CO_(2)跨临界制冷系统新型分布式压缩循环研究

Novel Distributed Compression Cycle for Carbon Dioxide Transcritical Refrigeration System

为了对CO_(2)跨临界蒸气压缩循环进行高效冷却并提升系统性能,提出分布式压缩循环系统(distributed compression cycle system,DCCS)。在DCCS中,气冷器出口的超临界CO_(2)不再被进一步过冷而是进行二次增压,并在常规热汇条件下进行放热冷却。通过热力学计算DCCS在不同工况下的性能随二次增压比变化情况。结果表明:相对于基础系统,DCCS可有效提升系统性能,在气冷器出口温度不变时,最大制冷COP增幅在8.2%~10.76%之间,制冷量的增幅最高可达约26%。在蒸发温度不变时,最大制冷COP增幅在8.57%~13.51%之间。DCCS中理想的二次增压比要求并不高,且对于二次增压所增加的系统功耗相对于基础系统不会超过20%。相对于目前仅采取单一过冷技术的系统,DCCS在系统性能系数上仍具有优势。DCCS的提出为跨临界CO_(2)蒸气压缩循环系统的性能提升与完善提供了全新的方向。

A critical research topic is the improvement of the system performance by efficiently cooling carbon dioxide in transcritical vapor compression cycles.In this study,a distributed compression cycle system(DCCS)is proposed.For the DCCS,the transcritical CO_(2) from the gas cooler outlet is not further subcooled but boosted.It is then cooled by conventional heat sink conditions.The DCCS performance under different operating conditions with variations in the second boost ratio is calculated by a thermodynamical cycle model.It is shown that the DCCS can effectively improve the system performance compared with the baseline system,with the maximum refrigeration COP increase ranging from 8.2%to 10.76%at a constant gas cooler outlet temperature.The refrigeration capacity is increased up to approximately 26%.The maximum refrigeration COP increase ranges from 8.57%to 13.51%at a constant evaporating temperature.The ideal second boost ratio requirements in DCCS are not high,and the additional system power consumption for the second boost is not more than 20%compared with the baseline system.The DCCS still has advantages in terms of the system COP compared with current systems that only adopt a single subcooling technology.The proposed DCCS provides a new path for improving and refining the performance of the carbon dioxide transcritical vapor compression cycle systems.