Transcritical CO2 (R744) refrigeration has come to South America, and other parts of Latin America.
That was the message shared by Richard Osma, General Manager for Weston, a Colombia-based manufacturer of supermarket refrigeration equipment, at a webinar during the ATMO World Summit on March 30.
The ATMO World Summit was organized by ATMOsphere (formerly shecco), publisher of R744.com. Marc Chasserot, CEO of ATMOsphere, moderated the webinar.
Founded in 1961, Weston began to explore transcritical CO2 refrigeration for supermarkets five years ago. At the time, Weston’s suppliers “did not recommend” installing CO2 systems “in the tropics,” said Osma. Stores were also skeptical about trying new technology.
Nonetheless, Weston formed a partnership with German OEM TEKO to bring its CO2 systems to Colombia. “We’re very enthusiastic about our alliance with TEKO,” said Osma. “We’re going to manufacture racks with the TEKO brand.”
Weston installed its first TEKO transcritical CO2 system in June 2019, at a Makro Valle de Lili store in Villavicencio, Columbia; it was the country’s first transcritical CO2 installation, said Osma.
To date, Weston has installed transcritical CO2 systems at 16 supermarkets in the region, about half at new stores, half retrofits at existing outlets. The company plans an additional six installations by July, at four new and two existing stores. To facilitate retrofits, Weston uses valve stations, and can change the evaporators in existing cases and cold rooms, Osma noted. In addition to manufacturing and installation, Weston handles after-market services as well.
Last year, Weston also began manufacturing propane (R290)-based commercial cases.
While Weston has led the way, over the past year, “many players” have joined the transcritical CO2 market, said Osma. “We have a lot of competition. [The CO2 market] is growing quickly. I see it exploding in the future.” He regards transcritical CO2 as especially suited, both economically and technically, for larger supermarkets.
With the growing number of suppliers, Osna is seeing training centers for CO2 systems emerging in Bogota.
The activity is not just in Colombia, but other countries in the region as well, including Mexico, Ecuador, Brazil, Argentina and Venezuela.
Although Colombia is located near the equator in a tropical climate, ambient temperatures vary depending on location in the mountainous geography. Stores using transcritical CO2 systems are situated in three altitude ranges: 2,500m (8,202ft) or more above sea level; roughly 1,200 to 1,400m (3,937 to 4,593ft) above sea level, and at or close to sea level. The particular location will affect the performance of the system, and whether it needs efficiency-boosting components.
In the capital city of Bogota, with an elevation of 2,640m (8,661ft), ambient temperatures range from 10 to 20°C (50 to 68°F), allowing the CO2 systems to operate up to 99% of the time in efficient subcritical mode. “It’s very easy to justify transcritical systems there,” Osma said, adding that energy savings compared to an f-gas system is often 30%. Those savings and the lower cost of CO2 refrigerant would deliver a “very fast” return on the cost premium (10 to 15%) that may be paid for a CO2 rack and gas cooler, he added.
In his presentation at the ATMO World Summit, Osma had data on six Bogota supermarkets with transcritical CO2 systems. At a new Éxito Nuestro store, a booster system, installed in April 2021 with capacities of 23kW (6.5TR) for low temperature and 98kW (27.9TR) for medium temperature, operates in subcritical mode 90% of the time. Some of the other Bogota stores use parallel compression to boost efficiency.
At the intermediate elevation, where ambient temperatures range from 23 to 35°C (73 to 95°F) , transcritical systems operate in transcritical mode 70-80% of the time, said Osna. Even so, efficiency improvements of up to 25% are achieved, sometimes with the help of parallel compression.
An example of a store at the intermediate elevation is an Éxito Laureles outlet in Medellin, which underwent a retrofit from R22 to a CO2 system in June 2020. The transcritical rack has capacities of 46kW/13.1TR (low temperature) and 222kW/63.1TR (medium temperature), and includes parallel compression.
At the lowest elevation, at or near sea level, temperatures range from 25 to 45°C (77 to 113°F). CO2 systems here, which run in transcritical mode 95 to 99% of the time, “always use parallel compression,” said Osma. Still energy savings of up to 10% are possible.
Weston installed a transcritical CO2 at a Makro Alto Prado store near sea level in Barranquilla, Colombia, in August 2020. It has capacities of 40kW/11.4TR (medium temperature) and 132 kW/37.5TR (low temperature).
Osma said Weston is now looking at using ejectors to increase efficiency in transcritical CO2 systems.
Weston’s supermarket clients now see transcritical CO2 refrigeration as a “good advertisement” that they are using equipment that is friendly toward the environment, said Osma.
“We have a lot of competition. [The CO2 market] is growing quickly. I see it exploding in the future.”Richard Osma, Weston
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