Novel Distributed Compression Cycle for Carbon Dioxide Transcritical Refrigeration System

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 CO₂ 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.