A device utilizing advanced control strategies, including adaptive mechanisms, to optimize commercial refrigeration system operation and reduce energy consumption.
Walk-in cooler or refrigerated case controllers are electronic devices that control temperature by controlling evaporator circulating air fans, refrigerant compressors, condenser fans, defrost cycle initiation and duration, lighting, and more. These controllers have been available in the U.S. since 1986, but the immature technology, low energy rates and high cost prevented their widespread adoption. By 1992, costs had dropped by about 75% and the technology had improved, but controllers still did not catch on in the U.S.
Walk-in and reach-in refrigeration units operate 24/7 year-round, using as much as 50% of the electricity consumed in a supermarket. Case controllers enable the intelligent operation of evaporator air circulation fans and refrigeration compressors, resulting in energy savings that typically range from 15% to 30%. In addition, refrigerated products can be maintained in better condition for longer than they might be in refrigerated cases with traditional control systems.
Modern controllers have software that can do data logging and provide special communication functions. Built-in alarms can prevent product loss with timely notification of facility staff.
Status:
Baseline Description: Conventional Refrigerated Case and Refrigeration System Controls Baseline Energy Use: 356747 kWh per year per rack
The savings reported are for a store that equipped three racks serving walk-in coolers with an Emerson Climate Technologies E2 refrigeration control system. The system achieved savings through reducing return gas temperatures, floating suction pressures, lowering discharge pressures, using variable speed control on condenser fans, optimizing deforst control, and monitoring dew point to optimize anti-condensate case glass door heater control. The controller was applied to one of two identical supermarkets in the Atlanta, GA area. Power meters were used in the field test to monitor energy consumption for the condenser and for rack power for one year. Results were a decrease in store refrigeration system energy use from a measured baseline of 1,070,241 kWh/year to 883,465 kWh/year--a 17.45% decrease. (Emerson Climate Technologies, "Optimum Refrigeration Control with E2"). Stores can also boost savings through replacing fractional horsepower single phase evaporator fan motors with variable speed electronically commutated peramanent magnet motors (ECPMs). Manufacturer claims are for case studies conducted in a variety of stores (liquor store, mini-mart, food & gas, grocery stores, and wine merchants).
"Typical" Savings: 17% Energy Savings Reliability: 3 - Limited Assessment
The Sacramento Municipal Utility District (SMUD) conducted a CoolTrol demonstration project in 2005 at six sites--three food and liquor stores, a health food store, an independent grocery store, and an agricultural warehouse. An examination of six months of billing data showed an average site energy savings of 13.2% (this is for the entire site, not just the refrigeration system). Project installed costs ranged from about $3,500 to $8,100 with simple paybacks varying from 2.0 to 4.2 years (one site had equipment malfunctions during four of the six months in the monitoring period and showed a simple payback of 7.7 years). Source: "SMUD Technology Brief...CoolTrol".
Energy Use of an Emerging Technology is based upon the following algorithm. Baseline Energy Use - (Baseline Energy Use * Best Estimate of Energy Savings (either Typical savings OR the high range of savings.))
Simple payback, new construction (years): N/A
Simple payback, retrofit (years): N/A
Cost Effectiveness is calculated using baseline energy use, best estimate of typical energy savings, and first cost. It does not account for factors such as impacts on O&M costs (which could be significant if product life is greatly extended) or savings of non-electric fuels such as natural gas. Actual overall cost effectiveness could be significantly different based on these other factors.
NRM, 12/11/2007. CoolTrol Cooler Control Systems –C-Store, Bay Area, California National Resource Management, Inc.
NRM, 2013. CoolTrol Cooler Control Systems Case Studies National Resource Management, Inc.
Abtar Singh, 03/29/2005. Optimum Refrigeration Control with E2 Emerson Climate Technologies
Douglas Kosar, 02/14/2006. Humidity Effects on Supermarket Refrigerated Case Energy Performance: A Database Review American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
John Minahan, 01/01/2011. Federal Industries announces a new total system approach Federal Industries
EERE, 10/30/2013. EnergyPlus Energy Simulation Software Energy Efficiency & Renewable Energy
Michael Garry, 10/04/2010. Case controllers give retailers better control of their refrigerated cases, but the technology has yet to catch on in the U.S. Supermarket News
CEC, 01/01/2002. Case Study: Controls Upgrade at a Winery Saves Energy and Increases Equipment Life California Energy Commission
SMUD, 01/01/2005. Technology Brief...CoolTrol Energy Efficiency and Customer Research and Development Group