CO2 hydrates in refrigeration processes

Global warming concerns have led the refrigeration industry to seek and develop new refrigeration systems with a reduced impact on the environment. The use of two-phase secondary refrigerants generated by a primary closed refrigeration circuit is a promising solution. Solid fluid secondary refrigerants are known for their higher energy efficiency compared to single-phase fluids, because of the additional latent heat of the solid phase. The objective of the present work is to investigate experimentally the latent heat of CO2 hydrate-ice mixture systems in comparison to that of ice slurry systems. By using a new DTA apparatus, the CO2 hydrate-ice mixture was shown to offer a dissociation enthalpy of 507 kJ/kg that is higher than that of ice (333 kJ/kg). Artificial tuned CO2 hydrate-fluid systems appear to be an environment-friendly alternative for refrigeration and air-conditioning systems that can be used in a wide range of applications.