Natural Refrigerant Based Cascade System for Seafood Application

Abstract

Refrigeration plays a vital role to ensure quality and safety of seafood. In a tropical country like India, the seafood industry has relatively larger cooling load throughout the supply chain due to higher temperature differences between ambient and chilled seafood. The cooling demands in a seafood processing plant are typically at four different temperature levels. Supply of chilled water at 2 °C, ice at −5 °C, cold storage maintained at −25 °C, and a plate or blast freezer at −40 °C. Commonly a multi-evaporator multi-stage refrigeration system with refrigerants like NH3, R404A, or R22 are used in India. However, R404A, and R22 have harmful effect on environment due to their high GWP. In this study, an all-natural CO2-NH3 cascade refrigeration system (CRS) with multi-evaporator was proposed. For comparison, the refrigeration demands in a surimi (seafood) processing and storage plant located in Mumbai were utilized. The potential benefits of the proposed CO2-NH3 cascade system with respect to NH3, R404A, and R22 in two-stage refrigeration system were highlighted in terms of coefficient of performance, annual energy consumption, and total equivalent warming impact. The study revealed that CO2-NH3 cascade system has the highest COP followed by NH3 two-stage system, for all investigated condenser temperatures. CO2-NH3 cascade system also had the lowest annual energy consumption and total equivalent warming impact which were 12.3% and 44.3% less respectively, compared to a R404A two-stage system.