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Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

Nuclear Science and Techniques 2009年第2期20卷 118-123页

作者： TIAN Wenxi SU Guanghui WANG Gaopeng QIU Suizheng XIAO Zejun State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi＇an Jiaotong University Xi＇an 710049 China National Key Laboratory of Bubble Physics ＆ Natural Circulation Nuclear Power Institute of China Chengdu 610041 China

The method of characteristic(MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System(PPFS) during the alternate startup *** motion of check valve disc was simulated using inertial valve *** parameters including the pressure oscillation,local flow velocity and slamming of the check valve disc *** been *** results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel *** induced maximum pressure vibration amplitude is up to 5.0 *** scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water *** has been numerically approved to be an effective approach.

关键词：止回阀建设部事件水锤泵给水系统启动过程压力振动瞬态参数

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CdS nanocrystallites sensitized ZnO nanorods with plasmon enhanced photoelectrochemical performance

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Chinese Chemical Letters 2019年第12期30卷 2363-2367页

作者： Li Cai Yuanchang Du Xiangjiu Guan Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering (MFPE) Xi’an Jiaotong University (XJTU)

A novel architecture of CdS/ZnO nanorods with plasmonic silver(Ag) nanoparticles deposited at the interface of ZnO nanorods and CdS nanocrystallites,was designed as a photoanode for solar hydrogen generation,with photocurrent density achieving 4.7 mA/cm^2 at 1.6 V(***),which is 8 and 1.7 times as high as those of pure ZnO and CdS/ZnO nanorod films,***,with optical absorption onset extended to^660 nm,CdS/Ag/ZnO nanorod film exhibits significantly increased incident photo-tocurrent efficiency(IPCE) in the whole optical absorption region,reaching 23.1% and 9.8% at 400 nm and500 nm,*** PEC enhancement can be attributed to the one-dimensional ZnO nanorod structure maintained for superior charge transfer,and the extended visible-light absorption of CdS ***,the incorporated plasmonic Ag nanoparticles could further promote the interfacial charge carrier transfer process and enhance the optical absorption ability,due to its excellent plasmon resonance effect.

关键词： ZnO nanorods Plasmonic Ag nanoparticles CdS nanocrystallites Photoelectrochemical water splitting Synergistic effect

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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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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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Experimental and Numerical Study on Co-combustion Behaviors and NO_(x) Emission Characteristics of Semi-coke and Coal in a Tangentially Fired Utility Boiler

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Journal of Thermal Science 2021年第4期30卷 1116-1131页

作者： WANG Chang’an FENG Qinqin JIN Liyan WANG Zhichao YAO Wei WANGPengqian DU Yongbo ZHANG Xilai YANG Zhongcan CHE Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Thermal Power Research Institute Co. LTD.Xi’an 710054China

The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery *** characteristic of low volatile results in poor combustion performance and high NO_(x) emission,and to co-fire with bituminous coal is a practical strategy to address this ***,the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently *** addition,the influences of secondary air arrangement,the boiler operation load,and the fuel type on co-combustion process are still unclear,which is urgent to be further *** the present study,experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO_(x) emission features of semi-coke and *** results demonstrated that the"out-furnace method"was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%,due to the limited combinations of the semi-coke injection *** was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the"in-furnace method"to improve the overall co-combustion *** critical value of the separated over fire air ratio in this study was 27.5%,over which a slight drop of carbon content in fly ash could come ***,the elevation in the proportion of separated over fire air gave rise to the significant decline of NO_(x) *** constricted secondary air arrangement was preferred to be employed due to the high boiler *** separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO_(x) emissions and the coking of *** the load reduction regulation method adopted in this study,the NO_(x) concentration first rose and then dropped,while the burnout ratio decreased obviously as the operation load was *** combinations of coa

关键词： semi-coke numerical simulation co-combustion NOx emission blending method

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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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Two-dimensional self-adapting fast Fourier transform algorithm for nanoparticle sizing by ultrafast image-based dynamic light scattering

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Particuology 2018年第6期16卷 74-84页

作者： Dechuan Zhang Xiaoshu Cai Wu Zhou Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Sdence and TechnologyShanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering (University of Shanghai for Sdence and Technology)Shanghai 200093China

