No abstract

Supermarket refrigeration systems have high environmental impact due to their large refrigerant charge and high leak rates. Consequently, the interest in using low GWP refrigerants such as carbon dioxide (CO 2) and new refrigerant blends is increasing. In this paper, an open-source Life Cycle Climate Performance (LCCP) framework is presented and used to compare the environmental impact of four supermarket refrigeration systems: a transcritical CO 2 booster system, a cascade CO 2 /N-40 system, a combined secondary circuit with central DX N-40/L-40 system, and a baseline multiplex direct expansion system utilizing R-404A and N-40. The study is performed for different climates within the USA using EnergyPlus to simulate the systems' hourly performance. Further analyses are presented such as parametric, sensitivity, and uncertainty analyses to study the impact of different system parameters on the LCCP.

This paper analytically investigates and compares the performance of a proposed 'all-natural' NH 3 /CO 2 cascaded booster system to a conventional R404A direct expansion system as well as to an 'all-CO 2 ' system with multi-ejector unit and flooded evaporator. Performance comparison is made based on the annual combined COP and Life Cycle Climate Performance (LCCP) for operation in selected cities of Middle East and India. Our results show that in extreme warm climate, the energy efficiency of the proposed configuration exceeds that of all-CO 2 configuration by a maximum of about 12.23% and the total emissions are lower by up to 11.20%. However, the all-CO 2 multi ejector system performs better in cold and mild warm climate. In the NH 3 /CO 2 cascade, the high temperature NH 3 system can be designed to be isolated from the accessible locations of the supermarket. The work presented is expected to help adoption of natural refrigerants such as CO 2 and NH 3 for commercial application in extreme warm climate conditions prevailing in many cities of Middle East and India.

No abstract