Chlorine decay in pipeline systems under sequential transients based on probability density function

摘要

The dynamic hydraulic condition in water distribution systems significantly affects the decay of chlorine concentrations. There is strong correspondence between the turbulence intensity and chlorine decay and its regression analysis provides a feasible method to determine the chlorine decay coefficients. This study focused on the applicability of chlorine decay under dynamic conditions through transient events at designated intervals with predetermined intensities. To address field conditions for transient generation, the probability density function (PDF), based on the demand curve of the water consumption, was derived and implemented to the generation of transient events with irregular intervals and durations. The temporal variation of residual chlorine concentration in a pipeline system under irregular intervals and intensity of transient events based on predetermined PDF was obtained. The parameters of various chlorine decay models were calibrated using genetic algorithm and the regression equations. The parameters of nth and limited nth order chlorine decay models from regression equation were almost identical to those obtained by calibrations. The performance of the regression equation under various transient intensities and irregular introduction of transients demonstrated potential for the application of the developed method to field of water distribution systems.