The guiding principle of these refrigerating machines schematically consists in compressing gas, to then bring it in the cold part (which one generally calls the cold finger) then finally to slacken it to produce cold. The objective is to have the maximum of gas compressed with the cold end during the phase of relaxation. In other words, since the variations of pressures (compression, relaxation) and of gas mass in the machine are in general generated by piston machines (oscillator of pressure) and are thus quasi sinusoidal, one needs a null dephasing between flow masses and wave of pressure to the cold end.
Two types of machines currently dispute the favours of the space market, Stirling and the pulsated gas-tube (TGP). Thermodynamically very effective, they differ by technology used to adjust dephasings débit/pression within the cold finger: mechanics with moving parts for Stirling, tire entirely static for the TGP. One guesses of course why this last, although more tardily developed, could in the long term supplant the Stirling machines. These two systems use similar oscillators of pressure primarily based on the technology of the membrane springs; although ECA-SBT developed at the beginning of the Nineties of the oscillators on stage gas, this work was arrétés with the profit of the use of these oscillators qualified available almost on rack near many industrialists of the space one.
The research led to ECA-SBT currently concentrates on cold the finger part and we have for example two contracts in progress with the European Agency Space in collaboration with Astrium and Liquid air. These developments relate to miniature TGP; the most recent performances exceed refrigerating Watt of power for 25 Watts provided.