This study investigates the mixing behavior in a Y-junction mixer for supercritical water hydrolysis using large eddy simulation with a discrete phase model. Yield changes were simulated using a two-step reaction model with first-order kinetics, based on particles’ temporal temperature data. Effective mixing produced closely matched mass and particle flow temperature distributions, both exhibiting bell-shaped profiles near the mixed temperature. Although variations in flow rate within ±25 % and changes in the inlet temperatures of supercritical water from 350 °C to 430 °C and subcritical water from 100 °C to 170 °C did not significantly affect the overall mixing performance, they did alter the mixed temperature and, subsequently, yield changes. Additionally, backflow occurred when Richardson number for the subcritical inlet reached approximately 7. In effective mixing, simulated yields were approximately 15 % lower than the ideal theoretical yields, calculated using the reaction rate constant at the mixed temperature.

中文翻译：

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Y 型液结混合器混合性能的数值分析及其对超临界水解收率的影响


本研究使用具有离散相模型的大涡模拟研究了 Y 结混合器中用于超临界水解的混合行为。使用具有一阶动力学的两步反应模型，基于颗粒的时间温度数据模拟产率变化。有效混合产生了紧密匹配的质量和颗粒流温度分布，两者在混合温度附近都表现出钟形轮廓。尽管流速变化在 ±25 % 以内，超临界水的入口温度从 350 °C 到 430 °C 和亚临界水从 100 °C 到 170 °C 的变化没有显著影响整体混合性能，但它们确实改变了混合温度，从而改变了产量。此外，当亚临界入口的 Richardson 数达到大约 7 时，会发生回流。在有效混合中，模拟产率比理想的理论产率低约 15%，使用混合温度下的反应速率常数计算。