FRidh's blog

Discovery consists of seeing what everybody has seen and thinking what nobody has thought -- Albert Szent-Gyorgyi

Thermoacoustic refrigerator

From February to June 2010 I worked on a project at SP Technical Research Institute involving thermoacoustics. Goal was to produce a thermoacoustic refrigerator delivering 100 watts of cooling power at 280 K using heat. A basic introduction to thermoacoustics can be found at Wikipedia here and here. Recently I have been adding pieces of information about thermoacoustics, and I intend to do more.

Here you can find my final report that I wrote as part of my bachelor thesis. Note that there are some mistakes in it, of which one I completely missed during my checks (hint: it has to do with with harmonics and length of a device).

The following is an abstract of my report:

Thermoacoustics is a field that combines thermodynamics, fluid dynamics and acoustics. In thermoacoustics it is possible to construct thermodynamic engines, prime movers and heat pumps which respectively use heat to create work, and use work to create or move heat.

Thermoacoustics is a relatively new field of science and engineering. The subject is still quite unknown and not much literature about the subject is available. But there is a positive trend in the amount of published papers about the subject.

There are two classes of thermoacoustic devices, travelling-wave devices and standing-wave devices. The first use a standard travelling acoustic wave and the second use a resonator in which the acoustic waves interfere causing a standing-wave.

The goal of this project was to develop a standing-wave thermoacoustic refrigerator. The refrigerator should be able to deliver 100 Watts of cooling power at 280 Kelvin. The device should be at most one meter long.

This report gives an introduction in thermoacoustics, and a summary of a paper by Greg Swift called ‘Thermoacoustic engines’. The different parts of a thermoacoustic device with their properties are discussed as well.

Several simple devices have been constructed during the project and these are discussed. Not all of these devices worked though. The model of the final refrigerator is presented as well. Because of lack of time and technical difficulties the final device was not constructed.