Determination of the Diffusion Coefficients of Binary CH4 and C2H6 in a Supercritical CO2 Environment (500-2000 K and 100-1000 atm) by Molecular Dynamics Simulations

CH Wang and KRV Manikantachari and AE Masunov and SS Vasu, ENERGIES, 17, 4028 (2024).

DOI: 10.3390/en17164028

The self-diffusion coefficients of carbonaceous fuels in a supercritical CO2 environment provide transport information that can help us understand the Allam Cycle mechanism at a high pressure of 300 atm. The diffusion coefficients of pure CO2 and binary CO2/CH4 and CO2/C2H6 at high temperatures (500 K similar to 2000 K) and high pressures (100 atm similar to 1000 atm) are determined by molecular dynamics simulations in this study. Increasing the temperature leads to an increase in the diffusion coefficient, and increasing the pressure leads to a decrease in the diffusion coefficients for both methane and ethane. The diffusion coefficient of methane at 300 atm is approximately 0.012 cm(2)/s at 1000 K and 0.032 cm(2)/s at 1500 K. The diffusion coefficient of ethane at 300 atm is approximately 0.016 cm(2)/s at 1000 K and 0.045 cm(2)/s at 1500 K. The understanding of diffusion coefficients potentially leads to the reduction in fuel consumption and minimization of greenhouse gas emissions in the Allam Cycle.

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