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作者： Deng, Zhian Luo, Yushan Wang, Haijun Chen, Tingkuan State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University No. 28 Xianning Road Xian China Xi'An Shiyou University 2 Dianzi Road Xian 710065 China

Under certain operating conditions, two-phase flow oscillations can occur and induce undesired problems such as system control, vibration, tube burn-out, etc. Therefore, it is essential to avoid and control two-phase flow instabilities when designing and operating equipments that are susceptible to such effects. The authors conducted an experimental study of vapor-liquid two-phase flow instabilities in vertical parallel tubes for a high-pressure vapor-water loop. Two types of vertical parallel rifled tubes (31.8 mm OD × 6 mm thickness, and 28.6 mm × 5.8 mm) were used as the tube sections. During experimentation, pressure-drop and density-wave type oscillations appeared, and the influence of the inlet pressure, mass flow rate, and inlet subcooling on the two-phase flow instability in both types of vertical parallel-connected tubes was studied. The results showed that with an increase in the inlet pressure and mass flow rate, the boundary thermal load of the pressure-drop and density-wave oscillations increased. As the inlet pressure increased, so the boundary quality of the pressure-drop and density-wave oscillations occurring in both types of the rifled tubes also increased. Experiments showed that under the same operating conditions, the stability of the 31.8 × 6 mm rifled tube is better than the 28.6 × 5.8 mm rifled tube. For the 31.8 × 6 mm rifled tube, the occurrence of the boundary quality of the pressure-drop type oscillation increased with the increasing mass flow rate. However, for the 28.6 × 5.8 mm rifled tube, the occurrence of the boundary quality of the pressure-drop oscillation first increased and then decreased with an increasing mass flow. © 201. Curtin University of Technology and John Wiley & Sons, Ltd.

关键词： Pressure drop

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Study on the Radiation Distribution in A Fluidized Tubular Reactor for Heterogeneous Photocatalytic Hydrogen Production

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Procedia Environmental Sciences 2012年 12卷 285-292页

作者： Zhao Liang Fan Liangliang Jing Dengwei Liu Wenxu Cao Fei Zhu Xule Yang Junyin Zhang Hailong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an P.R.China

Radiation distribution study is of importance for the design and the optimization of fluidized photocatalytic tubular reactor which has been developed for photocatalytic hydrogen production under direct solar light. In the present study, the radiation distribution in such reactor was successfully simulated by adopting Monte Carlo method and the six-flux radiation absorption-scattering models. Both the incident angles of light around the reactor and the concentration distribution of photocatalyst were taken into account. Our analysis indicates that the angles and the intensity of the incident rays significantly affect the radiation distribution. Moreover, it was also found that the equilibrium radiation distribution has a close relationship with the density distribution of the photocatalysts. The simulated results are expected to be helpful for obtaining the optimal operating parameters for solar photocatalytic hydrogen production.

关键词： Radiation distribution Fluidized tubular reactor Nanometer catalyst Compound parabolic concentrators

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Experimental study on condensation heat transfer of ethanol-water mixtures on a vertical mini-tube

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AIP Conference Proceedings 2012年第1期1428卷 35-42页

作者： XiPing Chen JunJie Yan RongHai Huang JiPing Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University Xi'an City 710049 China

Experiments were carried out to investigate condensation of ethanol-water vapor mixtures on a vertical mini-tube with outer diameter of 1.032mm. The length, inter diameter of the tube was 1.0mm, 0.727mm, respectively. The tests were performed at a wide range of ethanol concentrations (Cv=0%, 1., 2%,5%) and varied velocity of vapor (Uv=2m/s, 4m/s, 6m/s) and pressure (Pv=31.2kPa, 47.4kPa, 84.5kPa). With the change of the vapor-to-surface temperature difference, the heat transfer coefficients revealed nonlinear characteristics with the peak values under all ethanol mass fractions of vapor. The heat transfer coefficients decreased with increasing ethanol mass fraction of vapor.

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Surfactant’s Effect on the Photoactivity of Fe-doped TiO2

Surfactant’s Effect on the Photoactivity of Fe-doped TiO2

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中国材料大会201.

