Passive, intermittent cryocooler for vibration-free and load-leveling space applications

This paper describes the use of passive adsorption/phase change subsystems for use in nonvibration cryocooling modes of operation in space applications. The specific focus here is the optimization and identification of working fluids and adsorbents for use in these systems. The authors' previous research (1995) has demonstrated specific power densities capable of 1-6 W/kg of total weight for a 60 minute operation, exceeding conventional mechanical cryocooler systems (0.1-1 W/kg). For much shorter online passive cooling operations (e.g., 10 minutes), the cooling capacity will be in the range of 5-36 W/kg. Fluids and adsorbents suitable for the range of 30 K up to 200 K in space and biomedical applications are also detailed in this paper, and implications for use in hybrid mechanical cryocoolers are discussed.