Thermodynamic Performance Assessment of a CO2 Supermarket Refrigeration System with Auxiliary Compression Economization by using Advanced Exergy Analysis

Year 2017, Volume: 20 Issue: 4, 220 - 227, 29.11.2017

Paride Gullo Armin Hafner

https://doi.org/10.5541/eoguijt.325883

Cited By: 10

Abstract

Supermarkets are currently one of the most vital
service facilities, whose number of installations is ever-growing in both
developed and developing countries. On the other hand, these applications
feature a copious indirect contribution to the ongoing climate change, as well
as a massive use of potent greenhouse gases. In an attempt to promote
climate-friendlier technologies in commercial refrigeration sector, “CO₂
only” (transcritical CO₂ or pure CO₂) refrigeration
systems have become the mainstream of new food retails worldwide. In
particular, in the last few years parallel (or auxiliary) compression has taken
root in food retails as a means to enhance the energy efficiency of pure CO₂
units. The thermodynamic performance of such a promising solution can be
suitably assessed with the aid of the advanced exergy analysis.

The results obtained at the design outdoor temperature
of 40 °C showed that the main compressor has the highest priority of
enhancement, whereas the high-pressure expansion valve needs to be replaced
with a device for expansion work recovery. Also, close attention had to be paid
to both the gas cooler and the auxiliary compressor. The former can be improved
mainly by enhancing the other components, whereas the irreversibilities related
to the latter can be decreased by improving both the compressor itself and the
remaining components. Finally, the implemented sensitivity analysis revealed
that the improvement in the efficiency of the main compressor should be
seriously considered on the part of the manufacturers.

Keywords

refrigeration, R744, CO2, exergy, Supermarket

References

• Haydar Aras
• Claudio ZIlio
• Giampaolo Manfrida