Thermoacoustic systems, Stirling engines and pulse-tube refrigerators: analogies and differences in the light of generalized thermodynamics

Irreversibilities that play a constructive role (in the same sense explained by Prigogine) in the functioning of many engines are discussed. This behavior is used here to understand better analogies and differences among various kinds of systems. Standing-wave thermoacoustic devices, traveling-wave thermoacoustic devices, Gifford-Longsworth pulse-tube refrigerators and Stirling engines are chiefly considered and compared. It is shown that engines without such `essential´ irreversibilities are generally capable of higher efficiencies than those in which they are present