Transcript Float and coiled tubing

COAGULANTES
Final Project
Team Captain: Peter
Presidential Prez: Alana
Executive Mastermind: Roslyn
Benchwarmer: Monroe
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?”
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
SSF unit with flow control device and
head loss regulator
Float valve in flow
control device 
Raw water reservoir and SSF
Flow control device
Clean water reservoir
Coiled tubing
!! CALCULATIONS !!
Q
20 L 1000 ml
day
ml


 13.9
day
1L
1440 min
min
hf 
V
hf 
32uLV
gD 2
(Flow rate)
(Darcy-Weisbach Equation)
Q
20L/day

 .117 m/s
A  0.000795 2 m
(Continuity)
32  .001  1m  .117m/s
 .151m  15.1cm
1000kg/m 3  9.8m/s 2  .00159 2 m
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.
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.
LV 2
hf  f 2
D g
f = 64/Re
(Darcy-Weisbach equation)
(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??
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.
Re 
f i Vdtube

f

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.
Re coil
Vdtube d tube

*

d coil
So potentially, if Recoil > 1, the inertial forces outweigh the shear forces.
Recoil versus Diameter Ratio
30.0
25.0
Re(coil)
20.0
15.0
10.0
5.0
0.0
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
d(coil)/d(tube)
This graph illustrates the decreasing Recoil as the coil diameter increases; the
inertial effect of the coils decreases with width. [DIMENSIONLESS!!]
Reynolds Number versus Number of Coils
285
265
245
Raynolds Number
225
205
185
165
145
125
0
5
10
15
20
25
30
35
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??!
Ah, shoot.
What else could cause head loss in a 1.5
mm latex tube that is wound around a
cylinder?
..alas, the effects of squishage.
The flexibility of the latex tubing may have caused
the headloss we attributed to coiling.
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.
10.0
Percent Difference of Tube Diameters
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0.000
20.000
40.000
60.000
80.000
100.000
120.000
"64"
Effective differences in diameters were less than 0.1 mm
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.
Masters of…
Flow Control
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.
Literature Review
Civil and Environmental Engineering 454: Sustainable Small Scale
Water Supplies
Course Notes, Weber-Shirk
Engineering Fluid Mechanics, 7th ed., Crowe.