Morphology of Flashing Feeds at Critical Fluid Properties in Larger Pipes

Tailored conditioning and control of flashing feeds in industrial applications requires knowledge of the evolving flow morphology and phase fractions along the feed pipe. Design methods obtained from reference systems (e.g. water-air) are hardly applicable for commercial scales and critical fluid properties (e.g. high vapor densities, low surface tension). In this study, the flow morphology of flashing feeds in a novel refrigerant test rig at critical fluid properties was analyzed using wire-mesh sensors at two locations along the feed pipe and experimental data from the water-air system.     

超临界萃取装置新型快开结构

根据超临界流体萃取釜的特殊要求,提出一种新型快开密封结构,并采用安全连锁装置,具有开启方便、密封性能优良、安全、可靠等优点。     

Equipment and Separation Units for Flow Chemistry Applications and Process Development

Process development and small‐scale production gets more and more important in fine chemistry and pharmaceutical production. An equipment toolbox assists process synthesis presented in this contribution. A microfluidic calorimeter can measure kinetic and thermodynamic reaction data with commercial plate reactors. A tubular reactor coiled with 90° bends allows for long residence time with low axial dispersion, also known as coiled flow inverter (CFI). A similar setup is used for continuous‐flow cooling crystallization. Small‐scale columns with rotating internals are employed for distillation and liquid‐liquid extraction. Main emphasis will be put on automation and scale‐up in future steps.     

A Numerical Study on Fully Developed Fluid Flow and Heat Transfer in a Spiral Finned Tube

In this paper, the standard k-εtwo-equation model is adopted to numerically simulate fully developed fluid flow and heat transfer in a spiral finned tube within a cracking furnace for ethylene manufacturing. By variable transformation, the orlglnal 3-D problem is converted into a 2-D problem in spiral coordinates. The algorithm of SIMPLEC is used to study the fully developed fluld flow and heat transfer in the spiral finned tube at constant periphery temperature and constant axial heat flux, The computed results agree pretty well with the experimental data obtained from the industry, Further studies on the fluid flows and temperature profiles at different Reynolds numbers within straight and spiral finned tubes are conducted and the mechanisms involved are explored. It is found that with the spiral finned tube, pressure drop increases to a great extent whereas heat transfer tends to be decreased.     

油酸异丙酯的合成及其对生物柴油低温流动性研究

油酸与异丙醇在对甲苯黄酸催化剂的作用下发生酯化反应制备油酸异丙酯。单因素研究催化剂用量、醇酸配比、反应时间、反应温度等对酯化反应得率的影响规律,并通过测定凝固点、冷滤点、粘度来考察脂肪酸异丙脂对生物柴油的降凝效果。结果表明,催化剂的量3%,醇酸体积比2∶1（摩尔比8.2∶1）,反应温度80℃,反应时间4 h,酯化率达到90.5%。降凝实验结果表明把一定量的脂肪酸异丙酯添加到生物柴油中可有效地降低生物柴油的凝固点、冷滤点,改善其低温流动性能。     

直管内变质量流动规律和均布技术的研究

通过动量衡算及能量衡算方法分析并计算了直管内变质量流体流动的流量分配。讨论了孔径、孔间距、总管流量与流量均布的关系。摸拟计算值与实验测定值较为吻合。提出了二次分流技术,实践证明,流量均布效果良好。     

A Workflow for Crystallization Process Design with Simultaneous Process Optimization and Solvent Selection based on the Perturbed-Chain Statistical Associating Fluid Theory

Solvent selection is a critical part of crystallization process design and is inherently intertwined with optimization of the operating conditions. Computer-aided tools can greatly assist in solving these two problems simultaneously. However, the integration of predictive thermodynamic models and process optimization tools is often complicated, which may hamper industry adoption. This work presents a workflow for simultaneous solvent selection and process optimization for solution crystallization processes based on the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state. The workflow is provided with readily executable computational tools and aims to strike a balance between the resources needed to obtain experimental input data and good prediction performance. The use of the workflow is demonstrated through a case study involving aspirin crystallization, which shows that the workflow can provide suitable solvents and operating conditions for the crystallization process based on either cooling, antisolvent, or evaporative crystallization.     

