CO 2 with Mechanical Subcooling vs. CO 2 Cascade Cycles for Medium Temperature Commercial Refrigeration Applications Thermodynamic Analysis

摘要

A recent trend to spread the use of CO 2 refrigeration cycles in warm regions of the world is to combine a CO 2 cycle with another one using a high performance refrigerant. Two alternatives are being considered: cascade and mechanical subcooling systems. Both respond to a similar configuration of the refrigeration cycle, they being based on the use of two compressors and same number of heat exchangers. However, the compressor, heat exchanger sizes and energy performance differ a lot between them. This work, using experimental relations for CO 2 and R1234yf semi-hermetic compressors analyzes in depth both alternatives under the warm climate of Spain. In general, it was concluded that the CO 2 refrigeration solution with mechanical subcooling would cover all the conditions with high overall energy efficiency, thus it being recommended for further extension of the CO 2 refrigeration applications.