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Topic: Thermoacoustics

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	Frequently Asked Questions about Thermoacoustics
		When producing maximum output, a vapor compression refrigerator is more efficient than a thermoacoustic fridge of the same capacity, but when less output is needed (which is most of the time), the thermoacoustic device increases in efficiency, but the vapor compression fridge does not.
		Thermoacoustic refrigerators and air conditioners use inert gases which will never be controlled substances and will always be readily available (The atmosphere is 1% argon.
		There are no models for heat transport between the thermoacoustically oscillating gas and the heat exchanger surfaces which could be used to suggest what geometries would optimize the useful transfer of heat on and off of the stack.
	www.acs.psu.edu /users/sinclair/thermal/tafaq.html (2162 words)

	Physics - People Directory: Faculty
		His current areas of research are in quasicrystals and thermoacoustics, where he is investigating the basic phenomena and their applications.
		In the field of quasicrystals he and his group have developed methods of producing thin films of quasicrystals for studies of mechanical, transport, and optical properties; films of this new class of materials are important for coatings and a variety of applications.
		Thermoacoustic devices are becoming important for applications dealing with current energy issues.
	www.physics.utah.edu /people/faculty/symko.html (560 words)

	[No title]
		SPD is pursuing the development of new applications in thermoacoustics (TA), which is the physical process of converting sound energy directly into other forms of energy using the temperature oscillations associated with a sound wave in a gas or liquid.
		Thermoacoustic engines convert heat to sound power, which can in turn be converted to electricity.
		The principal advantage of these applications is that thermoacoustic engines and refrigerators have at most a single flexing moving part (as in a loudspeaker) with no sliding seals.
	www.arlut.utexas.edu /sisl/IndustrialAcoustics.htm (353 words)

	What is Thermoacoustics?
		Thermoacoustics (TA) is the study of the conversion of acoustic energy — compression waves in a gas (sound) - into heat energy and vice versa.
		Acoustic energy can be harnessed in sealed systems and used to create powerful heat engines, heat pumps, and refrigerators.Thermoacoustic devices use these compression waves to replace mechanical pistons, crankshafts, and valves, reducing the number of moving parts in their design and making them simple, reliable machines.
		Thermoacoustic cryocoolers generally have two major sections to their design: an electroacoustic transducer (like a loudspeaker) and a coldhead.
	www.qdrive.com /index.php?page_id=33 (123 words)

	Thermoacoustics -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-16)
		Thermoacoustics is the use of (The sudden occurrence of an audible event) sound waves to affect (The degree of hotness or coldness of a body or environment (corresponding to its molecular activity)) temperature and vice versa.
		Practical uses involve rapid (additional info and facts about acoustical) acoustical shocks to produce cooling, as might be employed in a (White goods in which food can be stored at low temperatures) refrigerator.
		Such a thermoacoustic (additional info and facts about Stirling engine) Stirling engine using the proper working fluid and a linear alternator could produce electric power from heat without pistons or seals.
	www.absoluteastronomy.com /encyclopedia/t/th/thermoacoustics.htm (200 words)

	Acoustics - Encyclopedia.WorldSearch (Site not responding. Last check: 2007-10-16)
		Physiological acoustics is the study of the mechanical, electrical and biochemical function of hearing in living organisms.
		Physical acoustics is the study of the detailed interaction of sound with materials and fluids and includes, for example, sonoluminescence (the emission of light by bubbles in a liquid excited by sound) and thermoacoustics (the interaction of sound and heat).
		Speech communication is the study of how speech is produced, the analysis of speech signals and the properties of speech transmission, storage, recognition and enhancement.
	encyclopedia.worldsearch.com /acoustics.htm (1110 words)

	Thermoacoustics (Site not responding. Last check: 2007-10-16)
		Thermoacoustics is the field of study that combines sound and heat.
		Thermoacoustic devices use the Ideal Gas Law and the Second Law of Thermodynamics to transform heat into sound waves or to use the oscillations of sound to transport heat.
		The core of every thermoacoustic device is the stack, a collection of closely spaced plates, an array of channels (right), or a forest of pins across which a temperature gradient is imposed.
	www.vu.union.edu /~stodolan/pyrophone/thermoacoustics.html (633 words)

	Re: thermoacoustics
		Thermoacoustics theories are applied for axial and centrifugal turbomachinery.
		There is a description of thermoacoustic theories applied to axial compressors and fan in: N. Cumpsty.
		Re: thermoacoustics - clifford bradford, Thu, 9 Aug 2001, 5:32 p.m.
	www.cfd-online.com /Forum/main_archive_2001.cgi/read/18320 (182 words)

	Thermoacoustics
		One dream had linear-motor-driven thermoacoustic heat pumps atop the hot-water heaters in half the homes in Phoenix, pumping heat from room air into the hot water-the production of a little cooling in the homes was a nice by-product.
		This system had a thermoacoustic engine, heated by combustion of natural gas, driving several pulse-tube refrigerators, which provided the cooling necessary to liquefy air, to distill it to produce purified nitrogen and oxygen, and to reliquefy the pure gases for storage in the dewars.
		A third dream had hundreds of enormous combustion-powered thermoacoustic natural-gas liquefiers arrayed on an offshore platform, using the natural gas (methane) itself as the thermoacoustic working gas and filling a vacuum-insulated supertanker with cryogenic liquified natural gas for transport to distant shores.
	asa.aip.org /books/thermoacoustics.html (1105 words)