作者： Qingyun Chen Chao Xue Xianglin Li Yunhai Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University

ISBN: (纸本)9783037856062

Ti(OC4H9)4 was used as the Ti precursor and titanium dioxide (TiO2 ) was prepared by sol-gel method. During the preparation process, Fe3+ was doped and different surfactants, such as SDS, PEG, CTAB, were added to improve the photocatalytic activity of TiO2 . The effect of the different type of surfactants on the structure of Fe-doped TiO2 was discussed. The photocatalysts were characterized by thermogravimetric thermal analysis, X-ray diffraction, scanning electron microscopy and UV-Vis spectrophotometer. The red shift of the absorption edge of the Fe-doped TiO2 prepared by using different surfactants was observed. Methyl orange (MO) solution was degraded under sunlight irradiation to evaluate the photocatalytic performance. The results indicated that the photocatalyst prepared with PEG addition had the highest activity and MO degradation ratio could reach 90% after 4 hours irradiation with the best photocatalyst.

关键词： Sol-gel, Iron-doped titania, Photocatalytic activity, Surfactant.

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Experimental Study on Condensation heat transfer of Ethanol-Water Mixtures on a Vertical Mini-tube

Experimental Study on Condensation heat transfer of Ethanol-...

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The 7th International Symposium on Measurement Techniques for multiphase {1.s

作者： Chen XiPing Yan JunJie Huang RongHai Liu JiPing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiao tong University

Experiments were carried out to investigate condensation of ethanol-water vapor mixtures on a vertical mini-tube with outer diameter of 1.032 *** length,inter diameter of the tube was 1.0 mm,0.727 mm,*** tests were performed at a wide range of ethanol concentrations(Cv=0%,1.,2%,5%) and varied velocity of vapor(Uv=2m/s,4m/s,6m/s) and pressure(Pv=31.2kPa,47.4kPa,84.5kPa).With the change of the vapor-to-surface temperature difference,the heat transfer coefficients revealed nonlinear characteristics with the peak values under all ethanol mass fractions of *** heat transfer coefficients decreased with increasing ethanol mass fraction of vapor.

关键词： Condensation Drop Heat transfer mini-tube

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Orientation-Singularity Representation and Orientation-Capability Computation of a Special Class of the Gough-Stewart Parallel Mechanisms Using Unit Quaternion

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Chinese Journal of Mechanical engineering 2012年第6期25卷 1096-1104页

作者： LI Baokun1. 2, CAO Yi1. 3, *, ZHANG Qiuju1. and HUANG Zhen4 1.School of Mechanical engineering, Jiangnan University, Wuxi 21.1.2, China 2 School of Mechanical engineering, Anhui University of Science and Technology, Huainan 232001. China 3 state key laboratory of Fluid power Transmission and Control, Hangzhou 31.027, China 4 Robotics Research Center, Yanshan University, Qinhuangdao 066004, China 1. School of Mechanical Engineering Jiangnan University Wuxi 214122 China 2. School of Mechanical Engineering Anhui University of Science and Technology Huainan 232001 China 3. State Key Laboratory of Fluid Power Transmission and Control Hangzhou 310027 China 4. Robotics Research Center Yanshan University Qinhuangdao 066004 China

Singular configuration seriously affects the performance of the Gough-Stewart parallel mechanism and has attracted many researchers’ attentions. However, most of existing topics often focus on the position-singularity of the mechanism for a constant-orientation, but few reports research the orientation-singularity for a given position. In order to investigate the orientation-singularity of the Gough-Stewart parallel mechanisms with two dissimilar semi-regular hexagonal platforms for a given position, after constructing the discrimination matrix of the singular configuration of the mechanism and computing the determinant of this matrix by using unit quaternion as the orientation parameters which can avoid the singularities in parameterization, a general symbolic expression representing the three-dimensional orientation-singularity locus for a given position is obtained and the three-dimensional view of the orientation-singularity locus is further described. The orientation-singularity-free void exists inside the orientation-singularity locus, but the shape of the orientation-singularity-free void is irregular and inconvenient for the design of the mechanism. The minimal inscribed sphere of the three-dimensional orientation-singularity locus namely the orientation-singularity-free ball is described. The radius of the ball orientation-capability is used as the measurement for the orientation-singularity-free void size. A new efficient algorithm is proposed for the computation of the orientation-capability. Finally, the influences of the geometry parameters and the different positions of the mechanism on the orientation-capability are discussed. A new method of the singularity analysis of the Gough-Stewart parallel mechanism is advanced based on the unit quaternion, and the research finds have important referential value for the configuration parameters optimization of this class of the parallel mechanisms with the goal of having the maximal singularity-free zone.

