Accelerate America Issue 5: Low-charge ammonia breaking with tradition

NXTCOLD’S low-charge ammonia system, created and first installed at Los Angeles Cold Storage, which specialises in handling seafood globally, challenges industrial refrigeration conventions. In the industrial Issue 5 of Accelerate America, LA Cold Storage’s John Scherer explains how he realised his goal to prompt change in the ammonia refrigeration industry.

Nearly a quarter of a century ago, refrigeration engineer John Scherer, speaking to the Los Angeles chapter of ASHRAE about the history of ammonia refrigeration, captured quite eloquently the industry’s penchant for sticking with the tried-and-true rather than venturing into new vistas.

“Just for a moment, let us recognise a strange phenomenon – the ironic tendency to resist change. This is one natural tendency we must strive to overcome,” John Scherer, ASHRAE presentation, 1991.

But little did Scherer know at the time the role he would be playing in 2015 to help the ammonia refrigeration industry embrace change. For more than 36 years, Scherer has been Manager of Engineering at Los Angeles Cold Storage, a public refrigerated warehousing company. In 2010, he added a second title: Chief Technology Officer for NXTCOLD LLC, a startup owned by Scherer and LA Cold Storage.

At NXTCOLD, Scherer developed an industrial refrigeration ammonia system with what he describes as a “very low” refrigerant charge (usually under 50 pounds), or less than a pound per ton of capacity, compared to the charges of traditional systems that can reach 50,000 pounds and more.

The system can be applied to a wide range of refrigerated warehouses and work with capacities ranging from 5 TR (tons of refrigeration) to 150 TR, replacing ammonia charges in excess of the regulatory threshold of 10,000 pounds. The system’s operating temperatures runs from -51°C to 16°C, covering blast freezers, freezer or coolers.

At a time when the refrigeration industry is moving in the direction of lower and lower ammonia charge, and away from F-gases, NXTCOLD’s unit represents the change that Scherer was alluding to in 1991.

By reducing the ammonia charge so dramatically, NXTCOLD’s low-charge unit enables end users to improve safety, reduce their regulatory responsibilities, and focus on their core business, at a reduced cost and greater energy efficiency than traditional ammonia systems.

Cold-storage base in LA

Los Angeles Cold Storage operates three cold-storage warehouses, which combined encompass 400,000 square feet of freezers, use 32,000 pounds of ammonia, and take up 10 acres.

In January 2012, a test cell began operation at LA Cold Storage’s Central plant, followed 14 months later by the installation of a rooftop ‘penthouse’ unit at the company’s Fourth St. facility. Since, many industry associations, including IIAR, AHSRAE and RETA, have sent representatives to LA Cold Storage to investigate the efficiency of the low-charge units. The company is in the planning stages to install several more units at its plants.

Safety was the big driver behind Scherer’s invention of a low-charge system for LA Cold Storage, due in part to the company’s close proximity to downtown L.A. and threat of an ammonia leak.

“This system was developed by an end user because we couldn’t handle big ammonia charges anymore,” he said. “I couldn’t sleep, it became an obsession to develop a low-charge system.” It took him four years, working nights and weekends, to come up with the design.

In addition to LA Cold Storage, NXTCOLD is installing multiple units at a facility in California, run by Lineage Logistics, the second-largest U.S. cold storage provider. NXTCOLD also has a backlog of 70 units it is building for additional customers, with most of its previous installations having been retrofits.

“There are hundreds of other people who want the equipment,” said Scherer. “We’re gearing up to handle those.”

NXTCOLD regards thousands of facilities in California with more than 2,000 pounds of HFCs or HCFCs - which are regulated under the state’s AB32 climate change law - as potential customers. And the company is also seeking to install its units at Craft Beer facilities, which range from 5,000 to 10,000 square feet. Other potential customers include supermarkets and ice rinks.

While NXTCOLD has focused so far on ammonia-only refrigeration, it plans to venture into ammonia-CO₂ cascade systems, which could also be applied to supermarkets.

Contractors hired to install NXTCOLD equipment can do so in less than a day as opposed to the six months to a year taken up by a traditional ammonia system, with its extensive permitting and pipefitting.

“They can do a couple of projects a week and make a much better margin. At the end of the year, they’re going to hold onto a lot more money and have a better quality of life. And they’ll have the environmental people and utilities behind them,” said Scherer.

Controlling refrigerant

To reduce its ammonia charge to under a pound per ton, NXTCOLD’s unit dispenses with many of the refrigerant-holding components typically found in ammonia systems, such as receivers and accumulators. Instead, the refrigerant travels directly from the condenser to the evaporator to a DX compressor.

NXTCOLD’s units have several energy-saving features, such as being close-coupled with open-drive ammonia equipment that has substantial heat-absorbing properties. The energy efficiency improvement over traditional ammonia systems is typically 8%, though ‘it’s not unusual for it to run anywhere from 15% to 35%, particularly when compared with HFC and HCFC systems,’ Scherer said.

NXTCOLD has estimated the cost savings of its system compared to traditional pumped-liquid ammonia-overfeed systems in a generic facility. With the NXTCOLD system, the plant has one fewer operating engineers, a savings of US $100,000 (€92,375) annually. By not building and maintaining an engine room, it saves $650,000 (€600,000) the first year, and $45,500 (€42,000) annually thereafter.

In addition, the unit saves eight percent on energy costs annually, translating to $205,597 (€189,920), and a 90% reduction in ammonia refrigerant, translating to $21,600 (€19,950) in the first year, and $1,920 (€1770) a year thereafter.