Praxair acquires acoustic technology
April 19, 2001 -- Praxair, Inc. has acquired the assets and licenses to acoustic heat engines and acoustic refrigerators. Assets acquired by Praxair include pilot plants, commercial demonstration equipment, exclusive patent rights, licenses and development programs.

The thermo-acoustic technology development was led by the Los Alamos National Laboratory's Material Science Technology Division. The prototype demonstration and validation previously was conducted by Chart Industries. Praxair will continue to work with these agencies to commercialize thermo-acoustic technology.

Acoustic heat engines convert thermal energy into sound waves. Acoustic refrigerators, also known as pulse tube coolers, use sound waves to produce refrigeration. The combination of an acoustic heat engine and pulse tube cooler has the potential to substantially reduce low-temperature refrigeration costs and further improve reliability. Applications include industrial gas production and liquefaction, natural gas processing and superconductor cooling. For full news release, click here.

Waste Not Want Not -- An Engine for the Future
In a step toward finding alternatives to conventional engines, scientists at the Department of Energy's Los Alamos National Laboratory have developed a remarkably simple, energy-efficient engine with no moving parts. The engine is described in a paper published in today's issue of Nature. Pollution concerns, global warming and shrinking fossil fuel reserves have focused world attention on how engines generate electrical and mechanical power. Engines with higher efficiency help conserve fossil fuels and reduce emissions by consuming less fuel to generate an equivalent amount of power. Today most engines are internal combustion or turbines... (go to Los Alamos Press Release 5/27/99)

Sound Idea Promises Cool Future
Fridges of the future could be powered by a highly efficient engine that runs on sound and has no moving parts. Inspired by an invention of a 19th-century Scottish cleric, the Backhaus-Swift engine builds on the principles of the Stirling engine, invented by the Rev Robert Stirling in 1816, and first used to pump water out of a Scottish quarry. The "thermoacoustic Stirling heat engine" can convert sound into heat and vice versa. The sound levels generated in such devices, using specialised speakers, are extreme: in one case the levels reach 190 dB, about 10 million times as intense as the front row levels at a rock concert and 300 times the intensity needed to ignite human hair. However, the sound levels outside the rigid pressure vessel are acceptable. "They are not noisy because the casing is a quarter of an inch thick," said Backhaus, one of the inventors at Los Alamos National Laboratory. "You hear a low frequency hum." A prototype refrigerator has already been built and uses sound to "pump" heat from a lower temperature to a higher. The engine has an efficiency of 30 per cent, which is comparable with that of a car engine (25-40 per cent).
--- by Roger Highfield (from the electronic version of the London Daily Telegraph)

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