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In addition to these designs, we also tested for the three limiting parameters of foam formation from water jets.
Figure: Setup testing parameters for foam formation
For this experiment, dial soap mixed in water, pump, flow accumulator, water tank and water container were used in order to create water jets.
Three parameters were investigated to study foam formation:
1) Average velocity of jets
2) Type of surface
3) Length the water travels down the incline plane
The velocity of the jets in our experiment was increased by increasing the flow coming from the pump, which substituted for increasing the head in the actual plants. In the first run, the jets fall onto the accumulated water on the tank, then a plane was used to catch the water jets before falling into the tank. The plane was placed at different distances and angles to observe the change in bubble formation. You can find the summary of this experiment at the Experimental Method for Limiting Parameters of Foam Formation from Water Jets page
Calculations
As a team, we worked in MathCAD to calculate the distance that the jets of water coming into the LFOM would travel inside the LFOM. If we had discovered that a bucket inserted into the LFOM below the orifices could catch the jets before they hit the water, the bucket theory would be a viable option. We determined that all but the top three jets of water would in fact hit the far wall of the LFOM before reaching any size bucket that we could place in the LFOM. Also, we used MathCAD to determine the size of the orifice needed in the bottom of the bucket to maintain the plant flow rate. We determined that the orifice would have to have a 4.5cm radius, which was far too large for our buckets. The MathCAD calculations eliminated both the bucket theory and the bucket with a hole theory as possible solutions. The MathCAD files are attached.
(Please document equations used and summarize results obtained on the wiki as well)
Jet Distance Calcs 7-13-09.xmcd
CDC_Retrofit_Designs.xmcd
Testing
After eliminating both bucket theories, we decided that testing the last two designs in a lab would not be difficult and would give more realistic, tangible results than our calculations. (You need to put this as a separate page and list separate experiments on different pages)
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We used the pilot plant to test our retrofit design in an environment that replicated the actual plants as closely as possible. We set the flow rate of the pilot plant at about 150L/min, which, coupled with the 7.5cm-diameter LFOM, would be roughly comparable to the 400L/min, 15cm diameter LFOM in the plant at Cuatro Comunidades. (You need to compare it to the sizes in AguaClara plants as well as parameters in AguaClara plants)
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We were able to document results for each variation of the designs visually with photographs and short movies on cameras, see the gallery below to view the photos.
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Testing for Three Limiting Parameters of Foam Formation from Water Jets
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Conclusions
At the end of all of our testing, we determined that inserting a 5cm-diameter pipe would effectively reduce the amount of bubbles produced by the LFOM, while not constricting the overall plant flow rate. Hopefully this design change can be easily executed in the AguaClara plants in Honduras to fix the foam problem. (This only works for a 7.5" I.D. LFOM. You cannot make this conclusion for the AguaClara plant. What about the inclined plane? Does this work??)