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The experimental setup used in Spring 2009 was modified at the beginning of the summer to include a taller pressurized aerator in order to increase the residence time of the bubbles and to establish more consistent supersaturation in the water going to the sand filter. The new aerator includes a valve to release water to maintain the appropriate water level. The hot and cold water valves present in the original set-up have been omitted in the new one, and the water source has been changed to a container with water whose temperature is maintained at 20 degrees Celsius. The flow that leaves the aerator and enters the sand filter is regulated by a valve that is controlled by the PID flow accumulator used in the previous setup. A temperature probe is used just to confirm that the water temperature is 20 degrees Celsius. From there, the water flows up through the sand filter, and then to the bubble collector, as in the original set-up. (A schematic of the original set-up is included for comparison.)
Presentation to the CEE Advisory Council on March 27, 2009
The Process Controller software is used to automate experiments and record data on Microsoft Excel spreadsheets. Two states have been developed for the experimental setup - an "On" and an "Off" state. Generally, experiments will be run with the system on the "On" state. However, as experiments are conducted, it may be necessary to increase the number of states. A rough draft of the Process Controller methods used can be found here.
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