SUMMARY

Regenerative cryogenic cooling systems are vital to space missions and scientific exploration. Within these cryocoolers, the regenerator is considered the most important component of the entire cooling system. Currently, space cryocooling limitations exist due to the lack of efficient low temperature, high capacity regenerators. The thermal and hydrodynamic phenomena occurring on the pore-level of the regenerator determine the efficiency and cooling load of the system. Although these pore-level considerations are immensely significant, very little is known about the pore-level thermal and hydrodynamic parameters due to the difficulties associated with periodic flow modeling and experimentation. Therefore, the goals of this project are to: theoretically demonstrate a complete two-stage pulse tube cryocooler with a 5 W or larger cooling capacity at 20 K; perform an in-depth investigation of the low temperature; and perform a detailed pore-scale direct simulation of periodic flow in generic porous structures for the extraction of instantaneous and time-averaged solid-fluid transport parameters. These parameters will be used for the development of correlations for the constitutive and closure relations for use in CFD simulations of periodic flow of cryogens in porous media. These correlations and the proposed 20 K regenerative space cryocooler will represent innovative space science technology advancements.