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Saving Energy
LINEAGE LOGISTICS TO DEPLOY ON-DEMAND SUBCOOLER AT AMMONIA PLANT Rebound’s IcePoint system provides bursts of cooling that boost throughput and save energy in blast freezing
But 80% of the economic value of the system for end users – initially as a retrofit in large liquid-overfeed ammonia systems used by cold-storage and food processing facilities – is from the acceleration of the freezing cycle, he said.
— By Devin Yoshimoto & Michael Garry
The key advantage of IcePoint is in its ability to provide precise on-demand, dynamic bursts of cooling capacity.
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ineage Logistics, a major U.S. cold-storage operator, will deploy Rebound Te c h n o l o g i e s ’ I c e P o i n t subcooling system to accelerate freezing times and save energy for an ammonia blast-freezing system, based on a successful pilot at a Lineage facility in Oxnard, Calif. The deployment take place this fall at a Lineage warehouse in Unadilla, Ga., said Kevin Davis, CEO and co-founder of Rebound Technologies. The Unadilla site will use a full-size two-skid IcePoint system with a two-stage economized large-charge ammonia system. According to Davis, IcePoint reduces the energy consumption of a single-stage economized ammonia system by 35%. It also offers peak-energy mitigation.
Accelerate Magazine // June 2019
At the Oxnard facility, which installed a single-skid IcePoint system in February 2018 with a single-stage economized large - charge ammonia system, the blast freezing of 1.7 million lbs of strawberries was accelerated by 2.3%, delivering 40,000 additional lbs of frozen strawberries over 5,000 hours. This increased revenue by providing more frozen strawberries in the same amount of time. The largest burst of cooling provided by IcePoint in Oxnard was for 10.5 TR (37.5 kW), using a tank temperature of -22°F (-30°C), with a COP of 3.3, reported Davis. The system can deliver capacity boosts of up to 140 TR, he added. Rebound's full-size commercial unit, operating for 5,000 hours during peak strawberry season at Oxnard, would help the facility freeze up to 11 million pounds of additional strawberries," said Davis.
HOW IT WORKS IcePoint’s subcooling is needed when a refrigeration system’s suction temperatures are rising and the system “doesn’t have enough capacity to keep those temperatures down,” Davis explained. “ That's when IcePoint can provide these strategic bursts of cooling to bring those temperatures and pressures back down to their set points." Instead of vapor compression, IcePoint uses a “freeze point suppression cycle” to generate cooling. Initially water is frozen at the most economical time of the day and stored in a tank. Next a non-chloride salt, or freeze suppressant, is injected into the bottom of the tank, mixing with the ice and lowering its temperature to about -25°F (-32°C) The low-temperature slurry can then be used at the appropriate time to subcool the liquid ammonia. In generating ice, the IcePoint sys tem employs a condensing unit that currently runs on an HFC refrigerant. However, Davis emphasized that the condensing unit is refrigerant agnostic. "If ammonia or CO 2 gets to the right economic price point, we're in, 100%," he said. "We'd prefer to be in." Meanwhile, David is focusing on validating the technology in ammonia systems. “Once we validate that, the sky's the limit." DY & MG