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Thermo-economic analysis and optimization of a novel self-condensing transcritical CO 2 power cycle with ejector refrigeration

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Process Safety and Environmental Protection 2025年 199卷

作者： Jiaxi Xia Jingjing Hou Jiangfeng Wang Juwei Lou Yumin Guo School of mechanical and Electrical Engineering Henan Agricultural University Zhengzhou 450002 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

The transcritical CO 2 power cycle stands out as a promising approach for the utilization of waste heat and renewable energy, but its practical application is restricted by the condensation challenges of working fluid. To tackle this issue, a novel self-condensing transcritical CO 2 power cycle (SC-TCO 2 PC), which integrates the transcritical CO 2 power cycle with an ejector refrigeration cycle, is proposed. Detailed mathematical models are formulated, and parametric study is carried out to illustrate the correlations between the crucial parameters and system performance from both thermodynamic and economic viewpoints. Then a multi-objective optimization is applied to explore the potential for performance enhancement. Furthermore, the comparative analysis of the SC-TCO 2 PC and the recuperative supercritical CO 2 Brayton cycle (SCO 2 BC) are conducted under optimized conditions. The results demonstrated that the enhanced turbine inlet pressure and temperature positively influence the thermal-economic performance of the SC-TCO 2 PC. Furthermore, the maximum thermal efficiency of 43.90 %, exergy efficiency of 72.97 % and minimum cost per unit of electricity of 0.0372$/kWh are attainable for the SC-TCO 2 PC, reflecting the improvements of 4.88 %pt for maximum thermal efficiency, 6.60 %pt for maximum exergy efficiency and a 8.87 % reduction for minimum unit power cost in comparison to the recuperative SCO 2 BC. In optimum conditions, the SC-TCO 2 PC is capable of achieving a thermal efficiency of 42.11 % and an exergy efficiency of 70.54 % with the cost per unit of electricity of 0.0440$/kWh.

关键词： Brayton cycle

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Numerical Investigation of Developing Turbulent flow in a Helical Square Ductwith Large Curvature

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Journal of Thermal Science 2001年第1期10卷 1-6页

作者： Gao Hui,Guo Liejin (state key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049, China ) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A fully elliptic numerical study has been carried out to investigate the three-dimensional turbulent developing flow in a helical square duct with large curvature. A two-layer zonal model is proposed and used, in which the whole region is divided into a viscosity-affected near wall layer and a fully turbulent region. A DSM closure is applied in the former, and a one-equation model is solved in the latter. The results presented in this paper cover a Reynolds number range of (l- 10) x 104. The development of flow is found to be dominated by radial pressure gradient and Dean-type secondary motion. The distribution of Reynolds stresses in fully developed flow exhibit a complex pattern of turbulence anisotropy The development of peripherally averaged friction factor and the distribution of local friction factor in fully developed flow are given and discussed.

关键词： curved pipe developing flow turbulence model numerical simulation.

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Recent advances in nonmetallic atom-doped metal nanocrystals:Synthesis and catalytic applications

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Chinese Chemical Letters 2021年第9期32卷 2679-2692页

作者： Ruiyun Guo Ke Zhang Shangdong Ji Yangzi Zheng Mingshang Jin Frontier Institute of Science and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Metal nanocrystals have been recognized as the main catalytic materials in many fields,but insufficient activity and stability,as well as high prices,have limited their large-scale potential *** one of the extremely promising alternatives toward metal in boosting their catalytic performance,nonmetallic atoms-doped metal nanocrystals have recently received extensive attention because of their high efficiency,chemical and structural durability,abundant reserve,and low *** this review,we highlight the most recent progress in this field and provide insights into their catalytic *** metalnonmetal nanocrystals prepared by doping metal nanocrystals with nonmetallic atoms are introduced and classified based on the types of nonmetallic atoms,including metal hydrides,borides,carbides,nitrides,oxides,phosphides,and ***,their applications in catalysis,especially in electrocatalysis and organic catalysis,have been summarized and ***,the conclusions and perspectives are given for the catalysis-driven rational design of metal-nonmetal nanocrystals in this minireview.

