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Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 162-172 doi: 10.1007/s11705-009-0267-5

摘要: Bubble columns are widely used in chemical and biochemical processes due to their excellent mass and heat transfer characteristics and simple construction. However, their fundamental hydrodynamic behaviors, which are essential for reactor scale-up and design, are still not fully understood. To develop design tools for engineering purposes, much research has been carried out in the area of computational fluid dynamics (CFD) modeling and simulation of gas-liquid flows. Due to the importance of the bubble behavior, the bubble size distribution must be considered in the CFD models. The population balance model (PBM) is an effective approach to predict the bubble size distribution, and great efforts have been made in recent years to couple the PBM into CFD simulations. This article gives a selective review of the modeling and simulation of bubble column reactors using CFD coupled with PBM. Bubble breakup and coalescence models due to different mechanisms are discussed. It is shown that the CFD-PBM coupled model with proper bubble breakup and coalescence models and interphase force formulations has the ability of predicting the complex hydrodynamics in different flow regimes and, thus, provides a unified description of both the homogeneous and heterogeneous regimes. Further study is needed to improve the models of bubble coalescence and breakup, turbulence modification in high gas holdup, and interphase forces of bubble swarms.

关键词: bubble column     computational fluid dynamics     bubble breakup and coalescence     population balance model     bubble size distribution    

Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor

Haoyi SUN, Tao LI, Weiyong YING, Dingye FANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 515-522 doi: 10.1007/s11705-010-0516-7

摘要: Slurry bubble column reactors (SBCR) is a three-phase fluidized reactor with outstanding advantages compared with other reactors and is difficult to scale-up due to lack of information on hydrodynamics and mass transfer over a wide range of operating conditions of commercial interest. In this paper, an experiment was conducted to investigate the bubble behavior in SBCR with a height of 5600 mm and an interior diameter of 480 mm. Bubble rise velocity, bubble diameter, and gas holdup in different radial and axial positions are measured in SBCR using four-channel conductivity probe. Tap water, air, and glass beads (mean diameter 75–150 μm) are used as liquid, gas, and solid phases, respectively. It shows that hydrodynamic parameters have good regularity in SBCR. Moreover, a commercial computational fluid dynamics (CFD) package, Fluent, was used to simulate the process in SBCR. The simulations were carried out using axi-symmetric 2-D grids. Data obtained from experiment and CFD simulation are compared, and results show that the tendency of simulation is almost uniform with the experiment, which can help to obtain further understanding about multiphase flow process and establish a model about the synthesis of alcohol ether fuel in SBCR.

关键词: SBCR     four-channel conductivity probe     hydrodynamics     CFD    

Experimental study on the stratum applicability and mechanisms of bubble–slurry for earth pressure balance

《结构与土木工程前沿(英文)》   页码 1387-1399 doi: 10.1007/s11709-023-0005-y

摘要: Soil conditioning is essential for addressing the stratum applicability problem of earth pressure balance (EPB) shields. Under high water pressures, EPB shields spew water and soil when excavating coarse-grained strata. Typically, foam combined with polymers and slurry is used to solve spewing. However, in current techniques, slurry, foam, and the other agents are mixed with soil separately, their synergistic effect is seldom realized. In this study, an anionic surfactant was used to foam in bentonite slurry to form bubble–slurry to maximize the synergy between bubbles and slurry. The slump, volume stability, and permeability test of bubble–slurry-conditioned sand was conducted to examine the conditioning effect, and the stratum applicability of bubble–slurry was determined from the perspective of permeability. It was found that the conditioning effect of bubble–slurry in coarse gravel soil was excellent and could expand the applicability of EPB shields. The main stabilization mechanism of bubble–slurry is that bentonite particles provide a space barrier for bubbles. And three seepage modes of bubble–slurry-conditioned sand were innovatively defined, and the occurrence conditions of the three seepage modes were analyzed according to the permeability coefficient of sand, initial dynamic shear force of bubble–slurry, and hydraulic gradient.

关键词: EPB shield     bubble–slurry     soil conditioning     stability     permeability    

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

《化学科学与工程前沿(英文)》 2023年 第17卷 第12期   页码 2127-2143 doi: 10.1007/s11705-023-2363-3

摘要: Foam trays with porous submerged orifices endow bubbles uniformly distributed, which are considered attractive column internals to enhance the gas-liquid mass transfer process. However, its irregular orifice and complex gas-liquid flow make it lack pore-scale investigations concerning the transfer mechanism of dynamic bubbling. In this work, the actual porous structure of the foam tray is obtained based on micro computed tomography technology. The shape, dynamic, and mass transfer of rising bubbles at porous orifices are investigated using the volume of fluid and continue surface force model. The results demonstrate that the liquid encroaching on the gas channels causes the increasing orifices velocity, which makes the trailing bubble easily detach from the midst of the leading bubble and causes pairing coalescence. Additionally, we found that the central breakup regimes significantly improve the gas-liquid interface area and mass transfer efficiency. This discovery exemplifies the mechanism of mass transfer intensification for foam trays and serves to promote its further development.