关键词： parallel mechanism unit quaternion orientation-singularity orientation-singularity-free void orientation-capability

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A Comprehensive Performance Evaluation Index for Metal Hydrides Reactor

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Energy Procedia 2012年 29卷 421-430页

作者： Xiangyu Meng Zewei Bao Zhen Wu Fusheng Yang Zaoxiao Zhang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering Mechanics Tsinghua University Beijing 100084 PR China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 PR China

A comprehensive performance evaluation index that reflects the heat transfer capacity of the metal hydrides reactor was introduced, and some advantages of this index were discussed. A mathematical model of hydrogen adsorption and desorption was set up, and the validity of the model was confirmed by experimental data reported in literatures. Numerical simulations about working processes of two types of classical reactors (tubular and disc reactor) were performed. The results of comparative study show that the new index can be used in a quantitative evaluation of the reactor performance, and it is more reasonable than traditional ones.

关键词： Index Performance Reactor Metal hydrides Heat transfer

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Validation analysis of different mass transfer formula in single droplet evaporation model

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Huagong Xuebao/CIESC Journal 2012年第6期63卷 1704-1708页

作者： Xin, Juanjuan Zhou, Zhifu Xin, Hui Chen, Bin Wang, Guoxiang Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China Department of Mechanical Engineering University of Akron Akron OH44325 United States

Droplet evaporation is one of the important physical processes in liquid spray. Various models have been formulated in literature to compute the mass flow rate of droplet evaporation. It is found that all these models can be written in a single formulation, with various models represented by different expressions in the driving force HM, which can be classified into three kinds, namely, classical model, mass analogy model and drift-flux model. In this paper, we perform an analysis of the assumptions involved in the derivation of the three kinds of models, and find that the drift-flux model, which takes into account the effects of Stefan flow and corrective mass transfer, is the correct expression, while the classical model ignores Stefan flow effect and the mass analogy model ignores transient effect. Then the influence of mass driving force HM on droplet evaporation is analyzed, and it is concluded that both the classical model and the mass analogy model underestimate the effect of evaporation especially at high evaporate rates.

关键词： Mass transfer

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Rapid solidification process of a water droplet due to depressurization

Rapid solidification process of a water droplet due to depre...

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第七届天地应用两相系统国际研讨会

作者： Lu Liu Qincheng Bi Guoxiang Wang Department of Power Engineering North China Electric Power University071003 BaodingChina State Key Laboratory of Multiphase FlowXi’an Jiaotong University710049 Xi’anChina State Key Laboratory of Multiphase Flow Xi’an Jiaotong University710049 Xi’anChina

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Spray, ignition and combustion characteristics of biodiesel and diesel fuels injected by micro-hole nozzle under ultra-high injection pressure

Spray, ignition and combustion characteristics of biodiesel ...

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8th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 201.

作者： Kuti, Olawole Abiola Zhu, Jingyu Nishida, Keiya Wang, Xiangang Huang, Zuohua Department of Mechanical Engineering Federal University of Technology PMB 704 Akure Ondo State Nigeria Department of Mechanical System Engineering University of Hiroshima 1-4-1 Kagamiyama Higashi-Hiroshima 739-8527 Japan Changan Automobile Corporation No. 199 Wuhong Road Yubei District Chonqing China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The spray and combustion characteristics of biodiesel (BDF) and diesel fuels injected by a micro-hole nozzle of 0.08 mm diameter under increasing injection pressure up to ultra-high value of 300 MPa were investigated in this research. The LIF-PIV (Laser Induced Fluorescence- Particle Image Velocimetry) technique was used to investigate the spray and entrained gas characteristics of the fuels while the OH chemiluminescence and two color techniques were utilized to study the ignition and combustion characteristics of the spray flames. From the research it was observed that at all injection pressures, due to inferior atomization processes, the normal velocity and total mass of the entrained gas by BDF was less compared to diesel. As a result of higher cetane number the BDF's flame ignition delay was shorter compared to diesel. The ratio of the mass flow rate of gas entrained to mass flow rate of injected fuel by BDF was less compared to diesel. Oxygen content in the BDF played a greater role in soot reduction as against the gas entrained. Copyright © 201. by the Japan Society of Mechanical Engineers.

关键词： Biodiesel

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