Using remote distributed condensing units, the system reduces ammonia charge to between 1.5 and 3 lbs./TR.
Frick engine-room compressor, part of its low-charge central system
Frick Industrial Refrigeration, a division of Johnson Controls, last week introduced a low-charge ammonia central system that uses “remote distributed condensing” (RDC) units to substantially reduce the amount of ammonia required in industrial applications.
The introduction took place at the 2017 IIAR Natural Refrigeration Conference & Heavy Equipment Expo in San Antonio, Texas.
The RDC units, which include a condenser (such a plate-and-frame or adiabatic) and a small liquid supply vessel, are placed near two-three DX evaporators – “the point of liquid use,” said Joseph Pillis, director, global industrial refrigeration technology, Johnson Controls, Waynesboro, Pa., adding, “The concept of distributed condensing is really what makes this different.”
Apart from the liquid ammonia transfer between the RDC and the evaporators, “only [ammonia] vapor is distributed through the plant,” he added. This eliminates long liquid lines and reduces the amount of liquid ammonia that needs to be stored. The use of DX evaporators also cuts down on the charge.
Frick’s low-charge central system is capable of limiting the ammonia charge “in the range of 1.5 to 3 lbs. per ton [of refrigeration],” said Pillis.
“The concept of distributed condensing is really what makes this different.”
– Joseph Pillis, Frick Industrial Refrigeration
Unlike low-charge ammonia packaged systems, Frick’s design maintains use of a traditional engine room, though it only contains compressors and a control panel. As a result, “compressors can be much larger machines [than in packaged systems], running at much higher efficiency than little machines – on the order of 5% to 25%,” Pillis said. “We can run two-stage compressors and do economizers off both stages. It’s a very flexible design.”
Controls are key to managing the ammonia charge in the liquid supply vessels. “They monitor the liquid levels to make sure we don’t run out of liquid in places where we need it,” said Pillis.
The low-charge central system is installed at a food processing facility, providing 660 TR of capacity with only 2 lbs./TR of ammonia charge. The range of capacities for which the system is typically designed range from 250-1,000 TR, said Michael Colley, Eastern regional sales manager for Frick.