非共沸混合工质用于螺杆膨胀机双循环低温余热回收系统的理论研究  

Analysis of Zeotropic Mixtures Used in Double Circulatio Low-temperature Waste Heat Recovery System with Screw Expander

作　　者：谈西锋[1] 李惟毅[1] 史维秀[1] 

机构地区：[1]天津大学机械工程学院,天津300072

出　　处：《机械工程学报》2012年第6期136-141,共6页Journal of Mechanical Engineering

基　　金："十一五"国家科技支撑计划重大资助项目(2006BAJ03A06)

摘　　要：以典型干工质R245fa和典型湿工质R152a为组元的按不同质量比例组成的M1、M2和M3这三种典型的非共沸混合工质,在设定工况下对其应用于螺杆膨胀机双循环低温余热回收系统性能进行理论研究。针对非共沸混合工质相变时发生温度滑移以及螺杆膨胀机压降小,出口参数高的特性,系统中引入内部回热器。分析结果表明,使用混合工质可拓宽螺杆膨胀机双循环系统的工质选择范围并且混合工质换热过程与变温热源能很好的匹配,从而可以减少传热温差带来的不可逆损失,同时使用混合工质可降低系统工质质量流量;非共沸混合等墒工质在设定工况下循环效率不是最高,但膨胀比最小,可减少膨胀机体积,降低设备制造成本;非共沸混合工质应用于螺杆膨胀机双循环系统时,引入内部回热器能够使循环效率得到明显提高。Different mass fractions of R245fa/R152a are chosen to compose three typical Zeotropic mixtures M1,M2 and M3.In the proposed temperature range,the Zeotropic mixtures are investigated as the working mediums of the double circulation low-temperature waste heat recovery system with screw expander.An internal recuperator is introduced to the system because of the obvious temperature glide during phase change for Zeotropic mixtures and low pressure drop,high export parameters with screw expander.The results show that utilizing Zeotropic mixtures can extend the range of choosing working mediums for double circulation low-temperature waste heat recovery system with screw expander and heat transfer process with variable temperature heat source can be a good match for Zeotropic mixtures and can reduce irreversible loss of temperature difference of heat transfer,meanwhile,can reduce mass flow rate of working medium;Among the proposed Zeotropic mixtures,the cycle efficiency of isentropic working medium is not the highest,but the expansion volume ratio is the lowest.For Zeotropic mixtures a significant increase of thermal efficiencies can be gained when an internal recuperator was introduced to the system.

关 键 词：螺杆膨胀机 双循环 非共沸混合工质 低温 余热回收 

分 类 号：TK123[动力工程及工程热物理—工程热物理]