Cryogenic technologies have become essential to modern infrastructure, supporting diverse applications ranging from medical instruments and quantum computing, cooling for scientific optical instrumentation to hydrogen liquification and zero-boil-off for aerospace. Each application presents unique requirements such as vibration-free operation, temperature stability, and stringent constrains on weight and size. While large-scale plants utilize established technologies for high cooling capacity, there is a growing demand for compact, onsite cooling systems. Miniaturized ultra-high-speed turbomachinery represent a critical enabling technology for this shift.
 
This paper presents a Reverse Turbo-Brayton (RTB) configuration designed to provide cooling power at cryogenic temperatures using helium as a process fluid. The system architecture is outlined, alongside the technical specifications of its core components. The advantages and inherent challenges of ultra-high-speed gas-bearing turbo systems are discussed in detail. Furthermore, the paper provides in-depth aerodynamic performance estimations of the turbo compressors and the expander turbines. Performance calculations for the RTB cycle, derived from digital models of the turbomachinery, are presented and analyzed.
 
The paper concludes with an assessment of the current development of turbomachinery for cryogenics and provides an outlook on realization of this RTB configuration. Additionally, potential adaptions for similar applications such as cryofans are explored.
 

Keywords
Expander|Pump|Compressor|Heat Exchanger|zurbo machinery