The company's requirements included a natural refrigerant, quick installation and energy efficiency.
CO2 transcritical was the natural refrigerant system of choice for a seafood processing facility in eastern Canada seeking to replace its freon system this year, according to a case study presented by Canadian contractor Cimco Refrigeration during the online ATMOsphere America 2020 conference on October 21.
Organized by shecco (publisher of this website), ATMOsphere America took place from October 20 to 22.
The seafood processor, which was not named, indicated that it wanted a natural refrigerant system to replace the freon equipment. Its approximately 16,000ft2 (1486.45m2) facility includes areas for receiving, storing, processing and distributing seafood.
“Right from the very beginning, it was clear that the customer valued technology and innovation,” said Jonathan Berney, Business Development Manager for Cimco, which has installed more than 50 transcritical CO2 systems. “And our system delivered on that by using some of the newest technology available to us.”
While the customer considered using either a CO2 transcritical or an ammonia (NH3)/CO2 cascade-based system, the CO2 transcritical system was seen as the best fit for all of the customer's requirements “while still delivering on [the] best combination of fixed and variable costs,” said Berney.
Tight timeline, future expansion
The customer's first requirement was that the project be delivered on a very short timeline with “minimum construction time on site,” said Berney.
This was achieved with the use of pre-packaged, factory assembled and tested transcritical CO2 racks, Berney explained. In addition, the relatively small piping of the CO2 transcritical system was advantageous because “it could be installed in a timely manner,” Berney said.
In addition, the customer also required that the project include plans for future expansion. The “compact size of the CO2 equipment allowed for future equipment footprint,” he said.
The project was split into two phases. The first phase, completed this year, saw the installation of two CO2 transcritical racks serving the cooling loads for the facilities holding freezer, shipping and receiving area, and cluster chill and brine tanks. Each rack is tied to an adiabatic gas cooler, and the system is backed up by a generator and condensing unit to maintain CO2 pressure.
The second phase is scheduled to be completed next year when a third CO2 transcritical rack will be commissioned to serve the cooling loads for the facility's remaining cooling loads (cold room, after freezer, palletizing and stretch wrap).
The total load for phase one is 390TR (1,371.6kW) for temperatures ranging from -2°F to 32°F (-18.9°C to 0°C); phase two’s load will be 56.5TR (198.7kW) with temperatures ranging from -22°F to 40°F (-30°C to 4.4°C).
Energy consumption comparison
Berney also presented an energy consumption forecast table which compared the monthly projected kWh consumption figures for one year for three systems: a two-stage CO2 transcritical system, a single-stage ammonia system with an economizer, and a single-stage NH3/CO2 cascade system.
The analysis showed the the CO2 transcritical system would consume the least amount of kWh each month except for July and August, when consumption would be comparable for all three systems. The total annual consumptions for each system was forecast to be 1.28 million kWh for transcritical CO2; 1.44 million kWh for ammonia; and 1.48 million kWh for ammonia/CO2 cascade.
The mean ambient temperature in the analysis never exceeded 15°F (-9.44°C).
Regarding the NH3/CO2 cascade system, Berney noted that “surprisingly the performance is not as good as one might expect and I think in this case, that is due to the fact that there is not a lot of low temperature load.”
Cimco was also able to offer heat reclaim with the CO2 transcritical system for their underfloor heating systems and “this supported a favorable payback scenario,” the presentation stated.
“Right from the very beginning, it was clear that the customer valued technology and innovation.” – Jonathan Berney, Business Development Manager, CIMCO