Appliance Design - April 2008 - (Page 14)

COOLING TECHNOLOGIES SOUND IDEA Fig. 1. Acoustic-Stirling cycle with inertial flow tube, compressing and rejecting heat near the piston, and expanding and accepting heat farther down the tube. Acoustic-Stirling refrigeration hits the field. C by john corey John Corey is president, CFIC-Qdrive, Troy, N.Y. 14 applianceDESIGN April 2008 ooling with the power of sound might very well represent the next wave in refrigeration. The science behind the idea is called thermoacoustics, and was originally developed at Los Alamos National Laboratory. The technology has since matured into an environmentally friendly cooling technique that is now available for some cryogenic applications and poised to break out into larger markets. The worldwide market for cooling is worth more than $100 billion in annual sales, and with the world becoming hotter and richer, demand for cooling is also heating up. The larger part of the market consists of the most familiar, vaporcompression equipment that cools not far from ambient temperature. But there is also the cryogenic world, below about 200 Kelvin (-100 DegF), where Claude-Linde cycles dominate the fixed-base air-separation industry, and where the GiffordMcMahon cycle is most commonly used to sustain liquid helium temperatures (4 K) for magnetic resonance imaging and other specialized imaging devices. Vapor-compression equipment is common and relatively low cost. The technology can be cascaded to reach the cryogenic boundary, but can’t go much lower. Claude-Linde systems are very efficient at liquid-air temperatures, but not so at near ambient. They also don’t scale down well to more portable devices. GiffordMcMahon devices and other small, deepcold systems can’t compete in efficiency, reliability, or cost except below about 50 K, and they don’t scale up beyond a few hundred watts capacity. Meanwhile, the Montreal Protocol has just been renewed, and the phase-out of www.applianceDESIGN.com http://www.appliancedesign.com

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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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