Commercial Refrigeration: A Working Example.
(commercial refrigeration systems)

CB Staff Report

A wide variety of commercial refrigeration systems are currently being used in supermarkets and retail food stores. These include central refrigeration systems connected to food display cases, self-contained display cases, and walk-in refrigerators and freezers.

New designs, known as distributed systems, are also being used and place refrigeration compressors and associated components near the display cases being refrigerated.

There are also indirect systems in which a primary refrigeration system cools a secondary fluid, which then circulates through a secondary loop to the display cases. In each case, the choice of refrigerant will depend on the specific requirements of the application.

Environmental Considerations for Commercial Refrigeration

Since the mid-1980s, commercial refrigeration systems have undergone a transition from using ozone depleting refrigerant compounds, including chlorofluorocarbons (CFCs), to low or non-ozone depleting compounds, such as hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). Ammonia, hydrocarbons, and carbon dioxide are being used to a lesser extent.

Several of these compounds, while non-ozone-depleting, do have global warming potential (GWP). There are two aspects to global warming that must be considered when selecting a refrigerant. One is the GWP of the refrigerant compound itself if emitted, the "direct effect."

Another concerns the amount of energy consumed to operate the equipment, the "indirect effect." The two aspects considered together represent the most significant portions of life cycle climate performance (LCCP). Significant additional considerations include the cost of the system and the safety of the users, service technicians, and the public.

Life Cycle Climate Performance
(Million Kg [CO.sub.2])

(1) 15 years of energy consumption, 0.65 Kg [CO.sup.2] per kWh

(2) 15 years of refrigerant emissions

Life Cycle Climate Performance

Fluorocarbon replacements for CFC-502 and CFC-12 include HCFC-22, HCFC-22-based blends, HFC-134a, -404A, and -507. Other replacements can also be used. However, significant system modifications may be required to properly manage the fire/explosion and pressure hazard potential, which greatly increases the cost.

An analysis of four configurations was performed using LCCP for a typical U.S. supermarket constructed in 1999 of 60,000 sq.ft. The results are found in the table on this page.

The distributed systems with HFCs are clearly the right choice based on LCCP. The HFC-404A or -507 distributed system had an LCCP less than half the direct expansion system and was at least 15% better than either secondary loop system. The secondary loop system with ammonia has an LCCP similar to that of the secondary loop HFC system.

A 1999 report by A.D. Little estimates that using ammonia would add costs of $660 million per year in the U.S. alone due to additional safety equipment, hardware, and increased energy consumption.

HFCs -- The Balanced Solution

When all factors are considered, HFCs offer the best solution for meeting the requirements of the commercial refrigeration industry. Commercially available throughout the world, HFCs are energy efficient, low in toxicity, cost-effective, can be used safely, and are reusable. When used in energy efficient applications, their excellent LCCP reduces fossil fuel consumption and with it, emissions of carbon dioxide, which is the most prevalent greenhouse gas.

Industry Principles

The environmental and cost superiority of HFCs in commercial refrigeration systems must be complemented with responsible HFC use.

The commercial refrigeration industry is committed to providing products that provide the best LCCP that technology, availability, and financial assessment will allow. This will differ across the various products and applications, and will continuously be evaluated as technology develops.

In addition to significant operating efficiency improvements, the industry has already made a concentrated effort to reduce emissions of refrigerants by designing leak-tight equipment, minimizing system charge, and promoting refrigerant recycling.

The industry actively promotes the following general principles that should be followed for all refrigerants:

* Use in tight systems that are leak tested and then frequently monitored after installation to eliminate direct refrigerant emissions

* Recovery, recycling, and reclaimation of all refrigerants

* Training of all personnel involved in the refrigerant handling

* Compliance with standards that govern proper refrigeration installation and maintenance of machinery spaces (e.g. ASHRAE 15, ISO 5149)

* Equipment sizing to match the specific need, thereby minimizing the refrigerant amount

* Design and installation and operation to optimize energy efficiency.

The information for this article was provided courtesy of The Alliance for Responsible Atmospheric Policy.

COPYRIGHT 2001 Penton Media, Inc.

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