The first-order model is the most widely utilized model for chlorine decay due to its having only one parameter and an analytical solution. While variable reaction coefficient type models have higher accuracy and wider application range, their widespread uses are hindered by their complexity and the non-existence of an analytical solution. The objective of this study was to develop a variable parabolic reaction coefficient model to simulate and predict chlorine decay in bulk water. The decreasing reactivity of the reacting agents is included in a variable coefficient, which decreases with increasing consumption of the chlorine-reactive species concentration. The model includes minimal parameters that must be calculated, and an analytical solution was derived. Experimental data, including chlorination with different initial chlorine concentrations or temperatures, rechlorination, and water mixing, were utilized to evaluate the accuracy of the variable parabolic reaction coefficient model under different conditions. The relationship between the parameters and temperature was established utilizing the Arrhenius equation. On the basis of assumptions that the chlorine consumed by reactions with the pipe wall does not decrease the variable rate coefficient, this study subtracted the instantaneous aggregate chlorine wall consumption from the total chlorine consumption, so that the parameter values in the VPRC model (derived from laboratory decay tests) can be used in the system model. For output water at the entrance of the WDN with unknown initial chlorine concentration and unknown decay duration from disinfection to entry into the water distribution network, an effective method to determine the model parameter is proposed.

由于一阶模型只有一个参数和一个解析解，因此它是最广泛使用的氯衰变模型。虽然可变反应系数类型模型具有更高的准确性和更广泛的应用范围，但其复杂性和不存在解析解阻碍了其广泛使用。本研究的目的是开发一个可变抛物线反应系数模型来模拟和预测散装水中的氯衰减。反应剂的反应性降低包含在可变系数中，该系数随着氯反应性物质浓度消耗的增加而降低。该模型包括必须计算的最小参数，并导出了解析解。实验数据，包括不同初始氯浓度或温度的氯化、再氯化和水混合，用于评估不同条件下可变抛物线反应系数模型的准确性。参数和温度之间的关系是利用阿伦尼乌斯方程建立的。在假设与管壁反应消耗的氯不会降低可变速率系数的基础上，本研究从总氯消耗中减去瞬时总氯壁消耗，从而使 VPRC 模型中的参数值（由实验室衰减测试）可用于系统模型。