Abstract:

Response surface methodology (RSM) was used for modeling and optimization of operating parameters and permeate flux for hollow fiber air gap membrane distillation (AGMD-HF) desalination process with simulated 3.5% (mass) seawater as feed solution. Hot feed-in temperature, cold feed-in temperature and fluid flow rate were chosen for experiment optimization based on central composite design (CCD). A quadratic polynomial regression model for permeate flux and operating parameters was developed. Accuracy of the model was validated by analysis of variance (ANOVA), RSM and comparison of predicted and experimental permeate flux response. Furthermore,the best optimal level of operating parameters and solar-powered verification were performed. During the experiments,permeate conductivity was constantly kept below 10 μS·cm^-1, and relative ion rejection rate was above 99.99%. A R² of 0.986,p-value smaller than 0.0001 for ANOVA were obtained, and average error of predicted and experimental permeate flux was 6.95%. Moreover, the best optimal operating parameters of 83.5℃,13.2℃ and 60.2 L·h^-1 based on desirability function and solar-powered process permeate flux of 6.47 L·m^-2·h^-1 were presented. Consequently, modeling and optimization of operating parameters for permeate flux response could be helpful for scaling up AGMD-HF desalination process, and introduction of solar power as an alternative of conventional electric heat source could have better application prospect for AGMD-HF desalination.

Key words: response surface methodology, hollow fiber air gap membrane distillation, modeling, optimization, distillation, desalination, design

摘要：

利用响应曲面法(RSM),以模拟标准海水(质量分数3.5%)为进水对中空纤维空气隙式膜蒸馏(AGMD-HF)海水淡化过程的影响因子和膜通量指标进行了模拟优化。通过面向中心复合设计法(CCD)实现了基于热料液进水温度、冷凝液进水温度和料液流量的实验优化设计,并建立了响应值与影响因子之间的二次多项式回归模型。方差分析(ANOVA)、RSM分析及实验响应值与预测值的对比验证了该模型对影响因子和膜通量模拟优化的可信度。进一步地,通过期望函数的引入确定了各影响因子最佳水平,并利用太阳能加热驱动过程实验进行验证。结果表明,ANOVA的决定系数R²达到0.986,p值则低于0.0001;实验膜通量与预测值平均误差仅为6.95%,产水电导率始终保持在10 μS·cm^-1以下,脱盐率稳定在99.99%以上;最佳影响因子水平分别为83.5℃、13.2℃和60.2 L·h^-1,在此条件下太阳能加热驱动过程膜通量达到6.47 L·m^-2·h^-1。该实验不仅为潜在可行的规模放大过程提供了可参照的操作参数,而且表明将太阳能引入AGMD-HF海水淡化过程具有很强的实际应用潜力。

关键词: 响应曲面, 中空纤维空气隙式膜蒸馏, 模拟, 优化, 蒸馏, 脱盐, 设计