Supermarket Technologies Take on Heat, Noise

October 10, 2000
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SAN DIEGO, CA — Too much heat, too much noise — and too much money going out to curb heat and noise troubles.

None of the above are good for supermarkets. One aspect of the 21st Food Marketing Institute Energy & Technical Services Conference here was to explore ways such problems can be brought under control. Five panelists took turns at that task during a seminar on the future of supermarket engineering.

Air Curtains

John Behr, director of Global R&D Engineering for Hussmann, Bridgeton, MO, said the heat load issue could be helped with improved display case air curtains. He noted that current air curtain improvements “are based on experience and test, test, test.”

But a relatively new technology called computational fluid dynamics (CFD), which has been used in the aerospace and automotive industries, as well as in some hvac design applications, is being looked at for refrigeration applications.

Higher speed computer technology is allowing “even more number crunching” in order to employ CFD. Current research is using 2-D computer models of a simple refrigerated jet and various experimental techniques operating with a multi-deck case. Future plans call for air curtain optimization studies.

“The idea is to help us design cases better and faster, and that means less cost for better display cases,” Behr said.

Equipment Monitoring Via the Internet

Douglas Horton, consultant for D.J. Horton & Associates, Lombard, IL, noted that increased attention is being paid to remote monitoring of equipment via the Internet.

The concept called for nodes to be mounted on virtually every piece of equipment, from the racks to the ice machines to the prep tables. Nodes are linked via gateways to the computer.

Each node can cost less than $50 and can communicate either with hard wiring or without wires, Horton said. “You can collect information from up to 1,000 nodes and send it to the Internet.”

The details, speed, and accuracy of the information allow “early warnings of deteriorating equipment, notification of equipment failures, and constant monitoring of critical-temperature cases.”

What Did You Say?

For Phil Lavrich, senior program manager for Aeroacoustics & Vibration Research at Carrier, Syracuse, NY, attention was given to the noise issue. “There is a perception,” he said, “that low noise means high product quality.”

A prime focus should be rooftop units, he said. The challenge there deals with fan speed. “You can slow down fan speed to cut noise, but that increases the cost of the unit.” The secret is “to develop low noise movement technology without the cost increases.”

Current research calls for looking at 30-in. redesigned fans from Europe and highly swept propeller fan technology, he said.

Another focus is on reducing compressor noise with such techniques as discharge mufflers and fiber glass absorption. At the same time, he noted the increasing use of self-contained units “because you have to be compact, so you can’t reduce noise as you could with larger units.”

However, he noted, such challenges can be met. “New technologies are available that are quiet, cost efficient, and compact.”

Ground-Coupled Efficiency

Jack Persem, vice president, System Marketing, Hill Phoenix, Conyers, GA, said more attention is being given to ground-coupled technology for supermarket systems.

The idea, he said, is to use “ground-coupled heat exchange to reduce the refrigeration condensing temperature. Significant energy savings are realized in the summer months. During winter operations, heat gain from the loop is used to raise the outdoor coil temperature for a heat pump, thus reducing the energy for heating.”

In one concept, he said vertical wells are drilled from 200 to 300 ft down. He said several dozen might be needed for a typical, 40,000-sq-ft supermarket.

He contended that energy and maintenance cost savings could be realized despite initial costs. When combined with a secondary loop system, “Additional savings can be achieved by reducing refrigerant losses and charge.”

Persem said a payback is possible within two years in most states. Further, he said, ground-coupled systems are typically “most effective in areas where electricity costs are low, gas costs are high, and heating energy consumption is high.”

Today’s Research

Van Baxter, project engineer at Oak Ridge (TN) National Labs, reviewed some ongoing research. Such efforts are focusing on:

  • Annual energy use in regards to compressor power, condenser fan power, display caseload and power, and secondary fluid pump power;
  • New, high-powered computers being employed in spreadsheet calculations;

  • Advanced approaches to supermarket refrigeration in terms of the lowest energy configuration for each system;
  • Examining the integration of hvac with refrigeration to utilize heat rejected from refrigeration;
  • Looking at different means of heat rejection for so-called distributed systems which have compressor cabinets throughout stores; and
  • Relying on advanced controls technology for use with low-charge, multiplex systems.
  • Finally, Baxter reported the following:

  • “Energy savings are possible for distributed or secondary-loop systems, [but] proper system design is needed.”
  • “The lowest charge and TEWI [total equivalent warming impact] is achieved with fluid-loop heat rejection.”
  • “Low-charge multiplex should have the lowest first cost premium and best payback.”
  • “The lowest overall operating cost [is] seen when a watersource heat pump is coupled with refrigeration.”
  • Publication date: 10/16/2000

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