A numerical study on the thermal conductivity of H2O/CO2/H2 mixtures in supercritical regions of water for coal supercritical water gasification system

Abstract

Coal gasification technology is an important means of clean coal utilization. In the process of coal supercritical water gasification, H2O/CO2/H2 or H2O/CO2 mixtures can be produced and used as the working medium for thermodynamic cycle power generation systems. The thermal conductivity of H2O/CO2/H2 or H2O/CO2 mixtures is one of the most fundamental thermal properties required for the design and optimization of a thermodynamic system based on coal supercritical water gasification. Thus far, the thermal conductivity of H2O/CO2/H2, H2O/CO2, and H2O/H2 mixtures in supercritical regions of water remains unknown. In this paper, the thermal conductivity of these mixtures in supercritical regions of water is predicted by equilibrium molecular dynamics (EMD) simulation and various theoretical models. The force field models and simulation strategies for the MD model are discussed and recommended. To validate the simulation method, the thermal conductivity of pure H2O, CO2, H2 and CO2/H2 mixtures is calculated by MD simulations and compared with available experimental and NIST data. The method and data provided in this article may facilitate the practical applications of coal supercritical water gasification.