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Brackets to hold inlet tubes

October 25, 2019 — BarryK

Currently undertaking some refinements to the solar water distiller. I recently posted that the water inlet was modified to be two silicone tubes:

Each end of the inlet assembly has a brass rod sticking out, which goes into 4mm holes drilled in the wood on both sides of the distiller. On the right side (looking from the front), there are two 6mm holes for the silicone inlet tubes:


As I want to mess around with the distiller, modifying things, I want to be able to pull out the inlet-assembly very easily. However, to do so requires the wood frame to be pulled slightly apart, so as to remove the brass rods.

Awkward, have an alternative design, metal brackets on each end. Here is the bracket for the left side:


...the washers are so that it stands out from the wood. A small off-cut of brass rod was inserted to aid placement of the drill holes. 2mm holes in the wood, and here is a sketch of the dimensions:


Zinc and aluminium don't go together very well in hot humid conditions, so will probably smear the mating surfaces with silicone sealant in the final assembly.

The right side has the two holes for the silicone tubes, and one of them is in the wrong place. I cut out a notch in the bracket for it to be moved to:


So of course the brass rods will be cut shorter, so as not to stick into the wood. Now, it should be very easy to click the inlet assembly out and remove, hence easy removal of the cloth also. More changes coming, stay tuned!  

Tags: nomad

First test of water distiller prototype 3

October 17, 2019 — BarryK

Continuing with reports on construction of solar water distiller prototype #3, here is the previous post:

The above link was a redesign of the inlet piping, with two nozzles. I rebuilt the inlet so now there are two silicone tubes coming into the distiller:


Today is Thursday, October 17, 2019, Perth, Western Australia. This morning there was haze in the sky, but still fairly bright sunlight. The haze persisted all day, however, the light intensity meter gave reasonably high readings.

I put the distiller together, and had it ready to go about 9.25am. I oriented the panel to face where I estimated the sun will be about 11am, and left it fixed at that orientation for the duration of the test. The panel cloth was dry, and after 10 minutes, this photo shows how far the water has progressed down the cloth:


The water has actually progressed a bit further than indicated by the mistiness on the glass. After 30 minutes:


...this photo shows the water in the cloth, just a bit further down than the condensation on the glass. It took about 50 minutes for the water to reach the bottom of the cloth.

I was messing around with setting up the outlet for the distilled water. It is a temporary arrangement, with a strip of balsa wood wedged between the top and bottom glass sheets. Had to fiddle with it to get the water to come out in one place, but finally placed a cup underneath at 10.30am.

At 10.30am, still hazy sky, but sun intensity was 840 watts/m2. Ambient temperature 22°C, front temperature 49°C and back 44°C (IR thermometer held about 4 inches from glass, about 3/4 way-up the glass).

I was inside the house having lunch, then came out at 12.30 and found the cup had overflowed. Not sure how much, but the puddle was small. Anyway, changed the cup.

At 12.30 sun was 790 watts/m2, ambient 24°C, front 51°C, back 44°C.

I kept the experiment going until 2.30pm, when the shade from the patio had just reached the distiller. Total water collected 500 millilitres, unknown amount lost when cup overflowed. This averages out to 125ml/hr. Surface area of the cloth is 0.3327m2. To compare with the F-Cubed distiller, which has a 1m2 cloth area, scaling up prototype #3 will be 375.6ml/hr. The F-Cubed gave 563.6ml/hr in this test:

It is only a ball-park comparison, but prototype #2 136ml/hr, cloth area 0.466m2, and scaling that up to compare with the 1m2 F-Cubed: 291ml/hr. Prototype #2 test is here:

Or putting it another way, if the F-Cubed efficiency is the reference, "100%", then prototype #3 has 67% efficiency, and #2 has 51%. An improvement, but not as much as I was hoping for. What is the secret of the F-Cubed? -- the cloth, the plastic sheeting?

Prototype #3 has the same rotating air principle as used in the F-Cubed. These are temperature measurements that I took at 1.30pm, IR detector held about 2 inches from the glass:


...this temperature differential causes the air to rotate. Air flows down underneath the middle glass sheet, and water condenses on the bottom sheet of glass. I could see condensation happening, but was unable to judge how much relative to the top.

