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\begin_body

\begin_layout Title
Linear Chemical Dose Controller
\end_layout

\begin_layout Abstract
The linear chemical dose controller, LCDC, is a key technology for AguaClara.
 The LCDC makes it possible for the plant operator to directly set the chemical
 dose for the coagulant.
 The LCDC is a combination of several technologies and although the AguaClara
 team has been developing these technologies since 2004, there is still
 a critical need to improve the performance and accuracy of the LCDC.
 The immediate priority is to be able to understand, quantify, and minimize
 the minor losses for a given CDC setup so that we can make system adjustments
 and improvements to decrease the minor losses.
 The next step is to build dose controllers for different design flow rates
 and test them.
 An alternative is modify our design protocol and set the maximum coagulant
 flow rate for all plant sizes smaller than 20
\begin_inset space \thinspace{}
\end_inset


\begin_inset Formula $\frac{L}{s}$
\end_inset

 to be 2
\begin_inset space \thinspace{}
\end_inset


\begin_inset Formula $\frac{mL}{s}$
\end_inset

.
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
students 3 FT
\end_layout

\begin_layout Labeling
\labelwidthstring 00.00.0000
skills fluid mechanics, fabrication, experimental methods, data analysis
\end_layout

\begin_layout Section
Minimize and Characterize Minor Losses
\end_layout

\begin_layout Standard
The minor losses scale with 
\begin_inset Formula $\frac{V^{2}}{2g}$
\end_inset

 and thus don't have the linear relationship between head loss and flow
 rate that we need for the linear chemical dose controller.
 These minor losses cause a departure from linearity and thus an error in
 the chemical dosing.
 Our goal is to minimize the minor loss coefficient and to increase the
 major losses sufficiently so that the error caused by the minor losses
 is acceptable small.
 The minor losses are caused by contraction and then flow expansion at the
 entrance, additional shear due to the initial high velocity gradients at
 the wall of the tube, expansions at fittings, expansion or jet discharge.
\end_layout

\begin_layout Standard
Modify the LCDC test apparatus to use barbed fittings that have inner diameters
 that are at least as large as the inner diameter of the tube.
 This will reduce the minor loss coefficient by eliminating expansions and
 contractions at the entrance and exit of the barbed fittings.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\begin_inset Graphics
	filename Barbed Fitting.png
	width 12cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Barbed fitting with inner diameter equal to the tubing inner diameter.
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Quantify the head loss through the entrance region (the region where the
 parabolic velocity distribution has yet to develop) of the small diameter
 tube in terms of a minor loss coefficient (k-value).
 The entrance region of the tube has higher shear due to the higher velocity
 gradient at the wall of the tube.
 This increased energy loss is characterized by Mohanty and Asthana
\begin_inset CommandInset citation
LatexCommand cite
key "key-1"

\end_inset

.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\begin_inset Graphics
	filename Entrance Losses.png
	width 10cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
Entrance losses characterized experimentally
\begin_inset CommandInset citation
LatexCommand cite
key "key-1"

\end_inset

.
 
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
Mohanty and Asthana (1978) characterize the total head loss in the entrance
 region.
 The total loss is the sum of the major loss 
\begin_inset Formula $\left(f\frac{L}{D}\right)$
\end_inset

 and the minor loss 
\begin_inset Formula $\left(K\right)$
\end_inset

 due to the additional wall shear.
\end_layout

\begin_layout Standard
\begin_inset Formula 
\begin{equation}
\frac{P_{0}-P}{\frac{1}{2}\rho V^{2}}=f\frac{L}{D}+K
\end{equation}

\end_inset


\end_layout

\begin_layout Standard
The minor loss coefficient approaches a value of 1.15 for values of 
\begin_inset Formula $\xi=\frac{2L}{DRe}$
\end_inset

 exceeding 0.12 (see Figure 
\begin_inset CommandInset ref
LatexCommand ref
reference "fig:Minor Loss"

\end_inset

) (Mohanty and Asthana, 1978).
 The value of 
\begin_inset Formula $\xi$
\end_inset

corresponding to 0.12 represents the transition to fully developed flow with
 a parabolic velocity distribution.
\end_layout

\begin_layout Standard
\begin_inset Float figure
wide false
sideways false
status open

\begin_layout Plain Layout
\begin_inset Graphics
	filename K for Entrance Losses.emf
	width 10cm

\end_inset


\end_layout

\begin_layout Plain Layout
\begin_inset Caption

\begin_layout Plain Layout
\begin_inset CommandInset label
LatexCommand label
name "fig:Minor Loss"

