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Study of depressurization process for supercritical fluid

Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2015年第3期49卷 440-446页

作者： Zhang, Jing Tian, Wen-Xi Zhu, Da-Huan Qiu, Sui-Zheng Su, Guang-Hui State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Nuclear Science and Technology Xi'an Jiaotong Univesity Xi'an710049 China

The loss of coolant accident (LOCA) research of the supercritical water-cooled reactor (SCWR) is the key and difficult task for the safety analysis, and especially the research of the depressurization process of the pressure vessel is of crucial importance. The reactor pressure vessel was simplified and mathematical physics models were established in this study. A transient calculating code was developed. A comparison between experimental and calculated results for supercritical carbon dioxide was carried out. It is showed that the predicted results by codes are in good agreement with the experimental data. The depressurization process was analyzed by the verified code. The influences of different initial conditions, breach areas and heating powers on the depressurization process were discussed. The results show that the models established in this study can simulate the depressurization process from supercritical to subcritical state, and the calculating results may provide a theoretical basis for accident analysis of the SCWR. ©, 2015, Atomic Energy Press. All right reserved.

关键词： Supercritical fluids

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Prediction of flow boiling heat transfer coefficient in horizontal channel by genetic neural network

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2015年第1期49卷 70-76页

作者： Zhang, Jing Cong, Teng-Long Su, Guang-Hui Qiu, Sui-Zheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China

The three-layer back propagation network (BPN) and genetic neural network (GNN) were developed to predict the flow boiling heat transfer coefficient (HTC) in conventional and micro channels. The precision of GNN is higher than that of BPN (with root mean square errors of 17.16% and 20.50%, respectively). The inputs include vapor quality, mass flux, heat flux, diameter and physical properties and the output is HTC. Based on the trained GNN, the influences of input parameters on HTC were analyzed. HTC increases with pressure in conventional channels. The pressure has a negligible effect at low pressure region on HTC for micro channels. However, at high pressure region, HTC increases in low vapor quality region, while decreases in the high vapor quality region with the increase of pressure. HTC increases with the mass flux and heat flux, and HTC initially increases and then decreases as vapor quality increases. HTC increases inversely with the decrease of diameter. Dry-out arises at a lower quality in micro channels than that in conventional channels and more easily occurs in a smaller channel. ©, 2015, Atomic Energy Press. All right reserved.

关键词： Heat transfer coefficients

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Visible light-driven water oxidation using metal oxide quantum dots modified with a cobalt catalyst

Visible light-driven water oxidation using metal oxide quant...

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中国化学会第九届全国无机化学学术会议

作者： Fujun Niu Ning Zhang Shaohua Shen Liejin Guo International Research Center of Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

Conversion of sunlight to chemical fuels is the holy grail to deal with the energy and environment issue.1,2 Inspired by the natural photosynthesis, molecular based photocatalytic system has been widely investigated. Generally speaking, such a system contains three part: a sensitizer to absorb light, a reduction catalyst to generate H2, and an oxidation catalyst to produce O2. The oxidation of water has been proved to be the key of the entire water splitting process, as the reaction kinetic limitation step.3 In this work, we developed a novel system with Co3O4 quantum dots(QDs) or Fe2O3 QDs as photosensitizer, a salophen cobalt(II) complex(Co SLP) as catalyst, and persulfate(S2-2O8) as the sacrificial electron acceptor(Fig. 1). The photocatalytic oxygen evolution rate of the systems were 75μmol/h/g and 84μmol/h/g over the cobalt(II) complex when Co3O4 QDs or Fe2O3 QDs was employed, respectively. While no O2 evolution were observed when either salophen cobalt(II) complex or QDs was absent. This high efficiency might be attributed to the interfacial hole transfer from photoexcited QDs to the cobalt(II) complex.

