Intelligent Store Discus™ compressors have motor protection, power interruption protection, simplified commissioning and an open protocol. (Photo courtesy of Emerson Climate Technologies)

When the Food Marketing Institute surveyed members of the food retail industry concerning top issues for 2009-2010, four of the top 15 issues were those that could be addressed by improvements in mechanical refrigeration systems.

In a report on compressor technologies, Kurt Knapke, program manager of electronics and supermarket, Emerson Climate Technologies, Refrigeration Division, listed those four issues as:

1.Local and national economy, #1

2.Local, state, and federal regulations, #6

3.Energy costs, #7

4.Environmental concerns, #14

In his report, Knapke also outlined options for addressing some of these top concerns. He said that reducing energy consumption and maintenance costs could help “maintain profit margins in a tough economy.”

He added that alternative refrigeration designs and reducing the total equivalent warming impact (TEWI) addresses the sustainability issues that are tied into regulations and environmental concerns.

Therefore, decision-makers in stores need to look at an ever-increasing number of options available to them, he said.

For example, in his report he drew attention to options for maintenance cost savings, such as the Intelligent Store Discus™ compressor with motor protection, power interruption protection, simplified commissioning, and an open protocol.

“With the Intelligent Store Discus compressor, there are potential annual store savings because of lower maintenance cost, greater refrigeration uptime, and reduced refrigeration leaks.”

In the report, Knapke also discussed options for reduced energy consumption with the Copeland Discus Digital™ compressor which was designed for “continuous capacity modulation from 10 to 100 percent and applicable on new and potentially existing Discus® compressors.”

He said benefits included “precise control of suction pressure and temperature, reduced cycling of compressors, and system efficiency improvements.” With this technology, he said, there is “no need for uneven paralleling for compressor staging, therefore allowing the use of common compressor selections and simplifying replacement needs.”

The idea is to allow energy reduction on the refrigeration system, cycling reduction, and tighter temperature control, he said. He noted positive results with use of the digital technology in Halifax, Nova Scotia, among locations where it is being used.


Another issue being researched by Emerson Climate Technologies involves some of today’s HFC refrigerants that can be used in supermarket refrigeration applications. One such refrigerant option involves R-407A and R-407C.

Emerson currently offers Discus compressors that can be used with R-407A and R-407C. In both cases, the refrigerants have a lower global warming potential than R-404A, the most popular of the current HFC refrigerants used in supermarket refrigeration. Knapke said efficiencies are comparable to HCFC-22, and pressures are comparable to R-22 and R-404A. He also cautioned that the R-407 refrigerants have 5 to 7°F of glide and “reduced low-temp capacity.”

Concerning R-744 (CO2), Knapke noted research that has been done with low-temperature applications in which a cascade system has an HFC on the high stage and subcritical R-744 on the low stage.

He noted “subcritical compressors are now available in the United States” and that his company’s ZO Copeland Scroll® compressor for subcritical was the “first CO2 compressor to get Underwriters Laboratories approval.”

He described the CO2 compressor as having a hermetic design, low weight and footprint, and high efficiency.


As to the future, Knapke had a prediction. He noted that currently supermarket refrigeration was approximately 55 percent parallel systems, 25 percent distributed systems in which backroom racks were replaced with smaller mechanical systems throughout the refrigerated areas of the store close to the cases, and 20 percent secondary loop systems in which a glycol-type fluid was used to help reduce HFC refrigerants needed.

He surmised that by 2013, the percentages could be closer to 40 percent secondary, 35 percent distributed, and 25 percent rack.

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Publication date:09/07/2009