Performance of the compression process of Carbon Dioxide (R744) in (A/C) and (H/P) systems depends on many factors related to fluid properties, equipment design and process parameters. Diversity of these factors represents a difficulty to have an overall-view of the hidden capabilities and limitations of the compression process. Thus, it is hard to apply any appropriate design optimization methods for the compressors, specifically for two reasons: (1) when the compression starts from the wet or saturation region and commences through the transcritical dry region of the fluid and (2) when the compressor works at off-design operating point during its working life-time. In an answer to these two points, the present paper utilizes the first and second laws of thermodynamics augmented by Monte-Carlo method to investigate, expose and discuss the compression performance (e.g. final temperature and pressure, work and size of compressor and second law efficiency) starting randomly from the wet/saturation region to the transcritical dry region of R744. The study shows that initial temperature has a greatly decreasing effect on compressor specific displacement volume per unit work and to a less extent on size of compressor, while its effects on all other parameters are insignificant. Initial pressure has similar expected trends as those of the initial temperature due to their linear relationship in the wet region. Final to initial temperature ratio has increasing effects on both final pressure and work of compressor and decreasing effects on both second law efficiency and specific displacement volume per unit work. The method presented here could open many ways for further theoretical design optimization applications of the compressor and hence greatly limits the trade-off methods that are usually adopted in the selection of such units.

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