中文摘要：

近年来随着低温余热的利用越来越受到重视,将LNG冷能和低温余热联合应用的有机朗肯循环研究也受到了广泛的关注,其中循环工质的选择更是提高系统热力性能的关键。针对循环工质选择的问题,将R236ea、R245fa以及两者按不同质量分数配比得到的9种混合工质作为亚临界ORC工质,结合窄点分析方法计算了系统在2种最佳设计工况下的热力学性能及热经济性。结果表明：混合工质R236ea/R245fa（0.9/0.1）和R236ea/R245fa（0.8/0.2）分别是以最佳热和冷回收效率为设计工况标准时的最佳循环工质;2种工况下,混合工质的热经济性均优于纯工质;在混合工质中提高R236ea的比例可以有效降低换热面积,提高系统经济性。为日后将低温余热和LNG冷能联合应用的有机朗肯循环二元混合工质选择提供一定的参考。

英文摘要：

The utilization of low-temperature waste heat attracted more and more attention. The organic cycle, in which low temperature waste heat and LNG cold energy are combined application, also widespread concern. The circulating refrigerant selection is regard performance. Aiming at circulating refrigerant selection, 11 substances ed as key factor to improve its were adopted as subcritical organic rankine arouses thermal Rankine cycle working fluid, including R236ea, R245fa and 9 binary mixtures in different mass ratio, combined with pinch analysis method, thermal economy of the system and the thermodynamic properties under two optimal design conditions were calculated. The results show that the mixtures of R236ea/R245fa（0.9/0.1 ） and R236ea/R245fa （0.8/0.2） are the best circulating refrigerant under designed conditions optimal thermal energy recovery efficiency and the best cold energy recovery efficiency respectively; under above two designed conditions, binary refrigerant have better thermal economy compared with pure refrigerant; as the ratio of R236ea in the binary refrigerant increased, the heat transfer area was decreased effectively and the system thermal economy was improved, which can provide references for refrigerant selection of subcritical organic Rankine cycle, in which low temperature waste heat and LNG cold energy were combined application.