BioMérieux, a French company that does in-vitro diagnostics and microbiological testing, has seen monthly energy savings of up to 60% after replacing its previous transcritical CO2 (R744) rack system with two Panasonic CO2 condensing units.
The air-cooled Panasonic CO2 condensers provided 60% energy savings in the summer and 44% energy savings in the winter. They replaced a CO2 system that required adiabatic cooling to operate in ambient temperatures above 35°C (95°F). BioMérieux sought to move away from adiabatic cooling in line with its goal to reduce water consumption.
“The data from BioMérieux tells us we have reached energy consumption improvements of up to 60%, which is so much more than the 20% we expected,” said Jaume Casanovas, a Technical CO2 Product Manager at Panasonic Europe.
“We can do absolutely anything with natural refrigerants at this point,” he added.
The biotechnology company’s cooling system case study was presented by Casanovas and Indy Tharnvithian, a Product Specialist at Panasonic France, at the ATMOsphere (ATMO) Europe Summit 2023 in Brussels. The event was organized by ATMOsphere, publisher of R744.com.
In seeking a replacement for the CO2 cooling system at its facility near Lyon, France, BioMérieux set the following base requirements:
- An efficient system using a green refrigerant.
- A back unit supplying redundancy.
- The ability to maintain a stable 5°C (41°F) cold room temperature without adiabatic cooling. The old R744 system could not sustain the temperature even with adiabatic cooling.
- No refrigerant leaks, even in standstill or shutdown conditions.
Panasonic met the requirements using two CO2 condensing outdoor units, each with 11.15kW (3.3TR) average cooling capacity set up in a backup/rotation function.
“Thanks to our embedded transfer control technology, we control the liquid pressure and the refrigerant mass flow rate to determine the best electronic expansion valve to stabilize the superheat, which maintains the temperature in the cold room,” Casanovas said.
The condensers use patented split-cycle technology with an intercooler and a two-stage rotary compressor, which reduces the compression ratio, Tharnvithian noted.
“With our system, we can evaporate at −45°C [−49°F], with ambient temperatures above 43°C [109.4°F],” Tharnvithian said. “There is no need to use an adiabatic system.”
Casanovas reinforced the system’s operational capability by graphing the compressor’s maximum cooling capacity (14.87kW/4.2TR) and minimum (7.43kW/2.1TR) against ambient temperatures.
“We can meet the 11.15kW cooling duty and the roughly 9kW [2.6TR] partial load even in summer high ambient temperatures,” he said, with the working loads well within the maximum and minimum compressor range even at 45°C (113°F) ambient temperatures.
To keep the system from leaking in standstill or shutdown conditions, Panasonic calculated, based on a 38°C (100.4°F) maximum ambient temperature design and an 80bar (1,160psi) rated evaporator, the required refrigerant refilling ratio to allow the system to work in any condition.
“Refilling the system at 0.21kg/m3 [0.16oz/ft3] means the safety valve will not activate until the system hits 50°C [122°F], which is almost impossible at this ambient temperature,” said Casanovas.
20HP available in 2024
In Europe, Panasonic offers 2HP, 4HP and 10HP models of its dedicated CO2 condensing outdoor unit with configurations for both medium- and low-temperature operation or for medium-temperature operation only.
“Next year, we are going to have the 20HP system available in Europe,” Tharnvithian said.
Casanovas indicated that supermarkets and small industrial applications will be the target for these larger units. “The 20HP [size] is one of our most requested products,” he said.
Panasonic’s CO2-based outdoor condensing units have run well in hot climates, including in Southern Europe and Australia, noted Benjamin Tissot, then a Business Development Manager at Panasonic Europe, during an interview with R744.com at the EuroShop 2023 trade show in Düsseldorf, Germany.
The previous year, Tissot noted that Panasonic’s CO2-based outdoor condensing units had run well in the hot climate on the Spanish island of Ibiza.
“We are moving towards becoming a CO2 company,” said Tissot. “Our path is clear; natural-only is the key message.”
Panasonic currently offers free installation and operation training for its CO2 condensing units, Tharnvithian said. “I would invite engineers, installers and consultants to make the most of it.
Since the 2017 European rollout of its 2HP unit, the company has installed over 3,000 CO2 condensers in Europe.
“We can do absolutely anything with natural refrigerants at this point.”Jaume Casanovas, a Technical CO2 Product Manager at Panasonic Europe