Meso-Scale Modeling: The EMMS Model for Gas-Solid Systems

  • Jinghai Li
  • Wei Ge
  • Wei Wang
  • Ning Yang
  • Xinhua Liu
  • Limin Wang
  • Xianfeng He
  • Xiaowei Wang
  • Junwu Wang
  • Mooson Kwauk
Chapter

Abstract

This chapter introduces the EMMS model for gas-solid two-phase flow and the motive for this series of work. The EMMS model focuses on the meso-scale phenomenon of particle clustering, correlating it to the micro-scale of single particles and the macro-scale of the vessel operating conditions, material properties, and boundary conditions by analyzing the compromise between dominant mechanisms to define the meso-scale stability condition. The EMMS model can be solved for the eight parameters that describe the meso-scale structure and capture the so-called choking and drag-reduction phenomena in gas-solid fluidization systems, and further enables the intrinsic regime, operation diagram and overall fluid dynamics of systems to be determined. This chapter provides a solid basis to integrate the EMMS model with computational fluid dynamics (CFD) simulations and develop the EMMS paradigm.

Keywords

Choking Cluster Compromise Drag EMMS Fluidization Hydrodynamics Meso-scale structure Multiscale Stability condition 

Notation

a

Acceleration, m/s2

Cb

Coefficient of added mass force, -

CD

Drag coefficient for particles, -

CD0

Drag coefficient for a single particle, -

d

Diameter, m

F

Gas-solid interaction, N

f

Volume fraction (of dense phase), -

Fi(X)

Conservation equation, -

g

Gravity acceleration, m/s2

Gs

Solids flow rate, kg/(m2·s)

H

Solids bed height, m

I

Solids inventory, kg

K

Proportional factor, -

K*

Saturation carrying capacity, kg/(m2·s)

m

Particle or cluster number in unit volume, m-3

N

Rate of energy dissipation per unit mass of solids, m2/s3

P

Pressure, kPa

Q

Volume flow rate, m3/s

r

Radial coordinate, m

R

Radius, m

Re

Reynolds number, -

t

Time, s

U

Superficial velocity, m/s

u

Velocity, m/s

W

Energy consumption with respect to unit volume, J/m3 s

z

Axial coordinate, m

δb

Bubble holdup, -

ν

Kinematic viscosity, m2/s

ρ

Density, kg/m3

σ

Variation of local solids concentration fluctuation, -

ε

Voidage, -

μ

Viscosity, Pa·s

Subscripts

*

Top dilute region

a

Bottom dense region

b

Bubble

c

Dense phase

cl

Cluster

d

Dissipation

e

Emulsion

f

Dilute phase, fluid

g

Gas

i

Interface

imp

Imposed pressure

max

Maximum

mb

Minimum bubbling

mf

Minimum fluidization

min

Minimum

p

Particle

pt

Value for choking point

s

Suspension, slip

T

Total

t

Transport, terminal

uni

Uniform

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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Jinghai Li
    • 1
  • Wei Ge
    • 1
  • Wei Wang
    • 1
  • Ning Yang
    • 1
  • Xinhua Liu
    • 1
  • Limin Wang
    • 1
  • Xianfeng He
    • 1
  • Xiaowei Wang
    • 1
  • Junwu Wang
    • 1
  • Mooson Kwauk
    • 1
  1. 1.Institute of Process EngineeringChinese Academy of SciencesBeijingPeople’s Republic of China

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