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In-line imaging measurements of particle size,velocity and concentration in a particulate two-phase flow

Particuology 2014年第2期12卷 106-113页

作者： Xiaozhen Chen Wu Zhou Xiaoshu Cai Mingxu Su Hailong Liu Institute of Particle and Two-phase Flow Measurement University of Shanghai for Science and Technology

A novel method is developed for in-line measurements of particle size, velocity and concentration in a dilute, particulate two-phase flow based on trajectory image processing. The measurement system consists of a common industrial CCD camera, an inexpensive LED light and a telecentric lens. In this work, the image pre-processing steps include stitching, illumination correction, binarization, denoising, and the elimination of unreal and defocused particles. A top-hat transformation is found to be very effective for the binarization of images with non-uniform background illumination. particle trajectories measured within a certain exposure time are used to directly obtain particle size and velocity. The particle concentration is calculated by using the statistics of recognized particles within the field of view. We validate our method by analyzing experiments in a gas-droplet cyclone separator. This in-line image processing method can significantly reduce the measurement cost and avoid the data inversion process involved in the light scattering method.

关键词： In-line measurements particle trajectory Image processing Multi-parameters

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Fast nanoparticle sizing by image dynamic light scattering

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Particuology 2015年第2期13卷 82-85页

作者： Chengze Xu Xiaoshu Cai Jie Zhang Lili Liu Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Science and Technology

In this paper, an image dynamic light scattering method for nanoparticle sizing is introduced. The spatial distribution of the scattered lights from nanoparticles undergoing Brownian motion was captured at a high frame rate by a digital camera within one second, which is considerably faster than the conven- tional photon correlation spectroscopy method. The captured series of photographs were meshed into thousands of small units for calculating the intensity autocorrelation functions in parallel. Experimental results from the measurements of three reference nanoparticle samples （27, 80, and 352 nm in diameters） demonstrated the feasibility of this method.

关键词： Nanoparticle sizing Image dynamic light scattering Real-time acquisition Brownian motion

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Resonance scattering characteristics of double-layer spherical particles

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Particuology 2012年第1期10卷 117-126页

作者： Xuejin Dong Mingxu Su Xiaoshu Cai Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Science and Technology Shanghai 200093 China

Based on the principle of ultrasonic resonance scattering, sound-scattering characteristics of double-layer spherical particles in water were numerically studied in this paper. By solving the equations of the scat- tering matrix, the scattering coefficient determined by the boundary conditions can be obtained, thus the expression for the sound-scattering function of a single double-layer spherical particle can be derived. To describe the resonance scattering characteristics of a single particle, the reduced scattering cross section and reduced extinction cross section curves were found through numerical calculation. Similarly, the numerically calculated sound attenuation coefficient curves were used to depict the resonance scattering characteristics of monodisperse and poIydisperse particles. The results of numerical calculation showed that, for monodisperse particles, the strength of the resonance was mainly related to the particle size and the total number of particles; while for polydisperse particles, it was primarily affected by the particle size, the coverage of the particle size distribution and the particle concentration.

关键词： UltrasonicResonance scatteringDouble-layerPolydisperseVisco-elastic

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particle size characterization by ultrasonic attenuation spectra

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Particuology 2008年第4期6卷 276-281页

作者： Mingxu Su, Minghua Xue, Xiaoshu Cai, Zhitao Shang, Feng Xu institute of particle and two-phase flow measurement, University of Shanghai for Science and Technology, Shanghai 200093, China Institute of Particle and Two-Phase Flow Measurement University of Shanghai for Science and Technology Shanghai 200093 China

This paper contributes to extracting information from signals of broadband ultrasonic attenuation spectrum for effective utilization in particle size characterization. The single particle scattering model and the coupled-phase model are formulated simultaneously, the relationship between particle size distribution and ultrasonic spectrum is established, and a convergence criterion for calculation is quantified. Demonstration inversion by the optimum regularization factor method is carried out to yield typical numerical results for discussion. With the experimental set-up developed by the institute of particle and two-phase flow measurement (IPTFM) at the University of Shanghai for Science and Technology, sand sediment particle size is measured by attenuation spectrum and analyzed using the above inversion algorithm and theoretical models. To validate the proposed ultrasonic spectrum particle sizing method, results are compared with those obtained by microscopy.

