对液氮的基本工作模式提出了两种改进的方案。考虑到开式朗肯循环中存在工质的相变和液氮汽化过程中的大量吸热及控制换热器管结霜的设计要求,在改进方案中引入以氦气为工质的斯特林发动机,组成两种液氮-斯特林联合循环.由各种工况下的计算结果可知这两种方案能大幅提高液氮的比功,在较低的工作压力下即能实现最大的比功输出. The basic working mode of liquid nitrogen proposed two improved programs. Taking into account the open Rankine cycle, there is a working fluid phase transition and liquid nitrogen vaporization process of a large number of endothermic and control of the heat exchanger tube frosting design requirements, the introduction of the improvement program to helium as working medium Stewart Lin engine, composed of two kinds of liquid nitrogen - Stirling combined cycle.From the calculation results under a variety of conditions we can see that these two programs can significantly improve the liquid nitrogen specific work, at lower working pressure that is to achieve the maximum Specific power output.