| Abstrakt: |
This study aims to evaluate the viability of employing ammonia (R717), a naturally existing refrigerant, within a transcritical cascade refrigeration configuration. The low temperature (LT) cycle of the cascade transcritical refrigeration system is driven by carbon dioxide, while the high temperature (HT) cycle is propelled by ammonia. Furthermore, the proposed transcritical cascade cycle has the potential to be utilized not just for cooling purposes but also for heat generation. The thermal performance of the cascade cycle has been evaluated for several combinations of design and operational parameters, leading to the identification of optimal presentation metrics like COPheating, COPcooling, COPsys, and the mass flow ratio of R717/R744. The lowtemperature cycle is dependent on two specific temperatures that are considered design parameters: the temperature of the evaporator and the temperature at which the gas cooler outlet is set. The analysis demonstrates that the coefficient of performance (COP) for cooling remains relatively constant, with values of approximately 0.601 at 32° and 0.680 at 40°. This suggests that variations in the evaporator temperature do not significantly impact the COP of the system. The impact of increasing discharge pressure on the system's coefficient of performance (COP), heating, and cooling becomes apparent. An inverse correlation exists between the discharge pressure and the coefficient of performance (COP) of the system. Specifically, the COP is measured at 0.791 when the discharge pressure is 8000 kPa, and it decreases to 0.620 when the discharge pressure increases to 12000kPa. [ABSTRACT FROM AUTHOR] |
