Abstract

In this study, a dynamic mathematical model for direct contact membrane distillation (MD) is developed and validated. Two model formulations were considered each of which can be cast in lumped or spatial structure. All types of models were verified against experimental transient data for the permeate and brine temperatures. The proposed models provided a perfect prediction of the measured data except at the lowest flow rates. Judicious model modification helped to enhance the model performance. The tuned model is used to analyze the process dynamic in one-dimensional space. It is found that the process possesses an enhanced convective heat transfer mechanism substantiated by the high values for the temperature polarization and Biot number. At very low flow rates, the membrane conduction resistance prevails limiting the heat transfer at the membrane interface and hence the process performance. Preliminary analysis of the special transient operation of the MD process to address challenging operations such as scheduled production strategy and/or intermittent energy sources is outlined.

摘要

在本研究中，开发并验证了直接接触膜蒸馏 (MD) 的动态数学模型。考虑了两个模型公式，每个模型公式都可以在集总或空间结构中进行铸造。所有类型的模型都针对渗透和盐水温度的实验瞬态数据进行了验证。除了在最低流速下，所提出的模型提供了对测量数据的完美预测。明智的模型修改有助于提高模型性能。调谐模型用于分析一维空间中的过程动态。发现该过程具有增强的对流传热机制，这由温度极化和 Biot 数的高值证实。在非常低的流速下，膜传导阻力占优势，限制了膜界面处的传热，从而限制了工艺性能。概述了对 MD 过程的特殊瞬态操作的初步分析，以解决具有挑战性的操作，例如计划生产策略和/或间歇性能源。