关键词： artificial photosynthesis oxygen production quantum dots cobalt catalyst

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A novel 3-layer mixed cultural evolutionary optimization framework for optimal operation of syngas production in a Texaco coal-water slurry gasifier

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Chinese Journal of Chemical engineering 2015年第9期23卷 1484-1501页

作者：曹萃文张亚坤于腾顾幸生辛忠李杰 Key Laboratory of Advanced Control and Optimization for Chemical Processes Ministry of Education East China University of Science and Technology State Key Laboratory of Chemical Engineering East China University of Science and Technology State Key Laboratory of Multiphase Complex Systems Institute of Processing Engineering Chinese Academy of Sciences

Optimizing operational parameters for syngas production of Texaco coal-water slurry gasifier studied in this paper is a complicated nonlinear constrained problem concerning 3 BP(Error Back Propagation) neural networks. To solve this model, a new 3-layer cultural evolving algorithm framework which has a population space, a medium space and a belief space is firstly conceived. Standard differential evolution algorithm(DE), genetic algorithm(GA), and particle swarm optimization algorithm(PSO) are embedded in this framework to build 3-layer mixed cultural DE/GA/PSO(3LM-CDE, 3LM-CGA, and 3LM-CPSO) algorithms. The accuracy and efficiency of the proposed hybrid algorithms are firstly tested in 20 benchmark nonlinear constrained functions. Then, the operational optimization model for syngas production in a Texaco coal-water slurry gasifier of a real-world chemical plant is solved effectively. The simulation results are encouraging that the 3-layer cultural algorithm evolving framework suggests ways in which the performance of DE, GA, PSO and other population-based evolutionary algorithms(EAs) can be improved,and the optimal operational parameters based on 3LM-CDE algorithm of the syngas production in the Texaco coalwater slurry gasifier shows outstanding computing results than actual industry use and other algorithms.

关键词： 3-Layer mixed cultural evolutionary framework Optimal operation Syngas production Coal-water slurry gasifier

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Biogas upgrading technologies: Energetic analysis and environmental impact assessment

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Chinese Journal of Chemical engineering 2015年第1期23卷 247-254页

作者：许亚晶黄莺武斌张香平张锁江 Beijing Key Laboratory of Ionic Liquids Clean Process State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences School of Chemistry and Chemical Engineering University of Chinese Academy of Sciences

Biogas upgrading for removing CO2 and other trace components from raw biogas is a necessary step before the biogas to be used as a vehicle fuel or supplied to the natural gas grid. In this work, three technologies for biogas upgrading, i.e., pressured water scrubbing(PWS), monoethanolamine aqueous scrubbing(MAS) and ionic liquid scrubbing(ILS), are studied and assessed in terms of their energy consumption and environmental impacts with the process simulation and green degree method. A non-random-two-liquid and Henry's law property method for a CO2 separation system with ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide([bmim][Tf2N]) is established and verified with experimental data. The assessment results indicate that the specific energy consumption of ILS and PWS is almost the same and much less than that of MAS. High purity CO2 product can be obtained by MAS and ILS methods, whereas no pure CO2 is recovered with the PWS. For the environmental aspect, ILS has the highest green degree production value, while MAS and PWS produce serious environmental impacts.

关键词： Biogas upgrading Monoethanolamine aqueous scrubbing Pressured water scrubbing Ionic liquid Green degree

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The principle of compromise in competition: exploring stability condition of protein folding

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Science Bulletin 2015年第1期60卷 76-85页

作者：徐骥韩孟之任瑛李静海 State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences

Thermodynamic hypothesis and kinetic stabil- ity are currently used to understand protein folding. The former assumes that free energy minimum is the exclusive dominant mechanism in most cases, while the latter shows that some proteins have even lower free energy in inter- mediate states and their native states are kinetically trapped in the higher free energy region. This article explores the stability condition of protein structures on the basis of our study of complex chemical systems. We believe that sep- arating one from another is not reasonable since they should be coupled, and protein structures should be dom- inated by at least two mechanisms resulting in different characteristic states. It is concluded that：（1） Structures of proteins are dynamic, showing multiple characteristic states emerging alternately and each dominated by a respective mechanism. （2） Compromise in competition of multiple dominant mechanisms might be the key to understanding the stability of protein structures. （3） The dynamic process of protein folding should be depicted through the time series of both its energetic and structural changes, which is much meaningful and applicable than the free energy landscape.