My reasoning also, is that the air flow will improve evaporation off the cloth. One thing I did notice, the front glass sheet remained clearer, like the F-Cubed -- prototype #2 front glass became very foggy.

This first test has revealed some things that I need to improve in the construction. Also, need to experiment with different cloth. 

Tags: nomad

Two inlet nozzles works

October 14, 2019 — BarryK

I posted yesterday that the inlet design was not spreading the water wide enough:

I have jury-rigged a setup with two nozzles. Externally, from the linline-filter there is a T-junction and two 4 litres/hour drippers, then 4mm trickle pipe taped onto the distiller:


...the 4mm pipes are taped on the up-flow-side of the aluminium channel, so as to flow horizontally somewhat before seeping underneath the channel.

This looks good. I managed  to take the photo at an angle where you can just see how the water has progressed down the cloth. It is covering the width of the cloth. Interesting, it looks like the left-hand outlet has a very slightly higher flow rate.

Next step, redesign the inlet to have two pipes. 

Tags: nomad

Inlet pipe design not satisfactory

October 13, 2019 — BarryK

Today I setup a test of the inlet pipe in the solar water distiller prototype #3:


...from the water container, there is an inline filter, then the flow-reducer as described in an earlier post:

Then there is a 13mm-to-4mm trickle-pipe reducer, and silicone tube into the distiller. Water comes out of the top-side of the aluminium square-section channel, so flows along the top before working its way underneath the channel and down the wicking cloth.

The design was a punt. I thought that the spreading effect would work, but didn't know how much. In the photo, the water has trickled down about halfway in the centre, and if you squint at the photo, you might just make out the spread. It is good, but not wide enough to reach the sides of the cloth.

So, need to rethink the design. Two holes would probably do it, but the problem is to get equal water flow through them. I don't want to put any trickle parts inside the distiller, as the temperature might get up to 65 degrees C and the plastic might soften. Thinking to have two flow-reducers externally. 

EDIT 2019-10-14:
Problem solved, see post: 

Tags: nomad

Assembling inlet of water distiller

October 08, 2019 — BarryK

Continuing construction of solar water distiller prototype #3, previous post here:

Holes needed to be drilled to mount the inlet pipe. The small holes are 4mm diameter, the large one is 6mm:


...there was a bit of messing around deciding exactly where the holes will be drilled. Exact measurements will be in the final DIY page. I assembled the central glass with silicone mat and wicking cloth, then placed the inlet pipe on top, to find out where those holes needed to be.

I didn't really want to glue anything together, as the aim is that the distiller can be totally pulled apart. However, the mat sits on the glass and want the edges folded up so as to contain the water. The top up-slope end of the mat is a problem, want it to stick up about 90 degrees from the plane of the mat. I used Selleys 401 silicone sealant to adhere the mat to the glass and achieve the top lip.

Here is the inlet pipe assembled:


...using the black towel used in prototype #2, which has a 6.3mm aluminium rod inserted along the top of the towel. The towel is cotton, from Kmart, it is plain black, no embossing. The aluminium rod is from Bunnings.

The rod was AU$2,32:

The towel was AU$6:

The great thing about the towel is that it already has a folded-over-end through which the aluminium rod fits snuggly:


As you can see in the second-last photo, the silicone mat top-end lip is not sticking up at 90 degrees, more like 45 degrees. So what I did was fold it right over 180 degrees and apply silicone sealant:


...left that overnight. Yes, that did the trick, it sprang back to about vertical:


The next exercise will be to construct the distilled-water runoff. That is tricky, as distilled water will be running down both top and bottom glass sheets. I have considered various ways to construct it, and trying to do it without any more gluing.

Tags: nomad

Constructing water distiller inlet

October 04, 2019 — BarryK

Continuing the construction of solar water distiller prototype #3, here is the previous post:

In the prototypes #1 and #2, the water inlet was an aluminium tube running horizontally across the top, with two or more tiny holes in it, through which the water trickled. I had difficulty with getting an exact flow rate, and experimented with an external flow reducer, see here:

I am using this external flow-control system for prototype #3. Inside the water distiller, there will just be one hole that the water comes out from, and it is intended to spread out so that it flows down the entire width of the wicking cloth.

