Innovative Refrigeration System, Combining the ‘Best of Both Worlds’

Creating a More Sustainable Approach to Refrigeration

When it comes to delivering on environmental promises, Groupe Auchan has an enviable record, having been rated among the greenest supermarket chains and openly publishing its ambitious annual carbon reduction targets.

Part of this eco-commitment involves finding greener ways of operating its stores – and this includes refrigeration – so when the company heard about the benefits of a new Honeywell HFO blend – Solstice® N13 (R-450A) – they were keen to test its credentials.
Solstice® N13, recently awarded official ASHRAE classification as R-450A, is an alternative to R-134a, offering similar  performance but with a superior GWP of ~600 and is ideally suited to chillers and MT refrigeration (distributed, CO₂ cascade), offering the best non-flammable replacement for R-134a.

Approval was given to design a combined Solstice ® N13/CO₂ refrigeration system for a  new large hypermarket opening in Epinay-sur-Seine (Paris), with measurement criteria  focused on energy efficiency, equivalent CO₂ emissions reduction and refrigeration  performance.
The test utilised a new design of low energy refrigeration unit and involved a team from Auchan, the company’s refrigeration partners Axima Refrigeration and Honeywell. The test focused on assessing the merits of a system that incorporated an N13  liquefaction unit alongside a CO₂ refrigerated distribution circuit. The system was then compared with  Auchan’s current standard set-up that uses R134a and glycol water with CO₂.

The results to date have been encouraging, and include:

•  Easy commissioning, with similar energy efficiency as R-134a.
  
• A global saving of 90 tons CO₂ eq/year compared with a secondary Glycol/R 134A/CO₂ system and savings of 960 tons CO₂eq/year compared with using a standard R404A DX system.

Background: Contributing to Groupe Auchan’s Environmental Goals

Groupe Auchan is at the leading edge of mitigating the ecological footprint generated byits different activities and constantly  strives to innovate in order to lower energy consumption, contribute to the fight against global warming and promote biodiversity.

All of the group’s businesses control their energy consumption by setting ambitious annual reduction targets. The installation of smart meters helps the chain to identify waste and to optimize consumption.
To help meet the European Union’s objective of 20% of all energy usage coming from renewable energy by 2020, Auchan has invested in solar and geothermal energy over recent years. All new buildings include autonomous energy production systems and, as a result, more than 55% of energy consumed by Auchan comes from renewable sources.

The refrigeration pilot project at Epinay-sur- Seine is, therefore, entirely in keeping with the context of building a greener operating environment.

Field Test Implementation: Monitoring and Assessing Data

Groupe Auchan worked alongside its refrigeration partner Axima Refrigeration to develop a system for the Epinay-sur-Seine store that combined the low GWP and energy efficiency benefits of a new refrigeration HFO blend named Solstice® N13 (R-450A) – and the proven performance of pumped CO₂.
The system uses Solstice® N13 in a liquefaction unit to convert gaseous CO₂ into a liquid that is then pumped to deep freeze containers, cold rooms and display cabinets. The CO₂ returns in a gaseous form to the Solstice® N13 liquefaction unit ready for converting again to liquid.

To support the yearly energy saving objectives of the project, the system includes a floating high pressure, a floating low pressure, as well as variable speed control on the compressors of the negative CO₂ rig, on the positive N13 compressor and on heat recovery units.

Field Test Results : Proving the Value of Solstice® N13 (R-450A)

Since the opening of the Auchan Epinay store in October 2013, a thorough evaluation of the results by the entire project team confirmed the energy efficiency benefits of the trial.
ENERGY CONSUMPTION
– The Solstice® N13/ CO₂ system is on par with energy consumption of the standard Groupe Auchan R-134a/ CO₂ system.
The new system was also measured against the following criteria to ensure the resulting performance was as good if not better than the current design.
– Discharge temperature at compressor head 110 °C (Below that of R-134a systems).

– Compressor Oil temperature 55°C (Below that of R-134a systems).

Sector Perspective: Rolling Out the Benefits of Solstice® N13

The Field Test with Groupe Auchan confirms the energy efficiency benefits of using Solstice ® N13 (R-450A) alongside CO₂ in a cascade system, with additional advantages in terms of CO₂ equivalent emissions reduction and much lower GWP (-58%) over  traditional refrigerants such as R-134a.

Feedback: A Greener Outcome for Group Auchan

„Groupe Auchan places environmental responsibility at the top of its business agenda and  we are very supportive of innovations such asthis new approach to refrigeration that delivers benefits to us as a business, to the customerswe serve and to the wider community.“ JEAN-MICHEL DEROO, Auchan Group

„We are continuously looking to apply more sustainable and lower GWP solutions into Supermarkets such as Auchan. With the experience and results of this Solstice® N13 trial, we are now confident we can deliver even greater environmental benefits to the industry. The choice of refrigerant is a fundamental elementin our strategy for the reduction of CO2 equivalent emissions and for maintaining or improving energy efficiency”.CÉDRIC LEROY, AXIMA REFRIGERATION

System Details:

Primary Refrigeration
• Refrigerant: Solstice® N13 (R-450A)
• Refrigerant charge: 1,200 kg’s
• Refrigeration power: 800 kW
• Consumption power: 350 kW
• Regime (evap. / condensing temp): -11 °C / +45°C
• Comp. type and manufacturer: Screw / Bitzer
• No. of compressors: 6 Comps (3 per pack)
• Pack Brand / Number: SCM Frigo / 2 Packs

MT Refrigeration
• Pumped Secondary Fluid: CO₂
• Secondary Fluid Charge: 2,000 kg’s

LT Refrigeration
• Refrigerant: CO2
• Refrigerant Charge: 2,000 kg’s
• Refrigeration power: 105 kW
• Absorption power: 21kw
• Regime (evap. / condensing temp): -45°C / +35°C
• Comp. type and manufacturer: S/Hermetic Recip/ Bitzer
• Number of compressors: 3 Comps
• Nº of chambers and packs: 1 pack