Process and Reactor Level Simulations of Coal-Direct Chemical-looping Combustion - Novel Combustion Concepts for Sustainable Energy Development - page 341

Table 8 Key modeling parameters for simulation of the TU-Darmstadt experiment
Average diameter of particles 2.5 mm

2,500 kg/m 3 Average density of particles

Mass load of particle in bed 0.73 kg

Inlet velocity 22.69 m/s

Background gas velocity 0.85 m/s

Primary phase Air

Secondary phase Glass beads

Outlet boundary condition Pressure outlet with P out,gage =0Pa

Inlet boundary condition Velocity inlet with central jet velocity of 22.69 m/s,

background flow velocity of 0.85 m/s

Drag law Syamlal-O ' Brien

Particle collision law Spring-dashpot

Spring constant 410 kN/m

Coef cient of restitution 0.97

Friction coefficient 0.1 0.5 based on relative velocity

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Numerical schemes Phase coupled SIMPLE, second-order upwind for

momentum eq., QUICK for volume fraction, second-
order implicit in time

10 − 5 s, Fluid: 5 10 − 4 s Time step size Particle: 5 × ×

Fig. 10 Particle distribution in the reactor for the first 300 ms of jet injection (top Fluent CFD/
DEM simulation, bottom TU-Darmstadt experiment)

Fig. 11 a Time variation of bed height and b static pressure at various heights