A Gas-solid fluidized bed CFD analysis is a modern research method used to study bed hydrodynamics, which is how gas and solid particles interact in these systems. This type of multiphase flow is very important in many industries. For example, a Fluidized Bed Fluent simulation can help optimize processes like chemical reactions, heat transfer, drying, and combustion. These beds are popular because of their great mixing and heat transfer properties. Therefore, a deep understanding of bed hydrodynamics is needed to design the best possible processes, which is why a Gas-solid fluidized bed Simulation is so valuable.

The main goal of this project is to perform a CFD VALIDATION. We will simulate a fluidized bed with ANSYS Fluent software and compare our results directly with Figure 9 from the experimental paper “Experimental and computational study of gas–solid fluidized bed hydrodynamics [1]”. This comparison will prove the accuracy of our Fluidized Bed CFD approach.

• Reference [1]: Taghipour, Fariborz, Naoko Ellis, and Clayton Wong. “Experimental and computational study of gas–solid fluidized bed hydrodynamics.” Chemical engineering science24 (2005): 6857-6867.

Figure 1: Comparison of bubble dynamics from a Gas-solid Fluidized Bed Fluent simulation with experimental data [1].

Simulation Process (Fluidized Bed CFD Simulation Process in ANSYS Fluent)

For this Fluidized Bed CFD study, we started with the 2D geometry shown in Figure 2, which was taken from the reference paper. We created this geometry using ANSYS Design Modeler software. After designing the geometry, we used ANSYS Meshing to create a high-quality structured grid with quadrilateral elements for the entire computational domain.

The core of this Gas-solid fluidized bed Simulation is the multiphase flow setup. In ANSYS Fluent, we activated the Eulerian Multiphase module. This approach, also known as the Eulerian-Eulerian model, treats both the gas and the solid particles as continuous fluids that interact with each other. To accurately model the solid phase, we made a granular flow assumption. This means we had to define specific properties for the particles, such as their granular viscosity, solid pressure, and granular temperature. All of these settings were carefully chosen based on the values reported in the reference paper to ensure our CFD validation would be accurate.

Figure 1- 2D schematic of the domain used for the Fluidized Bed CFD simulation.

Post-processing ( Fluidized Bed CFD Analysis & VALIDATION)

The CFD validation results show an excellent match between our Gas-solid fluidized bed CFD simulation and the experimental data, especially for the time-averaged voidage profile. The validation chart clearly shows three distinct zones within the bed. There is a dense lower zone (h/H < 0.2) with a measured voidage of around 0.4. Above that is a transitional region (0.2 < h/H < 0.6) where the voidage increases. Finally, there is a dilute upper region (h/H > 0.6) where the voidage reaches a maximum of about 0.8-0.9. A very important finding is that our Fluidized Bed Fluent simulation predicts these zones with high precision, where the maximum error from the experimental data is less than 10%. This high level of accuracy confirms that our use of the Eulerian-Eulerian model and the granular flow parameters was correct. The strong agreement validates that our model can capture the complex physics of a Gas-solid fluidized bed Simulation.

Figure 3: CFD validation chart comparing voidage from the Fluidized Bed CFD simulation against experimental data [1]

The animation from our Fluidized Bed CFD simulation clearly shows the dynamic bed hydrodynamics, focusing on the bubble dynamics. As gas enters from the bottom, small bubbles form and then grow larger as they rise through the particle bed. The particle movement shows a classic bubbling fluidization pattern, with particles falling down along the walls and being pushed up in the center by the rising bubbles. A key dynamic result from the Gas-solid fluidized bed Fluent simulation is that the bed expansion ratio is between 1.5 and 1.7 times the initial bed height. We can also see how eruptions at the bed surface throw some particles up into the freeboard area. This dynamic behavior seen in our simulation matches very well with established fluidization theory, proving that our model can predict both average and transient events. The clear visualization of bubble formation and movement gives us qualitative proof that our numerical method is correct, which supports the quantitative CFD validation from the voidage chart.

Figure 4: Solid volume fraction