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Coupling Effect of Heat Transfer and flow Resistance in the Rifled Tube Water Wall of a Ultra-Supercritical CFB Boiler

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Journal of Thermal Science 2019年第5期28卷 1078-1088页

作者： LI Yaode YANG Dong OUYANG Shijie LIU Dan WANG Wenyu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China North China Electric Power Test and Research Institute Co. Ltd Tianjing 300000 China

The coupling factor is used in this study to characterise the combined effect of the heat transfer and resistance characteristics of a rifled tube. Boundary layer theory is utilised to investigate the relationship between the comprehensive coefficient and Reynolds number in two regions, namely, higher and lower than pseudo-critical enthalpy. Results indicate that mass flux exerts a decisive negative influence on the coupling effect, and the impacts of pressure and heat flux are weak. The overall effect decreases rapidly as the mass flux increases, but it increases in the area behind the quasi-critical enthalpy. The coupling effect is also affected by specific heat ratio, thermal acceleration and buoyancy. The correlations of heat transfer and friction resistance are deduced with high precision according to experimental data.

关键词： supercritical pressure heat transfer frictional resistance coupling effect

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Enhanced efficiency in Concentrated Parabolic Solar Collector(CPSC) with a porous absorber tube filled with metal nanoparticle suspension

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Green Energy & Environment 2018年第2期3卷 129-137页

作者： Mohammad Hatami Jiafeng Geng Dengwei Jing Mechanical Engineering Department Esfarayen University of Technology (EUT) International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

In this study, effects of different nanoparticles and porosity of absorber tube on the performance of a Concentrating Parabolic Solar Collector(CPSC) were investigated. A section of porous-filled absorber tube was modeled as a semi-circular cavity under the solar radiation which is filled by nanofluids and the governing equations were solved by FlexPDE numerical software. The effect of four physical parameters, nanoparticles type, nanoparticles volume fraction(φ), Darcy number(Da) and Rayleigh number(Ra), on the Nusselt number(Nu) was discussed. It turns out that Cu nanoparticle is the most suitable one for such solar collectors, compared to the commonly used Fe_3O_4, Al_2O_3, TiO_*** the increased addition of Cu nanoparticles all the parameters φ, Da and Ra shows a significant increase against the Nu, indicates the enhanced heat transfer in such cases. As a result, low concentration of Cu nanoparticle suspension combined with porous matrix was supposed to be beneficial for the performance enhancement of concentrating parabolic solar collector.

关键词： Concentrating parabolic solar collector Porous absorber tube Nanofluid Nusselt number Finite Element Method

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The Behavior and Characteristics of the InterfacialWaves in Gas-Liquid Two-Phase Separated flowThrough Downward Inclined Rectangular Channel

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Journal of Thermal Science 1998年第1期7卷 29-36页

作者： Guangjun Li Lienjin Guo Xuejun Chen(National laboratory of multiphase flow in power engineering,Xi’an Jiaotong University,Xi’an,710049,China) National Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

An experimental investigation on the behavior and characteristics of interfacial waves in downward inclined rectangular channel was conducted. The interfacial waves were traced and measured by us-ing conductance technique. The wav patterns were distinguished and defined. The characteristics of the interfacial waves, such as time-averaged film thickness, wave height, wave propagation speed,wavlength and wave frequency, were systematically examined in terms of gas and liquid superficial volumetric fiuxes. The effect of the inclination and flow channel geometry of the test section on the interfacial wav was also investigated.