In nanoparticle sizing using the ultrafast image-based dynamic light scattering (UIDLS)method,larger impurities and dark noise from the complementary metal-oxide-semiconductor (CMOS)detector affect measurement *** solve this problem,a two-dimensional self-adapting fast Fourier transform (2D-SAFFT)algorithm is proposed for *** light scattering images of nanoparticles are processed using 2D fast Fourier transforms,and a high-frequency threshold and a low-frequency threshold are then set using the self-adapting algorithm to eliminate the effects of the dark noise of the CMOS detector and the *** signals caused by the dark noise of the CMOS detector and the impurities are cut off using the high-frequency threshold and the low-frequency *** signals without the high- and low-frequency components are then processed again using an inverse Fourier transform to obtain new images without the dark noise and impurities *** mean diameters of the measured nanoparticles can be obtained from images obtained using *** standard latex nanoparticles (46,100, 203,508,994nm)and commercial nanoparticles (antimony-doped tin oxide,indium tin oxide,TWEEN- 80,nano-Fe,and nano-Al2O3)were measured using this new *** show that 2D-SAFFT can effectively eliminate the effects of dark noise from the CMOS detector and the impurities.

关键词： Dynamic light scattering Nanoparticle size Fast Fourier transform algorithm Spectrum segmentation

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Study on the heat and mass transfer characteristics of wet air in metal foam in the space station environment

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Applied Thermal engineering 2025年

作者： Guowei Zhu Liang Zhang Yujuan Xia Hantao Zhou School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China China National Institute of Standardization Beijing 100191 China

This paper has developed a novel dehumidification device for space station environment, which uses foam copper as the core, with a Stirling refrigerator providing cooling, heat pipes assisting in heat conduction and a siphon water guidance system employed to remove condensate. Experiments on dehumidifying wet air within the foam copper were then carried out under simulated microgravity dehumidification conditions. The experimental conditions included different inlet air temperatures, humidities, air velocities, and cold end temperatures of the Stirling refrigerator. The experimental research indicates that as the inlet air temperature rises from 20 °C to 30 °C, the mass transfer coefficient increases by 57.06 %, and the sensible heat coefficient rises by 10.62 %. When the air velocity increases from 0.4 m·s −1 to 1.4 m·s −1 , these two coefficients increase by 111.79 % and 170.83 %, respectively. In contrast, increasing the relative humidity from 50 % to 80 % results in a 34.09 % decrease in the sensible heat coefficient, while the mass transfer coefficient increases by 11.4 %. When the cold-end temperature rises from 8 °C to 13 °C, the sensible heat transfer and mass transfer coefficients increase by 9.63 % and 4.06 %, respectively. Based on this, a sensitivity analysis was conducted using the experimental data, and heat and mass transfer correlations were fitted. The mean standard deviations of the heat and mass transfer correlations are 3.74 % and 6.30 %, respectively, indicating a high degree of fitting accuracy. This work provides a new humidity control solution for future space station thermal management systems.

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The Performance Study on Hydrogen Production From Medium Temperature Methane Chemical Looping Steam Reforming Using Lithium-based Absorbent

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2025年第5期46卷 1401-1408页

作者： Wang, Xuyun Li, Yang Gai, Zhongrui Rao, Qiong Liu, Mingkai Pan, Ying School of Engineering Science University of Science and Technology of China Hefei230027 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Lithium silicate serves as a novel CO2 absorbent with moderate absorptionregeneration temperature range (500∼700◦C) and excellent cycling stability. In this study, Li2CO3 was selected as the precursor for the preparation of lithium silicate. Additionally, a eutectic co-doping method with potassium elements was employed to enhance its reactivity. Using extrusion-spheronization, we successfully produced absorbent particles with high mechanical strength and cycling stability. The effects of absorption-regeneration temperature, CO2 concentration and particle diameter on the performance of absorbent particles have been studied in detail. Furthermore, mixed with NiO oxygen carriers, sorption-enhanced chemical looping reforming (SE-CLR) experiments were conducted at the range of 500∼650◦C for hydrogen production and in situ CO2 capture factors such as reaction temperatures and oxygen carrier to absorbent mass ratios were then investigated The results showcase that at the optimal reaction temperature of 600◦C, the SE-CLR process effectively lowered the reaction temperature by 25◦C, achieving a 13% increase in methane conversion rate and hydrogen purity and CO2 capture rate above 90% were attained. © 2025 Science Press. All rights reserved.

关键词： Silicates

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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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