关键词： Protein folding Dynamic structure -Multiple mechanisms Compromise in competitionMesoscale Stability

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Cover Feature: Phosphorus-Doped MoS2Nanosheets Supported on Carbon Cloths as Efficient Hydrogen-Generation Electrocatalysts (ChemCatChem 7/2018)

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ChemCatChem 2018年第7期10卷 1477-1477页

作者： Luozhen Bian Wei Gao Jiamin Sun Mingming Han Fulin Li Zhaofeng Gao Lei Shu Prof. Ning Han Prof. Zai-xing Yang Prof. Aimin Song Prof. Yongquan Qu Prof. Johnny C. Ho Shenzhen Research Institute Shandong University Shenzhen 518057 P.R. China Center of Nanoelectronics and School of Microelectronics Shandong University Jinan 250100 P.R. China Center for Applied Chemical Research Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an 710049 P.R. China Department of Materials Science and Engineering City University of Hong Kong 83 Tat Chee Avenue Kowloon Hong Kong P.R. China Shenzhen Research Institute City University of Hong Kong Shenzhen 518057 P.R. China State Key Laboratory of Multiphase Complex Systems Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 P.R. China

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Simulation of a Novel Single-column Cryogenic Air Separation Process Using LNG Cold Energy

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Physics Procedia 2015年 67卷 116-122页

作者： Zheng Jieyu Li Yanzhong Li Guangpeng Si Biao Institute of Refrigeration and Cryogenics Xi’an Jiaotong University Xi’an710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an710049China

In this paper, a novel single-column air separation process is proposed with the implementation of heat pump technique and introduction of LNG coldenergy. The proposed process is verifiedand optimized through simulation on the Aspen Hysys® platform. Simulation results reveal that thepower consumption per unit mass of liquid productis around 0.218 kWh/kg, and the total exergy efficiency of the systemis 0.575. According to the latest literatures, an energy saving of 39.1% is achieved compared with those using conventional double-column air separation *** introduction of LNG cold energy is an effective way to increase the system efficiency.

关键词： heat pump cryogenic air separation single-column process LNG cold energy recovery Aspen Hysys® simulation

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Thermal-hydraulic analysis and metal temperature computation for the water wall of a 1000MW ultra supercritical tower boiler with double reheat

Thermal-hydraulic analysis and metal temperature computation...

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International Conference on Power engineering, ICOPE 2015

作者： Yang, Dong Wang, Long Bi, Yanshuang Xie, Beibei Wang, Gang Yao, Danhua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an Shaanxi710049 China Shanghai Boiler Works Ltd. No.250 Huaning Road Minhang District Shanghai200245 China

The ultra supercritical boiler technology with double reheat can significantly increase the efficiency of a Rankine cycle power plant, and reduce fuel consumption for a given output. Recently China is developing 1000MW ultra supercritical boiler with double reheat which is arranged in tower type and the steam parameters are 350bar, 605oC/613oC/613oC. Thermal-hydraulic analysis is the key factors for the design and operation of ultra supercritical boiler with double reheat. According to the boiler structure and furnace-sided heat flux, the water wall of an ultra supercritical tower boiler with double reheat is treated in this paper as a flow network system consisting of series-parallel loops, pressure grids and connecting tubes. Based on the mass, momentum and energy conservations and some supplementary equations, a mathematical model is developed. Pressure drop, mass flux distribution, outlet vapor temperatures and metal temperatures data in the water wall at BMCR (boiler maximum continuous rating), 75% THA (turbine heat acceptance) and 30% THA load are obtained by iteratively solving the mathematical model. The results show that the water wall in the ultra supercritical boiler can operate safely. © 2015 The Japan Society of Mechanical Engineers.

关键词： Pressure drop

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Research on the penetration length of submerged sonic/supersonic steam jet

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2015年第10期36卷 2169-2172页

作者： Yuan, Fang Fan, Peng-Fei Wu, Lin-Fei Zhao, Quan-Bin Chen, Wei-Xiong Chong, Dao-Tong Yan, Jun-Jie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China CNNC Nuclear Power Operations and Management Co. Ltd Jiaxing314000 China

The continuous steam region generated by high-speed steam jet discharging into subcooled water is called the steam plume. The plume penetration length is an important index for heat exchange capability of steam jet. In this paper, the penetration length of sonic/supersonic steam jet at the stable condensation regime was investigated experimentally. It was found that the dimensionless penetration length increased with increasing steam mass ux and water temperature. Besides, the dimensionless penetration length of supersonic steam jet was smaller than that of sonic steam jet and decreased with the diminishing designed pressure ratio of supersonic nozzles. Moreover, a correlation was proposed based on the experimental data;the discrepancies between predicted and experimental penetration length were within ±15%. © 2015, Science Press. All right reserved.

关键词： Steam

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