There have been several iterations of the inlet pipe, and even got to the point of buying some parts then changing my mind, hence wasting money.

Until recently, it was going to be a 12mm OD aluminium round pipe, with 12mm holes drilled in the wood frame on both sides to hold it. However, the inner sheet of glass, on which the wicking cloth lies, will also have a silicone mat between glass and cloth -- that mat will have folded-up lips on the sides, to form a sloping tray, to keep the water contained.
The 12mm pipe resting on top of the wicking cloth will compromise the lips of the silicone mat at the sides. hence had to rethink the design.

What I decided on is to use 12x12x1.5mm aluminium channel, length slightly less than the inner width of the distiller, with brass rods extending into the wood frame to hold it in place. This creates a gap on the sides for the silicone mat lip.

First step, buy the channel, AU$5.81:

I decided to use standard 4mm trickle fittings for the inlet piping. I already have 13mm trickle/drip fittings, a inline filter and the flow-control construction described in the above link. Hence, need to reduce to 4mm and bought this, a 13mm to 4mm adaptor, AU$3.64:

I could have used cheap 4mm trickle irrigation pipe, however decided to go for silicone tube. Main reasons, it is translucent so can see the water inside, secondly it is highly UV-resistant. I went for silicone tube 3mm ID and 6mm OD, so the wall thickness is 1.5mm. Earlier this year I had purchased silicone tube from China, via eBay, to suit the 13mm trickle fittings, with a 1mm wall thickness, but I found that it kinks very easily. Smaller diameter tube is less likely to kink, but decided to play safe and go for the thicker wall.

I thought to also use this 3mm ID tube for the outlet of the distilled water, however, was concerned that the surface tension of water might impede the flow through such a small diameter tube. So for outlet, chose 4mm ID and 7mm OD, 1.5mm wall thickness.

The silicone tube can be purchased from China cheaply, for example:

However, I wanted it NOW, so purchased from a local supplier, here in Perth, Western Australia. A very premium price. The company also has an eBay store and they send by Toll Express:

When the DIY plans get published, it will be recommended to save some money and buy from China, if there is no cheap local supplier. The price will be AU$4.44 for 3mm ID 6mm OD, and AU$4.76 for the 4mm ID 7mm OD, 1 metre lengths.

The channel is cut to length 554mm, so as to fit inside the wood frame with slight gaps both sides of a couple of millimetres. A 4.5mm hole is cut in the middle, and a slot cut on the right side 6mm wide and 9mm deep. Like this:

img1 might not be able to make it out in the photo, but I gouged lines on the top and bottom insides, as the channel is to be filled with silicone sealant, and the gouges will help it to grip to the channel.

I purchased 4mm 90 degree elbow spur-fittings, supplied in a 10-pack, AU$4.20:

I cut the spur off one end of an elbow and attached the 3mm ID silicone tube to the other end. I pushed it into the hole, like this:


On the right side, the silicone tube is pushed slightly into the slot. The reason for this is there will also be a brass rod sticking out from the end, and there needs to be a slight separation between the two holes that will be cut in the wood frame. Snapshot:


...I cut off two short pieces of silicone tube and placed them on the left side -- when the brass rod gets positioned, it will be resting on top of the silicone tube, same situation at left and right sides.

I used some silicone sealant to fix the tube in place, and left overnight to set. The above photo shows the sealant applied, and the photo was taken the next day. I am using Selleys 401 acetic cure silicone, because it is rated food-safe and has superior bonding to silicone and glass, this one at AU$19.65:

Brass rod is available via eBay, however also sold at many local hobby shops. I purchased K&S brand (made in USA) 1 foot length 5/32 inch diameter (305mm, 3.97mm) brass rod from PerthRC hobby shop, Lord Street, Perth, for AU$4.49:

Cut it in half, gouged with a file edge, and placed into the channel, sticking out about 10mm each end from the channel, embedded in silicone sealant. Used various tools and implements to hold the rods in place and left overnight. Here is a view of the left side:

img4 can see that the rod is at the same height as the channel. To help fix it in place more securely, I wanted the sealant to have a convex surface, so as to completely encircle the rods. So, the following day, used a small piece of cardboard as a spreader for the final application of sealant:


The sealant was applied along the entire length of the channel, then dragged the piece of cardboard along the entire length to form a nice slightly-convex surface.

