Search

Mass transfer efficiency, heat transfer efficiency, and treatment capacity play important roles in the continuous flow chemical process. To enhance the continuous flow chemical process, a novel mixer with triangular-notched rectangular baffles structure was designed and optimized. The performance of mixers was characterized by a comprehensive computational fluid dynamics (CFD) method that couples heat and mass transfer. The results show that the optimized mixer has a maximum increase of 4.25 times in mixing efficiency and 83.8% in heat transfer compared with 10 mm mixer without baffles structure. Furthermore, the scale of the mixer with triangular-notched rectangular baffles structures was enlarged to 25 mm under the premise of ensuring high mass and heat transfer efficiency, low-pressure drop and high treatment capacity. This study provides a scale-up strategy for continuous flow chemical process enhancement. [ABSTRACT FROM AUTHOR]

Due to scale effects, directly enlarging the size of the micromixer is an easy way to reduce the efficiency of mass and heat transfer in the continuous flow chemical process. It is urgently needed to solve the problem of mass and heat transfer efficiency of the scale‐up mixer. A scale‐up microfluidic mixer with a porous structure was designed to improve the mass and heat transfer efficiency using computational fluid dynamics (CFD) simulations. The effects of rotation angle, porosity, and baffle spacing were studied to optimize the mixer structure. Compared with the 1 mm mixer without structure, the scale‐up mixer has a higher mixing efficiency and an 80% reduction in energy consumption at Re ≥ 700. A Nusselt number was used to evaluate the heat transfer efficiency of the mixer during fluid heating. The results show that the porous baffle promotes the generation of secondary flow and enhances the heat transfer effect, making its Nu increase by three times compared with the unstructured mixer. The scale‐up microfluidic mixer with a porous structure can effectively improve the mass and heat transfer performance. This study can provide a reference for the design or development of a novel scale‐up mixer. [ABSTRACT FROM AUTHOR]

The mixing uniformity plays a crucial role in a liquid-liquid two-phase chemical process. To quantify the uniformity of the liquid–liquid process, the specific surface area ratio is proposed and studied through computational fluid dynamics simulation. There is a scale effect in the liquid–liquid two phase chemical processing that the specific surface area ratio decreases to 7.01% when the diameter of the Y-like mixer increases from 1 mm to 10 mm. A millimeter-scale mixer with a fan-notched baffle structure was designed, and the baffle unit length, baffle tilt angle, baffle notch size and baffle thickness of the mixer were optimized. Compared with the 1 mm Y-like mixer, the specific surface area ratio of the 10 mm mixer with notched baffle structures increases to 2.5 times and the treatment capacity increases to 100 times. Additionally, experiment and simulation results prove that FNBS is considered to be a suitable structure for enhancing liquid-liquid two-phase. This study will provide a useful reference for the design of large-scale mixers applicable to liquid-liquid heterogeneous chemical processes. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the technology of micro‐segmented flow was applied for continuous synthesis safely and shape control accurately to lead trinitroresorcinate (LTNR) particles. Besides, a micro chemical reaction and crystallization system were built. Crystal shape control technology of LTNR and micro‐segmented flow technology were first combined using the system. Additionally, the effects of the flowing rate and chemical additives on LTNR micro‐particles preparation were researched for shape control. The LTNR micro‐particles were analyzed by XRD, DSC, laser scanning confocal microscope and laser particle size analyzer. The results shows that the LTNR particles size can be controlled from 20 to 400 μm by the flow rate and the concentration of hexadecyl trimethyl ammonium bromide (CTAB), while the shape of LTNR can be controlled by the concentration of glycerol and CTAB. Besides, there is a good linear relationship between the size and the activation energy. This illustrates that the LTNR particles with smaller size are more stable and have higher heat release. This study demonstrated the power of micro‐segmented flow for generation of LTNR micro‐particles with high quality and for tuning of particle properties. [ABSTRACT FROM AUTHOR]

With the application of GIS technique, fractal theory was employed to study the change of Chang-Zhu-Tan Region in 1986, in 1995 and in 2005 three periods of land utilization landscape pattern data. The land landscape type degree of fragmentation, the fractal dimension and the index of stability have obtained. The results show: during 1986 to 2005, woodlands and paddy fields are dominant, formed a kind of spatial pattern of forest land surrounded the city. The fragmentation of woodlands and paddy fields is smaller, while the fragmentation of rural residents land and urban use is bigger. The fractal dimension value of paddy fields and aquatorium waters is larger, while the fractal dimension value of unused land and rural residents land is smaller. The stability of unused land, rural residents land, and urban use is stronger; the stability of paddy fields, aquatorium, woodlands is relatively weak. [ABSTRACT FROM AUTHOR]