Investigation of Efficiency of R717 Refrigerant Single Stage Cooling System and R717/R744 Refrigerant Cascade Cooling System

Abstract

This study is an adaptation of ammonia cascade cooling systems using carbon dioxide on ice cream production machines and includes thermodynamic analysis of R717/R744 cascade refrigeration system with R717 refrigerant single-stage refrigeration system and investigation of its efficiency. As a result of the analyses, the COP value of the single-stage system was 3.67, the Carnot efficiency was 0.57, the second law efficiency was 0.19 and the power required to operate the compressor was 27.55 kW. In the cascade cooling system, the COP value was 4.46, the Carnot efficiency 0.59 and the compressor power 22.7 kW in the high-temperature part, while the COP value was measured as 14.65, the Carnot efficiency 0.58 and the compressor power 6.4 kW in the low-temperature part. For the whole cascade system, the COP 3.24 and the second law efficiency were found to be 0.43. When the results were compared, it was concluded that although the COP value of the cascade cooling system was 0.43 points lower than the single-stage ammonia system, when our country's climate conditions and the thermophysical properties carbon dioxide gas were considered together, one of the most suitable designs was the cascade cooling system. © Author(s) 2021.