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Study of the Liquid Phase Volume Expansion for CO_2/Organic Solvent Systems

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Chinese Journal of Chemical engineering 2005年第4期13卷 504-509页

作者： LI Zhiyi（李志义） XIA Yuanjing（夏远景） LIU Xuewu（刘学武） dENG Xiaoliang（邓小亮） Hu dapeng（胡大鹏） r＆d institute of fluid and powder engineering Dalian University of Technology Dalian 116012 China

The supercritical antisolvent （SAS） process has been developed in recent years for the tormation of nanoand micro-particles. It is necessary to study the liquid phase volume expansion （LPVE） and find the relationships between the operating conditions and the LPVE in order to develop a practical method for determining the operation conditions and selecting an organic solvent for SAS process. The Pr equation of state with vdW-1 mixing rule is used to calculate the LPVE for CO2/toluene, CO2/acetone and CO2/ethyl acetate systems, and the results show that the LPVE for each CO2/organic solvent system decreases as the temperature increases. The relationship between the LPVE and the solubility of CO2 in the liquid phase for CO2/organic solvent systems is investigated, and the results show that the LPVE is determined directly by the solubility of CO2 in the liquid phase, xCO2, and can be related to xCO2 independently. No matter what system of CO2/organic solvent is and how different the temperature is, the LPVEs have little difference as long as the solubility of CO2 in the liquid phase, xCO2, keeps constant. The lower temperature is always favorable to the SAS process. The higher the solubility of CO2 in an organic solvent under certain operation condition, the more suitable it is to the SAS process.

关键词： supercritical antisolvent process liquid phase volume expansion carbon dioxide organic solvent

Supercritical Antisolvent Precipitation of Microparticles of Quercetin

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Chinese Journal of Chemical engineering 2005年第1期13卷 128-130页

作者：刘学武李志义韩冰苑塔亮 r&d institute of fluid and powder engineering dalian University of Technology Dalian 116012 China

Supercritical antisolvent (SAS) process is a recently developed technology to produce micro- and nano particles. This paper presents a continuous apparatus to conduct experiment of SAS process. With the apparatus, the effects of pressure, temperature and flow ratio of CO2 to the solution on the shape and size of particles are studied for the quercetin-ethanol-CO2 system. Spherical quercetin microparticles with diameters ranging form 1 μm to 6μm can be obtained while ethanol is used as organic solvent. The most effective fact on the shape and size of particles is pressure, the next is temperature and the last is the flow ratio of CO2 to solution.

关键词： supercritical antisolvent process microparticles quercetin

The Collapse Intensity of Cavities and the Concentration of Free Hydroxyl radical released in Cavitation Flow

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Chinese Journal of Chemical engineering 2008年第4期16卷 547-551页

作者：张晓冬付勇李志义赵宗昌 r＆d institute of fluid and powder engineering Dalian University of Technology Dalian 116012 China

Enhancing the chemical reaction processes by means of the energy released in the collapse of micro bubbles or cavities in the cavitation flow is a new research area. In the previous work, a new approach of measuring concentration of free hydroxyl radicals induced in cavitation flow by using methylene blue as the indicator was developed and used to study concentration of free radical induced in Venturi cavitation flow under various experimental conditions. In the present research, the radial evolution of a cavity bubble and the corresponding collapse pressure in sonic cavitation field are obtained by solving three different bubble dynamics equations： rayleigh equation, rayleigh-Plesset equation and Gilmore equation. By comparing with the experimental data on the radial evolution of a cavity bubble in the literature, it is found that the predicted results by the Gilmore equation, which takes account of the compressibility of fluid in addition to the viscosity and interfacial tension, agree with the experimental ones better than those by other two equations. Moreover, the theoretically predicted collapse pressures are consistent with the concentration of the free hydroxyl radical induced in the experimental venture. Thus, the concentration of the liberated free hydroxyl radical not only influences the reaction rate but also is used as an available parameter for measuring collapse intensity of cavities.