关键词： liquid film thickness gas-liquid two-phase flow interfacial waves experiment study

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Experimental Study of Drop Deformation and Breakup in Simple Shear flows

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Chinese Journal of Chemical engineering 2007年第1期15卷 1-5页

作者：林长志郭烈锦 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

The experimental results of the deformation and breakup of a single drop immersed in a Newtonian liq-uid and subjected to a constant shear rate which generated by counter rotating Couette apparatus were presented in this paper. From experimental observations, the breakup occurred by three mechanisms, namely, necking, end pinching, and capillary instability. Quantitative results for the deformation and breakup of drop are presented. The maximum diameter and Sauter mean diameter of daughter drops and capillary thread radius are linearly related to the inverse shear rate and independent of the initial drop size, the dimensionless wavelength which is the wave-length divided by the thread width at breakup is independent of the shear rate and initial drop size, and the deforma-tion of threads follows a pseudo-affine deformation for Cai/Cac larger than 2.

关键词： drop deformation breakup Couette shear flow

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Experimental study on flow excursion instability of supercritical hydrocarbon fuel in scramjet regenerative cooling parallel channels

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Chinese Journal of Aeronautics 2023年第1期36卷 201-215页

作者： Xiaoyong LIU Zhuqiang YANG Ruipu MIAO Feng LIU Shujun ZHAO Qincheng BI Beijing Power Machinery Research Institute Beijing 100074China Liaoning Key Laboratory of Complex Energy Conversion and Utilization School of Energy and Power EngineeringDalian University of TechnologyDalian 116024China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

flow instability of supercritical hydrocarbon fuel is a crucial issue in scramjet regenerative cooling structure. In this study, flow excursion instability and flow distribution in parallel tubes were experimentally studied for supercritical fluids. Two types of flow excursion occur in a single tube. Type Ⅰ and Type Ⅱ excursions, and they are corresponding to decreasing and increasing flow rate respectively. They can trigger flow maldistribution between parallel tubes and the hysteresis phenomenon of flow distribution. The effects of system parameters, including inlet temperature,system pressure, and heat flux, on flow distribution were analyzed. In addition, the relationship between flow excursion and the pseudo-critical interval proposed in the literature was established according to the heated tube outlet temperature at the onset of flow instability. Finally, the flow excursion instability boundary was obtained using two dimensionless parameters. These experimental results can provide helpful insight on the mechanism of Scramjet regenerative cooling.

关键词： flow distribution Ledinegg instability Onset of flow excursion Parallel channels Regenerative cooling Scramjet Supercritical flow

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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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Acoustic Wave Prediction in flowing Steam-Water Two-Phase Mixture

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Journal of Thermal Science 1994年第3期3卷 147-154页

作者： Xu Jinliang Chen Tingkuan (State key laboratory of multiphase flow in power engineering, Xi’an Jiaotong University, Xi’an 710049,China) 1. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 710049 Xi’an China

The transient two-fluid model has been used to develop a general relation for acoustic waves. The analysis is valid in principle over the whole void fraction region. flow pattern transitions from one flow regime to the other are assumed to occur at certain void fractions. Different correlations are used to calculate the interfacial area and interfacial drag force per unit mixture volume for bubbly flow,slug flow and annular flow respectively. The Vapour-liquid interphase heat flux is derived from the one dimensional Fourier heat conduction equation to evaluate the interphase evaporation or condensatior *** on the present theory, a program has been carried out. Calculations are performed for pressure from 0.07 MPa to 16.0 MPa, void fractions from 0.0 to 1.0. The predicted sound speeds are compare with some experimental data for low pressures, good agreement has been achieved between sound speed predictions and experimental data.

关键词： two-phase flow perturbation wave sound speed

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Fast design of catalyst layer with optimal electrical-thermal-water performance for proton exchange membrane fuel cells

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Journal of Energy Chemistry 2023年第6期81卷 642-655,I0014页

作者： Jing Yao Yuchen Yang Xiongpo Hou Yikun Yang Fusheng Yang Zhen Wu Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina

