numerical simulations of particle deposition on super-heaters
DESCRIPTION
Numerical simulations of particle deposition on super-heaters. A fundamental study Oslo, 2010.02.16 Nils Erland L. Haugen. Introduction. Main focus: Particle inertial impaction No thermophoresis, eddy diffusion or Brownian motions This work has been done under the NextGenBioWaste project. - PowerPoint PPT PresentationTRANSCRIPT
Numerical simulations of particle deposition on super-
heatersA fundamental study
Oslo, 2010.02.16Nils Erland L. Haugen
Introduction
• Main focus: Particle inertial impaction– No thermophoresis, eddy diffusion or
Brownian motions
• This work has been done under the NextGenBioWaste project
Simulations
• Direct Numerical Simulations (DNS) are used– No modeling– No filtering– All space and time scales are resolved
• Including the thin but important boundary layer around the cylinder
• The Pencil-Code• 128 CPUs
The Stokes number
D
udSt
f
p
f
p
9
2
viscosityKinematic :
itymean veloc Fluid :
diameterCylinder :
diameter Particle :
density Fluid :
density Particle :
u
D
d
f
p
Particle impaction (0.01<St<0.3)Re=20 Re=420 Re=6600
Front side impaction efficiency
Front side impaction efficiency
Classical impaction
Boun
dary
sto
ppin
g
Boundary interception
Back side impaction
GKS (MSWI in Schweinfurt, Germany)
1685
mm 733
/sm 10
C600
m/s 5
24-
v
ud
d
T
u
Re
.
Super heater fluid specifications:
GKS particle impactionRe=20 Re=420 Re=1685
Impaction efficiency as function of particle diameter
Three ordersof magnitude
Impaction rate
Particle mass densitypr. bin (independent of bin size)
Conclusion
• DNS is required in order to resolve the important boundary layer
• Both the front and the back side impaction depends strongly on Reynolds number
• The total mass impaction rate at the super-heater of the GKS plant is totally dominated by particles larger than ~30 microns
Turbulence
Single cylinder vorticityRe=20 Re=420 Re=6600
Particle impaction (0.4<St<40)Re=20 Re=420 Re=6600
Alternative to the Stokes number
f
pSt