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Development of Liquid Slug Length in Gas-Liquid Slug flow along Horizontal Pipeline: Experiment and Simulation

Chinese Journal of Chemical engineering 2006年第5期14卷 626-633页

作者：王鑫郭烈锦张西民 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 liquid slug length distribution is crucial for designing the downstream processing system with mul-tiphase pipeline. Experiments were conducted in a 133m long horizontal test loop. The measurements were per-formed by conductivity probes to determine the liquid slug length distribution. The data covered both the slug and plug flow regimes. From experimental results, the mean liquid slug lengths were relatively insensitive to gas and liquid flow rates in the higher mixture velocity range. But in the lower mixture velocity range, the mean liquid slug length decreased and then increased with mixture velocity. It shows that the development length of slug flow was longer than x/D=1157. A slug tracking model was adapted to study the evolution of liquid slug length distribution in a horizontal pipeline. In the present model, the wake effect of elongated bubble and the pressure drop due to accel-eration are taken into account and random slug lengths are introduced at the entrance. The results of the model are compared with the measured slug length distributions of slug flow regime. It shows that the predicted mean and maximum slug lengths are in agreement with the experimental data at x/D=1157 and the form of the slug length distributions is also predicted well by the model.

关键词： two-phase flow slug flow liquid slug length slug tracking

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Formic acid dehydrogenation reaction on high-performance Pd_(x)Au_(1−x) alloy nanoparticles prepared by the eco-friendly slow synthesis methodology

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Frontiers in Energy 2023年第6期17卷 751-762页

作者： Yibo GAO Erjiang HU Bo HUANG Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Institute of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 712000China

Dehydrogenation of formic acid (FA) is considered to be an effective solution for efficient storage and transport of hydrogen. For decades, highly effective catalysts for this purpose have been widely investigated, but numerous challenges remain. Herein, the Pd_(x)Au_(1−x) (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1) alloys over the whole composition range were successfully prepared and used to catalyze FA hydrogen production efficiently near room temperature. Small PdAu nanoparticles (5–10 nm) were well-dispersed and supported on the activated carbon to form PdAu solid solution alloys via the eco-friendly slow synthesis methodology. The physicochemical properties of the PdAu alloys were comprehensively studied by utilizing various measurement methods, such as X-ray diffraction (XRD), N2 adsorption–desorption, high angle annular dark field-scanning transmission electron microscope (HAADF-STEM), X-ray photoelectrons spectroscopy (XPS). Notably, owing to the strong metal-support interaction (SMSI) and electron transfer between active metal Au and Pd, the Pd0.5Au0.5 obtained exhibits a turnover frequency (TOF) value of up to 1648 h−1 (313 K, nPd+Au/nFA = 0.01, nHCOOH/nHCOONa = 1:3) with a high activity, selectivity, and reusability in the FA dehydrogenation.

关键词： FA dehydrogenation face-centred cubic structures PdAu solid solution alloy nanoparticles slow synthesis methodology SMSI effect

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First law-based thermodynamic analysis on Kalina cycle

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 145-151页

作者： Ying ZHANG Maogang HE Zhen JIA Xun LIU State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Based on the first law of thermodynamics,and adopting the Peng-Robinson equation (P-R equation) as the basic equation for the properties of ammonia-water mixtures,a thermodynamic analysis on a single-stage distillation Kalina cycle is presented.A program to calculate the thermodynamic properties of ammoniawater mixtures,and that for calculating the performance of Kalina cycles,were developed,with which the heatwork conversion particulars of Kalina cycles were theoretically *** influences on the cycle performance of key parameters,such as the pressure and temperature at the inlet of the turbine,the back pressure of the turbine,the concentration of the working solution,the concentration of the basic solution and the cycle multiplication ratio,were analyzed.

