Can you hear that?? Far away… behind the horst… a dreadful but familiar sound can be heard faintly. It seems like Mariah Carey has defrosted once again, and All I Want for Christmas Is You echoes in the Kiwanda like it’s almost the 25th of December again. Saint nick might be long gone, but on the 10th of January the WOT is high on Christmas. Quite on time if I may say, my student house had its Christmas diner on the 25th of June last year. Which is literally the furthest date from Christmas.

Coincidentally, just a catapult shot away, Newton also had its Christmas dinner on the 10th. When I noticed this, I feared that some of WOT’s Mechanical engineers might be kidnapped and forced to go there instead. But luckily that was not case (with some exceptions). Even though I was sceptical about this date, our board assured us that the 10th was the right date because they ‘felt it’. Now, I have to admit (and I don’t do this often), were they right. We had a whopping 39(!!) WOTters show up for this fantastic candle lit dinner.

Preparation for the diner began two days beforehand with taking inventory, choosing recipes and of course the groceries. Then Friday morning the cooking began. I wasn’t there myself, but I can say with certainty that they cooked.
The appetizers (made possible by Norah and Erik) were savoury cupcakes with cheese, sun-dried-tomato and olive. Now whenever I hear ‘savoury’ and then something that’s not supposed to be savoury, like cupcakes, red flags go off in my head. I can confidently say that since I had these cupcakes those red flags have burned away. These cupcakes were a true delight, and I have plans to make them myself.

From here my light dimmed a bit, I may have had one to many glasses, or rather, bottles of wine. What I do remember very sharply are the next few dishes, and how great it all tased. The carrot-tomato soup, the Hachee with potatoes and red beet, and of course the apple crumble cake. Sometimes when I eat too much, I wonder whether all the food would be worth the extra weight. This is not one of those times. Hats off to Norah, Erik and Robin! The dishes they prepared were expertly made. Also, by pure coincidence, this was also the third homemade apple crumble cake I had in two weeks. Ranking these three is difficult since I made the other two myself, so I will have to call it a three-way pie.

Oh and we can’t forget the candles! As per WOT tradition, the candle holders are beuned just before the diner. Now all candle holders are special in their own way, but some were more special than others. Out of all of the candle holders, there are a lot of contenders for the nr 1 spot. But my personal favourite would have to be Nathan’s. Not because it was an original design, or because it had functionality, no in truth it’s a candle holder only it’s mother could love. That made burning the candle holder (which was just a block of wood with a hole in it), so much fun and memorable. Nathans attempts to save its pathetic creation just added fuel to the fire. And that’s why its nr 1… also because I forgot all the others.

All in all, it was a great Christmas diner. There was a lot of great food, deep conversations, flaming candle holders, and, of course, gezelligheid. Christmas is about sharing Joy with others. Whether you believe Joy goes through the stomach, or Joy is laughing with (or at) other people, or if you are an addict and think Joy is alcohol, there certainly was a lot of Joy. Here’s to next Christmas diner! As my great friend, and WOTter abroad Santiago would say, Happy Christmas, Happy New Year and Happy birthday!

Hand drilling a well by hand is affordable, quick, and uses local resources. But in many areas, it’s not possible due to low water yield. A new method developed by Wolfgang Buchner addresses this issue, allowing hand-drilled wells to be installed in more locations.
Hand-drilled wells are usually small in diameter, which creates problems in soils that don’t allow water to flow easily, like clay or mica-rich soils. The small diameter limits the surface area through which water can enter, and the well’s filter screen often clogs with fine particles, leading to slow refilling; the well is pumped dry quickly.

In these soils, hand-dug wells have traditionally been used, as their larger diameter provides better flow. However, digging is a lot slower and dangerous work. Buchner’s method solves these issues and makes manual drilling feasible, even in challenging soils.
Here’s how it works: After drilling, a temporary casing—a pipe with large side slots and an open bottom—is installed. Water is pumped out, flushing fine particles that would otherwise clog the filter. Once the water runs clear, a permanent, slightly smaller casing with a filter is installed inside the temporary one. The temporary casing is then removed for reuse.

This approach cleans the surrounding soil of small particles and effectively increases the well’s diameter, combining the benefits of a small-diameter well with the water yield of a larger one. Best of both worlds!
To learn more about the method, have a look at the video:

We all know WOTters are the sportiest people in the world, but sometimes they need some extra exercise. This was achieved by fitting an old motor from a kid’s toy on an old rowing machine out of gym, connect to some batteries and we have renewable energy!

Because the motor from the kid’s toy is a three phase permanent magnet motor, it generates a 3 phase Alternating Current (AC) when rotated. This is very useful for high power motors such as in trains or big milling equipment, but not so much for small scale off-gird power. This is why the generator is connected to a ‘full bridge rectifier’, this takes the three phase AC input and converts it to Direct Current (DC). Cheers for AC/DC! The output DC of the rectifier is then connected to a lead-acid battery (also DC) and voilla; we can put muscle power into a battery!

