id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
alkej-577	Mahdi, Iman Hahider	دراسة التشتت المحوري لعمود الطبقة الثابته من المبادلات الايونية	2009	12	.pdf	application/pdf	5355	146	49	Abstract A mathematical model is developed which predicates the performance of cylindrical ion exchange bed involving comparing of axial dispersion model for cation exchange column with different assumption, this model permits the performance to predicate the residence time within the bed with the variance, axial dispersion and Pecklet No. to indicated deviation from plug flow model. Several workers studied dispersion with porous media, the first who deal with axial dispersion O. Levenspiel 1958 when he study the commercial application of step experiment and he design chart to ease the calculation of axial dispersion, H. Dunck 1966 study he effect of axial dispersion on the elution band of nonlinear equilibrium chromatography and the effect change in axial dispersion coffin with elution velocity , O .Levenspiel 1972 found the c-curve in closed vassal for various extend of back mixing as predicated the dispersion model , C.Y. Wen, T. Tfan l.t. 1975 point that the axial dispersion provides satisfactory description only of mixing model that not deviated significantly from plug flow, R. Shinnar 1987emphasized that the application of axial dispersion model for Pe No. value for less than 10 is not advised, Iman Hahider Mahdi Al-Khwarizmi Engineering Journal, Vol. 5, No. 4, PP 1-12 (2009) 2 C. T. Tan1987 the value of dispersion coefficient are either assumed or calculated from molecular diffusivity and radial pore velocity prior to incorporation into the model the radial dispersion R. Y. A. Ofoli, 1991 reported that axial dispersion model is suitable for analysis of reactor up to 30% conversion , Y. Tsaur and D. Shallcross 1997 developed a model to simulate ion exchange performances with fixed annular bed which take into account the radial dispersion in effect in both solution and exchange phases, however the model assumes instantaneous equilibrium between ions in the solution and exchange phases existed throughout the exchanger, M. A. Barros and Aszpla 2002 analyze the Cr +3 ion to exchange in NaA zeolite in presence of K + ,Cu +3 ion in binary and ternary cation exchange with evaluate the dimensionless variance of Breakthrough curve which useful to estimate the axial dispersion of the bed, M. Doung and D. Shallcross 2002 developed theoretical model of fixed bed ion exchange and obtained the model for pure dispersion without ion exchange performance, I. M. Abu-Reesh and B.l F. Abu- Sharkh 2003 make a comparison of axial dispersion and tank-in-series models for simulating the performance reactors they found that tank-in-series models presents computational advantages compared to dispersion model , Doung M. and Shallcross D.2005 made a series of experiment in wedge-shape cell ion exchange for both Na-and H- form bed with different flow rate lead to indicated dispersion coefficient function of pore velocity and radial distant of the wall.	cache/alkej-577.pdf	txt/alkej-577.txt