A low-charge ammonia chiller is installed at a Campbell Soup plant

A low-charge ammonia packaged chiller is providing air conditioning at a Campbell Soup plant in Ohio. In Napoleon, Ohio, in the northwest corner of the state, a giant Campbell’s tomato soup can – 33 feet tall and 33 feet wide with the iconic red-and-white label – stands next to a Campbell Soup Company soup production plant. Passersby driving on state Route 110 just south of the Maumee River sometimes pull over to take a look or snap a photo, imbibing the aroma of fresh-cooked soup from the plant. The can is not there just as a roadside attraction – it contains up to 200,000 gallons of water for the facility’s sprinkler system, according to Ohio Magazine. What is less obvious about this location – but much more consequential – is another, much smaller metal container located next to the soup production building. (The site also includes a building for beverage production.) The container holds an air-cooled, low-charge ammonia chiller that generates cold glycol used by an air handler in the building to generate air conditioning – one of the first such chillers used for this application in North America. The chiller/air handler delivers comfort cooling to a labeling and packaging section of the building where the red-and-white labels are applied to soup cans – and where a cool environment is needed to ensure proper adherence of the labels to cans. (The area did not have air conditioning previously.) This year-old packaged low-charge chiller, produced by Missoula, Mont.-based Azane (a division of U.K-based Star Refrigeration Group), is part of a new breed of low-charge ammonia packaged chillers also made by OEMs Mayekawa and Evapco. The chillers represent a new direction for the natural refrigerants industry in North America. For one thing, they offer a portable, efficient and future-proof air conditioning solution to industrial plants and potentially other large commercial and residential units currently using HFC or R22 chillers. Virgin R22 will no longer be available in North America in 2020, while HFC is targeted for a global phase-down per the Kigali Amendment to the Montreal Protocol (with the U.S.’s status currently tied up in the federal courts). Ammonia’s zero GWP and ozone depletion potential protects it from a phase-down, and in small charges ammonia falls below the 10,000-lb threshold for strict federal safety regulations. “We estimate that 70% of all building types could be using ammonia packaged units, including office and retail buildings,” said Mike Kallas, Azane’s senior applications engineer, in a presentation at the ATMOsphere America conference last June. Low-charge ammonia packaged chillers had been available in Europe for more than a decade before they emerged in the North American market. In one example, Azane’s parent company, Star Refrigeration, installed a rooftop low-charge ammonia chiller at a Marks & Spencer department store in the U.K. The air-cooled unit generates chilled water at 43°F, using 213 lbs of ammonia to support a 160 TR load (1.3 lbs/TR). The chiller only needs to be serviced one or twice annually, said Caleb Nelson, Azane’s vice president of business development. At a bakery in a populated area in Portland, Ore., Azane plans to install three low-charge ammonia chillers outside at ground level for air conditioning and some process cooling, each at 300 TR and 450 lbs of ammonia (1.5 lbs/TR). “We can go to a higher load by ganging packages together,” said Nelson. The air-cooled units, using flooded plate heat exchangers for ammonia evaporation, received jurisdictional acceptance for overall environmental impact. At ATMOsphere America, Kallas outlined a scenario for a supermarket where a low-charge packaged chiller stationed on the roof or on the ground could generate chilled glycol to condense CO2 at subcritical temperatures for low- and medium-temperature display cases, while also delivering glycol for air conditioning; heat reclaimed from the system could generate hot water. “You could do refrigeration, air conditioning and heating with a low-charge ammonia chiller package,” said Nelson. Southern California Edison (SCE), one of California’s largest utilities, is gathering data on the efficiency of low-charge ammonia packages, with an eye toward incentivizing their use as a replacement for R22 and HFC air conditioning and refrigeration units. “If you look at the opportunity, the biggest market is air conditioning,” said Paul Delaney, senior engineer for SCE. “Using low-charge ammonia with a secondary loop fits the equation well for a number of applications.” SCE has partnered with the Electric Power Research Institute (EPRI) to support a new study of the efficiency, capacity and operational characteristics of low-charge ammonia units at Creative Thermal Solutions (CTS), Urbana, Ill. The study so far includes a water-cooled Evapcold unit from Evapco and an air-cooled Boreas chiller from Mayekawa. CTS has separately developed a 7-TR ammonia chiller with a charge of less than one lb. “That chiller works perfectly with a very high COP,” said Pega Hrnjak, president, CTS and professor at the University of Illinois, Urbana-Champaign. Another advantage of a low-charge ammonia chiller is that it offers industrial plants that deliver cooling from a remote machine room a lower-cost option