Day 01 HW Set Vocabulary and Notation Venn Diagrams

>> YOUR LINK HERE: ___ http://youtube.com/watch?v=rb47Hyg2ci8

In this video you see a simulation example for heat and mass transfer in a fluidized bed. Fluidized beds are robust industrial installations used for a number of applications from synthesis of chemicals to burning of waste sludge to roasting coffee beans and even making popcorn ( • Popcornmaschine ). Despite this, they are notorious hard to calculate and especially the start up phase is difficult to predict accurately with standard engineering calculations, double so, when chemical reactions are involved. • In our CFD simulation we are showing the start up of a fluidized bed including heat transfer. The geometry has been chosen to match a laboratory setting to be able to validate the simulation. The gas phase (air) enters the geometry over a number of spouts, every second of which is fed with hot gas to test the effect of heat transfer from the fluid to the solid phase (silica sand); details below. • The video loops a couple of times, highlighting various observations about the behavior of the system. It can be clearly seen for example, that the temperature change of the solid phase is very small, despite the high temperature difference of around 700 Kelvin. Due to the high density difference of gas and solid phase, a lot of hot gas is necessary to heat up the fluidized bed. This particular behavior is the reason why fluidized beds are often used for burning (relatively) wet sludge: once the bed is hot, it takes a lot more than the proverbial drop of water to cool down the hot stone. • Find more examples on our homepage: http://rheologic.at • • -- • Case based on: • Timo Niemi and Juho Peltola: Gas-Solid Bubbling Fluidized Bed Simulations with • compressibleTwoPhaseEulerFoam, 8th OpenFOAM Workshop Jeju, Korea, 11.-14. June 2013, VTT Technical Research Centre of Finland • • Geometry: • 0.9 x 2.0 x 0.015 m • (full 3D discretisation with front and back wall influence) • Gas: • Air, T_init=298K • cp=1007 J/kgK, rho=f(T), d_mean=3e-4 mm (constant, uniform), T_in=1000K, • U_in=3.2 m/s (uniform) • Solid: • Sand, T_init=298K, bed_height (init) = 0.6 m • cp=830 J/kgK, rho=2480 kg/m^3, d_mean=0.656 mm (constant, uniform)

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