关键词: bubble formation     porous submerged orifices     process intensification     foam tray    

Synchronous observation of rising soluble bubble through quiescent solution

Yifu ZHANG , Shuai TIAN , Weizhong LI , Yongchen SONG ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 307-312 doi: 10.1007/s11708-009-0028-7

摘要: An experimental method using computer image processing technology (CIPT) was proposed to observe and investigate the velocity, deformation, heat and mass transfer, etc. of a rising soluble gas (CO) bubble through a quiescent hot water. A model was set up to describe the behavior of the bubble in a visual experimental system in which a high-speed camera rose instantaneously with the movement of the bubble. A series of trajectory videos about the bubble were recorded by a computer linked to the camera. The trajectory, volume changes and rate of mass transfer of the bubble were obtained by the CIPT. It is found that the single bubble follows a rolling trajectory at the initial stage when there is mass transfer. With the volume decreasing, the disturbed behavior of the bubble becomes tempered. When the rising velocity of the bubble reaches the maximum, the velocity is nearly at a constant. The experimental and analysis results show that this method is useful for the research on the mass transfer and the movement of rising bubbles in liquid.

关键词: soluble bubble     mass transfer     synchronous observation     computer image processing    

Study on direct alcohol/ether fuel synthesis process in bubble column slurry reactor

Zhen CHEN, Haitao ZHANG, Weiyong YING, Dingye FANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 461-471 doi: 10.1007/s11705-010-0517-6

摘要: The recent studies of direct alcohol/ether synthesis process in slurry reactors were reviewed, and the research work in our laboratory was carried out in this paper. a global kinetics model for direct dimethyl ether (DME) synthesis from syngas over a novel Cu-Zn-Al-Zr slurry catalyst was established according to the total of 25 experimental data, and a steady-state one-dimensional mathematical model was further developed in bubble column slurry reactor (BCSR), which was assumed that the bubble phase was plug flow, and the liquid phase was fully mixed flow. The numerical simulations of reactor design of 100000 t/a dimethyl ether pilot plant indicate that higher pressure and lower temperature were favorable to the increase of CO conversion, selectivity of dimethyl ether, product yield and height of slurry bed. The optimal operating conditions for DME synthesis process were obtained: reaction temperature at 240°C, reactor pressure at 5 MPa and reactor diameter of 2.5 m.

关键词: syngas     alcohol/ether fuel     slurry catalyst     bubble column slurry reactor     global kinetics     mathematical model    

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

《化学科学与工程前沿(英文)》 2011年 第5卷 第2期   页码 194-202 doi: 10.1007/s11705-010-1019-2

摘要: In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%–1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

关键词: airlift rector     bubble diameter     gas hold-up     flow regime     ethanol    

Feasibility of bubble surface modification for natural organic matter removal from river water using

Yulong Shi, Jiaxuan Yang, Jun Ma, Congwei Luo

《环境科学与工程前沿(英文)》 2017年 第11卷 第6期 doi: 10.1007/s11783-017-0954-2

摘要: A novel, functionalized bubble surface can be obtained in dissolved air flotation (DAF) by dosing chemicals in the saturator. In this study, different cationic chemicals were used as bubble surface modifiers, and their effects on natural organic matter (NOM) removal from river water were investigated. NOM in the samples was fractionated based on molecular weight and hydrophobicity. The disinfection byproduct formation potentials of each fraction and their removal efficiencies were also evaluated. The results showed that chitosan was the most promising bubble modifier compared with a surfactant and a synthetic polymer. Tiny bubbles in the DAF pump system facilitated the adsorption of chitosan onto microbubble surfaces. The hydrophobic NOM fraction was preferentially removed by chitosan-modified bubbles. Decreasing the recycle water pH from 7.0 to 5.5 improved the removal of hydrophilic NOM with low molecular weight. Likewise, hydrophilic organic compounds gave high dihaloacetic acid yields in raw water. An enhanced reduction of haloacetic acid precursors was obtained with recycle water at pH values of 5.5 and 4.0. The experimental results indicate that NOM fractions may interact with bubbles through different mechanisms. Positive bubble modification provides an alternative approach for DAF to enhance NOM removal.

