Flow Distributions and Pressure Drops of Wall-Flow Diesel Particulate Filters

Liu, Z. Gerald; Miller, Robert

doi:10.4271/2002-01-1311

Cited by 14 publications

(11 citation statements)

References 11 publications

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“…5, 6) showed no recirculating flow at the entrance, the turbulent diffusivity maps ( Fig. 9) do indicate turbulent flow occurring ahead of the inlet plugs as predicted by Liu and Miller [17]. Though not shown, negative axial velocities were observed at the end of the inlet channel, indicating recirculating flow, again confirming the predictions of Liu and Miller.…”

supporting

confidence: 77%

“…Further, most models do not consider the flow profiles inside channels and the effects of flow maldistributions in such channels on heat and mass transfer [14,15]. A small number of three-dimensional simulations have been performed to study the contraction and expansion of gas at the ends of filters, notably by Konstandopoulos et al [16] and Liu and Miller [17]. Both studies report broadly similar flow features as shown schematically in Fig.…”

Section: Wall-flow Particulate Filtersmentioning

confidence: 99%

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Measuring velocity and turbulent diffusivity in wall-flow filters using compressed sensing magnetic resonance

Cooper

York

Sederman

et al. 2019

Chemical Engineering Journal

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Gas-phase compressed sensing magnetic resonance methods have been used to image gas flow velocity and turbulent diffusivity in wall-flow particulate filters. Two-dimensional magnetic resonance velocity imaging was used to observe the local distribution of gas velocity in the direction of superficial flow (z) in the entrance and exit regions of the filter at an in-plane spatial resolution of 140 µm (x) × 140 µm (y) and 140 µm (x) × 390 µm (z) perpendicular to and parallel with the direction of superficial flow, respectively. Images were acquired in 14 min. Three-dimensional images of the turbulent diffusivity were acquired at a spatial resolution of 286 µm (x) × 286 µm (y) × 1300 µm (z) for channel Reynolds numbers, Re c , of 210, 360, 720 and 1140. These data provide evidence of regions of turbulence inside the filter that has not been predicted by earlier numerical simulations. For Re c = 1140, a three-dimensional velocity image was also obtained at the same spatial resolution as the image of turbulent diffusivity; the data acquisition time was 2 h. Co-registration of these two images enables visualisation of the spatial extent and magnitude of these two characteristics of the flow field.

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supporting

confidence: 77%

Section: Wall-flow Particulate Filtersmentioning

confidence: 99%

Measuring velocity and turbulent diffusivity in wall-flow filters using compressed sensing magnetic resonance

Cooper

York

Sederman

et al. 2019

Chemical Engineering Journal

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“…The above mentioned flow features agree reasonably well with previous numerical studies [9][10][11][12][13][14] and that they have been identified in recent experiments [18].…”

Section: Discussionsupporting

confidence: 92%

“…However, in Konstandopoulos et al [13], the flow at the entrance was smoothly contracted into the inlet channels and the exiting jets induced strong mixing and pressure fluctuations for several plug lengths downstream of the filter. In contrast, Liu and Miller [14] found recirculations adjacent to the front and rear plugs.…”

Section: Introductionmentioning

confidence: 86%

“…Konstandopoulos et al [13] and Liu and Miller [14] performed 3D CFD simulations in order to evaluate the effect of the gas flow contraction and expansion at the ends of a filter that is formed of square and triangular channels, respectively. In both studies, the flow at the filter exit consists of high velocity jets and recirculating fluid areas behind the rear plugs.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Study of Flow and Particle Deposition in Wall-Flow Filters with Intact or Damaged Exit

Tzorbatzoglou

Μαστρόκαλος

Haralampous

2019

Fluids

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We examine the time-dependent three-dimensional gas-particle flow in an intact wall-flow filter consisting of channels alternatively plugged at each end and a partially damaged filter in which the rear plugs are removed. Our focus is placed on highlighting the differences in the flow pattern and the deposition process between the two geometries. The Navier–Stokes equations are solved for the fluid flow coupled with a Brinkman/Forchheimmer model in order to simulate the flow in the porous walls and plugs. Discrete particle simulation is utilized to determine the nanoparticle trajectories. Using this scheme, we are able to characterize the main features of the flow fields developing in the intact and damaged filters with respect to the Reynolds number and identify those affecting the transport and deposition of particles that have three representative response times. We present fluid velocity iso-contours, which describe the flow regimes inside the channels, as well as in regions upstream and downstream of them. We provide evidence of local recirculating bubbles at the entrance of the channels and after their exit, whereas back-flow occurs in front of the rear plugs of the intact channels. We show that the flow leaves the channels as strong jets that may break up for certain flow parameters, leading to turbulence with features that depend on the presence of the rear plugs. The removal of the rear plugs affects the flow distribution, which, in turn influences the flow rates along the channels and through the walls. We describe the particle trajectories and the topology of deposited particles and show that particles follow closely the streamlines, which may cross the surface of permeable walls for both flow configurations. The distribution of deposited particles resembles the spatial variation of the through-wall flow rate, exhibiting two peak values at both ends of the intact filter channel, and one local maximum near the entrance of the damaged filter channel that is diminished at the exit. We also investigate in detail the particle deposition on the frontal face and indicate that particle accumulation at the edges of the entrance is favored for particles with low response times in flows with high fluid mass rates for both intact and damaged filters. Finally, we examine the filtration efficiency for the defective channels without rear plugs and show that fewer particles are captured as the Reynolds number is increased. A smaller reduction of the filtration efficiency is also predicted with increasing particle size.

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Frictional and Heat Transfer Characteristics of Flow in Triangle and Hexagon Channels of Wall-Flow Monoliths

Wang

Bissett

2018

Emiss. Control Sci. Technol.

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Flow Distributions and Pressure Drops of Wall-Flow Diesel Particulate Filters

Cited by 14 publications

References 11 publications

Measuring velocity and turbulent diffusivity in wall-flow filters using compressed sensing magnetic resonance

Measuring velocity and turbulent diffusivity in wall-flow filters using compressed sensing magnetic resonance

Numerical Study of Flow and Particle Deposition in Wall-Flow Filters with Intact or Damaged Exit

Frictional and Heat Transfer Characteristics of Flow in Triangle and Hexagon Channels of Wall-Flow Monoliths

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