CIESC Journal ›› 2009, Vol. 60 ›› Issue (1): 28-34.
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LIU Xiaowei,MIN Jingchun
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刘晓伟,闵敬春
Abstract:
An experimental set-up was designed and constructed to investigate the water vapor permeation through membranes.The test section mainly consisted of an airflow channel, a membrane, and a water tank, which formed a sandwich structure.The channel had a 5 mm×50 mm cross-section and a 800 mm length.Flowing in the channel was an air fluid with a low humidity.The membrane was sandwiched between the channel and water tank, forming an air gap with a higher humidity between the water and membrane.Moisture was transferred from the water to the air stream in the channel through the air gap and membrane.Tests were conducted on two membranes that included the PVDF (polyvinylidene fluoride) and PES (poly ether sulfone) membranes.The water vapor permeations through membranes were investigated.The membrane resistance was obtained by subtracting the convective moisture resistance in the channel and the moisture resistance caused by the air gap from the total moisture resistance.Through combination with the sorption curves of membranes, the diffusivities of moisture in membranes were estimated.The results showed that the diffusivities of the PVDF and PES membranes were in the order of 10-6 kg·m-1·s-1, and the former was about 4 times as great as the latter.
Key words: 薄膜, 水蒸气, 传质阻力, 吸附曲线, 扩散系数
薄膜,
摘要: 设计制作了用于研究水蒸气透膜传递特性的实验装置,其中实验段主要由流体通道、薄膜和水槽三部分组成。通道的截面为5 mm×50 mm 的矩形、总长800mm,通道中通入相对湿度较低的空气。膜夹在通道与水槽之间,在水面和膜之间形成高湿度的空气层。水蒸气由空气层向通道内传递。基于这种结构,建立了对流传质阻力、薄膜传质阻力和空气层扩散阻力的三阻力串联模型。利用上述装置对PVDF(polyvinylidene fluoride)膜、PES(poly ether sulfone)膜以及纤维素膜的透湿特性进行了测量,通过用总阻力减去对流传质阻力和空气层阻力从而得到了薄膜自身的传质阻力,结合膜等温吸附曲线进而计算出水蒸气在膜中的扩散系数。结果表明PVDF膜中的扩散系数最大,纤维素膜最小。
关键词: 薄膜, 水蒸气, 传质阻力, 吸附曲线, 扩散系数
LIU Xiaowei, MIN Jingchun. Experimental study of moisture penetration through membranes[J]. CIESC Journal, 2009, 60(1): 28-34.
刘晓伟, 闵敬春. 薄膜透湿特性实验研究 [J]. 化工学报, 2009, 60(1): 28-34.
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