带回热器的R404a/CO_2复叠式制冷系统的理论分析

建立低温环境下带回热器的R404a/CO_2复叠式制冷系统的模型,为提高系统COP,对其进行热力学分析。应用控制变量法,通过理论计算对比分析系统的蒸发温度、低温循环冷凝温度、过冷度以及冷凝蒸发器传热温差等因素对该系统COP的影响。结果显示,在其他参数一定时,过冷度的增加对于提高系统COP具有显著作用;存在低温循环冷凝温度的最优值,使得系统COP最大;过冷度不变时,系统COP随着蒸发温度、冷凝蒸发器传热温差的增大而增大,随冷凝温度的增大而减小。

Theoretical analysis of R404a/CO2 cascad refrigeration system with heat regenerator

This paper, from the current situation of regional economic development in Hebei Province, selected the range, ratio, standard deviation, variation coefficient, Theil coefficient and Gene coefficient to measure the 6 economic indicators of differences, analyzed the changes of the economic differences in Hebei Province.The result show that the economic differences in Hebei province has a growing trend.The paper puts forward countermeasures and suggestions to promote the coordinated development of regional economy in Hebei province from the aspects of improving macro view control, Strengthening cooperation with Beijing and Tianjin, adjusting industrial structure and introducing talents.