关键词: Bubble surface modification     Chitosan     Disinfection by-product     Dissolved air flotation     Organic fraction    

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

《能源前沿(英文)》 2009年 第3卷 第4期   页码 396-401 doi: 10.1007/s11708-009-0049-2

摘要: Numerical simulations of flowing and boiling in micro channels are presented, including the modeling of bubble dynamics of nucleate boiling, and a description of the interface of two phases with the volume-of-fluid (VOF). The two calculated cases are compared with related experimental data in literature. Some simulated results are found corresponding well to the experimental data. The simulated results also show the details of 3-dimensional heat transfer and the flow in micro channels, which are helpful to the investigation of the mechanism of two-phase heat transfer and flow in micro channels.

关键词: volume-of-fluid (VOF)     micro channel     nucleate boiling     bubble dynamics     simulation    

Development of electrorheological chip and conducting polymer-based sensor

Xianzhou ZHANG, Weihua LI, Weijia WEN, Yanzhe WU, Gordon WALLACE,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 393-396 doi: 10.1007/s11465-009-0043-8

摘要: This paper presents the development of an integrated sensor using two types of smart materials: electrorheological (ER) fluids and conducting polymers (CPs). The developed ER chip worked as an actuator, and it was driven by different voltages and control frequencies. When the four electrodes are controlled synchronously, the diaphragm acts as a vibrator whose frequency can be adjusted in accordance with the frequency of the electrical signals. The response signals of the CP sensor were recorded, and its properties were analyzed. Experimental results show that the amplitude decreases monotonically when the frequency increases, owing to the time delay in the pressure buildup in the ER chip. However, the displacement fluctuation of the diaphragm below 20Hz can be detected clearly even if the value is very low. When the vibration frequency is larger than 20Hz, the CP sensor can hardly detect the displacement fluctuation. Thus, the upper limit frequency that the CP sensor can detect is about 20Hz. The practical applications of this microdevice are also discussed.

关键词: electrorheological (ER) fluids     conducting polymer (CP)     polydimethylsioxane (PDMS)     driving frequency     amplitude     bubble counter    

Removal of SO

Xiaolei LI, Chunying ZHU, Youguang MA

《化学科学与工程前沿(英文)》 2013年 第7卷 第2期   页码 185-191 doi: 10.1007/s11705-013-1326-5

摘要: In this work, the removal of SO from gas mixture with air and SO by ammonium bicarbonate aqueous solution as absorbent was investigated experimentally in a bubble column reactor. The effects of the concentration of ammonium bicarbonate, the SO inlet concentration of gas phase and the gas flow rate on the removal rate of SO were studied. The results showed that the higher the SO inlet concentration and the gas flow rate, the shorter the lasting time of SO completely removed in gas outlet, and then the faster the decrease in the removal rate of SO . The lasting time of SO completely removed in gas outlet increased with increasing ammonium bicarbonate concentration. During the process of SO absorption, there was a critical pH of solution. When the solution pH was less than the critical pH, it would sharply fall, resulting in a rapid decrease of the SO removal rate. A theoretical model for predicting the SO removal rate has been developed by taking the chemical enhancement and the sulfite concentration in the liquid phase into account simultaneously.

关键词: SO2 removal     bubble column reactor     removal rate     ammonium bicarbonate     absorbent    

Gas marbles: ultra-long-lasting and ultra-robust bubbles formed by particle stabilization

《化学科学与工程前沿(英文)》   页码 1681-1687 doi: 10.1007/s11705-022-2180-0

摘要: Bubbles and foams are ubiquitous in daily life and industrial processes. Studying their dynamic behaviors is of key importance for foam manufacturing processes in food packaging, cosmetics and pharmaceuticals. Bare bubbles are inherently fragile and transient; enhancing their robustness and shelf lives is an ongoing challenge. Their rupture can be attributed to liquid evaporation, thin film drainage and the nuclei of environmental dust. Inspired by particle-stabilized interfaces in Pickering emulsions, armored bubbles and liquid marble, bubbles are protected by an enclosed particle-entrapping liquid thin film, and the resultant soft object is termed gas marble. The gas marble exhibits mechanical strength orders of magnitude higher than that of soap bubbles when subjected to overpressure and underpressure, owing to the compact particle monolayer straddling the surface liquid film. By using a water-absorbent glycerol solution, the resulting gas marble can persist for 465 d in normal atmospheric settings. This particle-stabilizing approach not only has practical implications for foam manufacturing processes but also can inspire the new design and fabrication of functional biomaterials and biomedicines.

