Function of gas parcels in the pulse tube

The working mechanisms of the pulse tube in a pulse tube cryocooler (PTC) were revealed by tracking the thermodynamic cycles of typical gas parcels quantitatively in Lagrangian viewpoint. The influence of the phase angle on the periodic work-heat conversion of the gas parcels was studied. Research shows that the cold end phase angle determines the heat “transfer” direction of the gas parcels in the pulse tube. For the phase-shifting PTCs, the gas parcels in the pulse tube expand while absorbing heat at the hot side and are compressed while releasing heat at the cold side in a cycle due to the effect of the phase shifter. The gas parcels in the pulse tube do not contribute cooling but bring heat losses to the cold end, which is different with the traditional understanding that the heat is taken away from the cold end by the gas in the pulse tube.