Conjugate heat and mass transfer in a counter-flow spiral hollow fiber membrane tube bank for liquid desiccant air dehumidification

Abstract

Membrane contactor formed by spiral hollow fiber membrane tube bank (SPHFMTB) or straight bank (STHFMTB) has been employed for liquid desiccant air dehumidification. Comparative analysis on the dehumidification performance and the conjugate heat and mass transfer characteristics inside the membrane contactors are carefully investigated. The calculation domains contain straight and spiral types of hollow fiber semi-permeable membrane tubes and two internal streams in a counter-flow arrangement. The product of friction factor and Reynolds number fRea, Nusselt and Sherwood numbers (Nua and Sha) of the airflow for various tube numbers (4, 7, 9) and pitch ratios (0.6, 0.3, ∞) are obtained. It is found that the SPHFMTBs exhibit better moisture removal ability than the STHFMTBs. The fully developed mean Nua and fRea numbers increase with the Reynolds number of the air stream Rea for the both SPHFMTBs and STHFMTBs. Though the SPHFMTBs are relatively more beneficial to enhancement of heat transfer, the corresponding flow resistance is added as well. The relevant data obtained from the present simulation are expected to promote the development of the geometry optimization on hollow fiber membrane tube bank.