NH_3/CO_2低温制冷系统热力学分析

Thermodynamic analysis of low temperature refrigeration system with ammonia/carbon dioxide

用(火用)分析的方法对一种NH_3/CO_2复叠式低温制冷系统进行了研究。通过对NH_3/CO_2复叠式低温制冷系统的性能进行的模拟计算,分析了不同中间温度下系统各部件(火用)损失情况及整个系统的(火用)效率随中间温度和冷凝温度的变化情况。结果表明,不同中间温度下系统各部件(火用)损失所占的比重各不相同:同一冷凝温度下,复叠式两级低温制冷系统存在一个最佳中间温度使系统的(火用)效率最高;高温级冷凝温度变化时,系统总的倪效率也要随之变化,随冷凝温度的增加,系统所能达到的最大(火用)效率并不是一直增高,在一定范围内先增高后降低。研究结果为系统的进一步优化设计和节能提供了理论的依据。

Studied is a kind of ammonia/carbon dioxide two stage low temperature refrigeration system using exnergy analytic methods. The exergy loss of each part changing with the mean temperature is present at certain condensing temperature. The exergy efficiency of the system is simulated and analyzed by changing the mean temperature of the evaporator-condenser and the temperature of the condenser. It shows that evaporator and compressors are the maifi exergy loss parts; there exists an optimum mean temperature in evaporator-condenser to maximize the; exergy efficiency, and the maximal exergy efficiency of the system exists a peak point with heightening the condensing temperature.