Study on fouling characteristics of CaCO₃ at low reynolds number

To study the effects of hardness and Reynolds number on the fouling of calcium carbonate under a low Reynolds number, the experimental method and principle for determining the fouling thermal resistance were analyzed theoretically. The experimental device for the whole heat transfer was designed. By changing the concentration of calcium carbonate and the Reynolds number in the fluid, the fouling process of calcium carbonate at a low Reynolds number was studied. The experimental results show that the fouling resistance will reach a fixed value over time, that is, the asymptotic fouling resistance. In the case of a constant Reynolds number, the concentration of calcium carbonate increased exponentially, and the asymptotic fouling resistance increased approximately. When the concentration of calcium carbonate was constant, the fouling resistance growth rate increased, and the asymptotic fouling resistance increased with a decreasing Reynolds number. However, the difference in the fouling rate and the asymptotic fouling resistance under different Reynolds numbers is obvious. Combined with the experimental results, it can be found that the initiation period is mainly determined by the heat transfer surface, and the fouling thermal resistance may be negative in the initiation period. According to the experiment, a predictive model is established.