Mass transfer enhancement in double-pass concentric-tube mass exchangers under sinusoidal wall fluxes with external recycle

[[abstract]]The influences of external recycle at the ends on double-pass laminar counterflow concentrictube mass exchangers with sinusoidal wall flux distribution are investigated analytically. An analytical method is proposed to obtain a general solution by using the complex functions in combining the original boundary value problem into an ordinary differential equation with the aid of Frobenius method. Theoretical results show that a suitable adjustment of the permeable-barrier position can effectively enhance the mass transfer rate, leading to an improved device performance in mass transfer efficiency as compared with that in the single-pass operation (without a permeable barrier inserted in parallel into a circular tube). The mass-transfer efficiency enhancement due to the desirable effect of forced-convection increment in two flow patterns of double-pass devices has been illustrated with the recycle ratio, mass-transfer Graetz number, permeable-barrier location and dimensionless permeablebarrier parameter as parameters.[[notice]]補正完