Small off-grid systems often save solar energy in a battery and later convert that to 230 V AC. This can be done here too! So during the day one could use a solar panel and at night human power.

In the pictures above, the generator can be seen on the left. It is connected with gears and chain from a bike. This increases the rotational speed of the generator. Because the generated voltage is proportional to rotational speed, we can now generator higher voltages. On the right picture you can see two batteries in series (24 V). With higher voltages we can handle more power. With this setup, you could easily start a full sized diesel lorry (50 ton) if you row for a while!

Of course not everyone has an off-grid setup or a lorry with empty batteries. The energy in the battery can also be injected into the grid. Below is a picture of the generated power on the screen (every peak is someone pulling on the rower). To the left is a small solar converter that can inject DC into the national grid. This way we are powering an infinitesimal bit of the world!

This November we had our 4^th workingweekend of the year. And although it was cold and wintery outside ❄❄❄we were still kept warm by the all the work we put in projects. We prepaired the terrain for winter, fixed the PTB and the Diever and gave the Oasis a touch up.

Because of the upcoming winter the terrain needed to be prepaired. This meant that all the pipes needed to be cleared of water such that they do not break. WARNING PHYSICS SECTION: The reason this needed to be done is because of the very unique property of water that it expands if it freezes, you will not see this in almost all of the other substances. But why does water does this? When water (H2O) freezes it forms a hexagonal latice because of its distinct shape. This hexagonal latice takes up a lot of space, even more than the same amount of individual H2O molecules would. Conclusion: We need to close all the outside taps on the terrain every winter.

 
The Pump Testing Bench (a.k.a. PTB) has not been testing pumps for almost a year. Which of course is not what it is meant to do. Last summer the new tubes where ordered, but because of a mixup they did not have the right coating that would protect them against rust. So after a few weeks and multilple layers of paint they were finally ready to be put back in the PTB tower last weekend. They were also threaded and cut such that they have enough ground clearance such that a pump can be put under them.  Besides this, the motor that powers the PTB was stuk because of rust, but with a plumber’s wrench and a handy placement of a welding glove it was made unstuck again. In order to keep the PTB from being stuck we need to run the motor a few minutes every so often and we also started to design a cover that would protect it from rain.

At the start of the working weekend we noticed that the Diever was turning rather fast. Apparently the breaking pin broke, which (as its name says) is its purpose. But why do we inculde something a part with the purpose to break? You might ask. This is because we do not want the whole windmill to break itself in, for example; a storm. The breaking pin is meant to break the first in the system and is made to be easily replaced. This is why this job was easily done during the working weekend.

Our work on the Oasis began on Sunday with a relatively straightforward initial goal: to install a new pump. The first challenge was removing the T-shaped pipe connected to the windmill—a task we ultimately succeeded in with the help of a flamethrower. Once that was done, we moved on to installing the pump. This required fabricating a pipe to position the pump at the correct height within the water. However, we ran into a problem: we didn’t have the right thread maker available. As a result, the installation had to be postponed until some next Wednesday. In the meantime, we shifted focus to cleaning the windmill’s well in preparation for winter and to prevent the new pump from getting clogged. During the cleaning process, we discovered a family of frogs 🐸 living there. They were safely escorted to a new habitat.

As part of the cleaning effort, we decided to remove overgrown grass that was spilling into the well. While doing so, we uncovered gravel and brick edging around the Oasis base that had been hidden under a thick layer of grass. This led to a new goal: restoring the base of the windmill to its former glory. We carefully removed the gravel and bricks, cleaned them, and repositioned them. To enhance the restoration, we added bricks to the far side where they were missing and topped the base with fresh gravel. You can see the before and after in the images below.

On wednesday 9th of october Wissam Muases came to the Kiwanda to share about his field work in the refugee camps in Bangladesh. He told us about three projects that emerged from the problems in the Rohingya camps in Bangladesh.

He begon his presentation with explaining the sitiuation of these camps that emereged in late 2017. They are located in the south east of Bangladesh and have developed in an uninhabited area. He showed how the enviroment completely changed in just a couple of years. They are also located in the only hilly area of Bangladesh, which the established NGO’s do not have experience with.

One of the problems that are caused by the sudden emergence of the camps and the lack of knowledge of the enviroment are the flawed structures. They use a lot of bamboo to build houses that sometimes go up to 15 meters. They are also used to build retaining walls. But because the bare bamboo is exposed to the ground and open air it rots easily so a lot of buildings have to be replaced within a year. This conditions prevent the inhabitants to develop farms or other utilities.

Wissam came up with a solution to use plastic bottles to wrap around the bamboo poles. He designed an oven that shrink the bottles on the poles. It uses propane gas that is burned with an excess of oxygen to have a clean combustion. Bamboo that is treated with this process already show better resilience to the elements. They are predicted to live from 5 upto 10 years, which would be a huge improvement in sustainabillity compared to the current conditions in the camps.

Another problem Wissam encountered was the solid waste management. The current system uses concrete bins where the inhabitants deposit their trash, but these are hard to clear out and usually overflow. People use watersystems to dispose of their trash that includes both bio degradable items and plastics. To solve the problem with the overflowing waste bins Wissam designed nets that are light weight and can be easily removed and transported. This just leaves the problem of sorting the trash.

