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Black TiO_(2) for solar hydrogen conversion

Journal of Materiomics 2017年第2期3卷 96-111页

作者： Bin Wang Shaohua Shen Samuel S.Mao School of Science MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed MatterState Key Laboratory for Mechanical Behavior of MaterialsXi'an Jiaotong UniversityXi'an710049China International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityShaanxi710049China Xi'an Jiaotong University Suzhou Academy SuzhouJiangsu215123China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA94720United States Samuel Mao Institute of New Energy Science Hall1003 Shangbu RoadShenzhen518031China

Titanium dioxide(TiO_(2))has been widely investigated for photocatalytic H_(2) evolution and photoelectrochemical(PEC)water splitting since ***,its wide bandgap(3.0-3.2 eV)limits the optical absorption of TiO_(2) for sufficient utilization of solar *** TiO_(2) has been proposed as an effective strategy to enhance its solar absorption and thus the photocatalytic and PEC activities,and aroused widespread research *** this article,we reviewed the recent progress of black TiO_(2) for photocatalytic H_(2) evolution and PEC water splitting,along with detailed introduction to its unique structural features,optical property,charge carrier transfer property and related theoretical *** summarized in this review article,black TiO_(2) could be a promising candidate for photoelectrocatalytic hydrogen generation via water splitting,and continuous efforts are deserved for improving its solar hydrogen efficiency.

关键词： Black TiO_(2) Photoelectrochemical water splitting Photocatalytic Hydrogen evolution

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Multi-objective optimization of a printed circuit heat exchanger design 17

Multi-objective optimization of a printed circuit heat excha...

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17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2017

作者： Wang, L. Chen, M. Shi, S. Che, D. Sun, X. Department of Nuclear Engineering and Radiological Sciences University of Michigan 2355 Bonisteel Blvd. Ann ArborMI48109-2104 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi710049 China

Due to their high effectiveness and compact size, printed circuit heat exchangers (PCHEs) appear promising to be employed as intermediate heat exchangers (IHXs) in High-Temperature Gas-cooled Reactors (HTGRs). In the literature, PCHEs of zigzag mini-channel designs have demonstrated superior performance in heat transfer and pressure drop. In this research, a three-dimensional numerical simulation was performed for a PCHE using computational fluid dynamics (CFD) tool ANSYS FLUENT to study the effects of the zigzag pitch and angle, and channel diameter on its thermal-hydraulic performance. The mass, momentum, and energy equations were solved using a finite volume method by considering steady-state, incompressible laminar flow. The FLUENT numerical model was validated by comparing the simulation results with the experimental data obtained in a high-temperature helium test facility. The comparison showed overall good agreement between the simulations and experiments. In addition, it was challenging to obtain accurate correlations/models for the Nusselt number and friction factor with various geometrical and operational parameters considered. In our study, two artificial neural network (ANN) models were applied by utilizing the CFD results to predict the Nusselt number and friction factor in PCHE zigzag channels with different geometrical configurations and operational parameters. Consequently, the computation time needed for the PCHE design optimization process could be significantly reduced. The comparison between the ANN predictions and CFD results showed that the ANN models could predict the numerical data with good accuracies. Furthermore, to achieve an optimal heat exchanger design, two conflicting evaluation criteria were proposed based on the capital and operational costs. Finally, the Non-dominated Sorting Genetic Algorithms (NSGA-II) and the proposed ANN models were combined and utilized to optimize the geometrical design parameters of the zigzag-channel PCHEs.

关键词： Multiobjective optimization

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Correlations of Coal Chemical Properties in China: Quantitative Analysis from Thousands of Data

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Energy Procedia 2017年 105卷 1339-1343页

作者： Chang’an Wang Song Wu Wufeng Chen Qiang Lv Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University No 28 Xianning West Road Xi’an 710049 China

Coal chemical properties show conspicuous impacts on its reactivity and thermal conversion. Nevertheless, the quantitative analysis of coal property indice in China is insufficient. Here, we quantitatively analyzed the correlations of various chemical properties of coals from thousands of data. Noteworthy variations were captured with some quantified expressions between coal properties obtained.

