纤维素中空纤维膜气体加湿性能的研究

采用纤维素N甲基吗啉N氧化物(NMMO)水三元纺丝体系,以去离子水为芯液,自来水为凝胶浴,湿法纺制了纤维素中空膜.经自然干燥后该膜的轴向、径向都明显收缩,断面呈现均质致密结构.干膜在水中会明显溶胀,重新润湿后具有气密性.考察了加湿水温、水气压力差等因素对膜的水渗透通量的影响,并初步测试了膜对质子交换膜燃料电池(PEMFC)反应气体H2和O2的加湿性能.实验结果表明该膜透水性能较优,气体加湿效果明显,具有应用于PEMFC反应气体加湿系统的潜力.

GAS HUMIDIFICATION PERFORMANCE OF CELLULOSE HOLLOW FIBER MEMBRANES

With deionized water as bore fluid and tap water as external coagulant,cellulose hollow fiber membranes (CHFM) were prepared from a dope composed of cellulose/N-methylmorpholine-N-oxide (NMMO)/H_2O using a wet spinning process. The prepared CHFM showed dramatic dimension shrinkage after being naturally dried and the resulted dry CHFM possessed a homogeneously dense structure that could ensure the water permeation stability during the humidification process. The swelling performance of CHFM in water at different temperatures was tested and it was proven that increasing temperature would inhibit cellulose swelling in water. Also its permeation rates in “water-swollen" state for gases such as H_2 and O_2 were measured that could help to make sure only little gas leakage would happen during the humidification process. Influence of water-gas pressure difference and water temperature on the water permeation flux of CHFM was investigated. The results show that the water permeation flux of CHFM increased with both the water-gas pressure difference and water temperature. With water-gas pressure difference at 0.2 MPa and water temperature at 80℃,its water permeation flux could reach as high as 0.63 L/(m2·h). The preliminary experiments were carried out to test its humidification ability for reacting gases of proton exchange membrane fuel cell (PEMFC). With the self-made humidification module,the relative humidity of gases could be increased to over 90% under certain conditions. All these results show that the humidification ability of CHFM is excellent,which means that it is suitable to be used in the humidification system for PEMFC.