关键词： engineering thermophysics Kalina cycle ammonia-water mixtures P-R equation thermodynamic property

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Photochemical Systems for Solar‑to‑Fuel Production

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Electrochemical Energy Reviews 2022年第3期5卷 137-177页

作者： Ya Liu Feng Wang Zihao Jiao Shengjie Bai Haoran Qiu Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

The photochemical system,which utilizes only solar energy and H_(2)O/CO_(2) to produce hydrogen/carbon-based fuels,is considered a promising approach to reduce CO_(2) emissions and achieve the goal of carbon *** date,numerous photochemical systems have been developed to obtain a viable solar-to-fuel production system with sufficient energy ***,more effort is still needed to meet the requirements of industrial *** this review,we systematically discuss a typical photochemical system for solar-to-fuel production,from classical theories and fundamental mechanisms to raw material selection,reaction condition optimization,and unit device/system advancement,from the viewpoint of ordered energy ***-of-the-art photochemical systems,including photocatalytic,photovoltaic-electrochemical,photoelectrochemical,solar thermochemical,and other emerging systems,are *** highlight the existing bottlenecks and discuss the developing trend of this ***,optimization strategies and new opportunities are proposed to enhance photochemical systems with higher energy efficiency.

关键词： Solar energy Photochemical Hydrogen Carbon-based fuels

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A MODEL FOR LIQUID SLUG LENGTH DISTRIBUTION IN VERTICAL GAS-LIQUID SLUG flow

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Journal of Hydrodynamics 2009年第4期21卷 491-498页

作者： XIA Guo-dong CUI Zhen-zhen LIU Qing ZHOU Fang-de HU Ming-sheng College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong University Xi＇an 710049 China

The slug length and the trailing Taylor bubble velocity in an upward vertical slug flow were measured by using the optical probes and the EKTAPRO 1000 high speed motion analyzer. The correlation between the trailing bubble velocity and the length of liquid slug ahead of that bubble is derived from the experimental data. Based on this correlation as well as the bubble overtaking mechanism, a model for the slug length distribution at any designated locations along the pipe is proposed. The predicted results are in agreement with the experimental data.

关键词： gas-liquid two-phase flow slug flow Taylor bubble liquid slug

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Modeling and prediction of ultrasonic attenuations in liquid-solid dispersions containing mixed particles with Monte Carlo method

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Particuology 2019年第2期17卷 84-91页

作者： Jianfei Gu Fengxian Fan Yunsi Li Huinan Yang Mingxu Su Xiaoshu Cai Institute of Particle and Two-Phase Flow Measurement/Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China

We develop a theoretical model for predicting the ultrasonic attenuation in the liquid-solid system containing mixed particles. The ultrasonic attenuation coefficient is obtained by counting the number of phonons that reach the receiver. Using the Monte Carlo method (MCM), numerical simulations were performed to predict the ultrasonic attenuations with not only a single particle type but also monodisperse and polydisperse mixed particles. The simulation results for the systems with a single particle type were compared with various standard models. The results show that they agree well at relatively low particle volume concentrations (within 10%). For systems with mixed particles, the particle volume concentrati on was found to in crease to around 10%, and the variation of the ultrasonic attenuation agai nst the mixing ratio yields a nonlinear trend. Moreover, the ultrasonic attenuation is significantly affected by particle properties. The numerical results also show that both the particle type and particle size distribution should be carefully taken into account in the dispersions with polydisperse mixed particles, where the MCM can give a more direct description of the physics of sound propagation compared with the conventional models.

关键词： Ultrasound Ultrasonic attenuation Monte Carlo method Particle size measurement

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Estimation of thermodynamic properties of the ternary molten salt system, LiF-NaF-BeF2, by the modified Peng-Robinson equation

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中国高等学校学术文摘·能源与动力工程 2007年第2期1卷 174-180页

作者： ZHANG Dalin QIU Suizheng SU Guanghui JIA Dounan School of Energy and Power Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The molten salt reactor (MSR), which is one of the generation IV reactors, can meet the demand of transmutation and breeding. The thermodynamic properties of the molten salt system like LiF-NaF-BeF2 influence the design and construction of the fuel salt and coolant in the MSR for the new generation. In this paper, the equation of state of the ternary system 15%LiF-58%NaF-27%BeF2, over the temperature range from 873.15 to 1 073.15 K at one atmosphere pressure, is described using a modified Peng-Robinson (PR) equation. The densities of the ternary system and its components are estimated by this equation directly, and compared with the experimental data. Based on the equation of state, the other thermodynamic properties such as the enthalpy, entropyand heat capacity at constant pressure are estimated by the residual function method and the fugacity coefficient method respectively. The densities calculated by PR equation are highly in agr eement with the experimental data, and the enthalpy, entropy and heat capacity evaluated by the two different methods are consistent with each other. It can be concluded that the modified PR equation can be applied to evaluate the density of the molten salt system, and it is recommended that it be used as the basis to estimate the enthalpy, entropy and heat capacity of the molten salt system.

