Sublimation temperature of carbon dioxide for varying ambient pressure and far-field concentration

The cooling potential of sublimating solid carbon dioxide (dry ice) is vital in applications such as spray cooling food and pharma products and cryopreservation. The thermodynamic saturation temperature of solid carbon dioxide at normal atmospheric pressure is -78.5 ⁰C. Application engineers often use this temperature data to design cooling equipment without noticing that this temperature refers to the phase change process between the solid and vapor carbon dioxide. In the air, due to nearly zero far-field concentration of carbon dioxide, the diffusion of carbon dioxide vapor from a sublimating dry ice surface will decrease its internal energy, causing a further decrease in the sublimation temperature. We measured the temperature of a dry ice sphere in a climate chamber where the far-field concentration of CO2 and the absolute pressure is varied. This data is compared with a transport model that includes thermal and mass diffusion. This model predicts well the steady state sublimation temperature of the dry ice for various conditions.