American beverage giant Coca-Cola has installed the first low-charge direct-expansion ammonia refrigeration and air conditioning system in Costa Rica, at the Coca-Cola Concentrates Plant in Guanacaste.
The project was originally envisioned as a recirculated ammonia system by another contractor. However, concerns about the ammonia charge required for a system of this size (about 8,000lbs/3,629kg) led to a rethink. Local contractor Refrigeracion Y Soluciones De Frio (RSF) then instead chose an ADX ammonia (R717/NH3) system manufactured by Colmac Coil.
“After winning the job, there was questioning of the ammonia charge, then we were asked to redesign the system,” said Lisandro Salas Mora, Founder & CEO of Refrigeracion Y Soluciones De Frio. “This was the perfect opportunity to redesign the project with a new technology that has not been applied yet in Costa Rica,” Salas said. The new system, which has a charge of 2,800lbs (1,270kg), was installed in July 2020.
The redesigned project delivered an increased energy efficiency of 13%, and was designed to comply with both local Costa Rican INTECO and IIAR standards, according to a post on Colmac Coil’s website. The increased efficiency delivered a saving of approximate US$250,000 a year, Salas said.
“With this system, and unlike recirculation systems, the evaporators are fed only with the refrigerant necessary,” RSF explained in a report about the project. “Also in the pipes only the refrigerant that is required for cooling circulates, and the biggest difference is in the suction line where only gas circulates and as the pipe is larger and very long, the decrease in coolant is really important.”
“This was the perfect opportunity to redesign the project with a new technology that has not been applied yet in Costa Rica,”Edouardo Salas, RSF
The installation has a capacity of 208TR (731.5kW) for MT and LT refrigeration, and is equipped with plate heat exchangers and six identical screw compressors from Frick. The system also has a capacity of 750TR (2,638kW) for air conditioning, and 150TR (528kW) for the production of cold water for process cooling.
The Coca-Cola plant is about 463,000ft2 (43,000m2) and supplies drinks concentrate to Central America, the Caribbean, Chile, Mexico, Brazil and Argentina for the production of Coca-Cola and 89 other beverages.
During the design process, packaged 134a chillers were considered. However, this solution was rejected due to the high GWP of the refrigerant, and because the 134a solution was “an exclusive system per zone of application that is required to have equipment redundancy to achieve system backup as the project requires it, meaning the investment cost is higher and the installed power too,” the project report explained.
With the ammonia solution “It was possible to select identical equipment in model and power for all temperature levels, and thus standardize equipment to achieve much better control of maintenance and spare parts,” the engineers said.
“Another important improvement in the efficiency of the system was the use of heat recovered from the compressor oil for heating the glycol of the radiant floor system in the low temperature chamber,” the report explained.
“When having temperatures below zero degrees celsius, it is necessary to heat the floor to avoid freezing in the low humidity. In this project a modern system was used with glycol pipes embedded in the concrete floor to ensure a temperature above zero degrees celsius and prevent freezing.”
The energy efficient refrigeration system wasn’t the only effort to make the plant environmentally friendly. The facility has systems for monitoring lighting and air conditioning to “avoid waste,” according to the report. The facility has been awarded a LEED Silver certification.
Salas, who was the main engineer on the project, even received an Innovative Technologist Award from CITEC (College of Technologist Engineers). The CITEC award is “given to individuals who make outstanding contributions to their respective field of engineering,” Colmac Coil said.
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