28 // Trends
OPPORTUNITIES FOR CO2 IN THE INDUSTRIAL SECTOR Carnot’s distributed transcritical system avoids ammonia’s regulatory burden while offering energy and maintenance advantages – By Michael Garry
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a pioneer in manufacturi n g tr a n s c r i ti c a l C O 2 refrigeration systems, Quebec - based Carnot Refrigeration has produced more than 25 0 th ese sys te ms ove r th e pas t d e c a d e , m os tl y fo r fo o d re ta il e r s like Sobeys. More recently, 15 of Carnot’s transcritical CO 2 systems were made for industrial applications like cold storage and food processing, said Marc-André Lesmerises, its founder and president, in a webinar on May 16 called “Greening the Cold Chain: CO 2 in the Industrial Sector.” It was hosted by shecco Base, the market development arm of Brussels- based shecco, which pub lishes Accelerate America. “The more I work with CO 2 [in the industrial sector], the more I see opportunities,” Lesmerises said. By contrast, ammonia, the dominant refrigerant for industrial applications, presents challenges like its toxicity and the complexity and size of ammonia systems, he added.
CO 2 also enables a sharp reduction in regulatory compliance costs (such as labor), which “we have found to be the most important benefit for [industrial] end users,” said John Miranda, founder and chief marketer of Geneva, Ill-based Emergent Cold Technologies, who participated in the webinar with Lesmerises. Last year Emergent signed an agreement to distribute Carnot’s CO 2 systems in the U.S.
From left, John Miranda, Emergent Cold Technologies; and Marc-André Lesmerises, Carnot Refrigeration For industrial operators, Carnot – which recently doubled its production space in a new facility – is producing packaged transcritical CO 2 units that include gas cooler and evaporators. The units can be installed on a mezzanine or outdoors and don’t require a mechanical room. Lesmerises and Miranda outlined a number of the features of Carnot ’s industrial transcritical system, including several energy-saving elements. For example, it incorporates a hot-gas defrost system that saves condenser fan energy by “harnessing the pressure of CO 2 ," said Miranda. Lesmerises pointed to the substantial heat- reclaim capability of the tran scritical CO 2 system, which can be used for everything from space heating, hot water and dehumidification to dock heating, under-floor warming and reheating for food processing. With heat reclaim, “you improve so drastically the overall efficiency of your system, which gives you a system that nothing can compare to,” he said. The transcritical system leverages an adiabatic condenser/gas cooler to reduce condensing temperature in warm climates, thereby saving energy by preventing CO 2 from entering its supercritical phase. “Adiabatic is what brought CO 2 back to the table and it’s able to carve away some of the hot days that made CO 2 historically inefficient with air-cooled
condensers,” Miranda said at the IIAR Natural Refrigeration Conference & Expo in March. In more than 30 of its transcritical systems, Carnot has included ejectors, with which “we see huge benefits to overall efficiency,” said Lesmerises. Like adiabatic systems, ejectors enable the CO 2 system to operate efficiently in warm climates, he added. Carnot also optimized the CO 2 industrial system by “operating at higher suction [temperature] levels as a result of proximity [to the load] and lower piping pressure losses,” Miranda said.
Smaller piping The Carnot transcritical system also offers structural advantages compared to ammonia systems, Miranda said. For example, it employs significantly smaller piping, and eliminates an evaporative condenser, water basin/pump system , dif fusion tank , refrigerant pumps and circulation vessels. On the maintenance side, the CO 2 system eliminates oil-pot draining, compressor-shaf t seal replacement and belt adjustments. “One of the most critical things to make CO 2 work for industrial applications is proper oil management,” Miranda said at the IIAR Conference. “You want to keep the oil managed and in the rack and not out in the system.” MG Accelerate America // June -July 2018