Best Practice Guide

Food and Beverage Growers and Processors

Refrigeration

Proper Operations

Load optimization
Limit partial loads for compressors, evaporators and condensers. As load percentage decreases, so to does efficiency.

Partial loads are unlikely to be completely prevented. Consider retrofitting refrigeration equipment so that the system operates as efficiently as possible under partial loads.

  • Evaporators: cycle evaporator fans, optimize the use of two-speed fans, and/or install variable speed drives (VSDs) on fan motors.
  • Compressors: sequence compressors so that, as much as possible, output is closely matched to loads; use the most efficient compressors at partial loads as the "trim" compressor and, if cost-effective, add a VSD to this unit.
  • Condensers: add a VSD to condenser fans, which lowers energy use as well as improving operations.


Demand-shifting strategies
New studies on passive thermal energy storage indicate that the thermal capacity (i.e., ability to retain cold temperatures) of some stored product may make it possible to shift refrigeration operations to off-peak hours. For most businesses, this represents large cost savings since peak-hour energy rates are much higher than off-peak. The efficiency of your refrigeration system also improves since off-peak hours tend to be in the evening, night, and early morning when outside temperatures are lowest.

One study from the University of Wisconsin found that demand-shifting strategies could reduce operating costs by as much as 53 percent. Other studies have shown that demand-shifting strategies preserve food products in terms of product quality, shelf life, and nutrient value - important criteria for any food processor or grower. If you already have an automated control system in place, it may be worthwhile to investigate whether off-peak strategies are appropriate for your products.


Resources

Northwest Food Processors Association ENERGY PORTAL, online information on process efficiency for refrigeration and freezing.

Industrial Refrigeration Best Practices Guide. Prepared by Cascade Energy Engineering for the Northwest Food Processors Association and the Northwest Energy Efficiency Alliance.

The Industrial Refrigeration Consortium (IRC) is a collaborative effort between the University of Wisconsin Madison and industry. The goal of the IRC is to improve the safety, efficiency, and productivity of industrial refrigeration systems and technologies.

A Guide to Help You Reduce the Energy Use of Your Industrial Refrigeration System. Pacific Gas and Electric Company website.

Hochstein, A. Closing in on the Ideal: Door engineering that maximizes energy efficiency and handling productivity for today's cold storage facilities. Rite-Hite Corporation website.

Thermal Energy Storage Strategies for Commercial HVAC Systems. Application Note, Pacific Gas and Electric.