	Thermoacoustics (Site not responding. Last check: 2007-10-16)
		Thermoacoustics is usually understood as a branch of acoustics studying sound generation by means of heat.
		Afterwards, as early as in the Fifties of our century, studying of thermoacoustical oscillations has got practical orientation because of instabilities in combustion chambers of jet propulsions and in other facilities having great temperature overfalls.
		At the present time, research on thermoacoustics, studying reciprocal transformations of heat and sound fluxes is actually combined into an independent branch of acoustics.
	www.akin.ru /Spravka_eng/s_lect1e.htm (477 words)

	OhioLINK ETD: Petculescu, Gabriela
		In a traditional standing-wave thermoacoustic device, the energy conversion occurs in the stack, influencing the device effciency.
		When a gradient is imposed on the stack, thermoacoustic gain can be empirically determined from the compressibility, for any stack geometry.
		With a nonzero gradient, thermoacoustic gain was measured and found to be the same for both geometries.
	www.ohiolink.edu /etd/view.cgi?ohiou1020690543 (358 words)

	Thermoacoustics Research at WKU (Site not responding. Last check: 2007-10-16)
		Thermoacoustics is the study of how heat and sound interplay.
		Thermoacoustics takes a small region in the resonator, and replaces the empty resonator with a porous material that is effectively all wall, so that the thermoacoustic exchange is effectively utilized.
		As this is in a resonator, the random motion is amplified at the resonating frequency of the system, and the gas rapidly transitions from low-amplitude, random oscillation to a large amplitude resonant oscillation.
	physics.wku.edu /newsletter/v02_n01/7thermoacoustics.html (483 words)

	The Rolex Awards: thermoacoustic refrigeration, S. Garrett
		As they collide with a plate in the tube – the thermoacoustic stack – the plate absorbs the heat, which is then conducted away through a heat exchanger.
		The unit was designed to demonstrate the feasibility of using thermoacoustic refrigeration to provide highly reliable, low-vibration cooling for satellite opto-electronics, and it produced a temperature span of 80 degrees Celsius.
		Indeed, although commercial interest in the potential of thermoacoustics has been slow to develop, Garrett says Penn State is currently in negotiations with a large commercial manufacturer of air conditioners, based upon the TRITON project.
	www.rolexawards.com /laureates/laureate-36-lurie_garrett.html (1876 words)

	United Press International - Science & Technology (no pub) - Sound waves could replace refrigerants (Site not responding. Last check: 2007-10-16)
		The research team, led by Steven Garrett, professor of acoustics at Pennsylvania State University in College Park, said the thermoacoustics process could be a viable alternative to chemical refrigerants.
		Thermoacoustics can work both ways, by removing heat or adding heat.
		The thermoacoustic system demonstrated 5 kilowatts of power, the equivalent of nearly 7 horsepower, and managed to bring cooling temperatures down to 8 degrees below zero, well below the freezing point.
	www.upi.com /view.cfm?StoryID=20021203-031256-7052r (916 words)

	Cool Sounds: ScienCentral Video News
		They are using a process called thermoacoustics to create a "green" chiller.
		The patented prototype "thermoacoustic chiller," which was put on display at a Ben & Jerry's scoop shop in New York City on Earth Day and successfully kept the ice cream cold, has a container that holds a loudspeaker and a canister of helium.
		Garret published a summary of their research and other thermoacoustic refrigeration research in the January, 2004 issue of American Journal of Physics.
	www.sciencentral.com /articles/view.php3?type=article&article_id=218392316 (913 words)

	1pPA12 Thermoacoustics of traveling waves. (Site not responding. Last check: 2007-10-16)
		Standard thermoacoustic sources and refrigerators have the stack placed near one end in a standing wave tube.
		For certain applications, however, the effect of a thermoacoustic stack on a traveling wave is of primary interest.
		When the wave propagates in the direction of increasing temperature, the wave is amplified by an amount dependent upon the temperature gradient.
	www.auditory.org /asamtgs/asa93ott/1pPA/1pPA12.html (114 words)

	Harnessing the "Thermoacoustic" Effect
		Thermoacoustic engines typically have no moving parts; at most, there is a single oscillating part (such as a loudspeaker) with no sliding seals.
		Social Impact: Thermoacoustic energy conversion (including conversion of heat to acoustic power, acoustic power to refrigeration, and acoustic power to mixture separation) is reasonably efficient and should be inexpensive and reliable in mass production.
		Efforts are under way to develop a natural-gas liquefier for use in remote locations, a residential co-generation system to produce both electricity and gas heat, an electric generator for deep-space probes, and a water chiller for use on submarines.
	www.er.doe.gov /Sub/Accomplishments/Decades_Discovery/25.html (282 words)

