Comparative study of Exergetic and Economic analysis of Multi-evaporator NH3 and NH3-CO2 CRS for a Seafood Processing Plant

In a seafood processing plant, refrigeration is a vital and energy intensive process. In India, NH3 is predominately used to cater to such refrigeration demands. These industrial refrigeration systems have the multi-evaporator configuration with high pressure ratios necessitating adoption of multistage compression. In recent years, owing to excellent and favorable thermo-physical properties of CO2 in low temperature, adoption of NH3-CO2 cascade refrigeration system (CRS) with NH3 in high temperature cycle is gaining worldwide acceptance. In the present work, performance of a conventional NH3 multistage industrial refrigeration system is compared with a proposed NH3-CO2 CRS system in terms of energy, exergy and economic perspectives. Investigation is focused to thermodynamically evaluate and optimize the performance of the proposed cascade configuration with respect to operating parameters. A sensitivity analysis has been performed as well to study the effects of climatic conditions on system performance. The proposed NH3-CO2 CRS showed a maximum benefit of 13.3% in COP, 14% in exergy efficiency and 9% less TEWI compared to the baseline system. The estimated payback period is 25 months