Thermodynamic mechanism and heat transfer characteristics of CO2 hydrate for enhancing cold storage

Cold storage utilizing CO2 is an emerging trend, which is related to CO2 hydrate formation and decomposition. Yet, the quantitative effects of CO2 hydrate decomposition on cold storage characteristics still unclear. This study built an apparatus for cold storage characteristics of CO2 hydrate and investigated the CO2 hydrate decomposition effect on temperature evolution of cold storage system under temperatures of 283.07, 285.41, 287.95 K and pressures of 1430, 1633, 1400 kPa. The results indicate that CO2 hydrates plays an important role in controlling both temperature and duration of cold energy release. It is found that the CO2 hydrate decomposition amount and temperature follow the relationship y=y0+A∗eR0x, and the thermodynamic process of cold storage system with CO2 hydrate decomposition can be divided into the hydrate isothermal phase transition stage, hydrate-controlled temperature stage and uncontrolled temperature stage. Heat transfer analysis shows that the CO2 hydrate amount increased from 0.161 mol to 0.324 mol, and the heat released during hydration rose from 9960 J to 19440 J. When the CO2 hydrate saturation increased from 11.4% to 22.94%, the cumulative energy of cold release increases from 35.17% to 303.51%. This study reveals the enhancement of CO2 hydrate on cold storage, which is important for the development of novel cold storage systems with large-scale CO2 utilization.