	ASA 147th Meeting Lay Language Papers -A Brief Description of Thermoacoustics
		Thermoacoustics is the study of things that involve both acoustics and thermodynamics-in other words, the study of things that involve both sound waves and the conversion of one form of energy into another, such as heat into motion.
		Hence, current thermoacoustics research is often motivated by the desire to create new technology for the energy industry that is as simple and reliable as sound waves themselves.
		Acoustic power generated by a thermoacoustic engine can also be used to drive a thermoacoustic refrigerator, avoiding all use of moving parts when a heat-driven refrigerator is called for.
	www.acoustics.org /press/147th/thermoacoustics.htm (942 words)

	Thermo Acoustics Corp. - Developers of Thermoacoustic Refrigeration Technology
		This April, a fire-hydrant-size apparatus called a thermoacoustic freezer made its debut at a Ben and Jerry's in Manhattan.
		The event was a relatively quiet affair, which was no small achievement: inside the core of the steel cooling unit, which was attached to a standard ice-cream cabinet, a loudspeaker emitted a 195-decibel screech to keep quarts of ice cream cold.
		ThermoAcoustics is a simpler, better and more efficient way to cool your food, your house, your car, and your computer microprocessor.
	www.thermoacousticscorp.com (180 words)

	What is thermoacoustics? (Site not responding. Last check: 2007-10-16)
		The sound waves that are common in thermoacoustics however are extreme in magnitude, resulting in noticeable fluctuations.
		Within thermoacoustics a distinction is made between a thermoacoustic engine or prime mover (TA-engine) and a thermoacoustic heat pump (TA-heat pump).
		The first relates to a device creating an acoustic wave by a temperature difference while in the second an acoustic wave is used to create a temperature difference.
	www.ecn.nl /eei/research/waste_heat/tahp/what.en.html (515 words)

	Wet wall Thermoacoustics (Site not responding. Last check: 2007-10-16)
		The key to this enhanced heat pumping capacity is to utilize the latent heat of phase change during an acoustic cycle.
		The stack in a thermoacoustic engine can be thought of as a collection of these small tubes.
		The only assumptions needed in the approximation scheme is to assume the tube radius is much smaller than the wavelength of the sound and to assume that the axial velocity of the sound is much larger than the radial velocity of the sound within the tube.
	www.olemiss.edu /depts/ncpa/thermo/wetWall.htm (740 words)

	Thermoacoustics - Home (Site not responding. Last check: 2007-10-16)
		Thermoacoustic refrigeration is an emerging ‘green’ technology, and is of or relating to a process using rapid, repetitive acoustical shocks to achieve cooling.
		This website describes the development of thermoacoustic systems in the School of Mechanical Engineering, at the University of Adelaide, Australia.
		For those who are studying thermoacoustic devices, you might find our weblinks and forum useful.
	www.mecheng.adelaide.edu.au /anvc/thermoacoustics (188 words)

	Mahalanobis
		"Thermoacoustics involves essentially using sound to produce cooling," says Bob Smith, research engineer at the Penn State Applied Research Lab.
		"It's the interaction between sound and heat." The patented prototype "thermoacoustic chiller," which was put on display at a Ben and Jerry's scoop shop in New York City on Earth Day and successfully kept the ice cream cold, has a container that holds a loudspeaker and a canister of helium...
		here is a cool flash animation demonstrating how thermoacoustics works.
	mahalanobis.twoday.net /stories/291276/comment (272 words)

	RAP - Therm Refrigerators & Engines
		The research focus of the Thermoacoustics Laboratory is the study of acoustically driven heat transport.
		Our goals include an improved understanding of fundamental thermoacoustic processes and the development of new thermoacoustic refrigerators and heat engines with increased power density, temperature span, and efficiency, and the commercialization of those devices.
		Thermoacoustic refrigerators with cooling powers ranging from a few watts to chillers with cooling capacities in excess of 10 kW are currently in operation or under construction.
	www.arl.psu.edu /capabilities/rap_acous_refrig.html (173 words)

	Acoustics (Site not responding. Last check: 2007-10-16)
		Thermoacoustic heat transport, optical imaging of high intensity acoustics fields, ultrasonics, jet noise, upper atmospheric instrumentation
		Thermoacoustic refrigeration, acoustic gas analysis for diffusion of chemical vapors (e.g., VOC's) through porous media (sand and soil)
		Thermoacoustics and noise control using nearfield acoustic holography
	www.engr.psu.edu /ei/MembersPageListing/acoustics.htm (117 words)

	thermoacs.html (Site not responding. Last check: 2007-10-16)
		Thermoacoustics is the study of the thermoacoustic effect and the attempt to harness the effect as a useful heat engine.
		A thermoacoustic refrigerator uses the thermoacoustic effect to move heat with sound.
		In addition, since thermoacoustic refrigerators do not use the compressors, lubricants, sliding seals, and other gizmos present in vapor compression refrigerators, the thermoacoustic refrigerator should be more reliable.
	civil.colorado.edu /~muehleis/thermoacs/thermoacs.html (1057 words)

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