Built-up of a SoWaDi Plant

Over the weekend (06/15 – 06/17 2018) it was time again for the members of SoWaDi to meet for further tests regarding the renewed construction of the plant. In order to accomplish this, our team built up the whole device within two days. The main focus was on bending the aluminium sheets, copper pipe and the glass front of the absorber. In all three cases, extensive changes in implementation and quality have been made in recently which were finally audited for their efficacy.

The SoWaDi team after finishing the assembly of the plant
The copper pipe is being connected to the metal sheets

For the bending of the sheets, the new and oversimplified deep-drawing device was used. This allowed the sheets to be processed faster and much quieter (without hammering).

Also, the newly introduced sand filled copper pipe was used in during the construction to prevent constrictions during bending. The first hurdle was to completely fill the 10-meter pipe with sand and, if possible, without entrapping air inside, unfolding the coil and putting too much strain on the material itself. This was achieved by using a ladder and gently shaking the entire tube. All the effort proved to be worthwhile as the pipe remained completely intact without any constrictions by the time of its implementation. The removal of the sand could also be solved elegantly by rotating the construct like a stirring wheel after connecting the tube to the aluminium sheers.


Installation of the glass cover

The innovation of the glass front was to divide the bottom of the glass panes horizontally into several sections. This approach is intended to better distribute the thermal load and to mitigate the risk of the glass cracking via thermal expansion.

In the coming weeks, the system will be tested for its performance. In order to accomplish this the temperature of the water output and the solar radiation will be measured.

Preparations for the rebuilding

At the regional group weekend from May 25th-27th the motivated participants met once again in Mossautal at Haus St. Michael. The SoWaDi team used the time mainly to prepare for the upcoming construction of a SoWaDi plant in June. In order to have a successful reconstruction on June 15th-17th, a schedule was drawn up, which states which team will take over which tasks over the weekend and which tasks have to be completed in advance. Additionally, the last changes were made to the instruction manual and their corresponding actions were optimized accordingly. After the individual team work, the group found themselves back together to clarify what they should expect to accomplish. Besides the intensive work with one another, there was still enough time to share the results with the entire regional group.

A part of the team planning the construction of the plant

New tools for the installation

Bending the sheet with the new deep-drawing device

On January 13th, members from SoWaDi met at the University’s campus to test some changes they have been considering for the past few months. In hopes of supporting the system’s new development, the focus of the day’s assessment was fixed on two important prototypes: the pipe-bender and the deep-drawing device. Additionally, the surface of the plexiglass was evaluated.

Before Christmas break, small groups from SoWaDi had formed to consider what changes could be implemented to improve the efficacy of the system. An initial test in Tanzania the previous year had revealed that bending the pipe and processing the sheets needed for the system’s construction were not consistently precise. To bend the pipe, the group had already filled a copper pipe with sand during the Regional-Group-Weekend. This approach gave favorable results with a short pipe, and was further investigated on whether this principle could be transferred to a pipe of eleven meters in length. After the pipe was filled laboriously-intensive with dried sand, a newly built pipe-bender was used to evenly shape the pipe into the best possible form without any constriction. Despite the group’s success with the sand-filled pipe, they soon had learned that it was much more difficult to get the sand out. Therefore, the group is still considering the efficacy of this approach and is keeping other options in mind.

However, for the deep-drawing device, a completely new approach was taken: the sheet was clamped down with a few screw clamps and then bent manually around a metal tube with the aid of a lever. In order to compare results, the small group conducted another test with the previous deep-drawing device.

A third small group investigated whether Plexiglas could be used instead of glass panes to cover the absorber box. The team tested the scratch- and heat resistance of the new material.

It still remains unclear to which extent these new concepts will be used in the future when the team returns to construct the system next year in Tanzania.

Testing the pipe bending device

The copper pipe is filled with sand to avoid putting a too heavy load on the material while bending it.

On November 3rd, the SoWaDi team and the rest of the Darmstadt regional group of Engineers without Borders traveled to the St. Michael Guest House located in Mossautal, a small village situated in the Odenwald.

Regional Group Weekend – Along with the opportunity to play games and having fun getting to know one another better, the team also had the chance to work more intensively on their project. In addition to the long-term planning of SoWaDi’s development goals, the main focus of the weekend  was to improve the effectiveness of the pipe bending device: Lying at the heart of the current project phase, a few minor construction vulnerabilities of the plant that were discovered from the last visit to Tanzania in January are being evaluated. It is of particular interest that all of the new implementations will be easily understood by those constructing the plant in Tanzania who lack the context of the new design process. Improving the pipe bending device will aid in efficiently bending the copper tube situated underneath the absorber in which the disinfected water will travel through. In Tanzania, it was also discovered that a slightly thinner copper pipe contributed to kinking of the tube which reduced flow and output of the plant. To mitigate this problem, several solutions have been developed and were tested during the Regional Group Weekend which was not only fun for all the team members but also proved to be successful in moving them closer to their goals.

The bended pipe is checked for constrictions.

Now, all that is left is to evaluate is to see whether these solutions are practical to apply for the full length of the pipe. Results of this development are planned to be announced later this January when whole sections of the plant that integrate these new features will be reconstructed. This outcome was a result of the long-term planning discussed during the Regional Group Weekend. Until April, the focus will be on repairing all of the system’s vulnerabilities in which, till then, will conclude the current phase of the project. Afterwards, the departure to test these implications abroad for the beginning of 2019 will be planned.