Fluids

Fluids

Minimum fluidization velocity

    • harishravikale.201ch024
      Subscriber

      I am simulating a 2D fluidized bed(gas-solid),using eulerian-eulerian multiphase model and syamlal-o'brien drag model. The initial volume fraction of solid is 0.6. I need to find the minimum fluidization velocity but i am not sure how to do it. I tried searching for formula for using empirical relations to calculate it. The value of inlet velocity(gas),i got after calculating was low and i am not sure about the percentage error. Another way to calculate minimum fluidization velocity would be to plot change in pressure across bed vs superficial velocity but i am not sure how to do it in Ansys Fluent. Any help would be appreciated.

    • Rob
      Ansys Employee
      I'd use a hand calculation to find the minimum fluidisation velocity. Pretty sure it's covered in the Chemical Engineering text books, and no doubt also available on the internet.
    • harishravikale.201ch024
      Subscriber
      There are many emipirical relations,which vary based on mant factors like diameter of particle,density and bed voidage. I have tried calculating using empirical relations and ended up getting velocity as low as 0.003m/s. I got 0.037m/s after using an approximation of the Ergun equation but that was for smaller particles of lesser density. I read somewhere that a 5% error in minimum fluidisation velocity is observed while simulating it online. So i tried it with 1.5*0.037m/s. Didn't seem right.
    • Rob
      Ansys Employee
      It's also dependent on the depth of bed as that'll hold the rest of it down. What do Coulson & Richardson or Perry have to say on the subject? They're text/reference books, no idea if they're on line.
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