for areas that would otherwise require extensive piping from the machine (engine) room. That was the case at the 60-year-old Napoleon soup plant, where the Azane chiller is one of the first low-charge ammonia packaged units in the U.S. to be used for air conditioning at an industrial plant. “The Azane unit lent itself well because it’s a good distance from the engine room,” said Bing Cheng, Campbell’s manager of utilities engineering, based at the company’s Camden, N.J., headquarters. “We just put down a foundation pad outside, put the unit on top and hooked it up.” Using a flooded plate heat exchanger, 450 lbs of ammonia in the chiller cools a glycol solution to 44°F, and the glycol is piped to an air handler in the building, where the air is cooled to about 65°F. The chilled air is blown through ductwork to a section of the labeling area. The chiller is designed to supply glycol to two other air handlers for the same area that have not yet been installed. The total load requirement is 300 TR, at 1.5 lbs of ammonia/TR. Cheng praised the portability of the chiller. “If your cooling needs change or you need refrigeration elsewhere at the plant or at another facility, you can move it to another location.” Campbell Soup has, for more than two decades, been one of the industry leaders in shifting from large ammonia or R22 systems to low-charge systems. But rather than packaged systems, Campbell has opted to install self-designed low-charge ammonia skids in a centralized engine room, typically using ammonia as the primary refrigerant and glycol or chilled water as a secondary refrigerant piped to the cooling or freezing areas. For example, since 2011, Campbell has converted four Pepperidge Farm bakeries from R22 to low-charge ammonia, with another facility in Denver, Pa., scheduled for conversion. At a bakery in Richmond, Utah, which was converted in 2013, the machine room houses low-charge ammonia/glycol skids dedicated to HVAC. At a bakery in Lakeland, Fla., converted in 2016, water is used instead of glycol with the low-charge unit because of the warmer ambient temperatures. A number of Campbell’s thermal facilities have small charge (less than 10 TR) HVAC units using HFCs, which Cheng plans to replace over time with a natural refrigerant option (low-charge ammonia and/or CO2 systems). The Napoleon plant, for example, has two HFC “spot coolers” in production areas and others serving office space, said Allen Jackson, project foreman for Dunbar Mechanical, Toledo, Ohio, the plant’s HVAC&R contractor. “Down the road as HFC units break down, we typically design enough capacity in our low-charge ammonia [machine room] skids to replace the HFC units with air handling units that could use glycol or chilled water,” said Cheng. However, in the event an air conditioning load is far from the machine room (as in Napoleon) or the machine room lacks sufficient capacity, Campbell would consider installing more low-charge packaged units as a complementary solution, said Cheng. In fact, at its thermal plant in Paris, Texas, “we are looking to supplement the current machine room capacity,” he noted. “Instead of expanding the machine room, which would be costly, we’re looking at using an Azane unit to provide the new refrigeration load.” Though packaged low-charge ammonia chillers are new to the North American market, Jackson of Dunbar Mechanical was comfortable working with it, given his 30+ years of experience with ammonia systems. “It wasn’t completely different,” he said, adding that it was the first air-cooled system he has worked with. Nonetheless, Azane spent a few days after the start-up on training for Dunbar and Campbell technicians, said Nelson. Start-up of the Azane unit, which includes pressure and leak detection tests and on-site charging, may take a couple of weeks. But once it begins operation, the unit, with its industrial-quality design, is low maintenance compared to commercial HFC chillers that use copper pipes and hermetic compressors that are more prone to leaking or failure, Nelson said. Jackson acknowledged that he originally had “reservations” about the Azane unit because it was air-cooled. But having worked on it for over a year, he pronounced it “a good system” that has been running well, requiring “very little” maintenance, and experiencing no ammonia leaks. As for the hazard posed by ammonia in the unit, he said “there’s always some danger working with ammonia,” but added that it presents no risk to the public. Azane monitors the energy and performance of its chillers remotely. To save energy, the air handler can include an economizer that brings in outside air and turns off the chiller when the ambient temperature is low enough. At the Napoleon site, the chiller is performing “as-planned,” said Nelson.  This means that at full load (with three air handlers), seasonal performance will be close to 0.75 kW/TR, without VFD drives on the compressors. “So, the efficiency we’re seeing is really a baseline for our standard offering,” he said. The next version of the chiller (Azane chiller 2.0) is offering seasonal performances well below 0.6 kW/TR, “and we’re seeing a huge request for these already,” said Nelson. “These are efficiencies the HFC chillers can’t get to—even with every bell and whistle.” Source: ammonia21.com
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