Rate of Methane Hydrate Formation in Presence of Tetra-n-Butylammonium Chloride and Tween 80: Application in Air Conditioning Systems

Moderate hydrate forming conditions of tetra-n-butylammonium salts have made these compounds as attractive materials to store the cold in air conditioning systems. In this research, the rate of methane hydrate formation in presence of a thermodynamic additive, tetra-n-butylammonium chloride (TBAC), and a surfactant, Polysorbate 80, is studied. The tests were carried out in a 169 cm3 stirred batch reactor at isothermal condition of 278.15 K and initial pressures of 7 and 9 MPa. Investigating the results of hydrate formation within 50 min of the process showed that using TBAC with concentrations of 5 and 15 wt %, increases the rate of methane hydrate formation, compared to pure water. The addition of 15 ppm polysorbate 80 presented a positive effect on the rate of methane hydrate formation. The effect of initial pressure of the cell on the rate of methane hydrate formation is studied. The results showed that increasing the initial pressure of the cell from 7 to 9 MPa, increases the rate of methane hydrate formation for all tested solutions.