Abstract
The dissociation heat of gas hydrates is one of the important parameters that control the formation/dissociation speed of the gas hydrate. We investigated the effect of the ethane concentration on the dissociation heat of the mixed-gas (methane and ethane) hydrate. The dissociation heat of the mixed-gas hydrate [kJ mol-1] was within the range between the dissociation heat of pure methane hydrate and that of ethane hydrate, and it increased with the ethane concentration. Only several % of ethane composition was quite effective to increase the dissociation heat. The hydration number, which changed according to the crystal structure (sI/sII hydrates), determined the dissociation heat during the transition from hydrate to gas and water. The dissociation heat of the mixed-gas hydrate [kJ kg-1] was 6-30 % greater than that of pure methane and ethane hydrates during the transition from hydrate to gas and ice, and 3-8% greater during the transition from hydrate to gas and water.
