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Test sealant bonding to silicone tube

July 04, 2019 — BarryK

I have already reported that silicone sealant adheres extremely well to itself, that is, earlier-applied and cured sealant of the same type. I tested Parfix "roof and gutter" neutral-cure, and Selleys 401 acetic-cure.

I wanted to confirm that the sealant adheres just as well to silicone sheet, strips and tubing. I cut off a small piece of silicone tubing that was purchased off eBay, and applied both of these sealants:


Waited a couple of days, then tried to get it off. No, firmly stuck on. The bond is so good, there is no way to peal the sealant off, when apply excessive force actually tears the sealant. Both sealants have bonded this good. 

Tags: nomad

Third test of solar distiller prototype-2

July 02, 2019 — BarryK

I reported on the second test here:

For comparison, here is a test of the "gold standard", a Carocell 1000:

Today, Tuesday 2nd July, 2019, Perth, Western Australia, mostly sunny, more rain coming later in the week, so decided to do another test. For this test, have stuck two layers of cardboard on the bottom of the panel to reduce heat loss.

Got going at 9.25am. Mostly blue sky, a few wispy clouds, ambient temperature 12 degC, sun intensity 760 W/m2. It seems to be slow to "get going" and producing any output, and there was mistiness on the inside of the glass (internal moisture from the previous test), and I wonder if that was a factor?

10.30am. Ambient 16 degC, sun 820 W/m2, front temp 40 degC, back 25 degC. Still hardly any water out. Sky still mostly clear.

12.40pm. Sun 925 W/m2, front 57 degC, back 32 degC. A lot more clouds in sky, maybe up to 1/3 of sky, moving, so sometimes sun goes behind one.

2.07pm. Ambient 20 degC, sun 810 W/m2, front 47 degC, back 33 degC.

3.00pm. Stopped. Distilled water collected: 0.75 litres

OK, the test of the Carocell panel did have continuous sun, no clouds, so had that advantage. However, allowing for the different sizes, if my distiller had been of the same efficiency, I would have expected about 1.5 litres for today's test.

But, got half that. So, not happy with the design. My distiller is probably comparable with other DIY efforts out there, but I want to do much better. What I would really like to achieve is about 2 litres per day, mid-summer, as that is a minimum in a survival situation, for one person.

It does seem that the two-pane design of the Carocell is the way to go. I didn't do this before, as there are construction difficulties, and I went for the simpler construction. Now going to rethink the design. Will probably remove the prototype #2 DIY plans. 

Tags: nomad

Testing Pope 4 litre-per-hour dripper

June 29, 2019 — BarryK

I reported on testing of the Pope 2 litre/hour dripper, with various water heads:

The problem with that test is that the results are not accurate. The water head measurements are not right.

When I first setup the 2 l/h test, I assumed that when the tap is turned on, water would flow down and fill the pipe. Not so, it flowed down slowly and partially filled the pipe. Then I naively assumed the water head would still be accurate as the measurement from top-level in the holding tank, down to the dripper. Later on, I realised that is not so. The pipe has to be entirely filled with water.

So why didn't it fill? It seems that water flowed into the pipe, until the air pressure in the pipe equalled that at the tank tap outlet, and surface tension prevented air bubbles from getting out of the pipe. Perhaps this can be blamed on a fairly small opening inside the tap, for water to flow through.

Anyway, to test the 4 l/h dripper, I made sure that there was no air in the pipe. The setup is as per this earlier photo:


Except, now using the Pope 4 l/h dripper constructed with 13mm spurs on each end:


Making sure that the pipe was completely full for each measurement, now confident that the results are reasonably accurate:


This is very good. I am wanting about 1 litre/hour, so the "4 l/h" dripper is pretty much spot-on. I will be able to adjust flow by raising or lowering the water container. Though, I am hoping to find the "just right" height and construct that permanently, perhaps as part of the frame that holds the distiller. 

Tags: nomad

Inline dripper

June 29, 2019 — BarryK

I posted about the possibility of having a dripper external to the solar water distiller:

I was able to construct such a dripper, using irrigation parts from Bunnings. Note, for readers outside Australia, Bunnings is a nationwide hardware store, by far the biggest chain, in fact, is just about a monopoly. The only competitor in Western Australia is Mitre 10, a chain of individually-own stores.

Dripper, 4 litres/hour, openable
Reducing joiner, 19mm-13mm
Glue for plastic

I used a hacksaw to cut the 19mm barbs off the reducing-joiners, and the 4mm barb off the dripper. Then used a flat file to make the surfaces smooth.

I bought the Selleys glue, though don't how know how it will stand up to water immersion. The Loctite glue does state "water resistant", whatever that means. Here is the assembled "inline dripper":


The dripper has a screw thread, so can be opened for cleaning. Inside, there is a separate piece:


It works by interference principle, as the water swirls around the channel. The water enters at the center, travels clockwise to the end of the channel, and there is a hole through to the other side. The hole is not visible in the photo. On the other side, there is the same type of channel, the water flows around, then exits from the centre.

I bought the 4 litre/hour dripper, as that was the fastest-flow dripper that was sold separately, and also openable. If higher flow rate is required, a bit of surgery can be performed on the channels.

Note, there is also a 8 l/h dripper, available as a pack of 10, and they cannot be opened. They could be cut open, if desired, to extract the internal piece. 

If I use this external dripper, the internal water dispensing inside the distiller will need to be redesigned. But that is another story -- haven't yet figured out how to do that. 

Tags: nomad

Testing Pope 2 litre-per-hour dripper

June 26, 2019 — BarryK

I am conducting some experiments to find out how to obtain better control of the dripper rate for my solar water distiller. Prototype #2 has three 1mm holes drilled in an aluminium pipe, which does not give much control.

