Heat exchangers and regenerators

Thermoacoustic converters

Figure 1 - NASA thermoacoustic Stirling prototype (from [6])

Figure 2 - Classic Stirling machine geometries with mechanical piston drive

Figure 3 - Operation of the free piston Stirling machine

Figure 4 - Architecture of a simple Stirling machine with free pistons

Figure 5 - Free piston machine to generate 1 kWe (Sunpower company)

Figure 6 - Energy flows of a simple Stirling machine with free pistons

Figure 7 - Electric piston-generator

Figure 8 - Complete equivalent electrical diagram of the free-piston machine shown in figure

Figure 10 - Different DIPTR geometries for cryogenics

Figure 11 - Thales two-stage TGP cooler for 4 K

Figure 12 - Energy flow according to exciter arrangement in a thermoacoustic cooler

Figure 13 - Energy flow in a TGP or TAR cooler with feed-back effect

Figure 15 - Stack (or regenerator) with one of the hot or cold exchangers

Figure 16 - Illustration of the vortices created at the ends of limited plates, which have a major influence on heat transfer.

Figure 17 - Influence of heat exchanger length on acoustic fluid displacement: illustrations of fluid displacements

Figure 18 - Conductive heat exchanger for low power ratings

Figure 19 - Heat exchangers

Figure 21 - Evolution of f Re complex as a function of the Womersley number Wo, for circular tubes or plates

Figure 22 - Nu complex evolutions as a function of the Womersley number Wo, for circular tubes or plates

Figure 23 - Evolution of the  parameter according to Wo, case Pr ≥ 0.7

Figure 24 - Evolution of the  parameter according to Wo, case Pr ≥ 0.7

Figure 25 - Representation of the F1 function according to

Figure 26 - Evolution of the two members of the relationship

Figure 27 - Fine metal grids for regenerators

Figure 28 - Refrigerator rack made of mylar sheets separated by nylon threads bonded in parallel.

Figure 29 - Stack machined from square-mesh cordierite ceramic of the type used in automotive catalytic converters