COAGULANTES

1. COAGULANTES Final Project Team Captain: Peter Presidential Prez: Alana Executive Mastermind: Roslyn Benchwarmer: Monroe

2. Project Goal To design a SSF with *flow control* that could be incorporated into a sustainable small-scale water treatment system, and to investigate the use of a coiled tube to regulate the head loss through the system. “How are head loss, tube diameter, and coil diameter related empirically?”

3. Project Description • Design SSF with flow control to treat 20 L/day of turbid water • Implement flow control device AFTER the particle removal process to avoid clogging of small orifice and narrow tubing • Use a preassembled float valve to control head in system • Use narrow tubing (1.5 mm diameter) to increase head loss • Experiment with coiling the narrow tubing around different-sized cylinders to observe effects on head loss • Collect data on the increase in head loss from uncoiled tubing, coils in a 1-m long tube, and coils in a 2.1-m long tube • Test flow rate over 30 s, 1 min, and 10 min time intervals

4. SSF unit with flow control device and head loss regulator Float valve in flow control device 

5. Raw water reservoir and SSF Flow control device Clean water reservoir Coiled tubing

6. !! CALCULATIONS !! (Flow rate) (Darcy-Weisbach Equation) (Continuity) BASICALLY: The head measured from the water surface of the middle float valve container to the end of the 1 m tube should be about 15 cm. Also, the float valve should have a reservoir large enough to contain the float valve (it may not be obstructed by the sides of the container) and sufficient water to raise the float valve until it closes.

7. Analysis of Results We expected the friction coefficient f to change with the introduction of coils. If the inertial effects of the coils were significant (ie. the velocity of the water traveling through the coils was high enough relative to the diameter of the coils), distorted velocity profiles would decrease flow, thereby decreasing velocity and ultimately increase the value of f. (Darcy-Weisbach equation) f = 64/Re (assume laminar flow) By calculating new Reynolds Numbers from the measured flow rates, we found that both a greater number of coils and a smaller coil diameter contributed to a higher constant f, as expected. Or Did We??

8. Dimensional Analysis We want to find: The relationship between diameter of tube versus diameter of coil, and headloss. This ratio can be used to determine whether or not the inertial effects (against the inner surface of the tube) outweigh the shear effects as the fluid travels through the narrow tube. where fi = force of inertia and fµ = shear force. This led to a second dimensionless parameter, Recoil = Re/(dcoil/dtube), which compares the Reynolds Number of each run to the ratio of coil diameter/tube diameter. In other words, Recoil signifies the impact of different diameter ratios on this inertial/shear force balance. So potentially, if Recoil> 1, the inertial forces outweigh the shear forces.

9. Recoilversus Diameter Ratio This graph illustrates the decreasing Recoil as the coil diameter increases; the inertial effect of the coils decreases with width. [DIMENSIONLESS!!]

10. Reynolds Number versus Number of Coils This was our attempt to account for the different numbers of coils between each run. Ahhh, but what is wrong with this graph??!

11. Ah, shoot. What else could cause head loss in a 1.5 mm latex tube that is wound around a cylinder?

12. ..alas, the effects of squishage. The flexibility of the latex tubing may have caused the headloss we attributed to coiling.

13. Whereas we expected the “64” number to increase with the inertial effects of coiling, we see now that relatively small changes in tube diameter (due to stretching) could achieve the same results. Effective differences in diameters were less than 0.1 mm

14. CONCLUSIONS -If Recoil > 1, the inertial forces outweigh the shear forces. -Recoil does not give a quantitative relationship between the ratio of coil diameter versus the diameter of the tubing, and the resulting head loss—it only shows that a higher number of coils and a smaller coil diameter might increase headloss. -The Recoil value that signifies effective headloss due to coiling is still unknown. -It is very possible that stretching affected the headloss. -Further research is necessary to determine the exact relationship between coil diameter, tube diameter, number of coils, and resulting head loss.

15. Masters of… Flow Control

16. Recommendations for Improved Design: 1) Cover the flow control reservoir to prevent recontamination if bacterial challenge test are performed. 2) Add valves to shut off flow between sand filter/reservoir and flow control device. 3) Add second float valve so water does not leave the flow control device entirely after the sand filter empties to the level of the sand surface. 4) Design the flow control device so that the initial flow into the middle float valve container is not too fast. Recommendations for Further Research: 1) Analyze a larger set of data on the effects of the number and diameter of coils. 2) Coil the same length of tube each run. 3) Take care when coiling—Do Not Stretch The Tubing. 4) Analyze the head loss effects of different tube sizes and materials. 5) Research how long it takes for narrow tubing to clog in a functioning SSF.

17. Literature Review Civil and Environmental Engineering 454: Sustainable Small Scale Water Supplies Course Notes, Weber-Shirk Engineering Fluid Mechanics, 7th ed., Crowe.