I posted about testing of the Carocell 1000, which has custom drippers:

The documentation for the Carocell 1000 states a nominal input flow rate of 2 litres/hour is required. There are five drippers, so each will be outputing 0.4 litres/hour.

As my prototype has just under half the surface area, I expect to need an input flow rate of around 1 litre/hour.

Drippers used in garden irrigation have higher rates. Bunnings sell drippers rated at 2, 4 and 8 litres/hour.

But today I thought, I wonder how those Bunnings drippers would perform at lower water pressures? So, I bought a pack of these 2 l/h drippers (they are not sold singly):

Bunnings also sell Pope 2 l/h "precision drippers", designed for constant output with different water pressures, which I did not buy.

A very simple test setup, for differing heads of water, a dripper attached to the bottom of the pipe:


Only took three readings, at heads of 260, 590 and 1300mm:


Very interesting. Goes to show, must not just assume that because it is advertised as "2 l/h", that's what we will get. At low pressure, the flow drops right down.

I am rethinking the design. It will not be good to have the drippers inside the distiller, as many plastics become soft at around 60degC. Instead, thinking now will have just one dripper, outside the distiller. In that case, want one that will give about 1 l/h, so tomorrow plan to test the Pope 4 l/h and maybe 8 l/h drippers. I would like it to work with fairly low water head. 

Tags: nomad

Silicone sponge strip for solar distiller

June 20, 2019 — BarryK

For the solar water distiller prototype #2, I used EPDM sponge rubber strip, 3x10mm, as the gasket between the glass and wood frame. EPDM rubber is one of the better rubbers, but still not classified as "food safe".

Gradually working toward building #3, and for that have located a supplier of silicone sponge strips:

I ordered 5x15mm, 5m length, total cost including postage and GST to Australia was AU$30.47

For the record, here is another supplier:

Prototype #3 will probably not be built for a considerable time, as need to do more testing of #2, plus solve some issues, such as getting lower water drip rates. As mentioned in a post yesterday, I need to get the drippers down to about 0.4 - 0.7 litres/hour. Standard drippers from a hardware store only go down to 2 litres/hour. Carocell achieves this low rate by a custom designed dripper, and a water head of about 48cm.  Cuurently, have three 1mm diameter holes in aluminium pipe, but this does not give much control of dripping rate. 

Tags: nomad

Testing F-Cubed Carocell 1000 solar distiller

June 19, 2019 — BarryK

I posted about the F-Cubed Carocell 1000 solar water distiller, that was given to me about 5 years ago:

It has been in the shed all that time, and only recently I got it out and  put it together. Today is the first test. Yesterday, I tested my home-made prototype #2 solar water distiller:

I was expecting it to be overcast today, however, the rain has been delayed, and it is bright sunshine all day, just a few wispy clouds that came and went. So, an opportunity for more testing. Would like to test the two panels alongside each other, however, want to do some modifications to my prototype first. So, tested the Carocell on its own.

I set it up at 9.15am, Wednesday 19th June 2019, and allowed the water to disperse through the cloth until 9.25am when I connected the outlet bottle. As you can see strong sunshine:


At 9.25am, ambient was 11degC, front of the panel (about two inches above, measured with IR thermometer) was 34degC, back was 21degC. Blue sky, a few wispy clouds here and there.

At 10.30am ambient was 15degC, front 53degC, back 40degC. More wispy cloud in the sky, not in front of the sun though.

At 12.10pm, ambient 17degC, front 56degC, back 43degC. No cloud to be seen anywhere. measured irradiance: 870W/m2.

At 2.50pm, stopped the test, as shade from the patio had reached the panel.

Total collected distilled water: 3.10 litres.

The surface area of the cloth is 1.02m2. My prototype #2 is 0.466m2, so less than half. So, will need to take that into account when comparing. Much sunnier today than yesterday, but even so, my prototype has got some catching-up to do.

One thing that I want to improve is the water-dripping from the top pipe. The Carocell has a very nice design:

img2 seems, that purple/pink pipe has holes in it, with some kind of black plastic thing sitting on top of each hole. There is a water-head of about 48cm, and water bubbled out from under that black thing. I wonder how that is designed? Is it a standard part from somewhere?  -- don't think so, as it has "FCUBED" stamped on it. 

Tags: nomad

2nd test solar water distiller prototype-2

June 18, 2019 — BarryK

Just a short report. There is some sunshine today, Tuesday, 18th June 2019, the rest of the week overcast with showers, then next week rain, rain and more rain. So, have taken the opportunity to test the solar water distiller today.

This is prototype #2, that I reported on construction of, with DIY plans, a couple of days ago:

I looked outside at 9.00am this morning, and it was cool, with mostly sunny sky, just some wispy cloud here and there. So, at 9.05am had the panel setup and ready to go.

At 10.00am, ambient temperature was 13degC, the front of the panel, holding the IR thermometer at 90 degrees from the plane of the glass, about 2 inches away, got 28degC, and on the back 23degC.

I noticed about midday that the sky had become more cloudy.

I came back at 2.15pm, the sky had become more blue, less clouds, ambient now 17degC, front 43degC, back 37degC.

I had to stop the test at 3.10pm, as shade from the patio had reached the edge of the panel. Measured collected distilled water: 560 millilitres.

From today's test, have identified two issues. Firstly, the water flow from the three 1mm holes is a bit more than I want, and cannot adjust down. I think, need to try with two 1mm holes, or drill even smaller holes -- presuming that I can find a smaller drill-bit.

Secondly, the temperature on the back of the panel, 37 degrees C, will be reducing the efficiency of the panel. I am going to experiment with some extra insulation stuck onto the back.

Next test, will probably setup the Carocell solar distiller alongside, for comparison. That is the "gold standard" to measure against, as it is very high efficiency. 

Tags: nomad