Thermoacoustics - The Green Energy Champion


Thermoacoustic is concerned with the thermodynamic conversion between heat and intense sound in the presence of a solid chamber. Sound in this controlled environment creates pressure waves that transfers kinetic energy from one air molecule to the next using compression and expansion of the medium. Thermoacoustic engines-as opposed to sterling engines have no moving parts other than a single oscillating device (such as the diaphragm in a loudspeaker), which needs no lubrication or sliding-seals that are subject to wear. Thus, these engines have the potential to be simple, cheap and reliable while providing higher energy conversion rate without producing any harmful emissions.

The development of thermoacoustic systems will lead to major cost savings and economically attractive renewable energy options. Thermoacoustics may soon emerge as an environmentally attractive way to power hybrid electric vehicles, capture solar energy, refrigerate food, air condition buildings, liquefy industrial gases and in such other capacities. The best feature of thermoacoustic technology is that all the different applications can be developed based on the same technological principles and, that they can convert almost any heat source, like the waste heat from an internal combustion engine, into sound waves which can further be converted into electricity or air-conditioning/refrigeration.

Electricity Generation
Concentrated thermal solar energy generates an acoustic wave in a heated thermo acoustic engine. A linear motor generates electricity from this. Just recently a team of researchers at the American University in Cairo (AUC) developed a prototype which can convert solar energy into electricity with the efficiency rate of almost 30 percent, the highest possible rate for thermal engines. They are in the process of acquiring funds for the construction of a larger version of the engine, capable of generating four to five kilowatts of electricity which would be enough to power a modern household. In the future an even larger engine could produce up to 30 kilowatts of power, says the teamleader Abdel-Rahman.

Cooling Application
A thermoacoustic refrigerator is a cooling device that uses acoustic power to pump heat from a region of lower temperature to a region of ambient temperature. After transferring their heat to the stack media, the sound wave causes the molecules to expand and cool. Cold temperatures can then be tapped for chilling refrigerators, bedrooms, cars, or electronic components on satellites and inside computers.The technology could represent a major breakthrough using a variety of both nontoxic and environmentally benign refrigerants, and save up to 40% in energy.

Although the first-ever thermoacoustic device was built in 1983, research in thermoacoustic is accelerating rapidly now due to production ban of chlorofluorocarbons (CFC's and HCFC's) at the end of year 2015. The future with this technology looks promising.