Micromixing In Liquid-Continuous Impinging Streams

The pressure fluctuation in liquid-continuous impinging streams must affect the micromixing status and, consequently, it favors reaction kinetics. The substances related to this topic will be discussed in the following chapters. 

The results of the two kinetics investigations support the theoretical inference that the efficient micromixing and the considerably strong pressure fluctuation in liquid-continuous impinging streams promote process kinetics. 

Because the properties of liquids are essentially different from those of gases, impinging streams with liquid and gas as the continuous phases exhibit totally different performances and it is therefore necessary to discuss them separately. Part II focuses on liquid-continuous impinging streams and related problems, including the features of LIS that efficiently promote micromixing, pressure fluctuation phenomena in LIS, promotion of kinetic processes by LIS, and the application of LIS in the preparation of ultrafine particles, etc. Finally, this we will introduce some important research and development on LIS devices and look forward to the future applications of LIS. 

As explained in Chapters 10 and 11, the existence of pressure fluctuation and the promotion of micromixing are the major features of liquid-continuous impinging streams. For processes occurring on the molecular scale in liquid or multiphase systems with a liquid as the continuous phase, these features have important implications. One of their valuable applications is the promotion of process kinetics. 

The liquid-continuous impinging stream (LFS) device has the features of efficient micromixing and strong pressure fluctuation and, being the major equipment in the preparation of ultrafine powders by reaction-precipitation, it has exhibited excellent performances in a number of application cases. However, of the various preparation... 

Actually, the mechanism for the formation of HAP crystalline during the process under consideration is very complex and some suggestions proposed for the mechanism cannot be supported by experimental evidence so details of the chemical aspect will not be discussed here. In any case, precipitation, i.e., crystallization from a solution, must be involved in the process so the fact that liquid-continuous impinging streams cause strong micromixing and pressure fluctuation would favor the synthesis of nano HAP. 

As described in previous chapters in Part II, liquid-continuous impinging streams (LIS) has the feature of very efficient micromixing and can provide a uniform and controllable supersaturation environment for the crystallization process, favoring the production of uniformly large-sized crystalline also, it has been proved experimentally that, to an extent, LIS can enhance crystal-growth rate. For industrial application, Wu [237] designed and patented the impinging stream crystallizer, the structure of which is shown in Fig. 17.3. 

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