The System

Carrefour are not the only Romanian based company to invest in this technology, with many other businesses showing interest in CO2 refrigeration. The company’s branch in Timisoara has gone one step further by installing a CO2 refrigeration unit which has parallel compression and multi-ejector technology. Their team have been carefully observing the system and have found that so fair it is working as expected. They hope that in the near future the CO2 unit will save them up to 13% on their energy bills, compared to the CO2 units which use just parallel compression.

Two booster racks were installed into the new CO2 unit, which were produced by refrigeration experts, Enex. Other companies included in the production were Frigo-Consulting Ltd and Danfoss, who were responsible for the system’s control and multi-ejectors. Cabinet manufacturer ES System K and local refrigeration installation firm DAAS were also involved in the collaboration.

The system has a total capacity of 292 kW for positive and 65 kW for negative temperature demand. During high pressure expansion, the CO2 unit uses its parallel compressor feature along with the gas and liquid ejectors to recover any lost energy. This helps to reduce the chance of internal throttling loss, which would otherwise cause low energy efficiency.

Plans for the Future

The ejectors which are used in these CO2 units are able to raise the positive temperature range from -7 °C to -2 °C, depending on how well the evaporator works. The unit also combats the problem of evaporator becoming icy as it can be put in partially flooded mode, which increases the heat transfer capacity.

In the future, partially flooded evaporators could be integrated to reduce the user’s carbon footprint even more. Doing this would cause the evaporation temperature to increase to -2°C for positive temperature and -26°C for negative temperature, allowing the unit to run much more efficiently.

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