Not registered? Sign up to receive our email newsletter and access other members-only features.
 
more Share
Share & BookmarkX
|
Share This Link With A Friend

Coolers and Freezers: Walking into Energy Savings

Key Points
  • Federal regulations have resulted in significant energy savings for walk-in coolers and freezers.
  • The 2014 Commercial Refrigeration Equipment final rule limits maximum daily energy consumption.
  • A number of retrofits and operational strategies can improve the efficiency of existing equipment. 

Walk in coolerToday's refrigeration equipment is much more efficient than older models. That's due in large part to federal energy efficiency requirements. Title III of the Energy Policy and Conservation Act (EPCA) and later amendments set forth a variety of provisions designed to improve equipment energy efficiency, including walk-in coolers and freezers (known as walk-ins). Equipment manufactured on or after January 1, 2009 must meet these efficiency standards.

The following is a list of EPCA requirements which have resulted in significant energy savings:

  • Automatic door closers that firmly close all walk-in doors
  • Air infiltration protection for open doors
  • Double-pane glass for reach-in doors and windows with heat-reflective glass and gas fill. (coolers)
  • Triple-pane glass with either heat-reflective glass or gas fill (freezers or coolers)
  • Electronically commutated motors (ECM) for fans (< 1HP)
  • Minimum efficacy of 40 lumens per watt (lm/W) for interior lights
  • Maximum power draw for anti-sweat heaters around windows and door frames of 7.1W per square foot of door opening for freezers and 3W per square foot for coolers.

Efficiency standards are based on annual walk-in energy factor (AWEF); the ratio of the heat removed (in Btu) from a walk-in envelope to the total refrigeration energy input (in watt-hours) over a one-year period. The higher the AWEF number, the better.  

The most recent regulations designed to improve the efficiency of new walk-ins was the Energy Conservation Program: Commercial Refrigeration Equipment final rule, published in 2014. It limits the maximum daily energy consumption of refrigeration equipment based on total display area (TDA), the square foot sum of the projected area for visible product. The compliance date for the final rule was in June 2017. Energy savings of 10 to 38 percent are projected.

Cool savings for existing equipment

These measures can help improve the energy performance of existing walk-in coolers and freezers:

Install floating head pressure controls, which allow the compressor heat pressure to vary with outdoor conditions. The condensing temperature can fall from 90°F to 95°F down to 70°F. The compressor has to do less work at lower heat pressures. This improves system efficiency and extends the life of the compressor. 

Use hot gas defrost. During the hot gas defrost process, the evaporator temporarily becomes a condenser. The latent heat generated from the condensations of gas to liquid is used. 

Minimize defrost convective heat losses. Use the lowest possible defrost regulator setting; 75 to 90 psig (50°F to 60°F) should be adequate.

Shorten defrost duration.

  • Use top feed or direct expansion evaporator feed to reduce the time required for pump out.
  • Open the hot gas solenoid only long enough to clear the coil (8 to 10 minutes).
  • Install a separate hot gas solenoid and defrost regulator for pre- and post-heating of the pan loop.

Match the number of defrosts to the frost load. Choose evaporators with wide fin spacing (only 3 instead of 4 fins per inch) and large secondary fin surface area to maximize frost carrying capacity. 

Use demand defrost controls. Demand controls initiate defrosting in a variety of ways, including measuring the temperature or pressure drop across the evaporator, measuring frost accumulation and sensing humidity. All of these methods, if used properly, are more effective than using a simple timer to initiate defrosting.  

Recover heat with desuperheaters. Superheat is heat stored in the refrigerant vapor when it's heated above its evaporation temperature. A desuperheater heat reclaim device in series with the normal condenser cools the refrigerant only to the saturation point; no condensing takes place. This is controlled by a heat reclaim valve. A desuperheater can remove about 10 to 30 percent of the total heat that typically would have been rejected by the condenser. This reclaimed heat is used for space or water heating.

We can help 

National Grid has tools and energy solutions to grow your business and foster strong client relationships. For more information, contact us at 844-280-4325 or retrofit@nationalgrid.com

 

Image source: USDA

more Share
Share & BookmarkX
|
Share This Link With A Friend
Content provided for National Grid customers, Powered by Questline RelationshipBuilder. © Questline Inc.
Acceptable use and linking guidelines for this article
How would you rate the quality of this content?  Select a star rating and click submit below.
Comments or suggestions for additional content: (optional)
 

This message was sent by National Grid - 40 Sylvan Rd - Waltham - MA - 02451