Test constriction design

[JonathanDavidHarris]

The glass bead design or the wire constriction design. By April 3rd, 2018

[JacquelineDokko]

2D constriction model is in the process of being tested. Some adjustments (i.e. silicone thickeness) must be made to ensure floc flow through the constriction itself.

[JacquelineDokko]

Sand Model

We have begun the sand model testing as we wait for the microtubing for the single constriction model to come in. The sand model with the thicker (orange) silicone has shown to allow for easy backwashing since the sand particle diameters are on average smaller than the thickness of the silicone. This allows for more than one recording can be done for every flow cell cleaning/set-up. However, this model becomes clogged very easily as the flocs deposit and collect in a large and growing pile on top of the layer of sand.

[Thomas-Bradford]

The velocity at various headloss tubing heights seems to be inconsistent. The flow of flocs through the cell is overly fast compared to past videos and compared to the desired flow rate. Potentially because of different set of sand grains.

[JacquelineDokko]

Single Constriction Model

We have completed the construction of the single constriction flow cell. Initially, there were leaks from the inlet and outlet of the cell but adjusting the metal arm height decreased the pressure in the cell and further leakage stopped.

Constriction width is variable depending on how the flow cell is closed. Sometimes the constriction is so thin, it prevents flow.

[JacquelineDokko]

Single Constriction Model

We switched from the 100ft tubing flow cell to the old flow cell due to leakage in the new flow cell. This could be due to high pressure caused by the very long headloss tubing or because of improper microtubing fitting at the inlet and outlet of the new flow cell. due to this switch, the headloss tubing is not long enough to create the desired flow velocity. The flocs are going extremely fast through the constriction and is not depositing at all.

A new change we made is the addition of wires on both sides of the silicone in order to be able to control the width of the channel after having closed the flow cell. Previously, any adjustment had to be done by completely reopening the flow cell and then adjusting the silicone. Now, we are able to adjust the constriction (where the constriction would completely close up sometimes, depending on silicone positioning) in an easier and faster manner.

There has also been some clogging at the entrance, due to the positioning of the silicone when setting up the flow cell for today.

[Thomas-Bradford]

100ft. microtubing & attaching wires to silicone

• Because the pressure difference across the old flow cell was too high (the flocs' speed is too high to practically analyze on camera), we replaced the short microtubing with the 100ft. reel. We will test & record flow through the silicone channel.

• The 100ft. microtubing was punctured near the flow cell and had to be cut to a slightly shorter length.

• To make the silicone channel adjustable, we attached two 0.012" diameter wires to either side of the channel. This enabled minor adjustments of the channel's width to make sure it remained uniform.