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Use of Natural Refrigerants in Supermarkets

6  Results

For the second time, the supermarket sector has seen the design, installation and run-in of a refrigeration system whose principle is different and based on natural refrigerants. Unlike the components used in the first supermarket, components well known to a standard refrigeration fitter have now been used, and they have proved their capabilities.

The project has demonstrated how to use new design rules for copper pipe installations; how to use hoses for indirect refrigeration; that string control valves are not needed in small-scale brine circuits; that CO₂ installation for low temperatures (without oil separator and suction gas cooler) is simple; that EEx installations can be made at low costs; and that cascade refrigerator control is easy.

The project shows that the system principle is neutral in terms of energy compared with a conventionally optimised R404A system. The energy consumption of the Fakta Beder refrigeration system has been measured directly and compared with that of eight representative outlets. The system has thus reduced the direct, equivalent CO₂ contribution by 357 tonnes by removing 90 kilos of R404A from the outlet.

The project shows that it is possible to reduce the consumption of energy through brine circuit optimisation. The brine circuit is not optimal in terms of control. However, this has not caused the outlet any direct problems, but has resulted in too many and frequent compressor starts. It is therefore very positive to learn that the system is neutral in terms of energy at the moment.

The project shows that component and installation costs are about 20% higher than those of a conventional R404A system; that it is possible to reduce costs; and that HFC tax will feed “more clearly” through in large-scale systems. Consequently, the increase in costs will be negligible (5 – 10%).

Since its upstart, the refrigeration system has run with no failure or problems. The system has met the conditions intended and keeps the temperature at -20°C in freezer display cases and at +2°C in refrigerated display cases. The system’s qualities have proved satisfactory especially under very hot conditions.

This report has brought about a good deal of work and a large number of descriptions as regards the design of the propane system. The main reason is that commercial refrigeration has previously not been subject to Order no. 743, so data must be processed, interpreted and understood in order to form the basis for future discussions.

There has been no particular focus on the CO₂ system. This seems slightly unfair as this system is working exceptionally well. The CO₂ system had no difficulty keeping the temperature during

the summer although its dimensioned load equals the freezing system’s maximum capacity. The compressor has not run at full capacity during long periods – not even during the very hot days of July. The set point temperature is –32°C for suction pressures, and the freezer room temperature must be kept at –25°C .

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