Transcritical R744 refrigeration systems for supermarket applications: Current status and future perspectives

Abstract

Visible signs of climate change call for urgent actions on food retail industry, since such a sector is characterized by an abundant carbon footprint. Being CO2 (or R744) recognised across the world as the most promising working fluid for supermarket applications, commercial transcritical R744 refrigeration systems have emerged as leading hydrofluorocarbon (HFC)-free technologies. This study is intended to implement an in-depth review study covering the most important aspects related to the state-of-the-art pure R744 refrigeration plants for food retail applications, including the evolution of system architectures, some field measurements, the main available results from an energy, environmental and economic perspective as well as the indispensable future investigations. It could be concluded that, in spite of some persisting barriers which still prevent such technologies from a wider adoption, the usage of R744 as the only refrigerant in supermarkets is no longer open to dispute, even in warm locations.

CO2 Refrigeration and Heat Pump Systems—A Comprehensive Review

“…Many other studies on the applications of CO 2 system for supermarkets, e.g., [77,[98][99][100] with a recent review on the subject [101] point to the increasing popularity of these systems due to various factors discussed earlier.…”

Thermodynamic performance evaluation of the CO 2 parallel compression supermarket refrigeration system with a subcooler

“…From 2000, CO 2 is recognized across the world as the most promising working fluid for supermarket refrigeration and appears in European countries such as Italy and Norway, as it is more environment‐friendly and relatively safe with its non‐inflammability and nontoxicity, better suited for centralized direct expansion systems 4 . CO 2 has a high critical pressure of 7.38 MPa and a low critical temperature of 30.97°C; thus, in super‐critical mode, its volumetric refrigerating capacity (22 545 kJ m −3 at 0°C) is averagely 6.5 times larger than the traditional refrigerants due to the high operating pressure 5 .…”

Simulation of heat pumps for simultaneous heating and cooling using CO2

“…For the same reasons, Ma et al (2013) also announces a possible more common use of CO 2 transcritical cycles. The use of CO 2 in the promising supermarket sector was reviewed by Gullo et al (2018). Chesi et al (2012) has developed a test bench to study refrigeration cycles and equipment that work with this refrigerant.…”