关键词： Ultrasonic spectrum particle Size Inversion

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particle sizing in dense two-phase droplet systems by ultrasonic attenuation and velocity spectra

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Science China(Technological Sciences) 2009年第6期52卷 1502-1510页

作者： SU MingXu CAI XiaoShu XUE MingHua DONG LiLi XU Feng Institute of Particle and Two-phase Flow Measurement University of Shanghai for Science and TechnologyShanghai 200093China

Size and size distribution of particles in particulate two-phase flow play an important role in a wide variety of industrial areas,while their measurement still remains a hard task till *** wave as a mechanical vibration contains plenty of information about medium when it passes *** the size distribution could be extracted from the measured ultrasonic attenuation and velocity spectra by means of well established models and data processing *** paper contributes to the extraction of information of droplet size of a two-phase fat emulsion simultaneously from signals of broad-band ultrasonic attenuation and velocity *** to the formulated single particle scattering model,the relationship between particle size distribution and ultrasonic spectrum is *** sensitivities of ultrasonic spectra to the variation of particle size are ***-guishing features for attenuation and velocity spectra are *** calculations of inversion by optimum regularization factor method are carried out to yield the typical numerical results for *** on the proposed inversion algorithm and theoretical model,a fat emulsion sam-ple with a volume fraction up to 20% is measured and *** validate the proposed ultrasonic spectrum particle sizing method,the results are compared to those obtained from optical measure-ment.

关键词： two-phase flow ultrasonic particle sizing inversion

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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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AN INVESTIGATION ON CHARACTERIZING DENSE COAL-WATER SLURRY WITH ULTRASOUND: THEORETICAL AND EXPERIMENTAL METHOD

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CHEMICAL ENGINEERING COMMUNICATIONS 2010年第2期197卷 169-179页

作者： Xue, Minghua Su, Mingxu Dong, Lili Shang, Zhitao Cai, Xiaoshu Shanghai Univ Sci & Technol Inst Particle & Two Phase Flow Measurement Shanghai 200093 Peoples R China

particle size distribution and concentration in particulate two-phase flow are important parameters in a wide variety of industrial areas. For the purpose of online characterization in dense coal-water slurries, ultrasonic methods have many advantages such as avoiding dilution, the capability for being used in real time, and noninvasive testing, while light-based techniques are not capable of providing information because optical methods often require the slurry to be diluted. In this article, the modified Urick equation including temperature modification, which can be used to determine the concentration by means of the measurement of ultrasonic velocity in a coal-water slurry, is evaluated on the basis of theoretical analysis and experimental study. A combination of the coupled-phase model and the Bouguer-Lambert-Beer law is employed in this work, and the attenuation spectrum is measured within the frequency region from 3 to 12MHz. particle size distributions of the coal-water slurry at different volume fractions are obtained with the optimum regularization technique. Therefore, the ultrasonic technique presented in this work brings the possibility of using ultrasound for online measurements of dense slurries.

关键词： Attenuation Concentration Online particle size distribution Ultrasonic method Velocity

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In-line measurement of pneumatically conveyed particles by a light transmission fluctuation method

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flow measurement AND INSTRUMENTATION 2005年第5期16卷 315-320页

作者： Cai, XS Li, JF Xin, OY Zhao, ZJ Su, MX Shanghai Univ Sci & Technol Inst Particle & Two Phase Flow Measurement Techno Shanghai 201800 Peoples R China

An optical method for particle sizing in two-phase flow, the so-called light transmission fluctuation method, is presented in this paper. On the basis of this method, a novel optical instrument capable of in-line measurement of pneumatically conveyed particles is introduced. Quite a few medium-term tests validate the reliability and the applicability of this technique. Some measurement results are shown and discussed, concerning real-time in-line continuous monitoring of pulverized coal flow at coal-fired power plants and relevant laboratory experiments. (c) 2005 Elsevier Ltd. All rights reserved.

关键词： particle sizing in-line measurement pneumatically conveyed particles light transmission fluctuation

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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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Real prospects for the development of power technologies based on renewable energy sources in Poland

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Frontiers in Energy 2017年第2期11卷 168-174页

作者： Slawomir DYKAS Artur SZYMANSKI Xiaoshu CAI Silesian University of Technology Institute of Power Engineering andTurbomachinery Konarskiego 20 44-100 Gliwice Poland Institute of Particle and Two-Phase Flow Measurement University ofShanghai for Science and Technology Shanghai 200093 China

In Poland more than 40% of the power units have been operating for over 40 years now and more than 10% are over 50 years old, which indicates a high degree of decrease in the value of the energy sector. An analysis of the energy market shows that every year a new power plant should be built with a capacity of 1000 MW to ensure the national energy security. An energy market research indicates that in Poland the structure of energy production is changing in recent years-the share of fossil (solid) fuels in electricity and heat production was approximately 88% in 2009, while in 2004 it reached 93%. According to the analysis of the market, it can be seen that conventional energy, mainly based on coal and lignite, has been the most important segment of the sector for a long time. In this paper the prospects for the development of power technologies based on renewable energy sources (RES) in Poland are presented.

关键词： renewable energy sources energy sector energy mix Poland

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