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Thermodynamic Analysis on of Skid-Mounted Coal-bed Methane Liquefaction Device using Cryogenic Turbo-Expander

IOP Conference Series: Materials Science and engineering 2017年第1期278卷

作者： Shuangtao Chen Lu Niu Qiang Zeng Xiaojiang Li Fang Lou Liang Chen Yu Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China Xinjiang Coal Research Institute Urumqi 830091 PR China

Coal-bed methane (CBM) reserves are rich in Sinkiang of China, and liquefaction is a critical step for the CBM exploration and utilization. Different from other CBM gas fields in China, CBM distribution in Sinkiang is widespread but scattered, and the pressure, flow-rate and nitrogen content of CBM feed vary significantly. The skid-mounted liquefaction device is suggested as an efficient and economical way to recover methane. Turbo-expander is one of the most important parts which generates the cooling capacity for the cryogenic liquefaction system. Using turbo-expander, more cooling capacity and higher liquefied fraction can be achieved. In this study, skid-mounted CBM liquefaction processes based on Claude cycle are established. Cryogenic turbo-expander with high expansion ratio is employed to improve the efficiency of CBM liquefaction process. The unit power consumption per liquefaction mole flow-rate for CBM feed gas is used as the object function for process optimization, compressor discharge pressure, flow ratio of feed gas to turbo-expander and nitrogen friction are analyzed, and optimum operation range of the liquefaction processes are obtained.

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Au [email protected] @ZnIn 2 S 4 nanosheets with significantly enhanced visible-light photocatalytic H 2 evolution: The effect of different Au positions on the transfer of electron-hole pairs

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Applied Catalysis B: Environmental 2021年 282卷

作者： Siman Mao Jian-Wen Shi Guotai Sun Dandan Ma Chi He Zengxin Pu Kunli Song Yonghong Cheng State Key Laboratory of Electrical Insulation and Power Equipment Center of Nanomaterials for Renewable Energy School of Electrical Engineering Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

Herein, a new type of photocatalysts, Au [email protected] @ZnIn 2 S 4 nanosheets ( [email protected] @ZIS), is elaborately designed for the photocatalytic H 2 evolution from water splitting, where Au nanodots (NDs) are anchored in the pore space of thiol-functionalized UiO66 metal-organic framework (MOF) and ZnIn 2 S 4 nanosheets are wrapped around the UiO66 MOF containing Au NDs. It is found that the different Au positions have a grateful effect on the transfer of photogenerated charge carriers. In [email protected] @ZIS, the photoexcited electrons transfers from ZnIn 2 S 4 to UiOS and then to Au NDs, establishing a smooth transmission channel of electrons. As expected, the optimal sample (Au 4 @ [email protected] 40 ) presents a high photocatalytic H 2 production rate of 391.6 μmol/h (10 mg of catalyst) under visible light irradiation, which is 435.1, 61.2 and 10.2 times higher than that of the pure UiOS, ZnIn 2 S 4 and [email protected] , respectively.

关键词： Photocatalysis Hydrogen evolution Metal-organic framework Thiol- functionalization Au nanodots

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Corrigendum to “Entrainment at T-junction: A review work” [Prog. Nucl. Energy 70 (January 2014) 221–241]

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Progress in Nuclear Energy 2014年 71卷 279-279页

作者： Zhaoming Meng Laishun Wang Wenxi Tian Suizheng Qiu Guanghui Su School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No. 28 Xianning West Road Xi'an 710049 China

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A new non-destructive method for fault diagnosis of reciprocating compressor by measuring the piston rod strain

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IOP Conference Series: Materials Science and engineering 2019年第1期604卷

作者： Xueying Li Xueyuan Peng Xi'an Jiaotong University Xi'an Jiaotong University Xi'an 710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

As an established method to analyse the thermodynamic process inside the cylinder, the p-V diagram can identify typical faults such as leakages through the sealing rings and self-acting valves, loosening and fluttering of the vales, etc. However, the installation of the pressure sensor within the cylinder for recording the p-V diagram may lead to degradation of the cylinder integrity, and hereby potential leakage and lowered strength of the cylinder. This paper presents a new non-destructive method for fault diagnosis of the reciprocating compressor by measuring the piston rod strain, from which the p-V diagram was transformed. An algorithm for reconstruction of the p-V diagram was proposed based on the key feature points on the piston rod load curve that reflect the opening and closing events of the compressor valves. The reconstruction method was validated by comparing the calculated p-V diagrams with the experimental results. The reconstructed p-V diagrams were further used for fault diagnosis of the reciprocating compressors, with which the acoustic emission method was integrated. The results show that this method can easily monitor the working conditions and identify whether and where leakage, fluttering and delayed closing of the valves occur, which indicates that this method can be utilized as a powerful tool of non-destructive condition monitoring and fault diagnosis of the reciprocating compressors.

