Energy optimization methodology for a centralized cold store using a multi-temperature NH₃/CO₂ cascade refrigeration system

Multi-temperature cascade refrigeration systems have become the preferred choice in the cold store sector due to their excellent performance at low evaporation temperatures. Therefore, an energy management strategy tailored for a centralized cold store based on multi-temperature cascade refrigeration systems is critical. Currently, there is limited research on simultaneously optimizing intermediate temperatures, high-temperature condensing temperatures and the load sharing of parallel units in cascade systems. This necessitates the development of a comprehensive strategy combining set-point optimization with multi-compressor load sharing for cascade systems. This study proposes an energy management strategy for centralized cold store based on cascade refrigeration systems. Thermodynamic and data-driven models of the system's components were established. Furthermore, optimization algorithms were applied to optimize the load sharing of parallel compressors, intermediate temperatures, and high-temperature condensing temperatures in cascade systems to reduce overall energy consumption. Simulation results based on field data indicate that this optimization strategy significantly improves energy efficiency. The parallel compressor load sharing optimization strategy reduced power consumption by 6.1% for low-temperature compressors and 2.8% for high-temperature compressors. Building on this, further optimization of the intermediate and condensing temperatures in the cascade system reduced overall energy consumption by 14.6%.