Using computational modeling to enhance the understanding of the flow of supercritical carbon dioxide in wood materials

The flow of supercritical carbon dioxide in wood materials was investigated through the development of a computational model based on the viscous flow of a fluid traveling through a porous medium. Douglas-fir specimens were prepared by inserting pressure sensors into the cross-section of a specimen, so that a pressure profile could be measured during supercritical treatment. The computational model was evaluated by comparing the predicted values to the ones measured experimentally. Model performance was also assessed through comparisons with another proposed model with a similar theoretical foundation, which was applied to spruce wood under different test conditions. The model was a relatively accurate predictor of internal pressure development at sub-critical pressures, while a greater disparity was observed at certain pressures above the critical point. These disparities were observed in the prior model as well, but were not as large, and the rationale for these findings is presented. The present study confirmed that the theoretical foundation for the model, viscous flow through a porous substrate using Darcyʹs Law, is applicable to more than one wood species, and thus possesses the potential to be applied to a variety of wood species and supercritical treatment conditions.