CFD modeling of the forces in the wet scrubber acting on particulate matter released from biomass combustion

The flue gas from biomass combustion contains particulate matter, which is a considerable precarious constituent cause of serious health issues. The wet flue gas cleaning method is one of the most efficient solutions for smallscale boilers (approximate to 100 kW) and small particles. In this study, the forces on particulate matter in a wet flue gas cleaning process using an absorption solution have been studied with the implementation of compiled userdefined function code in Ansys Fluent 19.2 (R). The forces governing the wet cleaning process as well as the corresponding conditions of the system have also been studied. Drag, buoyancy, diffusiophoresis, and thermophoresis forces have been analyzed as the most important forces acting on particulate matters. Simulations have been conducted for velocities, particle sizes, temperatures, and water vapor mass fractions within the same range as experiments in order to acquire trends for particle collection for these variables. Moreover, the influence of diffusiophoresis force was compared to that of the thermophoresis force under different conditions. It was unveiled that the diffusiophoresis force had a significant effect on nanoparticle collection. The impact of diffusiophoresis is increased by the ascending gradient of temperature as well as water vapor mass fraction. Simulations declare that the thermophoresis force effect is small compared to the diffusiophoresis force effect in the particle collection process. Thereby, one could conclude that the diffusiophoresis force governs the collection of particulate matter in the wet scrubber method. The model validation is confirmed by comparing the results with previous empirical models.