Experimental investigation of a single-stage micro pulse tube cryocooler operating at 59 Hz with liquid nitrogen precooling: Achieving 14.8 K under 5 W input power.

In response to the inadequate cooling capacity of traditional single-stage pulse tube cryocoolers (PTCs) in the 20 K temperature zone, and the challenges posed by multi-stage systems, including excessive volume/weight and significant thermodynamic irreversibility between high/low temperature zones, this study proposes an innovative single-stage PTC architecture based on an 80 K precooling environment. The design aims to achieve dual objectives of system compactness and thermodynamic performance enhancement by replacing the second stage in traditional two-stage coupled systems with an optimised single-stage configuration. The following technical innovations have been identified: Firstly, the integration of components across the full temperature range at 80 K operation eliminates the substantial temperature gradient caused by traditional transitional regenerators, thereby achieving a more uniform axial temperature distribution and reducing regenerator thermodynamic losses. Secondly, pioneering frequency elevation to 59 Hz (approximately double that of traditional two-stage systems) enables miniaturization through high frequency operation. Thirdly, a cold inertance tube-cold gas reservoir hybrid phase-shifting system (currently under experimental verification) combined with liquid nitrogen (LN2) precooling is being developed. Operating at pressure of 1 MPa, this configuration has been shown to achieve breakthrough cryogenic performance. It has been demonstrated that this configuration attains a no-load temperature of 14.8 K with 5 W input power, while achieving 0.3 W cooling capacity at 25.7 K. This architecture provides an optimised power-to-mass ratio solution for spaceborne cryogenic systems, establishing a new technical method for the miniaturisation development of space refrigeration technologies.