抄録
Removal rate of renal toxic substances in a dialyzer depends on the mass transfer rate through a dialysis membrane and in the dialysate-side boundary films. To increasing dialysis fluid-side mass transfer rate, the most important factors are jacket structure and hollow fiber shape, so newly developed dialyzers with improved jacket structure and hollow fiber shape that optimize dialysis fluid flow have been made available on the market in recent years.
The overall mass transfer resistance is the sum of the resistances due to the membrane itself and the thin boundary film that is formed in the fluids on both sides of the membrane (Series Boundary Film Resistance Model). The boundary film mass transfer coefficient for a fluid flowing within a straight tube has been obtained theoretically. Colburn's equation converted to mass transfer by analogy with the theoretical approximation equation that yields the boundary film coefficient of heat transmission when laminar flow occurs in a straight tube, can be used to calculate the boundary film transfer in laminar mass transfer.
In the present study, mass transfer correlation equations between Sherwood number (Sh) containing dialysis fluidside mass transfer film coefficient and Reynolds number (Re) were formed for newly developed dialyzers. The exponents of Re were 0.62 for APS-15S whereas approximately 0.5 for the newly developed dialyzers. The dialysis fluid-side mass transfer film coefficients of the newly developed dialyzers were higher than those of the conventional dialyzer. Based on the mass transfer correlation equations, introduction of short taper, full baffle of dialyzer jacket and further wave-shaped hollow fiber improves the dialysis fluid flow.