关键词： hydrodynamic cavitation collapse pressure numerical simulation free hydroxyl radical

The Numerical Simulation of Collapse Pressure and Boundary of the Cavity Cloud in Venturi

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Chinese Journal of Chemical engineering 2009年第6期17卷 896-903页

作者：张晓冬付勇李志义赵宗昌 r&d institute of fluid and powder engineering College of Chemical Engineering Dalian University of Technology Dalian 116012 China

The idea that the collapse proceeds from the outer boundary of the cavity cloud towards its center for the ultrasonic cavitation proposed by Hasson and Morch in 1980s is further developed for calculating the collapse pressure and boundaries of cavity cloud at the collapse stage of bubbles for hydraulic cavitation flow in Venturi in present research. The numerical simulation is carried out based on Gilmore＇s eouations of bubble dynamics, which take account of the compressibility of fluid besides the viscosity and interfacial tension. The collapse of the cavity cloud is considered to proceed layer by layer from the outer cloud towards its inner part. The simulation results indicate that thepredicted boundaries of the cavity cloudat the collapse stage *** with the exPerimental *** is also found that the maximum collapse pressure of the cavity cloud is several times as high as the collapse pressure of outside boundary, and it is located at a point in the axis, where the cavity cloud disappears completely. This means that a cavity cloud has higher collapse pressure or strength than that of a single bubble due to the interactions of the bubbles. The effects of operation and structural parameters on the collapse pressure are also analyzed in detail.

关键词： cavity cloud collapsing layer by layer laydrodynamic cavitation collapse pressure bubble dynamics

Experimental and Simulating Study of Supercritical CO_2 Extraction of Ginger Essential Oil

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Chinese Journal of Chemical engineering 2005年第4期13卷 572-576页

作者：刘学武李志义陈淑花詹世平夏远景魏勇 r&d institute of fluid and powder engineering Dalian University of Technology department of Chemisty and Chemical engineering Dalian University

An experimental setup for separating ginger essential oil by supercritical fluid extraction is established. The effects of the extraction pressure, temperature, CO2 flow rate and particle size of raw material on the extraction rate are investigated, and the optimum process conditions of supercritical CO2 extraction are determined. A mathematical simulation model is established based on the mass conservation in differential units of extraction bed. The total mass transfer driving force and the equilibrium absorption constant are evaluated by the linear driving force theory. The results from numerical simulation agree well with the experimental data.

关键词： supercritical CO2 extraction ginger essential oil simulation

Effect of blade sweep on inlet flow in axial compressor cascades

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Chinese Journal of Aeronautics 2015年第1期28卷 103-111页

作者： Chang Hao Zhu Fang Jin donghai Gui Xingmin School of Energy and Power engineering Beihang University Gas Turbine Technology institute Shanghai Electric Power Generation R&D Center

This paper presents comparative numerical studies to investigate the effects of blade sweep on inlet flow in axial compressor cascades. A series of swept and straight cascades was modeled in order to obtain a general understanding of the inlet flow field that is induced by sweep.A computational fluid dynamics（CFd） package was used to simulate the cascades and obtain the required three-dimensional（3d） flow parameters. A circumferentially averaged method was introduced which provided the circumferential fluctuation（CF） terms in the momentum equation.A program for data reduction was conducted to obtain a circumferentially averaged flow *** influences of the inlet flow fields of the cascades were studied and spanwise distributions of each term in the momentum equation were analyzed. The results indicate that blade sweep does affect inlet radial equilibrium. The characteristic of radial fluid transfer is changed and thus influencing the axial velocity distributions. The inlet flow field varies mainly due to the combined effect of the radial pressure gradient and the CF component. The axial velocity varies consistently with the incidence variation induced by the sweep, as observed in the previous literature. In addition, factors that might influence the radial equilibrium such as blade camber angles, solidity and the effect of the distance from the leading edge are also taken into consideration and comparatively analyzed.

