摘要
为研究制冷剂R1234ze(E)替代R134a后离心压缩机及制冷性能的变化,基于两次节流中间不完全冷却的两级蒸汽压缩制冷循环(VCS-TS-FT),建立制冷循环数学模型及两级串联离心压缩机流动模型,详细分析了R1234ze(E)替代R134a对压缩机及制冷性能的影响。数值计算结果表明:R1234ze(E)替代R134a,在相同冷凝温度条件下,转速不变时,制冷量为R134a的83.7%,压缩机压比较R134a高2%,效率基本不变,排气温度低0.5%,压缩机轴功率低11.6%,制冷性能系数(ξ_(cop))由6.83下降至6.59。通过改变压缩机的转速,压缩机及制冷循环性能发生显著改变,转速提升7%,R1234ze(E)制冷量与R134a设计转速下设计制冷量相同,但压缩机效率下降5.9%,系统ξ_(cop)下降至6.15;相反,转速降低3.4%,压缩机容积流量不变,R1234ze(E)制冷量降低为R134a设计转速下设计制冷量的76%,系统ξ_(cop)上升至6.87。因此,在不重新设计压缩机的条件下,R1234ze(E)直接替代R134a无法达到ξ_(cop)和制冷量同时与R134a相等的水平。另外,为实现相同制冷量,也需对冷凝器和蒸发器进行改进。
To investigate the changes in the performance of centrifugal compressors and refrigeration efficiency after the replacement of refrigerant R134a with R1234ze(E),this study establishes a mathematical model of the refrigeration cycle and a flow model of a two-stage series centrifugal compressor based on a two-stage vapor compression refrigeration cycle with incomplete cooling between two throttling processes(VCS-TS-FT).The influence of the replacement of R134a with R1234ze(E)on compressor and system performance is analyzed in detail.Numerical results show that,after replacing R134a,under the same condensing temperature and unchanged rotational speed,R1234ze(E)achieves 83.7%of R134a’s cooling capacity,with a 2%higher pressure ratio,nearly unchanged efficiency,0.5%lower discharge temperature,11.6%lower shaft power,and a decrease in coefficient of performance(ξ_(cop))from 6.83 to 6.59.Adjusting the compressor speed significantly alters the performance of the compressor and refrigeration cycle.A 7%increase in speed results in a refrigeration capacity of R1234ze(E)equal to that of R134a at the designed speed,but the compressor efficiency decreases by 5.9%,and the systemξ_(cop) drops to 6.15.Conversely,a 3.4%decrease in speed with unchanged compressor volumetric flow results in the refrigeration capacity of R1234ze(E)being reduced to 76%of that of R134a at the designed speed,while the systemξ_(cop) rises to 6.87.Therefore,the direct replacement of R134a with R1234ze(E)without redesigning the compressor cannot achieve equivalent levels of bothξ_(cop) and refrigeration capacity compared to R134a.Additionally,improvements to the condenser and evaporator are required to achieve the same refrigeration capacity.
作者
刘丹
席光
段亚飞
陈翰
王志恒
李镇杉
刘智远
LIU dan;XI Guang;DUAN Yafei;CHEN Han;WANG Zhiheng;LI Zhenshan;LIU Zhiyuan(School of Energy and Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Chongqing Midea General Refrigeration Equipment Co.,Ltd.,Chongqing 401336,China)
出处
《西安交通大学学报》
北大核心
2025年第9期142-151,共10页
Journal of Xi'an Jiaotong University
基金
国家重点研发计划资助项目(2023YFC3806401)。
关键词
制冷剂替代
二级压缩循环
离心压缩机
制冷性能
refrigerant replacement
two-stage compression cycle
centrifugal compressor
refrigeration performance
