Space-Flight Assessment of a Small-Scale Collins Type Cryocooler Concept

"A compact, reliable, efficient and inexpensive cryocooler requiring less than 1kW of power for 2W of cooling at 10Kelvin is being developed and will be demonstrated. This performance is at least twice as efficient as the best current state-of-the-art forsmall low-temperature cryocoolers. The proposed technical approach, whose feasibility has been confirmed, is to apply the advantageous features of large-scale cryogenic refrigerators to compact and reliable small-scale systems by implementing a novelthermodynamic cycle in a mechanically innovative machine. Size, cost and complexity are reduced in the proposed concept by employing a modular design whereby each stage is of identical construction (except for length), and where the heat exchanger andexpander are constructed as an integral unit. The expanders are of extremely simple floating piston construction that requires no seals or mechanical power transmission devices to extract power from the cold expander. Piston motion is controlled byelectro-mechanically actuated "smart" valves that require no mechanical valve linkages or mechanical timing mechanisms. This further reduces system complexity, improves reliability, and eliminates thermal leakage paths. Expander power is dissipated inthe warm end of the expander by throttling gas to and from the compressor suction and discharge, and a reservoir volume. The proposed cryocooler is intended for use by Very Long Wavelength Infrare