Study on the use of porous materials with adsorbed helium as the regenerator of cryocooler at temperatures below 10 K

Applied Physics Letters, Volume 118, Issue 14, April 2021. Cryocoolers play a vital role in ground low-temperature experiments and space explorations. The regenerator is an important part of the cryocooler, which is used to store the cold produced by the expansion of the working fluid helium and absorb the heat produced during the next cycle of compression. However, the specific heat of helium at temperatures below 10 K is higher than that of almost all currently known regenerator materials, resulting in insufficient cold storage capacity and severely restricting the improvement of the cryocooler cooling performance. In this paper, the study of using porous material to absorb helium as the regenerator material for cryocoolers is carried out. An experimental system was built to test the helium adsorption capacity of super activated carbon in the temperature range of 3–10 K, and it was found that the activated carbon has a significant increase in specific heat compared with the current conventional materials. A thermodynamic calculation model was further established to investigate the dynamic cryogenic adsorption characteristics and the effect of adsorption/desorption heat on the performance of the regenerator. This work is an exploration in the research of low-temperature regenerators, which can provide useful help for the selection and use of regenerator materials for cryocoolers working below 10 K. It also has great application prospects in the fields of energy storage, low-temperature superconductivity, and sub-K refrigeration systems.