运行工况对多向扰流强化管CaSO4污垢特性的影响

为更深入并准确研究运行工况条件对多向扰流强化管CaSO_4污垢特性的影响,基于FLUENT软件的UDF功能构建了恒壁温条件下结垢传质过程与温度场的耦合作用关系,进一步采用田口法对运行工况致垢的贡献率进行了模拟比较,分析了贡献率较大的运行工况对污垢特性的影响。结果表明:溶液溶度致垢的贡献率占53.2%,而壁面温度、进口流速和进口温度的贡献率分别为22.2%、19.3%和5.3%;溶液溶度在4.0～2.5 kg/m~3,污垢热阻降低达90.47%,并且随溶度降低其相邻溶度间降低比例基本不变;壁面温度在340.0～315.0 K时,污垢热阻降低了65.22%,在前一阶段相邻温度间降低比例基本上不变,当达到320.0 K后降低明显;流速在1.0～2.5 m/s时,随流速的增加,污垢热阻降低68.65%,且随流速的增加,相邻流速间降低的速度明显减缓。

Operating conditions affecting CaSO4 fouling characteris-tics in multi-spiral groove enhanced tube

In order to more deeply and accurately study the effect of operating conditions on the fouling characteristics of CaSO4 in multi-spiral groove enhanced tube, the coupling function between the fouling mass transfer process and the temperature field under constant wall temperature conditions was constructed based on the UDF function of FLUENT software. The Taguchi method was used to simulate and compare the contribution rate of fouling in operating conditions, and the impact of operating conditions with large contribution rate on fouling characteristics was analyzed. The results show that the contribution rate of solution solubility to scale is 53.2%, while the contribution rates of wall surface temperature, inlet flow rate and inlet temperature are 22.2%, 19.3% and 5.3%, respectively; the solution solubility is in the range of 4-2.5 kg/m3, the thermal resistance of the fouling is reduced by 90.47%, and the decreasing ratio between the adjacent solubility is almost constant with decreasing solubility; the wall surface temperature is in the range of 340-315 K, the fouling thermal resistance is reduced by 65.22% and in the previous phase the reduction ratio between adjacent temperatures is basically the same, but decreases significantly when reaching 320 k; flow rate is in the range of 1-2.5 m/s, with the increase of flow rate, the thermal resistance of fouling is reduced by 68.65%, and with the increase of flow velocity, the rate of decrease between ad-joining flow rates has slowed down significantly.