In an effort to further reduce energy consumption and slash down greenhouse gas emissions, Migros commissioned a CO2 booster system with an integrated CO2 heat pump for a supermarket in Reiden, Switzerland in August 2014. By integrating a heat pump cycle into the booster system, heating power can be increased from 35 to 70 kW, which is enough for even the coldest winter days in the region.
Migros has promised its customers that it will reduce absolute electric power consumption by 10% and greenhouse gas (GHG) emissions by 20% from 2010 to 2020. An important factor in achieving this strategy is the use of CO2 refrigerant, which has been Migros’ standard refrigerant in its supermarkets for four years now. Migros has noted three major improvements through the use of CO2:
Integrated heat pump cycle doubles heating power
Migros has recently commissioned an innovation that promises to make CO2 systems even more attractive for heating purposes. Currently, its stores with up to 1,000m2 sales area are usually heated exclusively with the waste heat from the refrigeration system. This concept saves on investment costs of a further heating system, on running costs for gas connections or oil tanks and on real estate costs.
The heating power must be large enough for cold winters when the refrigerator’s capacity is at its lowest; however, not every store’s heat balance is able to guarantee sufficient heating with only waste heat. Migros found that by integrating a heat pump cycle into the CO2 booster system the heating power can be increased from 35 to 70kW. This was enough for even the coldest winter days at the store in Reiden, Switzerland, where this system was commissioned in August 2014.
CO2 system uses 45% less electric power than former R134a/R404A system
One of the special features of this unit is that the heat pump evaporator is integrated into the gas cooler; hence, the evaporator does not require an extra frame, fans or an electric heater for defrosting.
The evaporation pressures of the coolers and heat pump are controlled independently. Frequency converters are attached to the first compressors of both minus and plus cooling and the fourth compressor of plus cooling. The third plus cooling compressor is connected to the coolers during the summer and to the heat pump evaporator during the winter.
In the summer time, when ambient temperatures are above 22°C, the fourth plus cooling compressor is used for parallel compression, allowing for efficiency improvements of the CO2 booster with very few additional measures for valves and controls. In the store in Reiden, Migros found that although 25% more cabinets were cooled in September 2014, the CO2 refrigerator used approximately 45% less electric power than the former R134a/R404A system did in September 2013.
Lower investment costs for CO2 heat pumps
Previously, CO2 heat pumps were sometimes more expensive than conventional heat pump systems using synthetic refrigerants. With Migros’ new system, investment costs for the heat pump have proven far lower than for the R134a alternative. Furthermore, potential greenhouse gas emissions were avoided. Overall, Migros found that the Reiden store’s CO2 booster system is the perfect contribution to its climate and energy strategy.
- Reductions in greenhouse gas emissions
- Improved energy efficiency
- Optimised waste heat recovery
Integrated heat pump cycle doubles heating power
Migros has recently commissioned an innovation that promises to make CO2 systems even more attractive for heating purposes. Currently, its stores with up to 1,000m2 sales area are usually heated exclusively with the waste heat from the refrigeration system. This concept saves on investment costs of a further heating system, on running costs for gas connections or oil tanks and on real estate costs.
The heating power must be large enough for cold winters when the refrigerator’s capacity is at its lowest; however, not every store’s heat balance is able to guarantee sufficient heating with only waste heat. Migros found that by integrating a heat pump cycle into the CO2 booster system the heating power can be increased from 35 to 70kW. This was enough for even the coldest winter days at the store in Reiden, Switzerland, where this system was commissioned in August 2014.
CO2 system uses 45% less electric power than former R134a/R404A system
One of the special features of this unit is that the heat pump evaporator is integrated into the gas cooler; hence, the evaporator does not require an extra frame, fans or an electric heater for defrosting.
The evaporation pressures of the coolers and heat pump are controlled independently. Frequency converters are attached to the first compressors of both minus and plus cooling and the fourth compressor of plus cooling. The third plus cooling compressor is connected to the coolers during the summer and to the heat pump evaporator during the winter.
In the summer time, when ambient temperatures are above 22°C, the fourth plus cooling compressor is used for parallel compression, allowing for efficiency improvements of the CO2 booster with very few additional measures for valves and controls. In the store in Reiden, Migros found that although 25% more cabinets were cooled in September 2014, the CO2 refrigerator used approximately 45% less electric power than the former R134a/R404A system did in September 2013.
Lower investment costs for CO2 heat pumps
Previously, CO2 heat pumps were sometimes more expensive than conventional heat pump systems using synthetic refrigerants. With Migros’ new system, investment costs for the heat pump have proven far lower than for the R134a alternative. Furthermore, potential greenhouse gas emissions were avoided. Overall, Migros found that the Reiden store’s CO2 booster system is the perfect contribution to its climate and energy strategy.
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Oct 09, 2014, 12:12
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