|Harrison Horning of Delhaize America/Hannaford looks at the ongoing changes, especially the trend toward CO2 as a primary refrigerant in supermarkets.|
So, supermarket owners want refrigeration systems that are energy efficient to hold down costs and pro-environmental to portray political correctness. But, for engineers, contractors, and technicians, that approach may not be that easy when opening a new store or retrofitting an existing location.
At the most recent Food Marketing Institute (FMI) Energy and Store Development Conference, papers and presentations focused on these challenges. At the same time, nearly all the technologies being discussed were being used in some supermarkets today, and all were expected to gain increasing attention as the sector moves away from high-GWP (global warming potential) refrigerants and toward even more efficient equipment.
Comparing Refrigeration Systems
Danny Halel, senior technical training leader, Hussmann Corp., compared refrigeration systems, referencing a case study involving Hy-Vee supermarkets.
“You can’t compare apples to apples unless you only have apples,” he said. “But, you can compare commonalities between apples and oranges. So, our intent is to generate metrics derived from commonalities among refrigeration architectures that may provide insight on how those architectures compare.”
He discussed four systems at four Iowa locations — one with open-drive DX racks and evaporative cooling, one with multiple DX racks in a distributed approach, one with MT and LT secondary CO? racks, and one with distributed DX.
“There is not one solution for every application,” he added, stating:
• The impact to energy on the architecture and total store efficiency is significant when adding doors and LEDs on cases;
• The old assumption that 50 percent of the total electrical load comes from the refrigeration system is true; however, this can be reduced by paying close attention to the load structure;
• The impact of coefficient of performance (COP) is negatively affected when adding the condenser and evaporator energy; however, this can have a smaller impact by paying attention to loads such as fans including variable frequency drives (VFDs) on condensers, LED lights, and doors; and
• Leak management must be considered, even in an energy study.
Harrison Horning, director of energy and facilities, of Delhaize America/Hannaford, examined the ongoing push behind the use of CO? as a primary refrigerant in supermarkets. The refrigerant has suddenly become a factor in company commitments, pilot projects, planning and budgeting, operation and maintenance, monitoring performance, tracking progress, and long-term planning.
He spoke of a pilot store in Maine where only CO? was used in a transcritical approach. In that situation, energy-performance data was compared with two other stores, one of which uses hydrofluorocarbon (HFC)-407A in a DX approach with three racks and full condensing parallel heat reclaim using glycol and a second store using HFC-507 with three racks and a combination of series and full-condensing parallel heat reclaim direct.
He noted, “Project economics depend on many variables, but energy performance can be good, and maintenance can be manageable, when using CO2.”
And, he urged those considering CO2 to look beyond the U.S., where CO2 is more widely used. “We can learn a lot from Europe and other parts of the world,” he said.
Within his company, he said there are plans for more CO2 transcritical pilot projects as well as remodels and retrofits for existing systems and end-of-life equipment. He also said the company is contemplating an HFC phaseout.
More CO2 Talk
Benny Smith, vice president of facilities, Price Chopper Supermarkets, talked about the use of CO2 in a recently installed cascade refrigeration system. “The timing was good for the sustainable technology, and the refrigeration manufacturers had a next-generation opportunity.”
He noted with a cascade system: “The carbon footprint reduction due to the CO2 refrigeration system is 5,132 ton of CO2 equivalent.”
There was a learning curve in the discovery that most leaks occurred at the pressure relief valve, he said.
He also stressed the importance of involving service technicians in the whole process of moving to CO2 from the more familiar hydrochlorofluorocarbons (HCFCs) and HFCs. “There was positive feedback from the techs because we involved them early in the project.”
On the mechanical side, “Energy usage is compatible [with more conventional systems] and electronic expansion valve service is greatly reduced, while installation cost is comparable,” he said.
Publication date: 2/9/2015