analyzed the mechanical properties of the Pipe-Soil Coupling System (PSCS) under external loads from a mechanical perspective. The pipeline constitutive model, the soil constitutive model, the internal effect of the PSCS, the influence of external stresses on the PSCS, and the dynamic response of the PSCS under various research methodologies were all studied. First, different mechanical features of the pipes and soil were employed to investigate the pipe and soil constitutive models. Second, based on the different force directions within the PSCS, the earth pressure and axial friction of the PSCS were investigated to clarify the interaction between the pipe and soil. For the purpose of to better understand the degradation of the underground pipeline state, the impacts of man-made and natural stresses on the PSCS failure were explored. Finally, the results of the investigation of the dynamic response of the PSCS were examined for their applicability using three research methods: theoretical analysis, numerical simulation, and experimental analysis. It is found that the existing constitutive models of pipeline and soil are lack of basis, which increases the difficulty of the selection of constitutive models in the process of research. In the analysis of load effect, earth pressure plays a dominant role in affecting the local stability of pipeline, but the calculation accuracy of soil pressure needs to be improved. Due to the lack of experimental guidance for complex damage phenomena under external loads, it is impossible to accurately determine the limit state parameters of pipelines under complex damage modes. It is critical to create and refine the theory underpinned by numerous experimental data in order to address the issue of pipeline dynamic response under multi-field coupling, including explosion and earthquake. This work is critical for analyzing existing research findings, identifying future research problems, and enhancing buried pipeline safety management.
AtıfScopus15WoS13OpenAlex14İncele - MakaleYalnız künye2023Scopus SJRQ1Carbide slag recycling to fabricate shape-stable phase change composites for thermal energy storage
Xiong, Yaxuan; Wang, Huixiang; Ren, Jing; Nevzat, Akkurt; Xu, Qian; Nie, Binjian; Li, Chuan; Ding, Yulong
The mining and processing of traditional skeleton materials inevitably generates carbon emissions and pollutes the surrounding environment. To make full use of industrial solid waste, this work innovatively used carbide slag as skeleton material and Na2CO3 as phase change material (PCM) to fabricate shape-stable phase change composites (SSPCCs) via the cold-compression & hot-sintering method. Seven SSPCCs were fabricated with different mass ratios of carbide slag to Na2CO3. Then, the thermal energy storage (TES) performance, mechanical property, micromorphology, chemical compatibility as well as thermal cycling stability were investigated. The results showed that the carbide slag could combine with Na2CO3 to fabricate SSPCCs; Sample CN5 achieved the optimal performance with the mass ratio 52.5:47.5 of carbide slag to Na2CO3; Sample CN5 achieved a TES density of 993 J/g in the range of 100 to 900 °C, a compressive strength of 22.02 MPa and a maximal thermal conductivity of 0.62 W/(m·K); Both carbide slag and Na2CO3 were distributed uniformly in sample CN5, while good thermal stability after the 100 heating/cooling cycles and good chemical compatibility between the carbide slag components and the Na2CO3 were observed.
AtıfScopus34OpenAlex30İncele - MakaleYalnız künye2023Scopus SJRQ1Heat loss optimization and economic evaluation of a new fourth generation district heating triple pipe system
Chen, Xingli; Ren, Ling; Zheng, Qiang; Yang, Gang; Akkurt, Nevzat; Liu, Lin; Liu, Zhiwei; Qiang, Yujie; Yang, Huachao; Xu, Qian
In response to the heat loss caused by the temperature difference between the heating pipes and external environment during the pipe transportation, heat contradiction between the total heat loss of the piping system and heat transfer between tubes, as well as economic balance between the cost of heat loss and cost of material loss. Based on TOTS (Two-supply/One-return, triple pipe structure) heat loss theory of the fourth-generation district heating system, this paper optimizes structure of pipes by setting dimensionless characteristic parameters θ and β. Finally, a mathematical model is proposed to calculate economic efficiency of pipeline network by considering the cost of initial construction material loss and operation heat loss of the pipe. Results show that, from energy perspective, comprehensive heat as system energy consumption evaluation index is positively correlated with θ, decreases first and then increases as β increases. Total heat loss of system dominates comprehensive heat. Lowest comprehensive heat of system is 18.12 w/m for θ of 0.1945 and β of 0.0739. From economic perspective, total system loss cost as system economic evaluation index is positively correlated with both θ and β. Total system heat loss cost dominates total system loss cost. Lowest total system loss cost is $29.39/m for θ of 0.1945 and β of 0.0509.
AtıfScopus16OpenAlex20İncele - MakaleYalnız künye2020Scopus SJRQ2Synthesis and Characterization of Disodium Hydrogen Phosphate Dodecahydrate-Lauric-Palmitic Acid Used for Indoor Energy Storage Floor Units
Xu, Qian; Akkurt, Nevzat; Zou, Zhenwei; Liu, Yang; Feng, Junxiao; Yu, Chuqiao; Ding, Chong; Xiong, Yaxuan; Zhou, Jingzhi; Zang, Yong
Organic and inorganic phase change materials (PCMs) are considered potential materials for thermal energy storage (TES) with different phase change characteristics. In this study, a novel organic-inorganic composite phase change material (PCM) called disodium hydrogen phosphate dodecahydrate-lauric-palmitic acid (D-LA-PACM) was prepared. Expanded graphite (EG) was selected as the support material, and the novel organic-inorganic form-stable PCM called D-LA-PAPCM/EG was prepared using the vacuum adsorption method. Differential scanning calorimetry, Fourier transform infrared spectroscopy, X-ray diffraction, leakage testing, melting and solidification cycle testing, thermal conductivity testing, scanning electron microscopy observation of the micromorphology, and other characterization methods were used to study the micro structure and morphology, thermal physical parameters, thermal conductivity, stability of the PCMs, and the comprehensive material properties of D-LA-PAPCM under the composite action of EG. Results indicated that the melting and freezing temperatures and latent heats of D-LA-PAPCM/EG were measured to be 31.6°C and 34.3°C and 142.9 and 142.8 J/g, respectively. Although some of the lauric-palmitic acid (LA-PA) and disodium hydrogen phosphate dodecahydrate (DHPD) separated in the multiple porous structures of EG after 1000 cycles, they could still absorb and release latent heats independently, with D-LA-PAPCM/EG still exhibiting good thermal stability. The thermal conductivity of D-LA-PAPCM/EG was 1.361 W/(mK). Therefore, the material and thermal properties of the prepared D-LA-PAPCM/EG indicate that it could be well used as a feasible material for energy-saving phase change floor units in indoor TES systems.
AtıfScopus18OpenAlex18İncele