\end_inset

The minor loss coefficient corresponding to the losses in excess of major
 losses in the entrance region for laminar flow.
\end_layout

\end_inset


\end_layout

\end_inset


\end_layout

\begin_layout Standard
The exit losses for laminar flow are expected to have a loss coefficient
 value of 2 because of the parabolic velocity distribution.
 The kinetic energy content of the fluid in laminar flow is twice that of
 the same flow with a uniform velocity rather than the parabolic velocity
 profile.
 Although the entrance loss is measured to be 1.15, only 0.15 of that represents
 the loss of mechanical energy to thermal energy.
 A value of 1 represents the conversion of potential energy to kinetic energy
 with the parabolic velocity profile.
 The parabolic velocity profile in a tube has twice the kinetic energy that
 the same flow would have with uniform velocity
\end_layout

\begin_layout Standard
The sum of the minor loss coefficients is:
\end_layout

\begin_layout Itemize
Entrance: 0.5 (rough estimate for the sharp edged entrance)
\end_layout

\begin_layout Itemize
Entrance region: 0.15
\end_layout

\begin_layout Itemize
Exit: 2.0 (all of the kinetic energy is lost when the jet exits the tube)
\end_layout

\begin_layout Itemize
Total: 2.65
\end_layout

\begin_layout Standard
The minor loss coefficient total is must less than what is observed in practice
 with the LCDC.
 It is possible that curvature of the tube is a significant additional loss.
 The effect of tube curvature on losses is presented in 
\begin_inset CommandInset citation
LatexCommand cite
key "key-2"

\end_inset

.
\end_layout

\begin_layout Enumerate
Investigate the effect on minor head loss of the radius of curvature of
 the small diameter tube.
 Are these head losses significant? 
\end_layout

\begin_layout Enumerate
Determine the trade-off AguaClara wants to make regarding small diameter
 tube length and CDC system maximum percent error.
 From our results, we see that a longer tube reduces maximum percent error.
 How long is too long for a small diameter tube? What is the tradeoff here?
 
\end_layout

\begin_layout Enumerate
Design an easy way for the plant operator to measure the plant’s current
 flow rate and decide where, in the entrance tank, to place the label to
 measure it.
 Currently the operator's label the LFOM.
 Is that the best approach? Could the lever system include a read out for
 the plant flow rate?
\end_layout

\begin_layout Enumerate
Test the screw that fastens the slider to the lever.
 Will this screw wear out over time? Will it be damaged if alum or PACl
 is spilled on it? This will be important not only for the CDC but also
 to choose which of the new flow controller designs to implement.
 Test the reducer to see what its maximum chemical flow rate is for various
 tube lengths.
 
\end_layout

\begin_layout Enumerate
Devise a method to generate labels using AutoCAD or some other method that
 can be automated and included with the design files.
\end_layout

\begin_layout Enumerate
Evaluate the possibility of producing LCDCs with set maximum flow rates.
 Instead of calibrating the LCDC, the fill volume for the stock tank would
 be set so that when a bag of coagulant is added it produces a concentration
 that delivers the correct dose given the max flow of the LCDC.
 All the LCDCs would be the same over a wide range of plant flow rates and
 the stock tank concentration would be varied.
\end_layout

\begin_layout Enumerate
Develop a method to calibrate a new LCDC so that it produces the design
 flow rate.
\end_layout

\begin_layout Enumerate
Evaluate the possibility of placing a plant flow rate scale on the LCDC.
 Compare with the option of placing a scale on the LFOM.
 Choose the best option and implement the solution.
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
key "key-1"

\end_inset

A.
 K.
 Mohanty and S.
 B.
 L.
 Asthana, Journal of Fluid Mechanics / Volume 90 / Issue 03, pp 433 - 447,
 1978.
 Published online: 19 April 2006 
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status collapsed

\begin_layout Plain Layout

DOI:10.1017/S0022112079002330
\end_layout

\end_inset

 
\end_layout

\begin_layout Bibliography
\labelwidthstring References
\begin_inset CommandInset bibitem
LatexCommand bibitem
label "2"
key "key-2"

\end_inset

Zhou, Y., & Shah, S.
 (2006).
 New Friction-Factor Corrections for Non-Newtonian Fluid Flow in Coiled
 Tubing.
 SPE Drilling and Completion , 68-76 (
\begin_inset Flex URL
status open

\begin_layout Plain Layout

DOI:10.1017/S0022112079002330
\end_layout

\end_inset

).
\end_layout

\end_body
\end_document
