This paper discusses theoretical and experimental considerations of organic molecules nucleating inside tubular reactors or nucleators. Temperature evolution of these liquid systems is experimentally shown for different flow rates as a function of distance when these nucleators are immersed into a water bath set at spontaneous nucleating conditions. When different restrictions in the flow path are introduced before the cooling phase of the liquid; important differences on the nucleation rates are observed. For this study, Aspirin was dissolved in a blend of water and ethanol in a 50/50 vol%. At a concentration of 200 mg/mL and a nucleation temperature of 10 °C, demonstrated to be close to the metastable zonewidth, these flow restrictions show an antagonistic effect on the nucleation rate. One restriction, placed right before the nucleator enters the cooling bath, induces a reduction in nucleation rate. Putting more restrictions into the flow path with an equal separation of 5 cm in between, the nucleation recovers back to its initial value when a second restriction of an expansion ratio 2 is applied. Restrictions with an expansion ratio of 4 exceed this nucleation rate up to an order of magnitude when more than 2 restrictions are put in place.

At a higher kinetic driving force defined KDF, at a concentration of 300 mg/mL of Aspirin, the influence of the restriction becomes invariant as a function of the expansion ratio. For all experiments, the nucleation rates is highly increased with the number of restrictions introduced into the flow path. A thermal gradient difference by using the restrictions on the cooling rate of the liquid flowing inside the tubing was not observed experimentally. Therefore only hydrodynamic changes of the flow seems a plausible cause for this nucleation rate - restriction dependence as it is expected that finite amplitude perturbations, amplified by the use of restrictions, cause vortex shedding in current experimental setup.

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本文讨论了有机分子在管状反应器或成核器内成核的理论和实验考虑。当将这些成核剂浸入在自发成核条件下的水浴中时，通过实验显示了这些液体系统的温度变化对于不同流速随距离的变化。如果在液体冷却阶段之前在流路中引入了不同的限制；观察到成核速率的重要差异。在本研究中，将阿司匹林以50/50体积％的比例溶于水和乙醇的混合物中。在200 mg / mL的浓度和10°C的成核温度下，已证明接近亚稳区域宽度，这些流动限制显示出对成核速率的拮抗作用。一个限制 正好在成核剂进入冷却浴之前放置，会导致成核速率降低。将更多的限制以相等的5厘米的间隔放置在流路中，当施加第二个扩展比2的限制时，成核恢复到其初始值。当设置了两个以上的限制时，扩展比率为4的限制会超出此成核速率，达到一个数量级。

在阿司匹林浓度为300 mg / mL的较高KDF动力学驱动力下，限制的影响随膨胀比而变化。对于所有实验，成核速率随引入流路的限制数量而大大增加。在实验中未观察到通过限制在管内流动的液体的冷却速度而产生的热梯度差。因此，仅流体的流体动力学变化似乎是该成核速率的合理原因-限制依赖性，因为可以预期，通过使用限制而放大的有限振幅扰动会在当前实验装置中引起涡旋脱落。

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