Independent CFD

On-Board Scour versus conventional bottom plenum

On-Board Scour keeps uniform water velocity between each plate. A conventional bottom plenum shares one chamber under the stack and lets buoyancy sort the rest. Independent CFD stills of the two on identical plates.

Hydrodynamics only — fouling, flux, biology, and long-term operation are outside the scope. These are independent CFD predictions under the stated modeling assumptions. They are not plant data.

The CFD was run on a 20-channel section. The shipped module is 130 plates (single-deck, ≈136.5 m2) or 260 plates (double-deck, ≈273 m2). Figures of 20 panels, ≈21 m2, and 200 L/min described that modeled section only.

Schematic Left: conventional bottom plenum. Shared chamber under the stack. Some channels hot, some dead. Right: On-Board Scour. Air at the root of every channel. Uniform water velocity between each plate. Schematic, not plant data.
On-Board Scour plate with PES membrane. Handle at the top, manifold at the bottom.
The plate PES sheet on the faces. Manifold at the bottom.

What the study compared

Same plates, different injection
ConventionalThree-header bottom-plenum air scour. Shared chamber under the stack.
Zyramic On-Board ScourDirect injection at the base of each channel. No bottom plenum.
Modeled section20 channels (not the shipped module). Plate 1,047 × 502 × 7.60 mm, 6.40 mm channel gap. Identical in both cases.
DomainBi-symmetric quarter-domain. About ten of twenty channels genuinely resolved.

The conventional case is a conventional-style geometry on Zyramic’s own plate. It is not a named competitor’s product.

Independent CFD assemblies: conventional bottom-plenum air scour on the left, Zyramic On-Board Scour on the right. Shared 20-channel modeled section.
Fig. 1 Independent CFD. Left: conventional bottom-plenum air scour. Right: Zyramic On-Board Scour. Shared 20-channel modeled section. Not plant data.

Where scouring begins

Near-field water velocity at the channel base — the liquid shear where scouring starts — was 2.4–2.6 m/s with On-Board Scour versus 0.5–0.75 m/s in the bottom plenum. That is about four times the liquid shear at that location. It is not a claim of four-times scouring over the whole panel. In-channel peaks farther up the plate are similar in both designs, on the order of 0.7–0.9 m/s.

Direct rise through every channel

Independent CFD streamlines. Conventional bottom plenum shows closed recirculation loops in the chamber. On-Board Scour shows direct monotonic rise through the channels.
Figs. 17–18 Independent CFD. Air-phase streamlines. Conventional bottom-plenum air scour: closed recirculation in the chamber; injected energy spent stirring the plenum. Zyramic On-Board Scour: direct monotonic rise; no equivalent recirculation. Not plant data.

Channel to channel

Same cross-section, two heights. The mid-plate and upper-plate heat maps look down the identical channel array. On-Board Scour stays even in every channel at both heights. The conventional bottom plenum shows strongly-scoured channels next to starved ones, and that mix persists toward the top of the panel.

The uniformity finding and the near-field shear finding are separate. Together they show even scour in every channel, and a strong start at the plate base.

Independent CFD, same channel-array view at mid-plate height. On-Board Scour is even across every channel. Conventional bottom-plenum air scour shows strongly scoured channels next to starved ones.
Mid-plate Independent CFD. Same channel-array view at mid-plate height. Top: On-Board Scour — even, moderate pattern in every channel. Bottom: conventional bottom-plenum air scour — strongly scoured channels beside starved ones. Not plant data.
Independent CFD, the same cross-section at upper-plate height. On-Board Scour stays even in every channel. The conventional mix of strongly scoured and starved channels persists toward the top.
Upper-plate Independent CFD. The same cross-section at upper-plate height. On-Board Scour stays even in every channel. The conventional mix of strongly scoured and starved channels persists toward the top. Not plant data.

Shared limits, not differentiators

  • Both designs show an edge-high, centre-low pattern across the 502 mm panel width (riser/downcomer in the enclosed channel).
  • Both show decay of scouring velocity over the upper portion of the 1,047 mm panel. Zyramic’s response is a shorter panel, not a claim that the decay is absent.

What this study does not show

  • Lower fouling, higher flux, longer membrane life, or less blower energy in the field.
  • Physical or plant validation. None has been done against this model.
  • Full-rack header or manifold asymmetry. The quarter-domain cannot confirm it.

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