widescale unrest—the latest unrest was in Iran you might remember.

https://www.nytimes.com/2018/01/18/climate/water-iran.html

Have a read.

I would love to have a team of engineers and scientists at my disposal to work on my solar still design.

Getting water out of the air, Mike? What if the air is dry?

Hasn't South Africa run out of water?

Jo’burg is rationed.

Think it is Jo’burg, have only had time for quick glances at at articles lately—busy planning fruit trees for my Tassie block. Varieties, requirements etc. Very quick education!

Jovial Monk wrote on Jan 20^th, 2018 at 9:54pm:

Think it is Jo’burg, have only had time for quick glances at at articles lately—busy planning fruit trees for my Tassie block. Varieties, requirements etc. Very quick education!

Smart move to head South, you will escape these vicious summers.

Hell yeah, will put up with 2°C minimums, my area didn’t get over 20°C this week. Melting here in Adelaide, 2 consecutive days of 41°C, hotter than that in the shade—car themostat got to 44°C at times.

Heh, I am retired, don’t have to get up at 6.00am anymore!

Once I am there and settled in my biggest problem will be keeping cherry slugs out of my trees!

https://www.nytimes.com/2018/01/18/climate/water-iran.html

Oh, Lake Urmia?

"The lake has shrunk to 10% of its former size due to damming of the rivers that flow into it, and the pumping of groundwater from the surrounding area."

wiki

The good ole NYT, never lets a chance go by for alarmist stories.

Of course that 10% was reported in 2015. No water inflow, evaporation, dry lake. ;)

@Monk,

Hi Monk, not getting water out of the air.

Getting fresh water from saline water at a competitive price.

I thought of using extruded plastic pipe with a black base and a clear top, half way down the pipe there is a ridge that can catch the condensation and run it into the fresh line which runs along the outside of the pipe.

The salt water would be pumped up the top of a hill and fed into the solar still pipe.
The pipes run down the hill on a contour so the water travels at the right speed.

The ultra high saline water coming out at the bottom would go onto a drying pan,,, the ultra salty water is one of the problems with reverse osmosis desalination,,,, what to do with it.

The still line could make ultra salty water easier to evaporate than the  byproduct of a reverse osmosis unit.

In fact the solar still aray of pipes could be fitted to desal units to produce more water and treat the salty water by product.

Sounds promising Mike! Do you have a prototype?

As the southern half of Australia dries out desalination will become more important and we do also get long droughts. Also, maybe of use in desalinating saline groundwater? You solve that problem you will be filthy rich!

JV I only have a prototype in my head.

The beauty of solar desalination is,

Lower power costs (hopefully)

You can use extremely salty water ,, which is not suitable for reverse osmosis.

There is less waste water to dispose of.

I need to know about the temperature gradient required to condense the water vapour in the piping.

It would not be difficult to heat the saline water, as long as the  clear top half of the pipe is cool enough.

Perhaps if the saline water was cold coming out of the ground that coolness could be used to cool the top half of the pipes.

I am not sure if anyone can visualise what I have in mind.

As the southern half of Australia dries out desalination will become more important and we do also get long droughts. Also, maybe of use in desalinating saline groundwater? You solve that problem you will be filthy rich!


Not just Australia.


If we could use solar pumps to get the saline water to the top of the desal pipes, the units could be set up remotely,,, and passively produce fresh water.

The other thing it would do is to lower those salty water tables.

miketrees wrote on Jan 21^st, 2018 at 12:52pm:

JV I only have a prototype in my head. The beauty of solar desalination is, Lower power costs (hopefully) You can use extremely salty water ,, which is not suitable for reverse osmosis. There is less waste water to dispose of. I need to know about the temperature gradient required to condense the water vapour in the piping. It would not be difficult to heat the saline water, as long as the  clear top half of the pipe is cool enough. Perhaps if the saline water was cold coming out of the ground that coolness could be used to cool the top half of the pipes. I am not sure if anyone can visualise what I have in mind.

I am sure the temperature gradient needed is available in physics or chemical engineering books, websites etc. Must be websites with people talking about similar devices (if not exactly the same.)

miketrees wrote on Jan 21^st, 2018 at 12:52pm:

JV I only have a prototype in my head. The beauty of solar desalination is, Lower power costs (hopefully) You can use extremely salty water ,, which is not suitable for reverse osmosis. There is less waste water to dispose of. I need to know about the temperature gradient required to condense the water vapour in the piping. It would not be difficult to heat the saline water, as long as the  clear top half of the pipe is cool enough. Perhaps if the saline water was cold coming out of the ground that coolness could be used to cool the top half of the pipes. I am not sure if anyone can visualise what I have in mind.

I can see it, I have coils of poly pipe out the back hooked up to rain water tank and the water comes out steaming hot after 10 minutes in summer, free hot water, really hot water, to use a still type set up to condense the vapor on a big scale might just work.

I can see it, I have coils of poly pipe out the back hooked up to rain water tank and the water comes out steaming hot after 10 minutes in summer, free hot water, really hot water, to use a still type set up to condense the vapor on a big scale might just work.


I envisage using that pipe with its cool water to cool and condense vapour as it is pumped to the top of the desal tubes, it will be hot by the time its at the top , so a lot of the condensing will happen at the bottom .

Of course if night time air temps cool and the feed water is still red hot, a lot of condensation could take place at night.
this would require a large hot water storage at the top of the tubes.

You would need a triple–walled clear pipe:

Inner, part filled with water with plenty water vapor above it.
This inner part has two walls, inner one does not go to the top and water is not filled over the level of the inner wall.

Final outer wall gets cold water from out the ground running from the top, down the sides of the pipe, cooling the vapor and condensing it. condensed water runs down the wall of the pipe between the inner and centre wall and is collected and used.

I would elaborate that, have the cold water instead running in a coil in the water vapor part, in at the top out at the bottom.

Condensing, cooling is done with counterflow: hot vapor heads down, cooling water heads up.

In the shop a bloke came in wanting a new still: his didn’t work well. We were delighted to sell him an expensive still taking his still as trade in. His condenser was connected the wrong way round. We fixed that and sold his still for a near-new price. So work in counterflow, will really boost your system’s efficiency.