Research on the Enhancement of Methane Hydrate Decomposition with Phase Change Materials

Natural gas hydrates are a promising method for gas storage and transport due to their high storage density and low transport costs. However, during regasification, their strong endothermic decomposition causes a significant temperature drop in the tank, which inhibits the reaction and reduces the decomposition rate. To address this issue, this study proposes utilizing the characteristic of phase change materials (PCMs) to release substantial latent heat during solidification, thereby enhancing methane hydrate decomposition with a continuous and stable internal heat source. Based on the operational temperature range of natural gas hydrate storage, this study screened single and composite organic PCMs, including n-tetradecane, decyl alcohol and their composites with lauric acid. To further verify the enhancing effect of PCMs on hydrate decomposition, constant-pressure decomposition experiments were conducted under conditions of 8 °C and 2 MPa. The results demonstrated that both the lauric acid-n-tetradecane composite system and single n-tetradecane significantly improved the decomposition efficiency and process stability of methane hydrate: the maximum decomposition rate increased from 0.045 mol/min to 0.083mol/min, and the t90 time was reduced from 32.6 min to 12.2 min. To further evaluate heat-transfer-driven enhancement, additional strengthening strategies—including foam-aluminum fins, CuO nanoparticles, and copper-tube-encapsulated PCMs were investigated under 281 K and 3 MPa. Results revealed that improving the heat transfer pathway at the hydrate-PCM interface is crucial, with copper-tube encapsulation reducing t90 from 96 min to approximately 45 min. This study confirms that utilizing the solidification exothermic effect of PCMs to enhance methane hydrate decomposition is an effective and feasible technical approach.