Abstract
This study investigates the integration of waste energy recovery into three modified CO₂/NH₃ cascade refrigeration systems (CRS), evaluating their energy performance and economic feasibility compared to a conventional baseline CRS. The proposed modifications harness waste heat from the high-temperature circuit (HTC) compressor discharge to preheat boiler feed water used in fishmeal and fish oil production and utilize cold energy from seafood processing wastewater to de-superheat the low-temperature circuit (LTC). The first configuration (CRSH) employs a heat exchanger at the HTC discharge for heat recovery; the second (CRSC) repurposes wastewater cold energy to reduce the cascade heat load, and the third (CRSHC) integrates both strategies. Simulation results demonstrate that CRSHC achieves 1.5%–7.5% compressor power savings and a 1.6%–8.1% improvement in COP over the baseline. Under Mumbai's coastal conditions, CRSHC exhibits the lowest annual energy consumption (19.8% reduction) and the highest seasonal energy efficiency ratio (24.7% gain). Economically, CRSHC offers the lowest life cycle cost despite a higher initial investment. In light of global policy emphasis on sustainable seafood processing and the adoption of low-carbon technologies, these findings support the promotion of waste energy recovery in industrial refrigeration as a viable strategy to enhance energy efficiency, reduce operational emissions, and align with climate-resilient industrial policies. The study offers evidence-based insights for stakeholders and policymakers aiming to decarbonize the cold chain while improving resource utilization in coastal food industries.