Serving minimal compressors for multiple fixtures

By Sandra van Dijk | 27 October 2016

The Green Sage Café had three locations using 10 compressors, which was generating plenty of heat and wasted energy, not to mention the noise rattling around the restaurant.

According to the business owners Randy Talley and Roger Derrough, it was time to introduce a rack refrigeration system.

This means utilising minimal compressors to cool multiple fixtures.

“We wanted to implement a similar architecture which is commonly referred to as multiplexing,” Talley said.

“We were just not sure if this technology would translate into food service applications.”

To find out Talley contacted Refrigeration Design Technologies (RDT) who are experts in eco-friendly refrigerated system design.

“RDT were able to implement a system that would take the second location to the next level of energy efficiency,” Talley said.

RDT president, Brent Dyess, said he knew that Talley's lofty goals were within reach.

He said the RDT system, which is based on Emerson's Copeland Scroll Digital compressor, was implemented at the second Green Sage Café location.

“The system minimizes the compressors needed to provide refrigeration, servicing eight fixtures in the café’s medium-temperature suction group with one 4 HP Copeland Scroll Digital compressor,” Dyess said.

“With the ability to digitally modulate capacity from 10 to 100 per cent, the Copeland Scroll Digital enables matching of refrigeration requirements to the variable operating loads typical of a food service application.

“Instead of eight compressors kicking on and off, pulling full run-load amps each time, there is now a single compressor running at only the capacity needed to meet the load.”

The digital application has also reduced the piping required in conventional systems.

“Considering we have eliminated numerous one-to-one piping scenarios, we can run piping in a more efficient trunk line configuration,” Dyess said.

Originally RDT estimated that the system would provide the restaurant up to 30 percent in annual energy savings.

But an independent, third-party study found that in 90°F ambient conditions, the Copeland Scroll Digital-based Eco-Cool system delivered 48 percent energy savings.

At temperatures below 90°F, the potential for energy savings will continue to rise above the 48 percent mark.

By placing the Eco-Cool unit outside the restaurant and removing condenser surface areas that are present on each fixture in conventional systems, RDT also eliminated 53,856 BTUH of heat, or the equivalent of 4.5 tonnes of air conditioning.