Appliance Design - April 2008 - (Page 32)

COOLING TECHNOLOGIES The phase out of CFC-based refrigeration has been accelerated. 1,430 for R-134a. Ammonia has no ODP and zero GWP. Ammonia is toxic and flammable, but these characteristics have proven to be controllable. In the U.K. and elsewhere in Europe, ammonia is often used in a secondary coolant system in which the material is used in an externally located chiller, which cools a secondary refrigerant such as a glycol, brine, or CO2, which is then pumped around a secondary circuit to display cases and cold rooms. Supermarkets in the UK such as Tesco, Sainsbury’s, ASDA/Wallmart, and Marks & Spencer have committed to such an approach, says Colbourne. Hydrocarbons are flammable refrigerants and include propane (R-290), isobutane (R-600a) or hydrocarbon blends as working fluids in their equipment. The hydrocarbon refrigerants have no ODP. The GWP rating is considered negligible. Most hydrocarbon refrigerants have a GWP of < 3. They are often used in applications that require low temperature levels, which is one of the reasons that companies such as Unilever selected the hydrocarbon, propane. Suppliers of fluorocarbons, or F gases, agree that natural refrigerants have direct low GWP emissions, but claim that that doesn’t tell the whole story. They claim that natural-refrigerant based systems are less efficient, and thus require more energy to run them. They point to Life Cycle Climate Performance as a better measure of global warming potential because it takes into account both direct and indirect effects. An appliance with a low-GWP hydrocarbon refrigerant can still have a total high GWP value if it is inefficient and causes more indirect CO2 emissions at the power plant. According to a policy statement from INEOS Fluor regarding refrigerants, the main environmental impact of most refrigeration systems is the amount of energy that they use. On average, 80 percent of the climate impact from refrigeration and air conditioners is caused by indirect emissions of carbon dioxide. The energy efficient properties offered by HFCs are a significant advantage to designers, the company says. Fluorocarbon suppliers also point to some of the engineering challenges involved with natural refrigerants, such as the high operating pressure required for carbon dioxide, which would require redesign of cooling systems. C02 has dramatically higher operating pressures even compared with other natural refrigerants and these differences grow with increases in ambient temperature. For instance, at –69 DegF, the C02 pressure is 76.6 psia, while ammonia is 4.078. At 32 applianceDESIGN April 2008 –40 DegF, the CO2 pressure is 145.69, as compared to 10.093 for ammonia. Still, HFC refrigerant suppliers are aware of the GWP issues and a number of companies are already working to develop low-GWP refrigerant products. These products will initially be used for the automotive industry in the European Union, an industry that faces an EU deadline of 2011 to phase out HFC -134a refrigerant use in cars. INEOS Fluor is working on such a refrigerant that it believes will have a GWP below the 150 threshold for automotive refrigerants used in new cars that was set by the European Union’s F-Gas regulation. In March 2007, DuPont announced a joint development agreement with Honeywell to develop a low-GWP refrigerant for use in the automotive air conditioning industry in Europe. They are working with automotive OEMs on the development and commercialization of hydrofluoro-olefin (HFO)-1234yf, which would meet the European Union’s 2011 MAC Directive and could potentially replace HFC-134a in MAC systems. The HFO-1234yf has a GWP of 4 so it is close to C02, says O’Shea. “The results are very similar to R-134a, so we could use it without having to make drastic changes to the car’s design that would add weight and create servicing challenges,” O’Shea says. “This same technology could also be applied eventually to stationary air conditioning and refrigeration applications.” Despite these efforts, the drumbeat to replace HFCs with natural refrigerants can be heard. Denmark, in 2007, passed a law that limits an HFC charge and Austria is following suit. In the U.S., California has targeted HFC emissions from cars and commercial refrigeration. According to a report by the California Air Resources Board, approximately 500,000 vending machines are in use in California that have leak rates of about 30 percent per year or about 2.7 MMTCO2 (million metric tons of carbon dioxide). These could be a target application for a low GWP refrigerant. Perhaps the biggest push is coming from those companies that come closest to dealing with consumers such as Unilever and The CocaCola Company. The Coca-Cola Company is working to phaseout HFC refrigerant-based equipment and replace it with CO2 equipment. The company is focusing on emissions from its vending machines and coolers after an audit of their carbon footprint. What they found surprised them, says Bryan Jacob, energy and climate protection manager for The Coca-Cola Company. They found that equivalent CO2 emissions from this type of equipment far outstripped emissions from manufacturing and fleet operations. In 2000, more than 15 million metric tons equivalent of carbon dioxide was released from this source as compared to about 5 MMT from the company’s 900 manufacturing operations, and 3 MMT from the company’s 200,000 diesel-powered trucks. This led the company into making cabinet and refrigeration efficiency a priority. They looked at all of the refrigerants on the market and chose CO2 after conducting a survey analyzing the worldwide regulatory landscape. They felt that CO2 would be www.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - April 2008

Appliance Design - April 2008 Contents Editorial Shipments/Forecasts News Watch A Variant of Thermoacoustic Refrigeration Known as Acoustic-Stirling is Expanding Its Range Outside Cryocooling Into More Conventional Applications Such As Refrigeration and Air Conditioning Free-Piston, Stirling Coolers Are Now Showing Up in Mainstream Applications As Costs Come Down and Heat Transport Solutions Are Devised Heat Exchanger Innovations Are Helping To Improve the Overall Efficiency of Vapor Compression Systems Environmental Concerns Have Once Again Ignited a Debate Over Refrigerants A New Glass Ceramic Material for Induction Cooktops Can Be Decorated In a Variety of Glimmering Metallic, 3-D Looks That Can Employ a Number of Shades, Patterns, Styles, Colors, Intensities, and Textures Colorful, Reflective Coatings for Glass Create a Variety of Design Options To Help Designers Establish a Unique Look for Their Products Appliance Designers Faced With Different Motor and Drive Options Need To Understand the Differences and Tradeoffs Before Choosing A New MEMS Valve Offers a Number of Advantages Over Solenoids In Certain Applications, Including the Opportunity To Cut Energy Use The AHR Expo Set Attendance Records and Showcased Thousands of Innovative New Products Classifieds Design Marts Advertiser’s Index Association Report: CEA

Appliance Design - April 2008

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