A New Group Contribution Method based on Equation of State Parameters to Evaluate the Critical Properties of Simple and Complex Molecules

A new group contribution method to evaluate the critical properties (temperature, pressure and volume) is presented and applied to estimate the critical properties of biomolecules. Similar to other group contribution methods, the one proposed here divides the molecule into conveniently defined groups and evaluates the properties as the sum of the different contributions according to a specified model equation for each of the properties. The proposed method consists of a one‐step calculation that uses simple model equations and does not require additional data besides the knowledge of the structure of the molecule, except for isomers. For these substances the normal boiling temperature, the molecular mass and the number of atoms in the molecule are used to distinguish among isomers. The method is applicable to high molecular weight compounds, as most biomolecules and large molecules present in natural products.     

Cu and Cu-SWCNT Nanoparticles’ Suspension in Pulsatile Casson Fluid Flow via Darcy–Forchheimer Porous Channel with Compliant Walls: A Prospective Model for Blood Flow in Stenosed Arteries

The use of experimental relations to approximate the efficient thermophysical properties of a nanofluid (NF) with Cu nanoparticles (NPs) and hybrid nanofluid (HNF) with Cu-SWCNT NPs and subsequently model the two-dimensional pulsatile Casson fluid flow under the impact of the magnetic field and thermal radiation is a novelty of the current study. Heat and mass transfer analysis of the pulsatile flow of non-Newtonian Casson HNF via a Darcy–Forchheimer porous channel with compliant walls is presented. Such a problem offers a prospective model to study the blood flow via stenosed arteries. A finite-difference flow solver is used to numerically solve the system obtained using the vorticity stream function formulation on the time-dependent governing equations. The behavior of Cu-based NF and Cu-SWCNT-based HNF on the wall shear stress (WSS), velocity, temperature, and concentration profiles are analyzed graphically. The influence of the Casson parameter, radiation parameter, Hartmann number, Darcy number, Soret number, Reynolds number, Strouhal number, and Peclet number on the flow profiles are analyzed. Furthermore, the influence of the flow parameters on the non-dimensional numbers such as the skin friction coefficient, Nusselt number, and Sherwood number is also discussed. These quantities escalate as the Reynolds number is enhanced and reduce by escalating the porosity parameter. The Peclet number shows a high impact on the microorganism’s density in a blood NF. The HNF has been shown to have superior thermal properties to the traditional one. These results could help in devising hydraulic treatments for blood flow in highly stenosed arteries, biomechanical system design, and industrial plants in which flow pulsation is essential.     

测算散料低速栓流气力输送压降和栓速的新方法

低速栓流气力输送技术已广泛应用于散料输送,然而对其输送对象的研究大多数针对有规则形状的散料（如塑料切片、小麦）,对于不规则形状的散料（如牛奶什锦早餐、玉米芽等）的研究却很少。提出了一种新的预测方法,它根据粒子的特性及从一个简单的垂直测试筒得到的数据,可以精确地预测低速栓流气力输送系统中的压降和栓速,即使是大型的气力输送系统。该方法适用于规则、不规则或不同性能（如不同形状、密度、粒径和粒度分布）的散料的低速栓流气力输送,预测的结果可满足设计和操作要求。     

Tissue Printing and Dual Excitation Flow Cytometry for Oxidative Stress—New Tools for Reactive Oxygen Species Research in Seed Biology

The intracellular homeostasis of reactive oxygen species (ROS) and especially of superoxide anion and hydrogen peroxide participate in signaling cascades which dictate developmental processes and reactions to stresses. ROS are also biological molecules that play important roles in seed dormancy and germination. Because of their rapid reactivity, short half-life and low concentration, ROS are difficult to measure directly with high accuracy and precision. In presented work tissue printing method with image analysis and dual excitation flow cytometry (FCM) were developed for rapid detection and localization of O₂^•− and H₂O₂ in different part of seed. Tissue printing and FCM detection of ROS showed that germination of wild oat seeds was associated with the accumulation of O₂^•− and H₂O₂ in embryo (coleorhiza, radicle and scutellum), aleurone layer and coat. To verify if printing and FCM signals were specified, the detection of O₂^•− and H₂O₂ in seeds incubated in presence of O₂^•− generation inhibitor (DPI) or H₂O₂ scavenger (CAT) were examined. All results were a high level of agreement among the level of ROS derived from presented procedures with the ones created from spectrophotometric measured data. In view of the data obtained, tissue printing with image analysis and FCM are recommended as a simple and fast methods, which could help researchers to detection and level determination of ROS in the external and inner parts of the seeds.     

