Heterogeneous nucleation condensation of methane gas on the wall-A molecular dynamics study

Abstract

Methane is condensed in a low-temperature heat exchanger, a critical step in the liquefaction of natural gas. Currently, the microscopic mechanism regarding the heterogeneous condensation of methane on the heat exchanger wall remains unclear. This lack of understanding is of scientific importance in advancing the development of natural gas liquefaction processes. Therefore, molecular dynamics simulation is used in this paper to study the process of methane heterogeneous nucleation and core growth during the early stage of condensation, and analyze the influence mechanism of wall energy and cold source temperature on nucleation kinetics. The results show that the high-energy wall can enhance the interaction between cold wall atoms and methane molecules, facilitate heat transfer, accrete methane molecules to condense and adsorb on the wall to form a core, thus increasing the condensation rate of methane. Whereas, the low-temperature cold source promotes the condensation nucleation and growth process by increasing the supersaturation of methane. This study investigates the process and kinetic characteristics of heterogeneous nucleation of methane from a microscale perspective, providing guidance for the development of natural gas liquefaction in low-temperature heat exchangers, with the aim of enhancing the diversity and reliability of energy supply.