Conversão termoquímica em leito fixo: características, modelagem e implementação do solver BiomassGasificationFoam

Abstract

The thermochemical conversion processes are ways to convert solids into more convenientenergy carriers (charcoal), or turn them into liquid and gaseous fuels, or also heat or otherdiverse products. Many studies have been conducted aimming to make the thermochemicalprocesses more efficient and economically viable.The application of Computational FluidDynamics (CFD) models helps to optimize the design and operation of the thermochemicalreactors, such as fixed bed reactors. The free CFD softwares offer a cost-effective tool forthese studies. One such software that is gaining prominence is OpenFOAM. An solverfor OpenFOAM called biomassGasificationFoam was recently published for the simulationof biomass gasification in fixed bed. In this work, it was done an evaluation of the solverbiomassGasificationFoam and the auxiliary libraries that accompany it, in order to generalizetheir applicability in various solids thermochemical conversion processes in fixed bed. Itsmodels for heat and mass transport in a reactive porous medium were verified and validatedwith proposed tests, analytical equations and experiments. Some code details were changedand improvements were implemented. It was identified an overestimation of the diffusionprocess of the gaseous species caused by a hypothesis adopted in these species conservationequation. The kinetic model showed to be suitable for solid thermal decomposition processeswhere the reaction order is unitary. However, this model was not so suitable for solidhomogeneous reactions where the reaction order is different from one and for heterogeneousreactions. In overall, the biomassGasificationFoam presents an interesting potential, anuseful tool for the simulation of many solids thermochemical conversion processes in fixedbed. Finally, informations were provided about the software OpenFOAM, and, especially,about the biomassGasificationFoam, in order to serve as documentation to help future usersinterested in its use