A modified dubinin-radushkevich model describing the cryogenic adsorption of ⁴He on carbon materials

The ⁴He and ³He adsorption characteristics of porous materials serve as important references for designing and optimizing cryogenic components or systems, including adsorption pumps, helium adsorption refrigerators, and gas-gap heat switches. In this study, various types of activated carbon and carbon nanotubes were measured for their ⁴He adsorption characteristics in the range of 3–20 K and 1–18000 Pa. Parameters such as micropore volume and adsorption potential energy of porous materials were analyzed through Dubinin-Radushkevich (DR) model. A modified DR model describing the monolayer adsorption of ⁴He on different carbon-based adsorbents was developed in this study, greatly facilitating the design of adsorption systems. Further, the ⁴He adsorption model was applied to gas-gap heat switches, and a numerical model of the ⁴He gas-gap heat switch was established, which accurately predicts the actuation characteristics of several heat switches.