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White walls inside basin type solar still

November 22, 2019 — BarryK

The first prototype solar water still, simple basin type, was tested recently:

And the inside was coated with black silicone (except for some grey patching, and the photo below also shows some reflected clouds):


What has nagged at me though, is why are the side walls coated black? Because that is the way it is done in all the designs that I have seen so far!

This morning, I typed some appropriate keywords into Google search engine, to see if there are any arguments for a different colour, such as white, or even a reflective surface. Got hits!

OK, it seems that the rationale for painting the side walls black is to prevent condensation on the walls.

However, that also means the walls will absorb heat, and will need to be extremely well insulated. In my prototype, they are not.

I found a couple of research papers, where the authors painted the sides white, down to the water level:

...the second author is claiming an efficiency improvement of 6.8% when the side walls are coated white.

There are a lot of variables in this analysis, but I reckon that I will go for white walls in prototype #2. 

Tags: nomad

Silicone sealants for potable water

November 21, 2019 — BarryK

I have posted before about silicone sealants that are suitable for use in construction of the solar water distiller.

I have previously used Selleys 401, translucent, purchased from Bunnings, AU$19.63 for a 310g tube:

...rather expensive.

Besides, I am now wanting black sealant, and Bunnings only sell the Selleys 401 in translucent. Also, I am now favouring neutral-cure for applications other than glass.

I recently discovered Bostik Industrial Grade silicone, at the Total Tools website, for AU$6.95 per tube -- except that no stores anywhere in Australia actually stock it, and it is a "special order" with high postal charge. Anyway, here is the manufacturer's specs page:

...Bostik is an international company, and in many places, such as the USA, you could probably pick it up from your local hardware store.

The Fuller company, also international, do a "plumbers silicone", rated for potable water use, but not available in black.

About a week ago, I discovered Silastic 732, acetic-cure, available in black and white, and stocked at Autobarn, a car parts and accessories chain store in Australia. This is also rated for use in potable water. Price is AU$18.99 per tube:

...I bought two tubes.

There was something nagging at my memory though, another brand, locally available. Yes, found it: Prosil 10, neutral-cure, available in various colours including black. And cheap, AU$8.95:


Here is the manufacturer's page: 

There was another that I discovered some time ago... German company... forget the name, but they only sell to the trade here in Australia, No retail outlets, not even online ordering. I did phone them, and they gave me the number of a salesman. That's their marketing model, sales reps who go to tradie sites ...not interested. 

Tags: nomad

First coating silicone on aluminium mesh

November 20, 2019 — BarryK

I posted recently about the idea of using an inner liner for the basin-type solar still, constructed with aluminium insect-screen mesh and coated with silicone sealant:

The mesh is not raw aluminium, it has some kind of dark coating, I presume that is an anodized surface. Don't know anything about the properties of that surface, but the silicone seems to stick to it OK.

Now for the next step, to coat a large piece of mesh. The intention is that this will be inserted inside the distiller frame, and will completely isolate the frame from moisture. There will also be some insulation injected between the inner liner and the frame. Still planning on using pine for the frame.

Want one large coated surface, which will be folded afterward, so a minimum of cutting -- basically, the only cuts will be for inlet and outlet holes, and to trim the edges where the liner is sandwiched under the glass -- anyway, those details will be clarified as the project progresses.

Here is a photo of the mesh stretched out on a table:


...the g-clamp has two purposes, to prevent the mesh from folding up when I lift it off the table, and to hang it up on a hook. The other end has a length of small-section wood attached with wire.

Underneath the mesh is plastic sheet. That plastic just arrived in my backyard one day, a year or so ago. Thought it might be useful, so put it in the garage -- so, finally it has a use!

Wanted an area about 950x750mm. Used cheap Parfix kitchen-and-bathroom acetic-cure silicone sealant from Bunnings -- this has anti-mold additive, which I don't want, but it shouldn't matter in the final product, as it will be coated inside with black Silastic 732 sealant.

The end result was hung up:


...the white spots and streaks are holes. I have learned from experience not to try and patch the holes. Instead, let it set and tomorrow will give a second coat. Note, that large white area at the bottom is direct sunlight. One more detail: I wiped the plastic with a cloth, to remove silicone bumps, as the plastic will be used again tomorrow.  

Tags: nomad

First go using SolveSpace

November 20, 2019 — BarryK

I posted about SolveSpace:

After working through a couple of tutorials, had a bit of a go at drawing a basin-type distiller. Hmmm, got to the point where some things became difficult. This is as far as I got, exported as PNG:


I could plough ahead, however, there really isn't much point. I can create reasonable drawings with pen and paper, no need for the fancy 3D visualising. Even a 2D CAD program would be OK, to publish drawings that are more tidy than my hand-drawn sketches. 

Tags: easy

Using SolveSpace v2.3 in Pyro

November 19, 2019 — BarryK

Yesterday I posted about including SolveSpace v2.3 in the next build of Easy Buster, and v3.0alpha (latest from github) in Easy Pyro:

The latest source looks good, more features, however, last night I was working through this tutorial, running Easy Pyro:

Those tutorials are excellent, but they are written for v2.3 and I discovered slight UI differences -- only slight, not a show-stopper. Zoom in-out does not work in v3.0alpha (but later I found that it doesn't work in v2.3 either).

What did stop me was when I tried to open my creation in v2.3, that had been created in v3.0alpha -- which hung the application.

I can live with less features, for now want the compatibility, to be able to open and edit drawings created in either Easy Pyro or Buster. And then there's the tutorials being written for v2.3.