关键词： coal property quantitative analysis fuel ratio coal rank energy conversion fossil fuel

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Effects of Coal Blending and Operating Conditions on Combustion and NO x Emission Characteristics in a Tangentially-fired Utility Boiler

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Energy Procedia 2017年 105卷 4015-4020页

作者： Debo Li Qiang Lv Yongxin Feng Chang’an Wang Xuan Liu Kai Chen Kai Xu Jun Zhong Defu Che Electric Power Research Institute of Guangdong Power Grid Corporation Guangzhou 510080 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 influences of operating conditions, such as excess air ratio and SOFA arrangement, on temperature distributions, species distributions, NO x emissions and burnout of a tangentially-fired utility boiler using bituminous and blended coal were investigated by numerical approach in the present study. The simulation results show that the fuel type exhibits certain effect on the temperature distributions and the NO x emissions. Moreover, higher excess air ratio could restrain the CO formation but promote NO x emission. The temperature and the species distributions are highly related to the SOFA arrangement. In addition, SOFA technology is still an effective approach to control the NO x emissions during blended coal combustion, while the disadvantageous effect on char burnout should be considered.

关键词： coal blending combustion NOx emission numerical simulation utility boiler

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Numerical Study on Combustion and Heat Transfer Properties Under Oxy-fuel Condition in a 600MW Utility Boiler

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Energy Procedia 2017年 105卷 4009-4014页

作者： Debo Li Xuan Liu Chang’an Wang Kai Xu Qiongliang Zha Qiang Lv Yongxin Feng Jun Zhong Defu Che Electric Power Research Institute of Guangdong Power Grid Corporation Guangzhou 510080 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Oxy-fuel combustion is recognized as one of the most promising CO 2 capture technologies. Under oxy-fuel combustion, the concentrations of CO 2 and H 2 O are much higher, result in different temperature profiles and heat transfer properties. In this study, a modified computational fluid dynamics (CFD) model-was developed for a 600 MW tangentially-fired boiler. Different oxygen volume fractions and two flue gas recycle modes (dry recycle and wet recycle) were numerically investigated, focusing on the properties of combustion and heat transfer. The results indicate the peak temperature in the burner zone decreases in oxy-fuel combustion, because of the high heat capacity and chemical reactivity of CO 2 . Compared with air-fired combustion, similar total heat transfer rate in furnace can be achieved at 27.0% and 28.3% of oxygen volume fraction for wet and dry recycle. These findings indicate retrofitting an existing boiler with oxy-fuel combustion technology is entirely feasible.

关键词： oxy-fuel combustion WSGGM numerical simulation combustion properties heat transfer properties

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An overview of photocatalytic materials

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Journal of Materiomics 2017年第1期3卷 1-2页

作者： Shaohua Shen Coleman Kronawitter George Kiriakidis International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityShaanxi 710049China Department of Chemical Engineering University of CaliforniaDavisDavisCA 95616USA Institute of Electronic Structure and Laser Foundation for Research and Technology HellasP.O.Box 152771110 HeraklionGreece

Photocatalysis is an emerging technology that enables a wide variety of applications,including degradation of organics and dyes,antibacterial action,and fuel generation through water splitting and carbon dioxide *** inorganic semiconducting materials have been explored as photocatalysts,and the versatility of these materials and reactions has been expanded in recent *** the relationship between the physicochemical properties of photocatalytic materials and their performances as well as the fundamentals in catalytic processes is important to design and synthesis of photocatalytic materials.

关键词： materials. reduction. photocatalytic

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Gas and Liquid Flow Rate Measurement in Wet Gas Based on Differential Pressure Signals

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Jixie Gongcheng Xuebao/Journal of Mechanical engineering 2017年第24期53卷 55-62页

作者： Bai, Bofeng Zheng, Xuebo Qiu, Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Scientific Information Division Xinjiang Oilfield Company Karamay834000 China

The basic characteristics of differential pressure signals and the limitation of flow rate metering methods based on differential pressure are studied analytically and experimentally. Through the investigation into differential pressure signals of orifice plate and V-cone, it is found that the two-phase differential pressure is mainly caused by gas phase and is slightly affected by the liquid phase. In the case of low liquid hold up, the frictional pressure drop can be decreased due to the presence of the thin liquid film on the wall, resulting in that the two-phase differential pressure, pressure loss and pressure loss ratio decrease at first and then increase as the liquid hold up increases. The fluctuation of the differential pressure is stochastic, causing the fluctuation characteristic parameters, such as the standard deviation, having the properties of poor stability and repeatability. This makes it difficult to be applied to industrial wet gas metering. The error propagation analysis demonstrates that the prediction error of liquid phase flow rate is much larger than that of the gas phase, which is a universal phenomenon of metering methods based on over-reading correlations. Finally, we recommend that for wet gas with high gas void fraction, the liquid flow rate should be measured independently. The non-monotonicity of the pressure loss ratio needs to be concerned if it is chosen as the characteristic parameter. Parameters with poor repeatability, such as standard deviation, are not recommended for wet gas metering. © 2017 Journal of Mechanical engineering.

