Resolving passive heat transfer and phase‐change heat in cryogenic <scp> CO ₂ </scp> deposition (Desublimation) from <scp> CO ₂ </scp> / <scp> N ₂ </scp> mixtures

Abstract In cryogenic CO 2 desublimation systems where phase change dominates both heat transfer and separation, conventional lumped thermal‐resistance treatments embed interfacial latent heat into an overall heat‐transfer coefficient, obscuring how phase‐change heat is partitioned between the gas phase and the coolant and limiting diagnostic insight into energy efficiency. In this study, CO 2 desublimation experiments were conducted using CO 2 /N 2 mixtures, and a coupled heat‐ and mass‐transfer model incorporating phase‐change effects was developed. By explicitly treating the latent heat released at the gas–solid interface as an internal heat source within a thermal‐resistance network, a heat‐splitting performance index (HSPI) was introduced to quantify the fraction of latent heat coupled to the coolant side. The results show that both CO 2 recovery and coolant‐side latent‐heat utilization increase monotonically with the inlet CO 2 mole fraction, highlighting feed‐gas composition as a key determinant of separation performance and energy efficiency in cryogenic CO 2 capture.