The reactor was analysed by a tracer, which was made by electrochemical reaction out of fluid. Tracer was injected as a step of idealized shape in distributor, which evenly made the tracer. Axial dispersion coefficients are estimated from various methods of parameters model in inert fixed bed reactor by the analysis of the ideal step function technique. As a result, maximum values of distribution curves are higher than experimental value, and the response signals predicted are then compared with the measured signal; Method III agrees well with the measured signal : Method IV is very close to the measured signal, but Method II deviates significantly from the measured signal : Method IV is found to give parameter values close to those of the Method III analysis, from which the most realiable values are obtained. Next to the Method IV are, in order of Method IV fitting, the Method V and Method I and Method II. The experimental error of Method III is 1.04 %. Using the axial dispersion coefficient estimated from Method III, we could obtained the following relationship.
D_L = 0.824U_s^0.983 dp^0.933,（㎠/sec）