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Experimental investigation on CO2 hydrate formation/dissociation for cold thermal energy harvest and transportation applications

Choi, Sung, Park, Jungjoon, Kang, Yong Tae
Applied energy 2019 v.242 pp. 1358-1368
absorbents, carbon, carbon dioxide, cooling systems, dissociation, enthalpy, greenhouse gas emissions, heat transfer, ice, slurries, temperature, tetrahydrofuran, thermal energy, transportation
Based on growing demand for the CO2 capture issue, CO2 hydrate formation/dissociation technologies for carbon capture have been highly spotlighted. CO2 hydrate can be applied to the cold thermal energy storage since CO2 hydrate has relatively higher dissociation enthalpy (459 kJ/kg) than ice slurries (333 kJ/kg). In this study, a lab-scale cold thermal energy harvest and transportation system using the CO2 hydrate is tested. This system contains both hydrate formation and dissociation processes to study the effects of each component on the cold thermal energy harvest and transportation applications. Tetrahydrofuran (THF) based absorbents with various concentrations of tetrahydrofuran is produced and applied to the CO2 hydrate system. COP (coefficient of performance), required work, heat transfer rate, and density of hydrate slurry are measured to improve the cold thermal energy harvest and transportation performances of the CO2 hydrate system. The performance of CO2 hydrate system is evaluated under various experimental conditions such as temperatures, pressures, and tetrahydrofuran concentrations. From the experimental results, it is found that the COP of 7.03 is obtained under tetrahydrofuran concentration of 1.5 mol% and formation pressure of 4 bar. It is also concluded that the CO2 emission of the CO2 hydrate system is estimated to be 7986 tCO2/year, which is 31.3% of the conventional district cooling system with the cooling capacity of 51,600 RT.