【摘要】 为了使R744在复叠式制冷系统中运行的最低温度突破三相点的限制,用R744与自然工质(如R170或R1150)混合组成二元混合物,使其突破R744的三相点温度,完全使用自然工质混合物替代R13,在复叠式制冷系统的低温环路中运行.通过建立固液平衡和气液平衡的模型,得到保证R744在200 K不结晶的摩尔分数,并针对固定组分的二元混合物进行循环性能计算.计算结果表明,R744/R170的一种混合物在相同的冷凝和蒸发温度下与R13相比,压缩比相同,压力曲线非常接近,单位容积制冷量、单位质量制冷量和制冷系数相差不大,具有与R13相近的循环性能.质量比为2∶8的R744/R170混合物是R13的理想的自然工质替代物.更多还原

【Abstract】 To study the possibility of cascade refrigeration system using R744 running below R744 triple point temperature (216.58 K),the binary mixtures of R744 and nature working fluid(such as R170 and R1150) were introduced to reduce R744 triple point temperature and substitute for R13.The models of solid-liquid(equilibrium) and vapor-liquid equilibrium were proposed and mixture ratio which can make R744 not produce crystal blow its triple point temperature was found.The low-temperature cycle performance of cascade refrigeration system using mixture of R744/R170 and R744/R1150 at given component was simulated.From the calculation results at the same condensing and evaporating temperature,one of the mixtures of R744/R170 and R13 have the same compressor ratio and close pressure curve.Unit volume refrigeration capacity,unit mass refrigeration capacity and coefficient of performance(COP) of them also have little discrepancy.Then the mixture has close cycle performance to R13,and is a good alternative substitute for R13.更多还原