机械压汽蒸馏海水淡化系统的可用能分析

EXERGY ANALYSIS OF A EXPERIMENTAL MECHANIC VAPOR COMPRESSION DISTILLATION SYSTEM

为获得更加节能高效的海水淡化技术,用热力学第二定律分析机械压汽蒸馏(MVC)海水淡化实验系统的(火用)效率。实验测得MVC海水淡化过程的(火用)效率为2.8%;其中蒸发-冷凝器、压缩机、水泵和预热器的(火用)损分别占34.6%、35.5%、16.9%和10.2%。利用数学模型分析了压缩比、蒸发温度和盐水浓度等不可逆参数对实验系统(火用)效率的影响。MVC技术虽然充分回收利用了余热,具有较高的热效率,但实验结果表明该技术的(火用)效率仍然较低。从降低损失的角度来看,应用MVC技术的重点是选用高性能低压缩比的压缩机、经济且耐腐蚀的换热管和适当的蒸发温度。

The exergy efficiency of the experimental system of the mechanic vapor compression（MVC） desalination was analyzed with the second law of thermodynamics to obtain the high efficiency and enengy-saving art of desalination. The exergy efficiency of the process is just 2.8% ; and in evaporator-condensator, compressor, pump and preheaters, the exergy losses are 0. 346,0. 355,0. 169, and 0. 102 respectively. Parameters impacting exergy efficiency are eompression rate, evaporate temperature and the eoncertration of saline. The effect of thses irreversible parameters on the exergy efficiency of the experimental system was calculated with mathematic models. Although the waste heat was recovered in MVC art, the exergy efficiency was still low. The system design of MVC desalination had paid much attention on high effeient compressor, erode-enduring exchanger tubes and evaporation temperature.