关键词： Flow rate

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Investigation on Correlations between Chemical Properties of High-alkali Solid Fuels

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Energy Procedia 2017年 142卷 1040-1044页

作者： Chang’an Wang Xin Zhu Jun Song Xuan Liu Qiang Lv Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China Ningxia Electric Power Research Institute Yinchuan 750002 China

The ash-related issues due to the high-alkali characteristic are still unresolved during utilization of biomass and Zhundong coal. Here, the correlations of several chemical properties of high-alkali solid fuels were investigated. The distributions of ash compositions in various biomass exhibit obvious diversity, while the distribution of K 2 O content within wheat and corn straws are the most scattered. The ash content in biomass shows a decrease tendency with the increase of carbon content. Zhundong coals generally have medium but close ash fusion points despite of quite different ash compositions sometimes.

关键词： high alkali chemical property Zhundong coal biomass ternary distribution

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Layered sphere-shaped TiO_2 capped with gold nanoparticles on structural defects and their catalysis of formaldehyde oxidation

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Journal of Environmental Sciences 2016年第1期28卷 77-85页

作者： Chunyan Ma Guanglong Pang Guangzhi He Yang Li Chi He Zhengping Hao Department of Environmental Nano-materials Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power EngineeringSchool of Energy and Power Engineering Xi'an Jiaotong University

We describe here a one-step method for the synthesis of Au/TiO2 nanosphere materials,which were formed by layered deposition of multiple anatase TiO2 *** Au nanoparticles were stabilized by structural defects in each TiO2 nanosheet,including crystal steps and edges,thereby fixing the Au-TiO2 perimeter *** transfer occurred along the gaps between these TiO2 nanosheet layers and in contact with catalytically active sites at the Au-TiO2 *** doped Au induced the formation of oxygen vacancies in the Au-TiO2 *** vacancies are essential for generating active oxygen species（-＊O^-） on the TiO2 surface and Ti^3＋ ions in bulk *** ions can then form Ti^3＋-O^--Ti^4＋species,which are known to enhance the catalytic activity of formaldehyde（HCHO） *** studies on structural and oxygen vacancy defects in Au/TiO2 samples provide a theoretical foundation for the catalytic mechanism of HCHO oxidation on oxide-supported Au materials.

关键词： Layered Au/TiO2 nanospheres Structural defects Oxygen vacancy defects Reaction mechanism Formaldehyde oxidation

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Integration of Organic Rankine Cycle with Lignite Flue Gas Pre-drying for Waste Heat and Water Recovery from Dryer Exhaust Gas: Thermodynamic and Economic Analysis

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Energy Procedia 2017年 105卷 1614-1621页

作者： Xiaoqu Han Sotirios Karellas Ming Liu Konstantinos Braimakis Weixiong Chen Junjie Yan Emmanuel Kakaras State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China Laboratory of Steam Boilers and Thermal Plants National Technical University of Athens Athens 15780 Greece

The flue gas pre-drying of lignite produces a moisture rich dryer exhaust gas which can be further cooled to recover the waste heat and water vapor. An environmental friendly power system is investigated in the present work, which integrates the lignite flue gas pre-drying system with an organic Rankine cycle (ORC) to utilize the waste heat to generate power and capture the condensed water. Simulation models of the integrated system are developed, incorporating thermodynamic and economic evaluation indicators. The optimal energy and exergy efficiencies of the ORC system are calculated to be 3.10% and 24.57%, respectively, for an evaporation temperature of 51 °C when R245fa is used as the working fluid. Accordingly, the ORC power output is 3.61 MW and the absolute plant efficiency improvement is 0.27% points. Moreover, 55.17% of the water vapor can be recovered. The economic performance significantly relies on the specific investment cost of ORC and the electricity selling price. Typically, the break-even points of the specific investment cost are 2300 €/kW and 3700 €/kW when electricity selling prices are 0.05 €/kWh and 0.08 €/kWh, respectively.

关键词： Lignite Flue gas pre-drying Waste heat recovery Organic Rankine cycle

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