直接接触式膜蒸馏脱盐过程的建模及多指标优化

摘要

为了在较低能耗下获得较高的产水率,采用响应曲面法和满意度函数法对直接接触式膜蒸馏脱盐过程进行了建模和多指标优化,考察指标为产水率和热效率,考察因素包括操作参数料液入口温度、透过侧入口温度、膜面流速和组件参数装填系数、长径比等.通过方差分析对预测模型进行了验证.研究分析了各参数对指标的交互作用,发现各参数对考察指标影响显著.利用满意度函数法对膜蒸馏过程进行了多指标优化,获得最优条件为料液入口温度70℃、透过侧入口温度40℃、膜面流速60 m/min、装填系数50％和长径比20.在最优条件下进行实验,获得的产水率为1.697kg·h-1,热效率为88.2％.研究结果可为膜蒸馏过程的优化以及放大设计提供参考.%Modelling and multi-response optimization of direct contact membrane distillation for water desalination are studied to search for a balance between high water productivity and low energy consumption and to maximize water productivity and thermal efficiency simultaneously.Response surface methodology and desirability function approach are applied for modeling and multi-response optimization,in which the investigated objectives are water productivity and thermal efficiency.The effects of both operating parameters and configuration parameters of membrane module are investigated.These parameters include inlet temperatures of feed and permeate,flow velocity of feed,module packing density,and length-diameter ratio of module on the objectives.Models for predicting the objectives are developed and statistically validated by analysis of variance.It is found that both objectives are significantly influenced by the interaction effects of these variables.The different binary interaction effects of the variables on the objectives are illustrated.Multi-objective optimization is conducted using the desirability function approach.The optimal conditions are obtained as follows:70 ℃ in feed inlet temperature,40 ℃ in permeate inlet temperature,60 m/min in flow velocity of feed,50％ in module packing density,and 20 in length-diameter ratio of module.Experiments under the optimal conditions obtain water productivity 1.697 kg · h-1 and thermal efficiency 88.2％.This study may provide reference for optimization and scale-up design of membrane distillation process.