Original Research Article
Year: 2020 | Month: October | Volume: 7 | Issue: 10 | Pages: 219-229
Parametric Study of NH3/CO2 Cascade Refrigeration Cycles for Hot Climates
Chegnimonhan K. Victorin1,2, Aredokou Olorounto Louis2, Adomou Alain2, Guidi Tognon Clotilde2
1National Institute of Agricultural Research of Benin, Benin, PTAA Agonkanmey, Cotonou, Benin..
2Processes and Technological Innovations of the High National Institute of Industrial Technology of Lokossa, Benin.
Corresponding Author: Chegnimonhan K. Victorin
ABSTRACT
This article makes a parametric study of cascade refrigeration systems with a low carbon footprint in tropical climates. An NH3/ CO2 cascade refrigeration system is modelled, simulated under Engineering Equation Solver(EES) and the results are discussed. It is noted that the use of an internal heat exchanger in the R717/R744 cascade system reduces performance by 4.7%, whereas subcooling in both circuits increases the performance of the cascade systems by 16.50%. Exercise analysis of the cascade refrigeration system identified the temperature of -10°C as an optimal coupling temperature that allows for a low total irreversibility (i.e. a total irreversibility of 78.072 kW for a system with a cooling capacity of270 kW).The condenser and the compressor of the high temperature cell have been identified as the most critical components with a total irreversibility of 48%. Based on Total Equivalent Warning Impact(TEWI) calculation, 8 cascade refrigeration configurations are compared in the weather conditions of Benin (Cotonou). The natural refrigerants R717 and R600 seem to be suitable candidates in combination with CO2 for cascade systems. Furthermore, the refrigerant R717 (ammonia) appears to be a good choice to achieve high performance with a relatively low TEWI.
Keywords: Refrigeration, Cascade cycle, Carbon dioxide, Ammonia,tropical countries.
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