ACHRNEWS

New Twists In Supermarket Technology

November 28, 2003
WASHINGTON - Contractors usually encounter familiar fare in the backroom of supermarkets. There are large, direct-expansion rack systems, usually with compressors and components running on R-22 or -404A, or perhaps -507.

But a lot of things happening throughout the world may change the way technicians service supermarkets. Those changes range from mechanical configurations, to controls technology, to refrigerants.

Some of the latest developments were reviewed at the most recent International Congress of Refrigeration in a short course titled "Advances in Supermarket Refrigeration." Much of the focus was on a report on developments from the International Energy Agency Annex 26, a program set up to improve energy efficiency and reduce energy charges in stores.

According to Van Baxter of Oak Ridge National Laboratories, Annex 26 was set up to "analyze and field test advanced systems such as secondary refrigerant loops, distributed compressors, and low-charge, multiplex direct-expansion systems, as measured against a baseline of conventional DX systems."

Also under review was the integration of store HVAC with refrigeration with such approaches as "recovering refrigeration rejected heat for space heating and other uses such as heat pumps," and "combined cooling, heating, and power (CCHP) systems."

In his ICR report, he focused on projects in five countries.

Global View

Baxter noted two organizations that have been participating in Annex 26 activities in Canada. Natural Resources Canada was involved in a 9,000-square-meter store using a "cascaded secondary-loop system with horizontal scroll compressors in integral frozen food cases." The size of the store is similar to the largest in the United States, and about twice the size of larger stores in Europe.

In addition, Hydro Quebec is doing field tests on a multiplex DX system with integrated heat pumps. The organization reported that "heat pumps met all space heat needs" and realized "6 percent energy savings versus conventional."

Baxter said there is pressure in Denmark to phase out HFCs, which he noted are heavily taxed.

One project in the country is a cascade refrigeration system combining CO2 and propane in a small store. Initially, Baxter said, researchers are finding "energy consumption about the same as a conventional DX system and total system cost, about 15 percent above conventional."

Should HFCs survive a total phaseout, researchers are looking at ways to use 404A and CO2 in a large supermarket. A cascade system in that refrigerant combination yielded "energy consumption about 15 percent less than conventional DX, a 404A charge about 12 percent of conventional (systems), and a total system cost about 10 percent above conventional multiplex DX."

In Sweden, secondary-loop technology is undergoing testing in several locations. Special computer models have been developed.

Projects in the United Kingdom include investigations of CCHP systems involving engine and generator, waste heat-driven chillers with building A/C and refrigeration heat rejection, and other waste heat uses, such as space heating, water heating, and display case defrost.

Baxter said detailed reports may be found through the IEA Heat Pump Centre Web site, www.heatpumpcentre.org.

Publication date: 12/01/2003