Optimization of Injection-Molding Process for Mechanical and Tribological Properties of Short Glass Fiber and Polytetrafluoroethylene Reinforced Polycarbonate Composites with Grey Relational Analysis: A Case Study

This study analyzes the mechanical properties and tribological behaviors of polycarbonate (PC) reinforced with 20% short glass fiber (SGF) and 6% polytetrafluoroethylene (PTFE), which is applied to the bottom cover of the card reader body. The specimens were prepared under different injection-molding conditions, by varying the filling time, the melt temperature, the mold temperature and the packing pressure. Grey relational analysis is then applied to obtain an optimal parameter setting. Plans of experiments via nine experimental runs are based on the orthogonal arrays to determine the optimum factor level condition. The mechanical properties of ultimate stress, and the tribological behaviors of surface roughness and friction coefficient variation are adopted as the quality targets. The tensile test were performed with a 25 kN computerized MTS. Simultaneously, friction and wear tests were performed with a Schwingum Reibung Verschleiss (SRV oscillation friction wear) ball-on-plane tester. Additionally, the worn surfaces were examined with scanning electron microscopy (SEM). Melt temperature was found to be the most influenced factor inultimate stress, surface roughness, and friction coefficient for the injection molding process in this study.     

Antimicrobial Properties of Palladium and Platinum Nanoparticles: A New Tool for Combating Food-Borne Pathogens

Although some metallic nanoparticles (NPs) are commonly used in the food processing plants as nanomaterials for food packaging, or as coatings on the food handling equipment, little is known about antimicrobial properties of palladium (PdNPs) and platinum (PtNPs) nanoparticles and their potential use in the food industry. In this study, common food-borne pathogens Salmonella enterica Infantis, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus were tested. Both NPs reduced viable cells with the log₁₀ CFU reduction of 0.3–2.4 (PdNPs) and 0.8–2.0 (PtNPs), average inhibitory rates of 55.2–99% for PdNPs and of 83.8–99% for PtNPs. However, both NPs seemed to be less effective for biofilm formation and its reduction. The most effective concentrations were evaluated to be 22.25–44.5 mg/L for PdNPs and 50.5–101 mg/L for PtNPs. Furthermore, the interactions of tested NPs with bacterial cell were visualized by transmission electron microscopy (TEM). TEM visualization confirmed that NPs entered bacteria and caused direct damage of the cell walls, which resulted in bacterial disruption. The in vitro cytotoxicity of individual NPs was determined in primary human renal tubular epithelial cells (HRTECs), human keratinocytes (HaCat), human dermal fibroblasts (HDFs), human epithelial kidney cells (HEK 293), and primary human coronary artery endothelial cells (HCAECs). Due to their antimicrobial properties on bacterial cells and no acute cytotoxicity, both types of NPs could potentially fight food-borne pathogens.     

A new generalized corresponding-states equation of state for the extension of the Lee-Kesler equation to fluids consisting of polar and larger nonpolar molecules

The Lee-Kesler equation of state for the thermodynamic properties of small nonpolar fluids is extended to all fluids consisting of polar and larger nonpolar molecules, based on the general corresponding-states theory for highly nonspherical fluids. The thermodynamic functions are represented by an analytical equation of state. The results for polar fluids are substantially better than those obtainable from other currently available methods, while the results for nonpolar fluids are equivalent to and mostly better than those obtained by the Lee-Kesler method. The input data required are the critical temperature, the critical volume, the acentric factor and the aspherical factor, which is related to the critical compression factor; the critical volume is therefore required in the present method. The method developed in this work shows good accuracy for 15 representative nonpolar, polar, hydrogen bonding and associating fluids and provides a simple method for industrial applications. Average deviations for the compressibility factor, the heat capacity and the speed of sound for six nonpolar and nine polar fluids from the new equation of state are 0.74%, 2.1% and 2.3%, which are about 8 times smaller than those obtained from the Lee-Kesler equation (about 5.6%, 17% and 29%, respectively).