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Development of typical processes and key devices for direct air CO2 capture

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Meitan Xuebao/Journal of the China Coal Society 2024年第10期49卷 4203-4221页

作者： Yu, Binpeng Tan, Lei Wang, Ding Wang, Limin Xiang, Xiaofeng Wang, Zhichao Jin, Zhonghua Yang, Bolun Wu, Zhiqiang School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China Shaanxi Province Energy and Chemical Process Intensification Key Laboratory Xi’an710049 China School of Engery and Powerl Engineering Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an710049 China Shaanxi Engineering Research Center if Coal Fired Boiler Environmental Protection Xi’an710054 China

Conventional carbon capture and storage technologies and carbon capture, utilization and storage technologies mainly target CO2 emissions from fixed sources, while direct air capture CO2 (DAC) technology, as an emerging negative carbon emission technology, can capture CO2 emissions from distributed sources and further reduce the global atmospheric CO2 concentration. In this paper, the development process of DAC's typical liquid absorption process, solid adsorption process and the construction of relevant demonstration projects are introduced, the technical characteristics of emerging DAC processes are analyzed, and the key equipment schemes and future development trends of existing DAC processes are discussed. The DAC liquid absorption process has the characteristics of low cost of absorbent raw materials and high selectivity, which can realize a large-scale continuous capture, but high energy consumption in the regeneration process. The DAC solid adsorption process has the characteristics of modularity, low investment cost, and relatively low energy consumption in the regeneration process, but requires a regular replacement of adsorption materials and maintenance of adsorption equipment, which is suitable for small-scale DAC application scenarios. Two typical DAC process absorption/adsorption materials are reviewed. In the DAC electric oscillation adsorption process, CO2 is chemically captured in the solid electrode, and CO2 desorption is achieved by changing the polarity of the solid electrode with applied electric field. This process has a higher efficiency than that of the heat or pressure-based separation process. The CO2 in the air is selected through the DAC separation membrane to achieve an efficient carbon capture. The DAC process achieves the CO2 absorption and desorption through the change of humidity, which breaks through the high energy consumption limit of conventional variable temperature/pressure swing adsorption. The DAC bio-absorption process absor

关键词： Adsorption

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Corrigendum to “Promoting adiabatic core approximation in a rapid compression machine by an optimized creviced piston design” [Fuel 251 (2019) 328–340]

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Fuel 2019年 255卷

作者： Yingtao Wu Meng Yang Chenglong Tang Yang Liu Peng Zhang Zuohua Huang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China Department of Mechanical Engineering The Hong Kong Polytechnic University Hung Hom Kowloon Hong Kong

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Non-Hermitian delocalization in a 2D photonic quasicrystal

arXiv

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arXiv 2023年

作者： Zhang, Zhaoyang Liang, Shun Septembre, Ismaël Yu, Jiawei Huang, Yongping Liu, Maochang Zhang, Yanpeng Xiao, Min Malpuech, Guillaume Solnyshkov, Dmitry Key Laboratory for Physical Electronics and Devices The Ministry of Education Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information Xi’an Jiaotong University Xi’an710049 China Institut Pascal PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP Clermont-FerrandF-63000 France International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Physics University of Arkansas FayettevilleAR72701 United States National Laboratory of Solid State Microstructures School of Physics Nanjing University Nanjing210093 China Paris75231 France

Quasicrystals show long-range order, but lack translational symmetry. So far, theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localized eigenstates. This localization is due to the fractal structure of the spectrum in the Hermitian case and to the transition to diffusive bands via exceptional points in the non-Hermitian case. Here, we present an experimental study of a dodecagonal (12-fold) photonic quasicrystal based on electromagnetically-induced transparency in a Rb vapor cell. The transition to a quasicrystal is obtained by superposing two honeycomb lattices at 30◦ with a continuous tuning of their amplitudes. Non-Hermiticity is controlled independently. We study the spatial expansion of a probe wavepacket. In the Hermitian case, the wavepacket expansion is suppressed when the amplitude of the second lattice is increased (quasicrystal localization). We find a new regime, where increasing the non-Hermitian potential in the quasicrystal enhances spatial expansion, with the C12 symmetry becoming visible in the wavepacket structure. This real-space expansion is due to a k-space localization on specific quasicrystal modes. Our results show that the non-Hermitian quasicrystal behavior is richer than previously thought. The localization properties of the quasicrystals can be used for beam tailoring in photonics, but are also important in other fields. Copyright © 2023, The Authors. All rights reserved.