Wissam is currently looking into the waste processing plants and how to make them more efficient and more sustainable. Because of his background in art he also wants to upcycle plastic trash. He designed and is still prototyping a machine that can produce solid plastic sheets.

Wissam also has blogs where he writes about the progress of his projects and also collects lots of pictures taken by people from the refugee camps. It contains way more information about the topics that was discussed in the presentation. We also used these blogs as sources for this blogpost:

In the past the Breurram has been built and tested by the WOT. It is a type of hydraulic ram pump, made out of standard components using an airbuble in a piece of flexible tube as expansion ‘tank’.
More about the mechanism behind the Breurram can be found in this youtube video.

Several times the WOT has been asked: What would happen if you scale up the Breurram?
Our earlier demonstration and test set-up uses 1” valves. Following yet another advice request and subsequent visit at the WOT, we decided to test a larger version of our beloved ram pump.
The diameter of the Breurram can, according to the manual, not be larger than it’s supply line.
Because the supply of water from our ferrocement tank/cistern to our testing rig ends in a 2” pipe, a 2” Breurram has been constructed. Only the valves have been purchased, as other materials were present. The cost for these came down to about €95.

Upon first testing it became apparent that the system wouldn’t work reliably without the optional tensioning spring. Next to this problems were found with starting the pump. Therefore a bracket has been placed on the spill valve connected to a bolt sticking out of the pump, allowing the valve to be moved manually at start up. Depending on the setting of the tensioning spring and the pump head the system was able to work without human intervention. The frequency of the pump cycle was far less constant compared to our other, smaller, Breurram. What this is a result of remains a question at this point, but suggested are lower flow speeds and/or quality of components.
Tests are done using a supply head of 184 cm (approximately) and pump heads of 397, 582, 767 and 952 cm. Using a return line and a petrol pump pumping back used water to the supply tank, the supply head was held as constant as possible. So far one test has been completed at a constant setting of the tensioning spring. The yields at different pump heads and several curve fits can be seen in the following figures, as well as some pictures /visualizations of the test/setup.

The plot displays the data points along with an automatic second-order curve fit using the least squares method. It is expected that the flow should approach zero at a pump head approximately ten times the supply head. However, the second-order curve fit does not exhibit this behavior, even when considering the mean and standard deviation. To address this issue, a new curve fit was developed by defining a trial function and making several coefficient guesses

So far, in order to draw more accurate conclusions several more tests will be conducted, of which the results can be expected in the near future. This will also include a (rough) comparison with the yields of our other, smaller, Breurram. You can read more about hydraulic rams here.

Now that the winter has subsided, we decided it was time to turn on our solar shower again. A system that you can read more about here.
The system was turned on during the April working weekend, and two WOTters actually enjoyed a (still very cold) shower, a very welcome surprise after all the mud that was picked up at the other activities 🙃.

At an association night (Wednesday the 10^th of April) we noticed two problems with the system.
-The water temperature was rising unexpectedly fast on Saturday and Sunday (for the sun intensity those days) and dropping too fast at nights.
-The pump failed to switch on on Monday and Tuesday. The system thinks it switched on the pump but the return-line temperature was not following the collector temperature. Which also meant the tank-temperature was not increasing on those days.So that Wednesday we checked the water level of the tank and sure enough the tank was almost empty, during dinner we let the tank fill up. And we used the bottom flush of the tank to try to flush some rust out of the system, which might have been blocking the pump.

We were hoping this would work, but during the following days, we noticed that the pump still was not switching on correctly. On some days it was (like Saturday the 12^th of April), but on other days it was not. We can however see that the tank now heats up and cools down slower than it did when it was not completely filled.

Here you can find a graph displaying the data that is measured live from the solar shower system. This graph shows the temperatures of various sensors and the time the pump was on for every 10 minutes.
-The pink line shows how long the pump was on, the pump cycles on automatically when the collector temperature is higher than the tank temperature.
-The dark-blue line shows the temperature of the collectors, it quickly rises if the sun is shining.
-The red line shows the temperature of the water flowing out of the collectors and into the tank.
(This means it follows the collector temperature while the pump is on but the temperature quickly drops towards ambient once the pump has shut off)
-The light-blue and yellow line show the actual water temperatures in the isolated storage vat this is the water that is used to heat the shower water through a heat exchanger.

On Monday the 14^th of April we flushed more rust out of the pump, this time by actually manually disconnecting the pump and running it with some clean water. This did not seem to work, because on the 18^th the pump was jammed. On the 23^th a small hole was found in a pipe and had been welded shut, this explains why the tank was as good as empty during the working weekend. The pump was replaced with another one on the 24^th and this seemed to have helped, because the pump has been functioning every day up to the day of writing (the 3^th of May). Since the 29^th of May the days kept getting warmer and on the 1^th of May the tank was at a temperature of 45°C and someone had a nice and warm shower 😊.