Coupled heat and mass transfer through asymmetric porous membranes with finger-like macrovoids structure
Coupled heat and mass transfer through asymmetric porous membranes with finger-like macrovoids structure
复制标题
通过具有指状大孔结构的不对称多孔膜耦合传热传质
DOI：
10.1016/j.ijheatmasstransfer.2008.07.029
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发表时间：
2009-01-31
影响因子：
5.2
通讯作者：
Zhang, Li-Zhi
中科院分区：
文献类型：
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作者：
Zhang, Li-Zhi
具有指状大孔的不对称多孔膜已经被广泛应用于各种工艺中，无论是直接作为传输介质还是间接作为活性层的衬底。膜的传热传质是影响系统性能的关键参数。然而，以往关于热质传递的研究只把这些膜看作是均匀多孔介质的黑匣子，忽略了它们在结构上的非对称性，未能揭示膜结构与系统性能之间的关系。为了解决这一问题，本研究借助扫描电子显微镜(SEM)对膜的表面和截面结构的观察，对这些膜的热扩散和质量扩散进行了更详细的研究。在模型设置中，将整个膜分为三层：海绵状多孔支撑层，指状大孔洞的多孔介质层，以及较薄、致密、毛孔较小的皮肤层。然后将该模型应用于膜交换器中水分渗透的热质耦合传递分析。结果表明，由于膜内存在每米7万个以上的指状大孔洞，膜的有效扩散率得到了显著提高。(C)2008爱思唯尔有限公司。保留所有权利。
Asymmetric porous membranes with finger-like macrovoids have been extensively used in various processes, either directly as the transfer media or indirectly as the substrate for active layer. Heat and mass transfer through such membranes are the key parameters influencing system performance. However, previous studies on heat and mass transport only treated these membranes as a black box of homogeneous porous media by neglecting their asymmetric nature in structure, which fails to disclose the relations between the membrane structure and system performance. To solve this problem, this study gives a more detailed investigation of the thermal and mass diffusion through these membranes, with the help of scanning electron microscope (SEM) observations of membrane surface and cross-sectional structures. in the model setup, the whole membrane is classified into three layers: a sponge-like porous support layer, a layer of porous media with finger-like macrovoids, and a thin denser skin layer with smaller pores. The model is then incorporated into the analysis of Coupled heat and mass transfer in a membrane exchanger for moisture permeations. Results show that the effective diffusivity of the membrane has been dramatically improved due to the existence of more than 70,000 per meter large finger-like voids inside. (C) 2008 Elsevier Ltd. All rights reserved.