关键词： Nonmetallic atom-doping Metal-nonmetal nanocrystals Organic catalysis Electrocatalysis Catalyst design

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Improving sampling depth of laser speckle imaging by topical optical clearing:A theoretical and in vivo study

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Journal of Innovative Optical Health Sciences 2020年第2期13卷 33-43页

作者： D.Li Y.Zhang B.Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049P.R.China

The effect of optical cleaning method combined with laser speckle imaging(LSI)was discussed to improve the detection depth of LSI due to high scattering characteristics of skin,which limit its clinical application.A double-layer skin tissue model embedded with a single blood vessel was established,and the Monte Carlo method was used to simulate photon propagation under the action of light-permeating agent.808 nm semiconductor and 632.8 nm He–Ne lasers were selected to study the e®ect of optical clearing agents(OCAs)on photon deposition in *** show that the photon energy deposition density in the epidermis increases with the amount of tissue°uid replaced by *** with glucose solution,polyethylene glycol 400(PEG 400)and glycerol can considerably increase the average penetration depth of photons in the skin tissue,thereby raising the sampling depth of the *** the action of glycerol,PEG 400,and glucose,the average photon penetration depth is increased by 51.78%,51.06%,and 21.51%for 808nm,68.93%,67.94%,and 26.67%for 632.8 nm lasers,*** vivo experiment by dorsal skin chamber proves that glycerol can cause a substantial decrease in blood°ow rate,whereas PEG 400 can signicantly improve the capability of light penetration without a®ecting blood velocity,which exhibits considerable potential in the monitoring of blood°ow in skin tissues.

关键词： Laser speckle image topical optical clearing imaging depth Monte-Carlo simulation dorsal skin experiment

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Dynamic simulation of a space gas-cooled reactor power system with a closed Brayton cycle

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Frontiers in Energy 2021年第4期15卷 916-929页

作者： Chenglong WANG Ran ZHANG Kailun GUO Dalin ZHANG Wenxi TIAN Suizheng QIU Guanghui SU Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power EngineeringShaanxi Key Laboratory of Advanced Nuclear Energy and TechnologyXi’an Jiaotong UniversityXi’an 710049China

Space nuclear reactor power(SNRP)using a gas-cooled reactor(GCR)and a closed Brayton cycle(CBC)is the ideal choice for future high-power space *** investigate the safety characteristics and develop the control strategies for gas-cooled SNRP,transient models for GCR,energy conversion unit,pipes,heat exchangers,pump and heat pipe radiator are established and a system analysis code is developed in this ***,analyses of several operation conditions are performed using this *** full-power steady-state operation,the core hot spot of 1293 K occurs near the upper part of the *** 0.4$reactivity is introduced into the core,the maximum temperature that the fuel can reach is 2059 K,which is 914 K lower than the fuel melting *** system finally has the ability to achieve a new steady-state with a higher reactor *** the GCR is shut down in an emergency,the residual heat of the reactor can be removed through the conduction of the core and radiation heat *** results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat *** paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.

关键词： gas-cooled space nuclear reactor power closed Brayton cycle system startup and shutdown positive reactivity insertion accident

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Experimental and modeling investigation of zero net liquid flow in hilly terrain pipeline

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Petroleum Science 2025年

作者： Huang, Bo Xu, Qiang Chang, Ying-Jie Cao, Ye-Qi Yu, Hai-Yang Li, Yu-Wen Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China College of Petroleum Engineering Xi'an Shiyou University Shaanxi 710065 China

Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry. Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and accumulate to form slug flow, so it is necessary to remove the accumulated liquid by gas purging. In this paper, experiment is carried out in hilly terrain pipelines. Three flow patterns of stratified flow, slug flow and stratified entrained flow are observed. The process of gas purging accumulated liquid is divided into four stages, namely liquid accumulation, liquid rising;continuous outflow and tail outflow. At the same time, the flow pattern maps of each stage are drawn. The pressure drop signal is analyzed in time domain and frequency domain, and the contour map of pressure drop distribution is drawn. It is found that the ratio of range to average value can well distinguish the occurrence range of each flow pattern. Based on visualization, the transition process of slug flow to stratified flow and stratified entrained flow is studied, and the transition boundary prediction model is established. An image processing method is proposed to convert the image signal into a similarity curve, and PSD analysis is performed to calculate the slug frequency. The normal distribution is used to fit the slug frequency, and the predicted correlation is in good agreement with the experimental data. © 2025 The Authors

关键词： flow pattern transition Hilly terrain pipeline Quantitative image processing Slug flow Zero net liquid flow

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Investigation of the transfer ionization process in collisions of partially stripped ions on He

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Chinese Physics B 2010年第6期19卷 277-282页

作者：刘会平陈熙萌欧阳晓平席发元苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi'an Jiaotong University School of Nuclear Science and Technology Lanzhou University

In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq＋ ions and 0.25-6.35 MeV 0q＋ ions （q=1, 2, 3, 4） with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^0.60; the energy corresponding to maximum f is about 160q^0.60 keV/u.

