发生器中溴化锂水溶液的热力学分析

摘要

Basing on the thermodynamic properties of lithium bromide solution and the second law of thermodynamics,this paper deduced the formulas of enthalpy、entropy and exergy of saturated lithium bromide solution as well as the superheated steam.Then a regeneration process of one plate generator using waste heat was analyzed.The results showed that the exergy of outlet solution was a small number compared with the numerical values of waste heat or superheated steam,though it was a few times bigger than the inlet ones(expect the concentration of inlet and outlet solution was close).Thus the exergic efficiency was similarly equal to the exergy quotient of superheated steam and waste heat.The exergic efficiency was barely influenced by the inlet temperature or concentration of dilute solution or condensing pressure.The exergic efficiency would significantly decrease when the concentration of outlet increased.%依据溴化锂溶液的热力学性质和热力学第二定律,本文首先推导了饱和溴化锂水溶液及其过热蒸汽的焓、熵、火用的计算公式.然后对一种利用余热,加热溶液的板式发生器的再生过程进行了热力学分析,结果表明:虽然溶液的出口火用比入口火用要大几倍,但是相对于余热火用和过热蒸汽的火用来说是小量(除进出口浓度极为接近的情况外).所以可以用过热蒸汽的火用与余热火用之比近似反映火用效率.稀溶液的进口温度、浓度和冷凝压力对火用效率影响不大,而获得更浓的再生溶液会使火用效率大幅下降.