Oh, yes, v2.3 uses gtkmm v2, which is already in Easy Pyro. gtkmm v3 is a very big package. So including v2.3 in the next release of Pyro will hardly add anything to the download size.

Compile notes for v2.3 in Pyro 1.2.8:

requires json-c, gtkmm v2, unifont

# patch -p1 < ../debian/patches/01_RemoveGitHash.patch
# patch -p1 < ../debian/patches/20_use_system_unifont.patch
# patch -p1 < ../debian/patches/30_fix_ftbfs_glibc.patch

# mkdir build
# cd build
# make
# new2dir make install

The PET has been uploaded, as well as a 'unifont' PET, so in the "petget" package manager, update the package database. If you already installed v3.0-alpha, uninstall it first.

Got to say, liking SolveSpace! 

Oh bother! v2.3 is hanging in Easy Pyro. Have to use the v3.0alpha. Both are in the package manager. If you have already installed v2.3, uninstall it, and instead install package 'solvespace3'.

Tags: easy

SolveSpace parametric 3D CAD in EasyOS

November 18, 2019 — BarryK

SolveSpace is another CAD application. See links to QCAD and FreeCAD here:

Example construction in SolveSpace;


SolveSpace has various points in it's favour: looks easy to use (from a very superficial first-look), reasonably powerful, and small size. It uses the gtkmm library, and is in the Debian DEB repository.

The version in the Debian repository is a bit old, version 2.3, released in 2016, and uses gtkmm v2, which is already in the Easy Buster build. So great, I have added it to the package list and it will be in the next release of Easy Buster.

Note, if you are running Easy Buster and want to try it now, via "petget", there is also another package 'libslvs1' -- install that too. It is actually part of SolveSpace, looks like it is optional, and I don't know what it brings to the table, but might as well install it in case it is something useful.

For easy Pyro, I have compiled it from source, and got the latest out of github:

A downside of this latest source is that it requires gtkmm v3. However, as this project is very active, with lots of commits since 2016, I decided to compile the latest source. Compile notes:

needs json-c
# cd json-c-0.13.1-20180305
# ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --build=x86_64-pc-linux-gnu
# make
# new2dir make install

needs gtkmm-3.0>=3.18
gtkmm 3.22.3
# ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --build=x86_64-pc-linux-gnu --enable-static --enable-shared --disable-documentation --enable-x11-backend=yes --enable-wayland-backend=no
# make
# new2dir make install

# git clone --depth 1
# cd solvespace
# git submodule update --init extlib/libdxfrw extlib/flatbuffers extlib/q3d
# cd ..
# mv solvespace solvespace-20190920
# dir2tgz solvespace-20190920
# cd solvespace-20190920
# mkdir build
# cd build
# make
# new2dir make install

I have uploaded the PET packages, so via "petget" on the desktop, if you update the PET database, you can install SolveSpace -- or, wait until the next release of Easy Pyro -- yep, might as well be consistent with Buster. 

The thing for me to do now is learn how to use it, find out if it is suitable for my solar water still designing.

Here is the project home page:

On YouTube, there are tutorials, uploaded by Eric Buijs:

Found this, looks great: 

Tags: easy

QCAD 2D CAD application compiled

November 18, 2019 — BarryK

I posted earlier about FreeCAD provided as an SFS:

I have been exploring other CAD applications. QCAD has been around for a long time, and is very easy to use. It is only 2D, though does have isometric views. There is a paid-for version, also a free open-source GPL version.

I compiled the open-source version in Easy Pyro 1.2.8. Note, QCAD is not available in the Debian repositories, however the SFS that I have created will work in both Pyro and Buster.

It requires 'qtscript', so I had to compile that:

Downloaded from here:

# export OE_QMAKE_AR=ar
# qmake PREFIX='/usr' LIBDIR='/usr/lib' PKG_CONFIG='/usr/bin/pkg-config'
# make
# make install

...had to manually create the PETs.

Downloaded QCAD source from here:

# export OE_QMAKE_AR=ar
# qmake -r PREFIX='/usr' LIBDIR='/usr/lib' PKG_CONFIG='/usr/bin/pkg-config'

...errors, but go ahead anyway...

# make release
# cd release
# LD_LIBRARY_PATH=. ./qcad-bin

Created a PET and a SFS. The SFS has been uploaded, and you can get it by clicking on "sfsget" on the desktop. It will work in both Pyro and Buster, in the latter case in a container only.

Here is the QCAD home page:

If you go to YouTube, there are tutorials. 

Tags: easy

FreeCAD SFS created for EasyOS

November 17, 2019 — BarryK

I have been making very rough sketches of the solar water distiller prototypes, and have even published some of them to this blog. Planning for basin-type prototype #2, thought might have a go at better quality drawings.

Running Easy Buster 2.1.8, I installed FreeCAD from the Debian DEB repository, via the "petget" icon on the desktop. This has a massive number of dependencies. After installation, ran it, and it did start, but with an error message:

No module named StartGui

A google revealed this to be a known problem in Debian, that was fixed by running:

# update-alternatives --all

Now it works, well, starts anyway, and beyond that I haven't got a clue. However, there are lots of tutorials, including YouTube videos.

I made it into a SFS, a massive 239MB, and tested that it works in Easy Pyro 1.2.8 in a container.

If anyone reading this knows how to use FreeCAD, you are welcome to test it, and let me known if there are any issues. You just need to click "sfsget" on the desktop, and can download and install to either Buster or Pyro -- in the latter case, as a container only. 

Here is the FreeCAD home page: 

Tags: easy