Simulation Study of Cryogenic ¹¹CO₂ Capture System for RIB Project

A cryogenic radioactive ¹¹CO₂ trap is under development for the Radioactive Ion Beam project in VECC. The trap uses the process of de-sublimation (frosting) and sublimation for separating radioactive ¹¹CO₂ from the ¹¹CO₂/N₂ mixture. The mixture will be passed through the coiled stainless-steel tube submerged in liquid N₂. A pump maintains the pressure of the coil below 0.1013 MPa (1 atmosphere), preventing the condensation of N₂ gas, but allowing trapping of gases like ¹¹CO₂, NO₂, etc. Completing the entire separation process well within the half-life of the ¹¹C is a challenge in the design of the trap. This paper presents the overall scheme of the trap as well as its numerical modeling of frosting of ¹¹CO₂ inside the tube. Parametric study is performed to study of the effect of channel diameter, flow rate, and ¹¹CO₂ concentration on the frosting.