From f4dded54495a900c690bc38c71bda1a45c22e9d0 Mon Sep 17 00:00:00 2001 From: Felix Hilsky Date: Sun, 22 Nov 2020 20:10:58 +0000 Subject: [PATCH] my review before submission --- tex/header/preamble.tex | 3 +- tex/lab-1.tex | 62 ++++++++++++++++++----------------------- tex/lab-2.tex | 14 +++++----- tex/lab-3.tex | 30 +++++++++----------- 4 files changed, 49 insertions(+), 60 deletions(-) diff --git a/tex/header/preamble.tex b/tex/header/preamble.tex index 0215252..d2a9a1c 100644 --- a/tex/header/preamble.tex +++ b/tex/header/preamble.tex @@ -1,7 +1,8 @@ %! TEX program = lualatex \documentclass{scrartcl} -\usepackage[margin=1.5cm, bottom=2.5cm]{geometry} +\usepackage[top=1.5cm, bottom=2.5cm]{geometry} +% \usepackage{geometry} % \RedeclareSectionCommand % das kommt vom KOMA-Skript % [beforeskip=-1.5ex plus -.1ex minus -.1ex, % afterskip=.5ex plus .1ex minus .1ex]{section} diff --git a/tex/lab-1.tex b/tex/lab-1.tex index 246c9cb..1e4c016 100644 --- a/tex/lab-1.tex +++ b/tex/lab-1.tex @@ -12,7 +12,7 @@ Both the tap water with salt and the coffee were in plastic bottles and were circulated through pipes and the membrane module and back into the - respective bottle as you can see + respective bottle as one can see in the experiment setup image \ref{img:fo-setup}. In the module the feed and draw solution moved in opposite direction @@ -54,28 +54,22 @@ % \end{figure} % } -{ - \begin{figure}[ht] - \centering - \tikzinput{lab-diagrams/forward-osmosis.tex} - \caption{Measurements of the forward osmosis experiment. The dashed lines are the - corresponding conductivity measurements. I do not know why the legend - for them is missing. - Mass increase and conductivity of the three forward osmosis experiments. - There were always \SI{500}{\milli\litre} of salt water but the - measured weight also highly depended on the setup of the tubes - that were attached on the bottles. We were only interested - in the change of mass since the beginning of each experiment--the - extracted water. That is what is shown here. - The three experiment runs are shown on top of each other instead - of behind each other because it is easier to compare them this way. - They happened consecutively but this does not matter for the experiment itself.} - \label{dia:forward-osmosis} - \end{figure} - % As expected the mass increased in all three experiments while - % the conductivity in the coffee increased as well. -} - +\begin{figure}[ht] + \centering + \tikzinput{lab-diagrams/forward-osmosis} + \caption{Measurements of the forward osmosis experiment. + The dashed lines are the + corresponding conductivity measurements. + There were always \SI{500}{\milli\litre} of salt water but the + measured weight also highly depended on the setup of the tubes + that were attached on the bottles. We were only interested + in the change of mass since the beginning of each experiment--the + extracted water. That is what is shown here. + The three experiment runs are shown on top of each other instead + of behind each other because it is easier to compare them this way. + They happened consecutively but this does not matter for the experiment itself.} + \label{dia:forward-osmosis} +\end{figure} \paragraph{Osmotic pressure} { The osmotic pressure is calculated by \begin{equation*} @@ -98,7 +92,7 @@ We assume that we have no osmotic pressure from the coffee. } \paragraph{Membrane area} { - To calculate the flux we need the the area of the membrane. We measured + To calculate the flux we need the area of the membrane. We measured \SI{1.323e-3}{\square\metre}. } \paragraph{Water flux and water permeability constant} { @@ -148,9 +142,9 @@ \end{figure} The average changes of conductivity are \begin{align*} - \text{with \SI{7}{\gram\per\litre}: } & \SI{19}{\micro\siemens\per\centi\metre\hour} \\ - \text{with \SI{8}{\gram\per\litre}: } & \SI{21}{\micro\siemens\per\centi\metre\hour} \\ - \text{with \SI{9}{\gram\per\litre}: } & \SI{27}{\micro\siemens\per\centi\metre\hour} + \text{with \SI{7}{\gram\per\litre}: } & \SI{19}{\micro\siemens\per\centi\metre\per\hour} \\ + \text{with \SI{8}{\gram\per\litre}: } & \SI{21}{\micro\siemens\per\centi\metre\per\hour} \\ + \text{with \SI{9}{\gram\per\litre}: } & \SI{27}{\micro\siemens\per\centi\metre\per\hour} \end{align*} } \subsection{Error analysis} { @@ -178,7 +172,7 @@ to speculation though. I noticed that walking towards the scale had the floor vibrate so much - that I had to wait for several seconds until the scale didn't change + that I had to wait for several seconds until the scale did not change significantly anymore. This happened more in the second run and less in the third when I became more careful. } @@ -188,19 +182,17 @@ one would expect based on the calculated osmotic pressure as we can see in the different values for $A$. - After using the experiment setup with clean water - for cleaning the membrane looked perfectly clean, indicating + After running clean water through the experiment setup + for cleaning, the membrane looked perfectly clean, indicating no or little fouling. This is supported by the water flux measurements that did not decrease. This is expected for forward osmosis. The salt flux increased as well with higher salt concentration. - One would expect that $\frac{19}{21} = \frac{7}{8}$ and this + One would expect that $\frac{\SI{19}{\micro\siemens\per\hour\per\centi\metre}}{\SI{21}{\micro\siemens\per\hour\per\centi\metre}} \approx \frac{\SI{7}{\gram\per\litre}}{\SI{8}{\gram\per\litre}}$ and this roughly fits while based on the first two runs one would - expect a conductivity increase of $\SI{24}{\micro\siemens\per\centi\metre\hour}$ - instead of $\SI{27}{\micro\siemens\per\centi\metre\hour}$ but that + expect a conductivity increase of $\SI{24}{\micro\siemens\per\centi\metre\per\hour}$ + instead of $\SI{27}{\micro\siemens\per\centi\metre\per\hour}$ but that is not as far off as the water flux. } -% \appendix -% use \textinput as described in /header and _TEMPLATE \docEnd diff --git a/tex/lab-2.tex b/tex/lab-2.tex index 1f82506..5f474ae 100644 --- a/tex/lab-2.tex +++ b/tex/lab-2.tex @@ -7,7 +7,7 @@ \subsection{Experiment setup} \label{sec:experiment_setup_cross} { In this experiment we want to find the critical flux for - bentonite filtering. + bentonite cross-flow filtering. The membrane is a PVDF microfiltration membrane with a pore size of \SI{0.2}{\micro\metre}.% @@ -15,7 +15,8 @@ \SI{0.2}{\micro\metre}. In my memory and our notes we have a pore size of \SI{2}{\micro\metre}.} Bentonite is a type of clay. - We used \SI{500}{\milli\gram\per\litre}. + We used \SI{500}{\milli\gram\per\litre} in the feed. + The bentonite solution was pumped in a loop from the containing bottle through a pressure pump, then the membrane module and back into the bottle. The other side of the membrane module for @@ -110,14 +111,14 @@ } \subsection{Error analysis} { \label{sec:cf_error_analysis} Reading the pressure meters was never exact since they - fluctuates a lot with every round the pump was doing. + fluctuate a lot with every round the pump was doing. So we looked for some seconds and took the middle between the lowest and the highest value we saw. Those usually differed by about \SI{10}{\kilo\pascal}. That means that only very significant changes in the trans membrane pressure could be noticed and this error is relatively bigger for smaller pressure - absolutely bigger for lower rotation numbers. + and absolutely bigger for lower rotation numbers. We measured every two minutes but since we had to look at the clock (did not have an alarm ringing every two minutes) @@ -149,8 +150,7 @@ As already noted in the previous sections we cannot tell what the critical flux for this membrane is. Since the TMP was a lot higher at 8~rpm we first - assumed, the critical flux must be somewhere between - % todo: check that number again: + assumed that the critical flux must be somewhere between 6~rpm (\SI{267}{\litre\per\square\metre\per\hour}) and 8~rpm (\SI{302}{\litre\per\square\metre\per\hour}). But the increase in TMP over the ten minute periods @@ -164,7 +164,7 @@ while the pressure increases a lot. This might be caused by fouling within the first two minutes of the 8~rpm period or some other reason, - e.\,g.\ that the peristaltic cannot guarantee an high flux. + e.\,g.