Located in the Bellecombe district of Lyon, U Express is a city-centre shop with a modern concept, offering a wide range of fresh produce and non-food essentials. This U Express franchise represents a major brand in the SYSTÈME U group’s network of convenience stores.
To reduce energy consumption and improve customer satisfaction, Rui Inacio, the shop manager, decided to install refrigeration cabinets with doors for medium and low temperature cooling. This was an opportunity to reorganise the 975 m² sales area and improve customer comfort. The ambient temperature could be raised from 3°C to 5°C in the fresh produce area, where shoppers would be more inclined to stay at the shelves to make their choice. Work is also under way on the roof to bring in more natural light.
In January 2023, the project was launched and Rui Inacio called on his various suppliers for this remodelling, to be carried out during the summer off-peak period. The FCT Rhône-Alpes agency studied the refrigeration equipment in order to recommend the most environmentally-friendly solution.
Renovation of the U Express: clear, precise specifications
FCT (Froid Climatisation Techniques) is considering several solutions with a number of criteria to be met, including:
- the budget,
- the cost of energy,
- the configuration of the building,
- the environmental footprint,
- F-Gas regulations and future developments.
In this configuration, new Solstice® N71 (R-471A) refrigerant for medium temperature refrigeration as a replacement for R-134a comes at just the right time.
“When Climalife told me that Solstice® N71 could be a solution for replacing R-134a, it was a good opportunity for us and this project. Initially, we were considering a CO2 installation to meet the specifications, but this would have been very complicated to implement, given the building and the structural modifications that would have had to be made, while keeping within the budget,” explains Philippe Gipe, FCT Rhône-Alpes branch manager.
The machine room, where the refrigeration plant is installed, is located in a very small space in the basement. The condenser and liquid receiver are located on the first floor near the offices.
In order to validate the choice of technology, the Honeywell and Climalife technical teams carefully studied the shop’s configuration and compared different architectures to offer the best solution for U Express Bellecombe in terms of eco-efficiency.
What architecture should you choose for the best return on investment?
Three configurations are being studied: a new CO2 booster installation, a Solstice® N71 / CO2 cascade and a conversion of the R-134a medium temperature (MT) system with Solstice® N71 and the installation of R-290 integral low temperature (LT) cabinets.
The Solstice® N71/ CO2 cascade compared with an improved CO2 booster (parallel compression and multiple ejectors) offers significant financial benefits, with a €139k reduction in electricity bills over 10 years and a reduction in emissions of 128 tCO2e according to the eco-efficiency model validated by Cemafroid. However, this would require additional work on the building’s structure and significant costs for its installation.
It was therefore decided to convert the R-134a MT system to R-471A. The installation of cabinets with doors compensates for the 36% loss in refrigeration capacity between the two refrigerants by reducing the required refrigeration capacity. As a result, the capacity of the existing plant is far greater than the cooling requirement, making it possible to validate the solution, keep the installation in good working order and reduce investment costs (see eco-efficiency study diagram). Solstice® N71 meets all the specifications, with a GWP of 148, high energy efficiency and a greatly reduced environmental impact.
Solstice® N71: easy to install and maintain
At the end of July, the challenge was launched for FCT and their refrigeration technician Mohamed Chebel. The aim was to carry out the work on the MT system in less than 48 hours and produce the cooling required to bring the new display cases into service.
After recovering the R-134a, Mohamed Chebel carried out a state-of-the-art oil change to remove as much of the original oil as possible as an oil of a higher viscosity was recommended in order to ensure correct lubrication of the compressors with R-471A. The circuit was evacuated and then charged with 360 kg of R-471A, supplied by Honeywell in collaboration with Climalife.
The technician then adjusted the various regulation and safety devices (HP- LP). The new EPTA units selected for R-134a were fitted with DANFOSS AKV electronic expansion valves.
The Danfoss AKCC controller was programmed with the Antoine equation coefficients for R-471A.
