Abstract: Based on correlations of flow resistance and sea water boiling point elevation (BPE) applicable to the low-temperature multiple effect distillation (LT-MED) desalination plant, the thermodynamic losses in a large-scale LT-MED desalination plant were calculated and analyzed, including the distribution and proportion of various thermodynamic losses caused by BPE and flow resistances. The effect of the number of evaporator/condenser on thermodynamic losses was studied. The result indicates that, for a large-scale LT-MED desalination plant with constant production capacity, the total thermodynamic losses increases with the number of effects. The thermodynamic loss caused by BPE constitutes the highest proportion while that by the flow resistances can not be ignored. According to the analysis on the loss, the operating characteristics of LT-MED desalination system are summarized as small temperature difference, low pressure drop, saturation states and high sensitivity.

Key words: desalination, multiple effect evaporation, heat transfer, thermodynamic process, thermodynamic loss, boiling point elevation, operating characteristic

摘要： 基于低温多效蒸发海水淡化装置的各种阻力和海水沸点升高（BPE） 关联式，计算了海水淡化装置中流动阻力、海水沸点升高等造成的传热过程热力损失，分析了各项热力损失在各效蒸发/冷凝器中的分布、随蒸发/冷凝器数量的变化规律等。结果表明：产水量、浓缩比和加热蒸汽温度等参数均保持不变的前提下，总的热力损失随着装置的蒸发/冷凝器数量而增加；BPE引起的热力损失占最大比例，但流动阻力引起的热力损失不可忽略。通过对海水淡化装置热力损失的分析，提出了低温多效蒸发海水淡化装置“小温差、低流阻、饱和态、高敏感”的工作特征理论。

关键词: 海水淡化, 多效蒸发, 传热, 热力学过程, 热力损失, 沸点升高, 工作特征