The catalyst layer(CL)is the core component in determining the electrical-thermal-water performance and cost of proton exchange membrane fuel cell(PEMFC).Systemic analysis and rapid prediction tools are required to improve the design efficiency of *** this study,a 3D multi-phase model integrated with the multi-level agglomerate model for CL is developed to describe the heat and mass transfer processes inside ***,a research framework combining the response surface method(RSM)and artificial neural network(ANN)model is proposed to conduct a quantitative analysis,and further a rapid and accurate *** the help of this research framework,the effects of CL composition on the electrical-thermal-water performance of PEMFC are *** results show that the mass of platinum,the mass of carbon,and the volume fraction of dry ionomer has a significant impact on the electrical-thermal-water *** the selected points,the sensitivity of the decision variables is ranked:volume fraction of dry ionomer>mass of platinum>mass of carbon>agglomerate *** particular,the sensitivity of the volume fraction of dry ionomer is over 50%at these ***,the comparison results show that the ANN model could implement a more rapid and accurate prediction than the RSM model based on the same sample *** in-depth study is beneficial to provide feasible guidance for high-performance CL design.

关键词： Catalyst layer Agglomerate model Sensitivity analysis Response surface Artificial neural network

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Towards efficient solar-to-hydrogen conversion: Fundamentals and recent progress in copper-based chalcogenide photocathodes

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Nanophotonics 2016年第4期5卷 468-491页

作者： Chen, Yubin Feng, Xiaoyang Liu, Maochang Su, Jinzhan Shen, Shaohua International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Shaanxi710049 China

Photoelectrochemical (PEC) water splitting for hydrogen generation has been considered as a promising route to convert and store solar energy into chemical fuels. In terms of its large-scale application, seeking semiconductor photoelectrodes with high efficiency and good stability should be essential. Although an enormous number of materials have been explored for solar water splitting in the last several decades, challenges still remain for the practical application. P-type copper-based chalcogenides, such as Cu(In, Ga)Se2 and Cu2ZnSnS4, have shown impressive performance in photovoltaics due to narrow bandgaps, high absorption coefficients, and good carrier transport properties. The obtained high efficiencies in photovoltaics have promoted the utilization of these materials into the field of PEC water splitting. A comprehensive review on copper-based chalcogenides for solar-to-hydrogen conversion would help advance the research in this expanding area. This review will cover the physicochemical properties of copper-based chalco-genides, developments of various photocathodes, strategies to enhance the PEC activity and stability, introductions of tandem PEC cells, and finally, prospects on their potential for the practical solar-to-hydrogen conversion. We believe this review article can provide some insights of fundamentals and applications of copper-based chalco-genide thin films for PEC water splitting. © 2016 Y. Chen et al.

关键词： Photocathodes

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Numerical investigation and analysis of heat transfer enhancement in channel by longitudinal vortex based on field synergy principle

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中国高等学校学术文摘·能源与动力工程 2008年第1期2卷 71-78页

作者： Wenquan TAO Junmei WU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Environment and Chemical Engineering Xi'an Polytechnic University Xi'an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

3-D numerical simulations were presented for laminar flow and heat transfer characteristics in a rectangular channel with vortex generators. The effects of Reynolds number (from 800 to 3 000), the attack angle of vortex generator (from 15° to 90°) and the shape of vortex generator were examined. The numerical results were analyzed based on the field synergy principle. It is found that the inherent mechanism of the heat transfer enhancement by longitudinal vortex can be explained by the field synergy principle, that is, the second flow generated by vortex generators results in the reduction of the intersection angle between the velocity and fluid temperature gradient. The longitudinal vortex improves the field synergy of the large downstream region of longitudinal vortex generator (LVG) and the region near (LVG); however, transverse vortex only improves the syn-ergy of the region near vortex generator. Thus, longitudinal vortex can enhance the integral heat transfer of the flow field, while transverse vortex can only enhance the local heat transfer. The synergy angle decreases with the increase of Reynolds number for the channel with LVG to differ from the result obtained from the plain channel, and the triangle winglet performs better than the rectanglar one under the same surface area condition.

关键词： longitudinal vortex heat transfer enhancement field synergy principle

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