As for the evaporators, since the display cabinets use R-134a and R-471A has a lower volumetric refrigeration capacity, the question arose as to whether the refrigerant mass flow would be sufficient. The preliminary theoretical study showed that the plant’s available refrigeration capacity would be able to supply them. It has to be said that after a month’s operation, the display cases are maintaining the desired temperature without any difficulty, even during an exceptionally hot period in the Lyon region.
To keep the vegetables fresh, a double-flow evaporator connected to the R-471A circuit is positioned above this new display unit to maintain the ideal temperature and provide greater comfort for consumers.
The existing Murco detector is being replaced by two Samon Glaciär Midi detectors distributed by Climalife. One is installed in the machine room in the basement, the other on the condenser floor where the liquid tank is located. Samon, the Swedish manufacturer of room controllers, is in the process of qualifying R-471A for its entire range. This installation is a great opportunity to validate this new model of detector on the market.
The U Express reopened its doors on 16 August this year, and the installation in service is providing full satisfaction. The refrigeration engineer noticed right from the start that this new R-471A refrigerant generates lower pressures, a key factor in reducing leaks and energy consumption
“We had a few questions when we started up, when we noticed differences in pressure compared with R-134a. But your technical support quickly reassured us. We very quickly found the right balance in terms of settings, and all the refrigeration units and cold rooms came down to the required temperature” explains refrigeration technician Mohamed Chebel.
This A1 refrigerant, with its classic physical characteristics (medium pressure and non-flammable), means that any refrigeration technician with standard training can easily perform with the skills needed to service and maintain the system.
Solstice® N71 is a forward-thinking solution for medium temperature refrigeration, perfectly suited to the future needs of commercial refrigeration.
“During this heatwave, Mohamed and I came to the conclusion that if all shops operated like this one, it would be perfect” concludes Philippe Gipe.
Remodelling of the medium temperature cooling installation and its specifications
Original configuration of the U Express shop
- The R-134a MT pack is equipped with 5 Bitzer 6H25 2Y compressors (110.5 m3 /h) to supply open cabinets and the 2 cold storage rooms.
- Operating temperature is -10°C / +40°C, with 83.4 kW cooling capacity. Maximum output per compressor is 846 kg/h.
- A R-404A refrigeration unit supplies the LT cabinets and LT cold room.
New configuration of the U Express shop using cabinets with doors
- New R-134a EPTA cabinets are installed and fitted with Danfoss AKV electronic expansion valves.
- With these new units with doors, refrigeration power requirements are reduced to 47kW.
- The existing R-134a MT refrigeration plant has been retrofitted with new Solstice® N71 (R-471A) refrigerant. It supplies the fresh produce display units and the two medium temperature cold rooms.
- The R-471A charge is 360 kg
- Operating at – 7°C / + 40°C, the compressors deliver 25 kW each, so only 3 compressors are needed to cover requirements with R-471A. The output per compressor is 695 kg/h.
- The BSE 32 oil was replaced by a BSE 55; an oil with a higher viscosity was selected in order to limit the solubility of R-471A, which is greater than that of R-134a.
- Two new Samon Glaciär Midi detectors have been installed.
- R-290 integral cabinets for the low temperature requirement.
Eco-efficiency study carried out to compare different architectures
In this new study, we have compared two configurations that meet the same refrigeration needs of the point of sale for MT systems:
- Direct expansion at medium temperature with R-744.
- Direct expansion at medium temperature with R-471A.
The figure below shows the results obtained, both in terms of total CO2 emissions, including direct (leaks) and indirect (energy consumption) effects, and the total cost of ownership (TCO) over the lifetime of the facility.
As we can see, R-471A offers the best economic compromise and a significant reduction in CO2 emissions.
The solution
Solstice® N71 (R-471A) is the new refrigerant developed by Honeywell, based on HFO technology with a GWP less than 150. It is non-flammable, non-toxic, and offers significant advantages over CO2 and traditional fluids such as R-404A. It enables medium temperature refrigeration installations to make energy efficiency gains and helps to reduce the overall carbon footprint.
It can be used in a wide range of installations and is perfectly suited to shop design. It is a safe, energy-efficient solution that is easy to install. It is a medium-pressure A1 refrigerant, easy to manage when handling, storing and transporting.