关键词： thermodynamic properties molten salt LiF-NaF-BeF2 Peng-Robinson equation

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Effect of ignition timing and hydrogen fraction on combustion and emission characteristics of natural gas direct-injection engine

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 194-201页

作者： Jinhua WANG Zuohua HUANG Bing LIU Ke ZENG Jinrong YU Deming JIANG State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

An experimental study on the combustion and emission characteristics of a direct-injection spark-ignited engine fueled with natural gas/hydrogen blends under various ignition timings was *** results show that ignition timing has a significant influence on engine performance,combustion and *** interval between the end of fuel injection and ignition timing is a very important parameter for direct-injection natural gas *** turbulent flow in the combustion chamber generated by the fuel jet remains high and relative strong mixture stratification is introduced when decreasing the angle interval between the end of fuel injection and ignition timing giving fast burning rates and high thermal *** maximum cylinder gas pressure,maximum mean gas temperature,maximum rate of pressure rise and maximum heat release rate increase with the advancing of ignition ***,these parameters do not vary much with hydrogen addition under specific ignition timing indicating that a small hydrogen fraction addition of less than 20% in the present experiment has little influence on combustion parameters under specific ignition *** exhaust HC emission decreases while the exhaust CO2 concentration increases with the advancing of ignition *** the lean combustion condition,the exhaust CO does not vary much with ignition *** the same ignition timing,the exhaust HC decreases with hydrogen addition while the exhaust CO and CO2 do not vary much with hydrogen *** exhaust NOx increases with the advancing of' ignition timing and the behavior tends to be more obvious at large ignition advance *** brake mean effective pressure and the effective thermal efficiency of natural gas/hydrogen mixture combustion increase compared with those of natural gas combustion when the hydrogen fraction is over 10%.

关键词： natural gas hydrogen ignition timing combustion emissions direct-injection

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Bubble Behavior and Heat Transfer of Nucleate Pool Boiling on Micro-Pin-Finned Surface in Microgravity

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Chinese Physics Letters 2011年第1期28卷 160-163页

作者： WEI Jin-Jia XUE Yan-Fang ZHAO Jian-Fu LI Jing State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi'an 710049 Key Laboratory of Microgravity (National Microgravity Laboratory)/CAS Institute of Mechanics Chinese Academy of Sciences Heijing 100190

Nucleate pool boiling on micro-pin-finned surface structure is proposed for efficiently cooling electronic compo- nents with high heat flux in microgravity, and was verified by experiments performed utilizing the drop tower Beijing. Micro-pin-fins with tile dimensions of 50 × （30 μm2 （thickness × height） and the space of 50 μm were fabricated on the chip surface by the dry etching technique. FC-72 was used as the working fluid. Nucleate pool boiling of FC-72 on a smooth surface was also tested for comparison. Unlike much obvious deterioration of heat transfer of nucleate pool boiling on the smooth surface in microgravity, constant heater surface temperature of nucleate pool boiling for the micro-pin-finned surface was observed, even though a large coalesced bubble completely covered the surface under microgravity condition. The performance of high efficient heat transfer on micro-pin-finned surface is independent of the gravity, which stems from the sufficient supply of fresh liquid to the heater surface due to the capillary forces.

关键词： Fluid dynamics Surfaces, interfaces and thin films

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Study on Thermo-Conductive Plastic Finned TubeRadiators

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Journal of Thermal Science 1997年第1期6卷 21-26页

作者： Yang Jiehui Cheng Lixin(Chemical engineering School, state key laboratory of multiphase flow in power engineering, Xi’anJiaotong University, Xi’an 710049, China) Chemical Engineering School State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

This paper discusses thermo-conductive plastic finned tube radiators used in water saving type powerstations. First, the development of thermo-conductive plastics is introduced. Second, in order todetermine the rational geometric dimensions of thermo-conductive plastic finned tubes, an objectivefunction which takes the minimum volume of the consumed material for making finned tubes as an ob-ject is introduced. On the basis of the function, the economy comparison between thermaxonductiveplastic finned tubes and metal finned tubes is conducted.

关键词： air-cooling radiator thermo-conductive plastic finned tube optimum geometric parameters economy comparison

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