Multispectral image analysis method to determine dynamic fluid saturation distribution in two-dimensional three-fluid phase flow laboratory experiments

The need for measuring dynamic fluid saturation distribution in multi-dimensional three-fluid phase flow experiments is hampered by lack of appropriate techniques to monitor full field transient flow phenomena. There is no conventional technique able to measure dynamic three-fluid phase saturation at several array points of the flow field at the same time. A multispectral image analysis technique was developed to determine dynamic NAPL, water and air saturation distribution in two-dimensional three-fluid phase laboratory experiments. Using a digital near-infrared camera, images of sand samples with various degrees of NAPL, water and air saturation were taken, under constant lighting conditions and within three narrow spectral bands of the visible and near-infrared spectrum. It was shown that the optical density defined for the reflected luminous intensity was a linear function of the NAPL and the water saturation for each spectral band and for any two and three-fluid phase systems. This allowed the definition of dimensionless lump reflection coefficients for the NAPL and the water phase within each spectral band. Consequently, at any given time, two images taken within two different spectral bands provided two linear equations which could be solved for the water and the NAPL saturation. The method was applied to two-dimensional three-phase flow experiments, which were conducted to investigate the migration and the distribution of LNAPL in the vadose zone. The method was used to obtain continuous, quantitative and dynamic full field mapping of the NAPL saturation as well as the variation of the water and the air saturation during NAPL flow. The method provides a non-destructive and non-intrusive tool for studying multiphase flow for which rapid changes in fluid saturation in the entire flow domain is difficult to measure using conventional techniques.     

Evaluation and application of blast furnace slag as a mud cake modifier

The aim of this research was to reuse blast furnace slag (BFS) as a mud cake modifier (MCM) to improve the annular isolation quality in oil and gas wells. For the optimum formula of drilling fluid, the effects of MCM on the drilling fluid rheology were investigated. The relationship between the MCM addition and shear strength at cement–formation interface (SSCFI) was evaluated. The experimental results showed that the optimized formula of the drilling fluid has 1.0 wt% MCM and 0.5 wt% XY-27. The simulation results showed that SSCFI increased significantly with the addition of MCM. Based on the mechanism analysis of BFS as an MCM to improve SSCFI, it is found that the transformation of mud cake to agglomerated cake can be the main reason. The application results showed that the success rate of five wells reached 100%, and the rate of quality in cement was 100%. Especially, the average high quality rate of five wells reached 83.7%. Compared with conventional methods, the average high quality rate is increased by 32.6% points. This research provides a new way for sustainable utilization of BFS.     

Computational fluid dynamics simulations of hydrogen releases and vented deflagrations in large enclosures

This paper presents model predictions obtained with the CFD tool FLACS for hydrogen releases and vented deflagrations in containers and larger enclosures. The paper consists of two parts. The first part compares experimental results and model predictions for two test cases: experiments performed by Gexcon in 20-foot ISO containers (volume 33 m³) as part of the HySEA project and experiments conducted by SRI International and Sandia National Laboratories in a scaled warehouse geometry (volume 45.4 m³). The second part explores the use of the model system validated in the first part to accidental releases of hydrogen from forklift trucks inside a full-scale warehouse geometry (32 400 m³). The results demonstrate the importance of using realistic and reasonably accurate geometry models of the systems under consideration when performing CFD-based risk assessment studies. The discussion highlights the significant inherent uncertainty associated with quantitative risk assessments for vented hydrogen deflagrations in complex geometries. The suggestions for further work include a pragmatic approach for developing empirical correlations for pressure loads from vented hydrogen deflagrations in industrial warehouses with hydrogen-powered forklift trucks.     

并流旋转床气相压降数值模拟与实验研究

旋转床气相压降是设计旋转床的重要技术指标之一。通过分析并流旋转床结构与工作原理,建立气相压降的理论模型。采用Eulerian多相流模型和k-ε模型对并流旋转床气相压降进行数值模拟,探索液体分布器结构对气相压降的影响。实验表明所建立的压降模型较好地解释了实验现象,孔型分布器有利于减小气相压降。     

Removal of polycyclic aromatic hydrocarbons from soil: a comparison between bioremoval and supercritical fluids extraction

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic substances which are resistant to environmental degradation due to their highly hydrophobic nature. Soils contaminated with PAHs pose potential risks to human and ecological health, therefore concern over their adverse effects have resulted in extensive studies on their removal from contaminated soils. The main purpose of this study was to compare experimental results of PAHs removal, from a natural certified soil polluted with PAHs, by biological methods (using bioaugmentation and biostimulation in a solid-state culture) with those from supercritical fluid extraction (SFE), using supercritical ethane as solvent. The comparison of results between the two methods showed that maximal removal of naphthalene, acenaphthene, fluorene, and chrysene was performed using bioremediation; however, for the rest of the PAHs considered (fluoranthene, pyrene, and benz(a)anthracene) SFE resulted more efficient. Although bioremediation achieved higher removal ratios for certain hydrocarbons and takes advantage of the increased rate of natural biological processes, it takes longer time (i.e. 36 d vs. half an hour) than SFE and it is best for 2-3 PAHs rings.     

