Microscale effects on methane hydrate dissociation at low temperature in the micro porous media channels by depressurization

As for the dissociation of methane hydrate accompanied by multiphase multicomponent flow through micro porous media channels, it is necessary to investigate the microscale effects on the multiphase flow behavior as well as the mass and heat transfer between phases. Meanwhile, the interaction between hydrate dissociation or reformation and ice formation or melting is one of the most important factors. In this paper, with the consideration of ice formation/melting and heat transfer between phases, the momentum and energy equations for all phases and a comprehensive Users' Defined Subroutine (UDS) are solved in a proposed numerical model to investigate methane hydrate dissociation. The reliability of current model has been proved by comparing with the experiment data and previous simulation results in a good agreement, and then the model was used to study the methane hydrate dissociation at low temperature in the micro porous media channels. The microscale effects on methane hydrate dissociation was studied in two cases (with/without microscale effects), and our results showed that water temperature, volume fraction of phases, ice distribution, hydrate dissociation rate, methane velocity, mass transfer rate between water and ice and saturation of phases are affected seriously by the micro scale effects. Especially the water temperature, which is one of the critical factors for hydrate dissociation, shows an unstable change when the microscale effects is ignored. (C) 2018 Elsevier Ltd. All rights reserved.