Dipartimento di Fisica e di Scienze della Terra, Università degli Studi di Messina, Contrada Papardo, I-98166 Messina, Italy.
J Phys Chem B. 2013 Jul 11;117(27):8189-95. doi: 10.1021/jp403332y. Epub 2013 Jun 25.
The return of a supercooled liquid to equilibrium usually begins with a fast heating up of the sample which ends when the system reaches the equilibrium freezing temperature. At this stage, the system is still a microsegregated mixture of solid and liquid. Only later is solidification completed through the exchange of energy with the surroundings. Using the IAPWS-95 formulation, we investigate the adiabatic freezing of supercooled water in a closed and rigid vessel, i.e., under thermally and mechanically isolated conditions, which captures the initial stage of the decay of metastable water to equilibrium. To improve realism further, we also account for a fixed amount of foreign gas in the vessel. Under the simplifying assumption that the system is at equilibrium immediately after the nominal freezing temperature has been attained, we determine-as a function of undercooling and gas mole number-the final temperature and pressure of the system, the fraction of ice at equilibrium, and the entropy increase. Assuming a nonzero energy cost for the ice-water interface, we also show that, unless sufficiently undercooled, perfectly isolated pure-water droplets cannot start freezing in the bulk.
过冷液体恢复平衡通常始于样品的快速加热，当系统达到平衡冻结温度时结束。在这个阶段，系统仍然是固体和液体的微分离混合物。只有在通过与周围环境交换能量后，才会完成固化。使用 IAPWS-95 公式，我们研究了封闭刚性容器中超冷水的绝热冻结，即在热和机械隔离的条件下，这捕获了亚稳水衰减到平衡的初始阶段。为了进一步提高现实性，我们还考虑了容器中固定数量的外来气体。在假设系统在名义冻结温度达到后立即处于平衡的简化假设下，我们确定了-作为过冷度和气体摩尔数的函数-系统的最终温度和压力、平衡时的冰分数以及熵增加。假设冰-水界面存在非零能量成本，我们还表明，除非过冷度足够低，否则完全隔离的纯水液滴在本体中无法开始冻结。