关键词： ion atom collision transfer ionization single electron transfer

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Cascade utilization of full spectrum solar energy for achieving simultaneous hydrogen production and all-day thermoelectric conversion

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Journal of Energy Chemistry 2024年第9期96卷 318-327页

作者： Tuo Zhang Liang Dong Baoyuan Wang Jingkuo Qu Xiaoyuan Ye Wengao Zeng Ze Gao Bin Zhu Ziying Zhang Xiangjiu Guan Liejin Guo International Research Center for Renewable Energy(IRCRE) State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

Solar-driven photocatalytic water/seawater splitting holds great potential for green hydrogen ***,the practical application is hindered by the relatively low conversion efficiency resulting from the inadequate utilization of solar spectrum with significant waste in the form of ***,current equipment struggles to maintain all-day operation subjected to the lack of light during ***,a novel hybrid system integrating photothermal catalytic(PTC)reactor,thermoelectric generator(TEG),and phase change materials(PCM)was proposed and designed(named as PTC-TEG-PCM)to address these challenges and enable simultaneous overall seawater splitting and 24-hour power *** PTC system effectively maintains in an optimal temperature range to maximize photothermal-assisted photocatalytic hydrogen *** TEG component recycles the low-grade waste heat for power generation,complementing the shortcoming of photocatalytic conversion and achieving cascade utilization of full-spectrum solar ***,exceptional thermal storage capability of PCM allow for the conversion of released heat into electricity during nighttime,contributing significantly to the overall power output and enabling PTC-TEG-PCM to operate for more than 12 h under the actual *** to traditional PTC system,the overall energy conversion efficiency of the PTC-TEG-PCM system can be increased by∼500%,while maintaining the solar-to-hydrogen *** advancement of this novel system demonstrated that recycling waste heat from the PTC system and utilizing heat absorption/release capability of PCM for thermoelectric application are effective strategies to improve solar energy *** flexible parameter designing,PTC-TEG-PCM can be applied in various scenarios,offering high efficiency,stability,and sustainability.

关键词： Hybrid solar energy conversion system Photocatalytic overall seawatersplitting Thermoelectric power generation Phase change materials All-day operation

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Evaluation of stability and catalytic activity of Ni catalysts for hydrogen production by biomass gasification in supercritical water

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Carbon Resources Conversion 2019年第1期2卷 95-101页

作者： Youjun Lu Hui Jin Rui Zhang State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina

Supercritical water gasification is a promising technology for wet biomass *** this paper,Ni and other metal catalysts were synthesized by wet *** stability and catalytic activities of Ni catalysts were ***,catalytic activities of Ni,Fe,Cu catalysts supported on MgO were tested using wheat straw as raw material in a batch reactor at 723 K and water density of 0.07 cm^(3)/*** results showed that the order of metal catalyst activity for hydrogen generation was Ni/MgO>Fe/MgO>Cu/***,the influence of different supports on Ni catalysts performance was *** results showed that the order of the Ni catalysts’activity with different supports was Ni/MgO>Ni/ZnO>Ni/Al_(2)O_(3)>Ni/ZrO_(2).Finally,the effects of Ni loading and the amount of Ni catalyst addition on hydrogen production,and the stability of Ni/MgO catalyst were *** was found that serious deactivation of Ni catalyst in the process of supercritical water gasification took *** if carbon deposited on the catalyst surface was removed by high temperature calcination and the catalyst was reduced with hydrogen,the activity of used catalyst was only partially restored.

关键词： Ni catalyst Deactivation Biomass gasification Supercritical water Hydrogen production

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Heat Transfer Characteristics of a Microchannel Heat Sink with Highly-Dense Micro-Jet Arrays

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Journal of Thermal Science 2024年第3期33卷 1148-1160页

作者： ZHANG Yu CHEN Xiaoyan MIAO Lin CHEN Liang HOU Yu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an710049China Beijing Aerospace Technology Institute Beijing100083China

This paper proposed a new structure of highly-dense micro-jet arrays for hybrid jet-impingement/microchannel heat sinks(~120 jet per cm^(2) with jet width of 0.35 mm).Parametric study is performed to investigate the influence of structure and flow parameters on the convective heat transfer of water jet cooling in confined *** simulation results show that the optimal jet width,jet spacing and impingement distance are around 0.2 mm,0.2 mm and 0.3 mm,respectively,which can achieve a low thermal resistance as well as a relatively low pressure *** analysis of the heat transfer pathways shows that the micro-fin jet structures can extend the impinging heat transfer area and conduct a considerable proportion of heat,which can reach up to 38.9%with the Reynolds number ranging from 797.1 to *** heat transfer characteristics in the heat sink will shift from impingement dominated heat transfer to the channel-convection dominated heat transfer as the jet impingement distance increases.A correlation is proposed to predict the average Nusselt number on the stagnation area for the heat sink with different structure parameters,and the deviations of predictions from the numerical results are less than 10%.

关键词： hybrid heat sink impingement microchannel thermal management high heat flux

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