\ that the peristaltic pump cannot guarantee an high flux. Hence the most efficiant flux is in between \SI{267}{\litre\per\square\metre\per\hour} and \SI{302}{\litre\per\square\metre\per\hour}. diff --git a/tex/lab-3.tex b/tex/lab-3.tex index 21fed61..c473c2b 100644 --- a/tex/lab-3.tex +++ b/tex/lab-3.tex @@ -7,7 +7,7 @@ \subsection{Experiment setup}% \label{sec:experiment_setup} { - This experiment used dead-end filtratiozn with the same + This experiment used dead-end filtration with the same bentonite solution and the same membrane as in experiment \ref{sec:cross-flow}. Due to water extracted in the other experiment, the @@ -36,7 +36,8 @@ \end{figure} The goal is to measure the resistance due to fouling - and evaluate if intermittent operation is helpful. + and evaluate if intermittent operation is helpful to + avoid fouling. For that we first filter clean water for \SI{10}{\minute} with a pump rotation number of 5~rpm to calculate @@ -55,7 +56,7 @@ the intermittent operation. Firstly we test it with \SI{4}{\minute} with 5~rpm of clean water filtering. In the intermittent operation we filter the bentonite - solution for with 4~rpm ten minutes of which every second minute + solution with 4~rpm for ten minutes of which every second minute the pump is turned of. } \subsection{Measurements and Calculations}% @@ -65,9 +66,7 @@ \centering \tikzinput{.maindir/zeichnungen/lab-diagrams/dead-end} \caption{Here we see the TMP and the flux against time - for the three parts of continous operation. Since we - forgot to measure the membrane size, the flux is given - in \si{\litre\per\hour}.}% + for the three parts of continous operation.} \label{dia:dead-end} \end{figure} In all three parts the TMP increases, see diagram @@ -76,8 +75,7 @@ for the bentonite filtering. The increase in TMP is highest in the second filtering with clean water. This starts with a slightly lower - TMP than the bentonite filtering ended with. The - membrane was cleaned in between. + TMP than the bentonite filtering ended with. The permeate flux increased at every part. @@ -119,9 +117,9 @@ If we used the average pressure during the bentonite filtering or the second clean water filtering we - would distorte the calculation since the membrane resistance increases during + would distorte the calculation since the fouling resistance increases during these runs. So we have to take single pressure measurements and assume - that the the pump was able to sustain a constant flux (which is is supposed + that the the pump was able to sustain a constant flux (which it is supposed to do). The bentonite flux and the total fouling resistance: @@ -136,14 +134,13 @@ }{\SI{e-3}{\pascal\second} · \frac{\num{256e-3}}{60}\si{\cubic\metre\per\hour\per\square\metre} } = \SI[per-mode=reciprocal]{9.38e8}{\per\metre} \\ - ⇒ R_f &= \SI[per-mode=reciprocal]{9.38e8}{\per\metre} - R_m = \SI[per-mode=reciprocal]{3.73e8}{\per\metre} \\ + ⇒ R_f &= \SI[per-mode=reciprocal]{9.38e8}{\per\metre} - R_m = \SI[per-mode=reciprocal]{3.73e8}{\per\metre} \end{align*} - % During the membrane cleaning we removed the cake layer and therefore can estimate the remaining fouling resistance with the pressure measurement of the second clean water run: \begin{align*} - J_2 &= \frac{\SI{i59.12}{\milli\litre}}{10\si{\minute} · \SI{1.19e-3}{\square\metre}} + J_2 &= \frac{\SI{59.12}{\milli\litre}}{10\si{\minute} · \SI{1.19e-3}{\square\metre}} = \SI{298}{\litre\per\hour\per\square\metre} \\ R_m + R_f - R_c &= \frac{Δp}{μ J_2} = \frac{\SI{3.6e3}{\pascal} @@ -179,13 +176,11 @@ \tikzinput{lab-diagrams/intermittent} \caption{TMP during intermittent operation. We see that TMP is zero when the pump is turned off. - % So the diagramm is misleading: we have plateaus of almost constant - % TMP and breaks between them. }% \label{dia:intermittent} \end{figure} We see in diagram \ref{dia:intermittent} that the measured - TMP values are constant. + TMP values during the intermittent operation were almost constant. } \subsection{Error analysis} { \label{sec:error_analysis} @@ -198,7 +193,7 @@ We did not always guarantee that but I cannot estimate if this had an significant impact. - In the second clean water filtering we once forgot + In the second clean water filtering we once forgot to set the alarm. So the time is not exact which can (at least partly) explain the higher water flux. } @@ -233,6 +228,7 @@ in TMP. When we compare the TMP of the clean water filtering + before the intermittent operation with the first clean water filtering we see that the membrane indeed is (almost) clean. In the intermittent operation the TMP does not