关键词： Quasicrystals

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Numerical Study of Evaporation and Motion Characteristics of Liquid Nitrogen Droplet in High-Speed Gas flow

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IOP Conference Series: Materials Science and engineering 2017年第1期278卷

作者： Y. Ruan L. Chen X. Liu S. Chen Y. Hou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 PR China Xi'an Jiaotong University Suzhou Academy Suzhou 215123 PR China

In the cryogenic wind tunnel, cooling the circulating gas to cryogenic temperature by spraying liquid nitrogen (LN2) is an efficient way to increase the Reynolds number. The evaporation and motion of LN2 droplets in the high-speed gas flow is the critical process that determines the cooling rate, cooling capacity and the safe operation of the down-stream compressor. In this study, a numerical model of droplet motion and evaporation in high-speed gas flow is developed and verified against experimental data. The droplet evaporation rate, diameter and velocity are obtained during the evaporation process under different gas temperatures and flow velocities. The results show that the gas temperature has dominant influence on the droplet evaporation rate. High flow speed can increase droplet evaporation effectively at the beginning process. Evaporation of droplets with different diameters follows a similar trend. The absolute evaporation rate increases with the increase of droplet diameter while the relative evaporation amount is highest for the smallest droplet due to its high area-volume ratio. This numerical study provides insight for understanding the evaporation of LN2 droplets in high-speed gas flow and useful guidelines for the design of LN2 spray cooling.

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Performance of V-Cone flowmeter applied to cryogenic fluid measurement considering cavitation

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IOP Conference Series: Earth and Environmental Science 2019年第6期240卷

作者： Denghui He Bofeng Bai Senlin Chen Jie Zhang Pengcheng Guo State Key Laboratory of Eco-hydraulic in Northwest Arid Region Xi'an University of Technology Xi'an 710048 Shaanxi China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

The V-Cone flowmeter is a promising differential pressure flowmeter for metering the cryogenic fluid for its many advantages. When the cryogen velocity increases to a certain value, the cavitation may occur in flowmeter, which may significantly affect the performance of V-Cone flowmeter. However, the effect of cavitation on performance of V-Cone flowmeter remains unclear and there are no published studies to our knowledge on this issue. Here we investigate the performance of V-Cone flowmeter when measuring the cryogenic fluids, especially the effects of cavitation on the discharge coefficient and pressure loss coefficient of the flowmeter. Two cryogenic fluids are investigated, including liquid nitrogen (LN2) and liquid hydrogen (LH2). For comparison, the water is also investigated. The realizable κ-ε model is used to describe the turbulence. The Schnerr-Sauer cavitation model is used to investigate the effect of cavitation on the performance of the V-Cone flowmeter. The results show that there was little effect of cavitation on the discharge coefficient and pressure loss coefficient at the initial stage of cavitation. When the cloud cavitation occurred downstream of V-Cone, the discharge coefficient decreases rapidly with Reynolds number increasing, while the pressure loss coefficient rises quickly. The average discharge coefficient is almost the same for different fluids in the stable region; while the cryogenic fluids have wider stable Reynolds number ranges than the water. The lower limits of the Reynolds number for the constant discharge coefficient is very close for three fluids, however, for the upper limits of Reynolds number are quite different. We conclude that measurement range of the cryogenic fluid is much larger than that of the water, which shows that the V-Cone flowmeter exhibits great potential in the measurement of cryogenic fluid. This study provides insights into the effect of cavitation on the measurement of V-Cone flowmeter and opens a new aven

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Thermal management matters in photovoltaic–electrocatalysis for solar hydrogen production

EcoEnergy

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EcoEnergy 2024年

作者： Jie Chen Xin Chen Jie Sun Jingkuo Qu Xiangjiu Guan Shaohua Shen School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Photovoltaic–electrolysis (PV-EC) system currently exhibits the highest solar to hydrogen conversion efficiency (STH) among various technical routes. This perspective shifts the focus from the materials exploration in photovoltaics and electrolysis to the critical aspect of thermal management in a PV-EC system. Initially, the theoretical basis that elucidates the relationships between temperature and the performance of both photovoltaics and electrolyzers are presented. Following that, the impact of thermal management on the performance of PV-EC for solar hydrogen production is experimentally demonstrated by designing variables-controlling experiments. It is observed that while utilizing identical PV and EC cells under varying thermal conditions, the highest STH can reach 22.20%, whilst the lowest is only 15.61%. This variation underscores the significance of thermal management in optimizing PV-EC systems. Finally, increased efforts to enhancing heat transfer and optimizing heat distribution are proposed, thus facilitating the design of more efficient PV-EC systems with minimized thermal energy losses.

关键词： device design photovoltaic-electrolysis solar to hydrogen thermal management water electrolyzer

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