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Experimental Determination of Isothermal Vapour Transfer Rates between Moist Air and a Hygroscopic Solution through a Hydrophobic Synthetic Membrane
Author(s) -
Isetti Carlo,
Magrini Anna
Publication year - 1996
Publication title -
indoor air
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.387
H-Index - 99
eISSN - 1600-0668
pISSN - 0905-6947
DOI - 10.1111/j.1600-0668.1996.t01-1-00009.x
Subject(s) - mass transfer , water vapor , membrane , isothermal process , chemistry , chemical engineering , chromatography , thermodynamics , organic chemistry , biochemistry , physics , engineering
This paper reports on an investigation into the rates of isothermal vapour transfer taking place between moist air and a hygroscopic solution through a hydrophobic synthetic membrane. The membrane acts as a porous barrier between the phases, being permeable to the vapour but not to the contacting liquid. Experimental results, obtained for a polyethylene membrane with a thickness of 170 μm, show that the total mass transfer coefficient between moist air and a saturated LiCl solution is of the order of 0.078 g/m 2 hPa at 21°C, at least when the air phase moves at a velocity ranging from 1.5 to 3 m/s. The vapour transfer rate through the membrane is essentially controlled by the convective resistance to vapour transport on the air side and by the resistance to mass transport offered by the membrane. The vapour flux exchanged between the moist air and the hygroscopic solution, although limited by the membrane, appears to be sufficiently high to make the use of vapour membrane exchangers technically feasible in air dehumidification and conditioning.