Abstract
After the recent renewed interest in CO2 as the refrigerant (R744) for the food retail industry, many researchers have focused on the performance enhancement of the basic transcritical R744 supermarket refrigeration unit in warm climates. This task is generally fulfilled with the aid of energy-based methods. However, the implementation of an advanced exergy analysis is mandatory to properly evaluate the best strategies needing to be implemented to achieve the greatest thermodynamic performance improvements. Such an assessment, in fact, is widely recognized as the most powerful thermodynamic tool for this purpose. In this work, the advanced exergy analysis was applied to a conventional R744 booster supermarket refrigerating system at the outdoor temperature of 40 °C. The results obtained suggested the adoption of a more sophisticated layout, i.e., the one outfitted with the multi-ejector block. It was found that the multi-ejector supported CO2 system can reduce the total exergy destruction rate by about 39% in comparison with the conventional booster unit. Additionally, the total avoidable exergy destruction rate was decreased from 67.60 to 45.57 kW as well as the total unavoidable exergy destruction rate was brought from 42.67 down to 21.91 kW.
Highlights
A prominent positon as a fundamental service facility in modern society is held by supermarkets.these applications feature a significant contribute to global climate change, being massively energy-consumptive
All the outcomes obtained at the outdoor temperature of 40 ◦ C for the advanced exergy analysis
8, highlighting that only of the total exergy destruction rate could be the potential associated with the application of the aforementioned avoided
Summary
A prominent positon as a fundamental service facility in modern society is held by supermarkets These applications feature a significant contribute to global climate change, being massively energy-consumptive. The entry into force of the EU F-Gas Regulation 517/2014 [1] aims at preserving the environment by enormously decreasing the use of hydrofluorocarbons (HFCs) as well as encouraging the adoption of natural working fluids in the whole refrigeration sector. This regulation imposes a ban on the use of fluorinated refrigerants with a GWP100 years. An exception was introduced for the primary circuit of cascade/indirect arrangements in which working fluids with a GWP100 years below
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