Análise exergética do ciclo transcrítico de um refrigerador de garrafas operando com CO2

Abstract

The second law of thermodynamics deals with the quality of energy. More specifically, it is concerned with the degradation of energy during a process, the entropy generation, and the lost opportunities to do work; and it offers plenty of room for improvement. This paper aims to identify key factors that affect refrigeration system performance with CO2. Due to the impact of global warming of CFC´s and HFC's, the use of natural refrigerants has received worldwide attention. The natural refrigerant, carbon dioxide (CO2/R744) is promising for use in cooling systems, especially in the transcritical cycle. An exergetic analysis through the cycle of a bottle cooller (exposer) adapted for commercial use with carbon dioxide was carried out so that the effectiveness of the system components can be estimated and classified, allowing direct efforts to improve performance of components to the transcritical cycle. The analysis revealed that the compressor and expansion valve are the largest sources of losses in the system, and therefore, efforts should focus on improving these components