基于分布参数方法,对低温多效海水淡化系统中的单效水平管降膜蒸发器进行三维数值模拟,分析蒸发器传热参数在不同进料海水盐度及喷淋密度下的变化及空间分布规律.模拟结果显示:蒸发器平均传热系数随进料海水喷淋密度的增加及盐度的降低均有所升高.在管内蒸汽在二管程末端完全凝结的前提下,蒸发器表观传热温差随进料海水喷淋密度的增加及盐度的降低而减小.二次蒸汽最大饱和温度降随进料海水喷淋密度的增加及盐度的降低而减小.传热量及传热系数在蒸发器内空间分布规律随喷淋密度变化而改变.
Based on the distributed parameter model (DPM),a three-dimensional simulation is conducted on a single horizontal tube falling film evaporator applied in the low temperature multi-effect distillation system.The variation law of the of heat transfer parameters within the evaporator under different brine inlet salinities and spray densities are analyzed.The results show that the averaged heat transfer coefficient of the evaporator increases with the increment of brine inlet spray density and the decrement of brine inlet salinity.On the premise that the steam condenses completely at the end of the second tube pass,the superficial temperature difference of the evaporator decreases with the increment of brine inlet spray density and the decrement of brine inlet salinity.The maximum intertube vapor temperature drop decreases with the increment of brine inlet spray density and the decrement of brine inlet salinity.The distribution law of heat transfer rate as well as heat transfer coefficient varies as the variation of brine inlet spray density.
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