Theoretical and experimental studies of flux enhancement in air gap membrane distillation

• Main Authors: Chun-Hsuan Cheng, 鄭竣軒
• Other Authors: Chii-Dong Ho
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/66857532057930563106

碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 102 === The air gap membrane distillation (AGMD) device is a membrane distillation (MD) operation for which air gap between the membrane and the condensation surface in contact with the cold stream. The existence of temperature gradient in a AGMD system means that the membrane surface temperatures always contact with bulk temperatures. Attempts to reduce the effect of temperature polarization were made implementing eddy promoters to improve the flow characteristic. A new design of the parallel-plate AGMD device using roughened-surface flow channel for heat transfer enhancement was proposed to increase the pure water productivity in saline water desalination. The purposes of this study are (1) to develop the heat-transfer coefficient correlation for the roughened-surface channel; (2) to develop a one-dimensional mathematical model and propose a general numerical method for predicting pure water productivity of membrane distillation systems; (3) to study the effect of temperature polarization on the pure water productivity improvement. The correlated equation of estimating heat-transfer coefficient for the eddy promoter by using roughened-surface flow channel was obtained, and the results show that the agreement between the experimental results and the theoretical predictions are fairly good.