Abstract

Heat exchanger fouling is a complex process and closely associated with the operating conditions and surface properties. Many studies have been carried out to model various stages of the fouling process. These include the induction period, initial fouling rate (IFR), and fouling growth. Among them, IFR is of primary importance since its reduction leads to a longer operating time. Several studies have been conducted to model IFR as a function of operating conditions. In these studies, it has been assumed that IFR is closely attributed to mass transfer and surface adhesion while the removal stage has not been taken into consideration. Moreover, the adhesion stage was defined by a chemical reaction, which was not a function of surface properties even though many other studies showed otherwise. In this study, the nucleation based model is proposed to predict IFR as a function of operating conditions as well as surface properties. Mass transfer, adhesion, and removal stages are also considered as part of the modelling in this study. The adhesion stage is also defined by a chemical reaction, which is a function of nucleation rather than bulk concentration. The comparison of the proposed model and experimental data shows a regression coefficient of 0.96106. This implies that there is a reasonable agreement between experimental data and model prediction. Finally, the impact of all influential parameters has been prioritized by a partial derivative approach. The results show that, under the experimental conditions in this study, the IFR sensitivity with respect to surface energy is 19%. This indicates surface energy, as a surface property, is one of the dominant parameters in IFR modelling and cannot be neglected.

中文翻译：

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基于成核率的二水硫酸钙初始结垢率的数学模型

摘要

热交换器结垢是一个复杂的过程，并且与运行条件和表面特性密切相关。已经进行了许多研究以模拟结垢过程的各个阶段。这些包括诱导期，初始结垢率（IFR）和结垢增长。其中，IFR是最重要的，因为减少它会导致更长的运行时间。已经进行了几项研究以根据运行条件对IFR进行建模。在这些研究中，已假定IFR与传质和表面粘附密切相关，而未考虑去除阶段。而且，粘附阶段是由化学反应确定的，尽管许多其他研究表明并非如此，但化学反应不是表面性质的函数。在这个研究中，提出了基于成核的模型来预测IFR与操作条件以及表面性能的关系。传质，附着和去除阶段也被视为本研究建模的一部分。粘附阶段也由化学反应定义，化学反应是成核作用而不是体积浓度的函数。所提模型与实验数据的比较表明回归系数为0.96106。这意味着实验数据和模型预测之间存在合理的共识。最后，所有影响参数的影响已通过偏导数法进行了优先排序。结果表明，在本研究的实验条件下，IFR对表面能的敏感性为19％。这表明表面能作为表面性质，