Numerical study on transport properties of the working mixtures for coal supercritical water gasification based power generation systems

Abstract Viscosity of H2O/CO2/H2 mixtures or H2O/CO2 mixtures is a vital transport property and required in the design of equipment for coal supercritical water gasification based power generation systems, however, no experimental data and studies have examined these viscosities in supercritical regions of water. In this paper, viscosity of these mixtures in supercritical regions of water is investigated by molecular dynamics method and different theoretical models. Moreover, the self-diffusion coefficient, radial distribution functions and H-bond number are also calculated via molecular dynamics simulations to make a better understanding of the temperature dependences of the viscosity of the mixtures in supercritical regions of water at a molecular level. The breakdown of Stokes–Einstein relation for the H2O/CO2/H2 mixture in supercritical regions of water is found and discussed. The prediction models and data put forth in this paper offer great value for practical application systems involving coal supercritical water gasification.