关键词： compressor blade inlet sweep axial radial straight averaged momentum consistently

An Artificial Intelligence Algorithm for the real-Time Early detection of Sticking Phenomena in Horizontal Shale Gas Wells

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fluid dynamics & Materials Processing 2023年第10期19卷 2569-2578页

作者： Qing Wang Haige Wang Hongchun Huang Lubin Zhuo Guodong Ji CNPC engineering Technology r&d Company Limited Planning and Support InstituteBeijing102206China

Sticking is the most serious cause of failure in complex drilling *** the present work a novel“early warning”method based on an artiﬁcial intelligence algorithm is proposed to overcome some of the known pro-blems associated with existing sticking-identiﬁcation *** method is tested against a practical case study(Southern Sichuan shale gas drilling operations).It is shown that the twelve sets of sticking fault diagnostic results obtained from a simulation are all consistent with the actual downhole state;furthermore,the results from four groups of veriﬁcation samples are also consistent with the actual downhole *** shows that the pro-posed training-based model can effectively be applied to practical situations.

关键词： Shale gas drilling sticking fault artificial intelligence risk early warning technology

Effects of High Hydrostatic Pressure Treatment on Physicochemical Characteristics of Sea Cucumber

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Journal of Food Science and engineering 2012年第4期2卷 227-238页

作者： Yuanjing Xia Zhijun Liu Zhiyi Li r＆d institute of fluid and powder engineering Faculty of Chemical Environmental and Biological Science and TechnologyDalian University of Technology Dalian 116024 China

The effects of high hydrostatic pressure （HHP） treatment on sea cucumber qualities, such as shelf-life, autoenzyme, total volatile basic nitrogen （TVB-N）, mucopolysaccha ride and protein, were investigated experimentally. The shelf-life of sea cucumber was greatly prolonged by HHP treatment. High pressure treatment of sea cucumber significantly reduced the activity of autoenzyme at 550 MPa. The TVB-N content was 8.4 mg/100 g in the HHP-treated samples after 38 days＇ storage at 4 ~C, while it had already reached 11.2 mg/100 g in the untreated ones after 5 days＇ storage under the same condition. The relative mucopolysaccharide content of the HHP-treated samples was 94.3%, while that of the heat-treated ones was only 35.5%. The sodium dodecyl sulfate polyacrylamide gel electrophoresis （SdS-PAGE）, differential scanning calorimetric （dSC）, ANS fluorescence probe method and fourier-transform infrared （FTIr） spectroscopy results indicated some changes in protein subunits, denaturation, surface hydrophobicity and secondary structure of sea cucumber protein. This study has provided complementary information of pressure-induced structural changes on both the molecular and the sub-molecular level of sea cucumber protein.

关键词： High hydrostatic pressure sea cucumber shelf-life autoenzyme.

Modeling heat transfer for phase transition during pressure assisted thawing treatment

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Journal of Chemistry and Chemical engineering 2009年第6期3卷 15-21页

作者： CHEN Shu-hua ZHAO Qi-cheng XIA Yuan-jing LIU Ke-gang X-UE Lu-zhou r ＆ d institute of fluid and powder engineering School of Chemical Engineering Dalian University of Technology Dalian 116012 China

The thawing time of ice and freezed Salomon fish during high pressure assisted thawing process was evaluated by computer simulation using a finite element and the results were compared with those under atmospheric pressure. The apparent specific heat method was adopted to treat the release of latent heat. The effects of different factors on the high pressure assisted thawing process were analyzed. The time reductions of different sample dimensions were estimated and the temperature contour of thawing at different conditions was obtained. The results showed that the temperature gap of phase transition was the main factor, which could shorten the thawing time. Moreover, a second order relationship was obtained between pressure and phase transition time.

关键词： pressure assisted thawing phase transition heat transfer computer simulation