Cimco Refrigeration, a Toronto-based industrial refrigeration contractor, has reduced energy consumption at a Quebec-based meat-processing plant operated by Viandes Paquette by 2.5 million kWh annually with a low-charge ammonia/NH3 (R717) system. By reclaiming excess heat from the ammonia system, Cimco removed the need for any boilers at the plant.
Cimco has dubbed this system, installed in 2010, the “first low-charge ammonia net-zero industrial” plant.
“In my mind, the HVAC system and refrigeration system is net zero,” said Benoit Rodier, Director of Business Development at Cimco. This is due to the absence of a gas boiler, the region’s “clean and renewable” hydro electricity from utility Hydro Quebec and the use of ammonia as the refrigerant.
“In my mind, the HVAC system and refrigeration system is net zero.”
Benoit Rodier, Cimco Refrigeration
Rodier described the installation during the End User and Contractor session at the ATMOsphere (ATMO) America Summit 2022 on natural refrigerants. The conference, which took place June 7–8 in Alexandria, Virginia, was organized by ATMOsphere (formerly shecco), publisher of Ammonia21.com.
Replacement for facility that burned down
In 2009, Viandes Paquette – a small, family-owned business that runs independent supermarkets across Quebec – built a large meat-production plant to supply its stores. Shortly before opening, the plant burned down.
Cimco was commissioned to design the new refrigeration system, which had to be innovative, reliable, low-maintenance and integrated with the building’s HVAC, as per the owner’s request. To be eligible for a grant from Hydro Québec, Viande Paquette also wanted to focus on energy reduction and heat reclamation.
According to Rodier’s presentation, the plant was equipped with two ammonia-based systems: a low-charge NH3 system for the low-temperature (LT) units, such as the spiral freezer and blast freezer, and a self-contained ammonia/glycol packaged chiller for the plant’s medium-temperature (MT) needs. In relation to the MT system, Rodier emphasized that the ammonia doesn’t leave the mechanical room and the LT system only pumps low-charge ammonia to unoccupied areas.
Across the plant, there’s roughly 1,200lb (544kg) of ammonia in use, which is less than half what a normal system of this size would use, according to Rodier.
For heat reclamation, Cimco installed a thermal buffer containing warm glycol that stores energy for when the plant needs it, and three ice batteries, which have two-purposes. In the summer, the plant freezes the ice batteries overnight when the load is lower and uses it the next day for air-conditioning. In the winter, the system is forced to run to produce heat that is then pumped around the plant.
This system produces hot water for cleaning and for defrosting the spiral freezer, as well as air-conditioning and heating for the plant and its offices. It also defrosts the truck docking area and employee terrace in the winter via glycol pipes laid under the concrete. All of the plant’s heating needs come from the central ammonia system.
In total, Cimco’s installation has reduced the amperage at the plant by 29%, from 2,800amps to 2,000amps. It removing the need for separate systems for hot water (260kW), heating (1,200kW) and air-conditioning (62kW/18TR). The refrigeration package that Cimco installed was also 200kW (57TR) less than the original system.
Lessons learned
Rodier shared with ATMO America attendees that if he were to design the system today, he would add CO2 (R744). For the LT system, he would pump CO2 instead of ammonia, and for the MT system, he would pump R744 instead of the glycol. Rodier added that he would use either a secondary or cascade system, “depending on the performance of the compressor.”
“I would use two CO2 loops,” Rodier explained. “One that would be pumped into low temperature, and I would use another one on the medium temperature replacing the glycol just to make the piping smaller and the evaporator way more efficient.”
In addition to higher efficiency, adding R744 to the system would reduce the ammonia charge to 400–500lbs (181–227kg).
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