中空纤维膜接触器的计算流体力学模拟

利用随机顺序添加算法(Random Sequential Addition,RSA)建立中空纤维膜组件壳程三维几何模型,研究膜组件壳程复杂结构条件下的流体力学特征,并进行了组件壳程流动的数值模拟.结果表明,高雷诺数有利于组件壳程传质.较低的封装分率下,组件壳程对流作用明显,有利于减少死区,充分利用膜接触面积.另一方面,增加封装分率有利于提高相际接触面积,但会降低对流在传质中的作用,并造成成本的提高和膜丝表面积的浪费.

中空纤维膜组件结构对其膜蒸馏性能的影响

对一系列不同封装分率和不同膜面积的中空纤维膜组件进行了直接接触式膜蒸馏对比实验,并考察了操作方式对跨膜通量的影响。结果表明:提高封装分率可以明显降低沟流效应,使壳程流体分布趋于均匀,总体传质、传热效果得到改善,从而使跨膜通量提高,增幅可达40%以上;在组件封装分率较低时,热流体走管程更有利于跨膜传质。在进料状况不变的条件下,随着膜面积的增加,组件单位膜面积的跨膜通量明显降低,而总产量则有所增加。

Prediction Model of Data Envelopment Analysis with Undesirable Outputs

Data envelopment analysis (DEA) has become a standard non parametric approach to productivity analysis, especially to relative efficiency analysis of decision making units (DMUs). Extended to the prediction field, it can solve the prediction problem with multiple inputs and outputs which can not be solved easily by the regression analysis method.But the traditional DEA models can not solve the problem with undesirable outputs,so in this paper the inherent relationship between goal programming and the DEA method based on the relationship between multiple goal programming and goal programming is explored,and a mixed DEA model which can make all factors of inputs and undesirable outputs decrease in different proportions is built.And at the same time,all the factors of desirable outputs increase in different proportions.

用于膜蒸馏的中空纤维组件中沟流效应的数值模拟研究

对用于膜蒸馏的中空纤维组件数学模型进行了求解 ,并用模拟计算结果分析组件中存在的沟流效应。结果表明 ,与纤维丝规则分布的理想组件相比 ,纤维丝随机分布的实际组件中存在的沟流效应使膜蒸馏组件通量大大降低 ;提高组件封装分率可以减轻沟流效应 ;提高膜两侧流体流量可以增加膜蒸馏推动力 。