New Sherwood correlations for hollow fiber membrane contactor modules: Comparison of porous and nonporous asymmetric membranes

A critical drawback of the membrane contactor (MC) process is the detrimental pore-wetting phenomenon, necessitating the use of hydrophobic membranes. A straightforward solution could be to implement nonporous asymmetric membranes; however, the exact implications of this strategy have not yet been quantified. In this work, we compared porous polypropylene (PP) and nonporous polymethylpentene (PMP) asymmetric membranes for the CO₂ degassing MC process. Although the porous PP membrane displayed 7-fold higher CO₂ permeance than PMP, their actual CO₂ degassing performance was similar in the MC process. The membrane resistance for porous PP and nonporous PMP was calculated to comprise 3–20 % and 10–30 % of the total mass transfer resistance, respectively. Upon wetting, however, the membrane resistance for porous PP exacerbates up to 95 %. Therefore, we assert in this work that employing nonporous membranes offers better long-term reliability without performance loss, especially for solutions containing organic compounds. Moreover, we found that PP and PMP membrane performance can be clearly distinguished on the Sh vs Re^b plane; hence, we proposed new Sherwood correlation models specific for nonporous asymmetric membrane modules, displaying better precision than conventional Sherwood models.