A Comparative Study on the Application of Porous PES and PEI Hollow Fiber Membranes in Gas Humidifcation Process

Humidification process is one of the applications of membrane contactor in which partial pressure of a vapor in the gas stream increases. In this study, two different polyethersulfone and polyetherimide hollow fiber membranes were fabricated and characterized by various test methods and their performance in humidification process under different operating conditions was investigated. The PES membrane has more porous skin layer which its mean pore size and gas permeance are 191% and 566% more than PEI membrane, respectively but its porosity is lower that can be related to its more spongelike structure and higher concentration of the polymer at the cloud point. On the other hand, the water vapor flux of PEI membrane is higher than PES membrane that can be related to the difference in the sublayer structure of the membranes which causes water vapor to condense along the pores of the membrane. Furthermore, the difference in water vapor fluxes between PEI and PES membrane increases as the operating pressure/liquid temperature increases that may be related to the intensification of pore condensation phenomenon. The results of this research show that the structure of membrane sublayer has critical effect on the vapor flux in the humidification process.