FRANCE: A supermarket in Lyon has become the first in France to install the HFO blend refrigerant R471A as a lower GWP replacement for R134a.
The case study featured on the website of refrigerant supplier Climalife reveals that the choice was made for the U Express store after considering a number of options. These included a new CO2 booster installation, an R471A/CO2 cascade system and a conversion of the R134a medium temperature system to R471A and the installation of R290 integral low temperature cabinets.
The choices considered the budget, cost of energy, configuration of the building, the environmental footprint, F-gas regulations and future developments.
The R471A/CO2 cascade system is said to have offered significant financial benefits compared to an improved CO2 booster (parallel compression and multiple ejectors). Specifically, this would offer a €139,000 reduction in electricity bills over 10 years and a reduction in emissions of 128tCO2e according to the eco-efficiency model validated by the French testing and verification company Cemafroid. However, this option would have required additional work on the building’s structure and significant costs for its installation.
It was therefore decided to convert the R134a MT system to R471A with the installation of cabinets with doors to compensate for the 36% loss in 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.
Developed by Honeywell and marketed as Solstice N71, R471A is an A1 blend of the low GWP HFOs R1234ze(E) and R1336mzz(E) (78.7% and 17%, respectively) with 4.3% of the fire suppressant HFC227ea. This combination gives it a GWP of 148.
Located in the Bellecombe district of Lyon, U Express is a city-centre convenience store with a sales area of 975m².
Philippe Gipe, the Rhône-Alpes branch manager of contractor FCT, revealed that a CO2 installation was initially considered but this would have been very complicated and expensive to implement, given the structural modifications that would have had to be made to the building.
The machine room, where the refrigeration plant is installed, is in a very small space in the basement. The condenser and liquid receiver are located on the first floor near the offices.
Working within a timeframe of less than 48 hours to bring the new display cases into service, the R134a was recovered and as much of the original oil as possible removed. An oil of a higher viscosity was recommended in order to ensure correct lubrication of the compressors with R471A. The circuit was evacuated and then charged with 360kg of R471A, supplied by Honeywell in collaboration with Climalife.
The various regulation and safety devices were adjusted and the new Epta cabinets selected for R134a were fitted with Danfoss AKV electronic expansion valves. The Danfoss AKCC controller was programmed for R471A.
As for the evaporators, since the display cabinets use R134a and R471A 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. After a month’s operation, the display cases are said to be maintaining the desired temperature without any difficulty, even during an exceptionally hot period in the Lyon region.
The existing detector was replaced by two Glaciär Midi detectors, manufactured by Swedish manufacturer Samon and distributed by Climalife. One is installed in the machine room in the basement, the other at the condenser level on the upper floor where the liquid tank is located.
The U Express reopened its doors in August this year. The refrigeration engineer noticed from the outset that this new R471A refrigerant generates lower pressures, a key factor in reducing leaks and energy consumption.
Before and after
Before the remodelling, the system in the U Express shop comprised an R134a MT pack, equipped with five Bitzer 6H25 2Y compressors (110.5 m3/h) to supply open cabinets and the two cold stores. Operating temperature was -10°C/+40°C, with 83.4kW cooling capacity. Maximum output per compressor was 846 kg/h. An R404A refrigeration unit supplied the LT cabinets and LT cold room.
The new MT configuration supplies the fresh produce display units and the two medium temperature cold rooms. It comprises three 25kW compressors operating at -7°C/+ 40°C. The output per compressor is 695kg/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 R471A, which is greater than that of R134a.
The low temperature requirement is met using R290 integral cabinets.