Biomonitoring marine habitats in reference to antibiotic resistant bacteria and ampicillin resistance determinants from oviductal fluid of the nesting green sea turtle, Chelonia mydas

During the egg-laying process, oviductal fluid was collected using a non-invasive procedure from the cloacal vent of the green turtles. Forty-two independent isolates of antibiotic-resistant bacteria from 11 genera were obtained from 20 turtles during nesting. The dominant isolate was Citrobacter (52.4%), followed by Pseudomonas, Proteus, Enterobacter, Salmonella, Escherichia coli, Shigella, Edwardsiella, Morganella, Providencia and Arcomobacter. Most of the isolates were resistant to ampicillin. Ampicillin-resistant isolates showed variations in their resistance for the following classes of β-lactamases: extended-spectrum β-lactamases (EBSLs), AmpC type β-lactamases C (AmpC), and screen-positive β-lactamase. None of the isolates produced metallo β-lactamase. Some ampicillin-resistant genes were detected by multiplex polymerase chain reaction (PCR) only. Inhibitor based test (IBT) categorized some isolates as AmpC β-lactamase producers. β-Lactamase genes were detected from a few strains. The sequencing of those genes revealed the presence of cephamycinase (CMY) and AmpC β-lactamases. The oviductal fluid was used in this study as a source of bacterial antibiotic-resistant determinants for biomonitoring marine turtles exposed to contaminated effluents. This data can be of value in understanding the decline of this endangered species as a result of exposure to marine pollution which is threatening their survival.     

Dissolution of beryllium in artificial lung alveolar macrophage phagolysosomal fluid

Dissolution of a lung burden of poorly soluble beryllium particles is hypothesized to be necessary for development of chronic beryllium lung disease (CBD) in humans. As such, particle dissolution rate must be sufficient to activate the lung immune response and dissolution lifetime sufficient to maintain chronic inflammation for months to years to support development of disease. The purpose of this research was to investigate the hypothesis that poorly soluble beryllium compounds release ions via dissolution in lung fluid. Dissolution kinetics of 17 poorly soluble particulate beryllium materials that span extraction through ceramics machining (ores, hydroxide, metal, copper-beryllium [CuBe] fume, oxides) and three CuBe alloy reference materials (chips, solid block) were measured over 31 d using artificial lung alveolar macrophage phagolysosomal fluid (pH 4.5). Differences in beryllium-containing particle physicochemical properties translated into differences in dissolution rates and lifetimes in artificial phagolysosomal fluid. Among all materials, dissolution rate constant values ranged from 10⁻⁵ to 10⁻¹⁰ g cm⁻² d⁻¹ and half-times ranged from tens to thousands of days. The presence of magnesium trisilicate in some beryllium oxide materials may have slowed dissolution rates. Materials associated with elevated prevalence of CBD had faster beryllium dissolution rates [10⁻⁷-10⁻⁸ g cm⁻² d⁻¹] than materials not associated with elevated prevalence (p < 0.05).     

超临界CO_2流体环境中线路板分层实验分析

在超临界CO2流体环境下,当温度达到240℃以上时,印刷线路板就会发生分层现象。同时,在实验中发现在非超临界流体环境下,当温度达到260℃以上时,线路板也会发生分层现象。从线路板粘接材料发生热解反应的角度出发,在对比超临界CO2流体环境下与非超临界流体环境下的线路板分层效果的基础上,对超临界CO2流体环境下的线路板分层做出合理分析,最后发现临界CO2流体对线路板分层过程有促进作用,并对其分层效果有优化作用。     

气箱脉冲袋除尘器在复合肥冷却床的应用

阐述了气箱脉冲袋除尘器的原理,以及在复合肥冷却床烟气集中处理的技术方案和应用结果.     

活性污泥对回用净水中钙离子的去除研究

在静态条件下,进行了活性污泥对净水中钙离子的去除实验研究和机理探讨。在去除实验中,考察了活性污泥用量、搅拌强度、搅拌时间、初始钙离子浓度、溶液pH对钙离子的去除效果的影响。结果表明:用活性污泥去除钙离子可以获得较好的效果,去除量可达19mg/g,并且去除速度很快,5min即可完成;且去除机理可能有生物吸附、静电吸附和化学沉淀;适当的剪切力可以加速吸附反应的进程,证实了流体力化学效应的的存在。溶液pH不同,发生的沉淀反应不同,低pH条件下,钙离子与活性污泥中磷酸根生成Ca3(PO4)2沉淀,较高pH条件下,生成的沉淀为Ca5(OH)(PO4)3。