A thermoacoustically driven orifice‐pulse‐tube cryocooler Free

The orifice pulse tube is a variant of Stirling‐cycle refrigerator in which the cold, work‐absorbing piston and crankshaft are replaced by a simple dissipative structure. To date, the oscillatory pressure needed to drive pulse tubes has been provided by complex, unreliable room‐temperature pistons and crankshafts. In this presentation, plans and design calculations for driving an orifice pulse tube with a thermoacoustic engine will be discussed. In this composite device, heat flowing from a high‐temperature source to a room‐temperature sink will generate high‐amplitude acoustic oscillations in high‐pressure helium gas; these oscillations will power the orifice pulse tube, thereby pumping heat from a low‐temperature source to a room‐temperature sink. Thus the device is a heat‐driven cryocooler with no moving parts. in this planned small laboratory device, it is expected that a few W of refrigeration at roughly 80 K using about 2 kW of heat at 1000 K will be produced. The nature of the oscillatory heat transfer and time‐averaged enthalpy flow in the various components of the engine and cooler will also be discussed, comparing and contrasting the acoustic‐frequency Stirling cycle in the cooler with the thermoacoustic cycle in the engine.