The importance of supersaturation on determining the solid-liquid equilibrium temperature of waxy oils
The importance of supersaturation on determining the solid-liquid equilibrium temperature of waxy oils
复制标题
DOI：
10.1016/j.fuel.2017.06.042
复制
发表时间：
2017-10-15
期刊：
影响因子：
7.4
通讯作者：
Negrao, Cezar O. R.
中科院分区：
文献类型：
--
作者：
Andrade, Diogo E. V.;Marcelino Neto, Moises A.;Negrao, Cezar O. R.
结晶是从无序相形成有序固体结构的过程。这一事件分为两个主要阶段，即成核和晶体生长。由于石蜡成核是一个随机过程，需要过冷来启动该过程。也就是说，晶体沉淀的开始与最高热力学固液平衡温度不一致。因此，在冷却期间，要求流体达到低于饱和的特定温度，即，一种亚稳态，以启动晶体成核过程。饱和温度与结晶温度之差称为过冷度。由于这种亚稳条件不仅存在于结晶过程中，而且存在于晶体的溶解过程中，因此本文提出了一种利用流变仪和DSC实验结果来确定最高固液热力学平衡温度的方法。可以预期，拟定方案规定，当以非常低的加热速率加热材料时，认为最高固液热力学平衡温度接近溶解温度。(C)2017爱思唯尔有限公司版权所有
Crystallization is a process where an ordered solid structure is formed from a disordered phase. This event is divided in two main stages, namely nucleation and crystals growth. As paraffin nucleation is a stochastic process, a supercooling is needed to initiate the process. In other words, the beginning of crystal precipitation does not coincide with the highest thermodynamic solid-liquid equilibrium temperature. Therefore, during the cooling it is required that the fluid reaches a certain temperature below saturation, i.e.,a metastable state, to initiate the crystal nucleation process. The difference between the saturation temperature and the crystallization temperature is called degree of supercooling. As this metastable condition may exist during not only the crystallization but also the dissolution of crystals, this work proposes a procedure to determine consistently the highest solid-liquid thermodynamic equilibrium temperature by using the results of rheometer and DSC experiments. It can be anticipated that the proposed protocol states that the highest solid-liquid thermodynamic equilibrium temperature is considered to approach the dissolution temperature when the material is heated at a very low heating rate. (C) 2017 Elsevier Ltd. All rights reserved.