Finally, here are views at the right side:


There is one important detail. Notice the outlet hole, where the 4mm plastic elbow is pressed through the channel. It is on the up-slope side, not facing down-slope. So, there will be a slope, about 30 degrees, and the hole seems to be on the wrong side. This is part of the plan. The water will trickle out and run along the up-slope side of the channel and work its way underneath through the wicking cloth. This mechanism is intended to help the water to spread out the width of the distiller. This is so far entirely theoretical!

The next step will be to drill holes into the wood frame so as to mount this assembly. 

Tags: nomad

Router frame wobble fixed

October 03, 2019 — BarryK

I posted about the ill-fitting frame in my el-cheapo 30 bucks trimmer router:

Here is a closeup showing the cause of the wobble:

img1 can see the plastic "bridge", that prevents the lower-end of the frame from closing tightly to the body. You may also be able to make out where it cracked when I tightened the knob too much.

Today decided to try an experiment: cut off the bridge. Simple exercise, with a hacksaw blade cut the section of plastic that holds the two sides apart, cutting a slot as wide as possible. Photo:


...magic, problem fixed! Yep, a simple bit of surgery and the frame now tightens up top and bottom, no wobble, grips the body tightly.

So, two surgical operations have been performed on the frame, front and back, and now I can recommend this cheap router. 

Tags: nomad

Cutting inner slots and runoff holes

September 28, 2019 — BarryK

Continuing with construction of solar water distiller prototype #3. Here is the previous post:

Today have cut the inner slots and holes for the runoff tube. The runoff tube is 16mm outside-diameter aluminium, and I posted previously how a 10mm wide slot was cut in it. One end of the tube has to be blocked off, so I purchased a rubber stopper from Clark Rubber:

I chose the 24x16x13mm stopper, and cut off the narrow end and pushed it into the end of the tube:


...I managed to push it in a bit more than shown in the photo, until it was just about flush with the end of the tube.

Cutting the inside slots taught me more about router bits! I used the 4mm straight single-flute bit, and as I was moving the router along, suddenly realised that it was cutting much deeper. The single flute causes more vibration, and although I thought that I had tightened the chuck very well, the bit was gradually working its way out.

What a lesson that was. Fortunately, I spotted what was happening and readjusted the depth of the bit in the chuck, and tightened it up as much as I could.

But then I observed something else: the 4mm bit was cutting a fractionally-over-4mm wide groove. Before, when cutting the outside grooves, I used a Diablo 3.2mm (1/8 inch) straight dual-flute bit, then later ran through the grooves with the 4mm single-flute bit to widen the grooves. That resulted in a pretty well spot-on 4mm width, that the glass fitted into very snuggly.

We are talking about sub-millimetre difference here, but it is still significant. I put the wider cut of the single-flute bit being due to the vibration as it cuts one side then the other.

I did receive advice that dual-flute bits are better, now I know from experience. Though they are expensive. Here is the Diablo 1/8 inch bit:

...unfortunately, there isn't a 4mm (5/32 inch) dual-flute bit. Not at Bunnings anyway.

The steps that I followed today, was to firstly drill the round holes to hold the runoff pipe. I did that before cutting the slots.

I will post a diagram showing exact measurements when the final DIY page is uploaded. Basically, there is a 16mm hole cut 10mm deep on the left side, and cut right through on the right side. To do this, I purchased a set of spade drill bits, at only AU$7.98:

...require the 16mm bit, and later on the 12mm bit, so it was cheaper just to buy the set.

After drilling the holes, the router was then setup and the slots cut, 630mm long, well slightly over, as the glass is 630mm long.

Finally, a check to see that it goes together. Here is the inner sheet of glass and runoff tube inserted:


...just eyeballing it, I think that if I ever make another runoff tube, I will make the slot slightly narrower, down from 10mm to 8mm. But 10mm is OK. The important thing is that the runoff should not be able to splash out -- the design is such that there won't be any splashing anyway. 

Tags: nomad