关键词: bubble     particles     interfaces     armored bubble     liquid marble     gas marble     Pickering emulsion    

Nucleate boiling in two types of vertical narrow channels

Lei GUO, Shusheng ZHANG, Lin CHENG

《能源前沿(英文)》 2011年 第5卷 第3期   页码 250-256 doi: 10.1007/s11708-010-0128-4

摘要: To explore the mechanism of boiling bubble dynamics in narrow channels, we investigate 2-mm wide I- and Z-shaped channels. The influence of wall contact angle on bubble generation and growth is studied using numerical simulation. The relationships between different channel shapes and the pressure drop are also examined, taking into account the effects of gravity, surface tension, and wall adhesion. The wall contact angle imposes considerable influence over the morphology of bubbles. The smaller the wall contact angle, the rounder the bubbles, and the less time the bubbles take to depart from the wall. Otherwise, the bubbles experience more difficulty in departure. Variations in the contact angle also affect the heat transfer coefficient. The greater the wall contact angle, the larger the bubble-covered area. Therefore, wall thermal resistance increases, bubble nucleation is suppressed, and the heat transfer coefficient is lowered. The role of surface tension in boiling heat transfer is considerably more important than that of gravity in narrow channels. The generation of bubbles dramatically disturbs the boundary layer, and the bubble bottom micro-layer can enhance heat transfer. The heat transfer coefficient of Z-shaped channels is larger than that of the I-shaped type, and the pressure drop of the former is clearly higher.

关键词: nucleate boiling     narrow channel     numerical simulation     bubble dynamics    

Removal of dyes from wastewater by growing fungal pellets in a semi-continuous mode

Tao Lu, Qilei Zhang, Shanjing Yao

《化学科学与工程前沿(英文)》 2017年 第11卷 第3期   页码 338-345 doi: 10.1007/s11705-017-1644-0

摘要: To increase the efficiency of dye removal from wastewater using mycelial pellets, a bubble column reactor with a simple structure was designed and efficiently used to remove dyes from solution containing dyes. The mycelial pellets were prepared by marine fungus ZJUBE-1. Eight dyes were tested as dye targets for the adsorption capacity of mycelial pellets and good removal results were obtained. Eriochrome black T was selected as a model dye for characterizing the adsorption processes in detail. The measurement results of Zeta potential and FT-IR analysis indicate that the electrostatic attraction may play a key role in the biosorption process. The bubble column reactor was utilized to study the batch dye-removal efficiency of mycelial pellets. A re-culture process between every two batches, which was under non-sterile condition, successfully enhanced the utilization of mycelium biomass. The dye removal rate is 96.4% after 12 h in the first batch and then decreases slowly in the following batches. This semi-continuous mode, which consists of commutative processes of dye-removal and re-culture, has some outstanding advantages, such as low power consumption, easy operation, high dye removal rate, and efficient biomass utilization.

关键词: dye     mycelial pellets     marine fungus     bubble column reactor     semi-continuous biosorption    

膨化硝酸铵自敏化理论研究

吕春绪

《中国工程科学》 2000年 第2卷 第11期   页码 73-77

摘要:

膨化硝酸铵自敏化理论是膨化技术发明的核心,它是基于热点理论把微气泡植入硝酸铵炸药中。微气泡临界热点温度热力学计算为自敏化提供理论依据。与普通硝酸铵及珍珠岩相比较,微气泡在膨化硝酸铵内适当的分布为自敏化成功提供了有力的保证。

关键词: 膨化硝酸铵     自敏化     微气泡    

标题 作者 时间 类型 操作

Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

期刊论文

Experimental study on bubble behavior and CFD simulation of large-scale slurry bubble column reactor

Haoyi SUN, Tao LI, Weiyong YING, Dingye FANG

期刊论文

Experimental study on the stratum applicability and mechanisms of bubble–slurry for earth pressure balance

期刊论文

The role of single deformed bubble on porous foam tray with submerged orifices on the mass transfer enhancement

期刊论文

Synchronous observation of rising soluble bubble through quiescent solution

Yifu ZHANG , Shuai TIAN , Weizhong LI , Yongchen SONG ,

期刊论文

Study on direct alcohol/ether fuel synthesis process in bubble column slurry reactor

Zhen CHEN, Haitao ZHANG, Weiyong YING, Dingye FANG

期刊论文

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

期刊论文

Feasibility of bubble surface modification for natural organic matter removal from river water using

Yulong Shi, Jiaxuan Yang, Jun Ma, Congwei Luo

期刊论文

Numerical simulation of micro scale flowing and boiling

Wen WANG, Rui ZHUAN,

期刊论文

Development of electrorheological chip and conducting polymer-based sensor

Xianzhou ZHANG, Weihua LI, Weijia WEN, Yanzhe WU, Gordon WALLACE,

期刊论文

Removal of SO

Xiaolei LI, Chunying ZHU, Youguang MA

期刊论文

Gas marbles: ultra-long-lasting and ultra-robust bubbles formed by particle stabilization

期刊论文

Nucleate boiling in two types of vertical narrow channels

Lei GUO, Shusheng ZHANG, Lin CHENG

期刊论文

Removal of dyes from wastewater by growing fungal pellets in a semi-continuous mode

Tao Lu, Qilei Zhang, Shanjing Yao

期刊论文

膨化硝酸铵自敏化理论研究

吕春绪

期刊论文