Laminar flow and heat transfer between a regularly distributed elliptical hollow fiber membrane tube bank

Abstract

Effects of the various semiaxis ratios (ble/ale, bri/ari), longitudinal and transverse pitch-to-diameter ratios (SL/d, ST/d) on the longitudinal fluid flow and heat transfer between a regularly distributed elliptical hollow fiber membrane tube bank (EHFMTB) employed for air humidity control are investigated. In the tube bank, the liquid stream flows inside the fibers, while the air stream flows axially between the fibers in a counter flow arrangement. Two regularly populated arrangements of the tube bank, in-line and staggered, are considered. Two representative elements containing two fibers and the air stream flowing axially between the fibers are selected as the calculating domains. The governing equations for the fluid flow and the heat transfer between the EHFMTB are established and numerically solved via a boundary-fitted coordinate transformation method. The fully developed Poiseuille numbers (fRe) and local Nusselt numbers under a uniform temperature condition (NuT) under various semiaxis ratios, longitudinal and transverse pitch-to-diameter ratios are then obtained. It can be found that the fRe and NuT have their largest values when the ble/ale and bri/ari both are equal to 1.0 and 1.5 for the in-line and the staggered arrangements, respectively. The SL/d and ST/d have larger influences than the ble/ale and bri/ari on the fRe and NuT.