CO_(2)跨临界双级压缩制冷系统的[火用]分析

Exergy analysis of transcritical two stage CO_(2) refrigeration system

目的:提升CO_(2)跨临界双级压缩制冷系统性能。方法:对该系统进行了常规[火用]分析与高级[火用]分析,围绕内源可避免[火用]损失、内源不可避免[火用]损失、外源可避免[火用]损和外源不可避免[火用]损失这4个方面进行各部件[火用]损失计算。结果:CO_(2)跨临界双级压缩制冷系统有很大提升效率的潜力。常规[火用]分析与高级[火用]分析所得优化部件的优先级不同。高、低压级压缩机和蒸发器的性能优化是提高系统能效的重点。结论:高、低压级压缩机和蒸发器的内源可避免[火用]损失分别占系统总内源可避免[火用]损失的20.9%,15.2%,36.5%,且通过改进高、低压级压缩机和蒸发器可分别减少其58.8%,49.3%,90.2%的[火用]损失,常规[火用]分析无法提供此类建议。

Objective:In order to improve the energy efficiency of the transcritical two stage CO_(2) refrigeration system,the conventional exergy analysis and advanced exergy analysis of the system were conducted.Methods:Advanced exergy analysis provides more valuable information on the interaction between system components and the potential for component improvement by splitting the exergy destruction into endogenous/exogenous and unavoidable/avoidable parts.Results:The results indicated that the transcritical two stage CO_(2) refrigeration system had significant potential for efficiency improvement.The priority of the optimized components from conventional and advanced exergy analysis was different.The advanced exergy analysis showed that performance optimization of the high-pressure stage compressor,low-pressure stage compressor and evaporator were the focus of improving system energy efficiency.Conclusion:The endogenous avoidable exergy destruction of the high-pressure stage compressor,low-pressure stage compressor and evaporator accounted for 20.9%,15.2%and 36.5%of the endogenous avoidable exergy destruction of the system,respectively.The improvement of the high-pressure stage compressor,low-pressure stage compressor and evaporator are able to reduce their exergy destruction by 58.8%,49.3%and 90.2%,respectively.The conventional exergy analysis cannot provide such recommendations.