In this paper, a comprehensive comparative study of various geometrical characteristics of microcapillaries used for chemical reactions is carried out. Three main shapes of microcapillaries are considered: serpentine, fractal and lobular. The focus is on how microcapillary geometry affects key parameters of the reaction process, including reactant mixing efficiency, flow distribution, heat transfer, and reaction rate. Optimization of these parameters is critical to improve the performance of chemical processes at the microscale. COMSOL Multiphysics software was used for the simulations, which enabled the evaluation of hydrodynamic characteristics such as Reynolds number, mixing coefficients and temperature distribution profile. The study also includes calculations of criteria used to quantify the efficiency of reagent mixing. In addition to numerical modeling, experiments were conducted, the results of which were used to verify the obtained calculated data. This improved the accuracy and reliability of the conclusions. The results of the study show that the choice of microcapillary geometry has a significant influence on the hydrodynamic parameters of the flow and, consequently, on the overall efficiency of chemical reactions. For example, serpentine geometry may provide better mixing in the early stages of the reaction, whereas a brush-like shape may be optimal for long-term processes with high heat transfer rates. The conclusions of this work provide practical recommendations for the choice of microcapillary geometry depending on the specifics of the chemical reaction. Using the example of acetone self-condensation, a suitable geometry, lobular, was identified. The recommendations are aimed at increasing productivity, improving the quality of reaction products and reducing energy costs.

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