Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

Condensation.

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

Direct the moist air into a room with a dehumidifier.

The Rev Dodgson said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

Direct the moist air into a room with a dehumidifier.

He wants to recycle the wetness from the dehumidifier.

roughbarked said:

The Rev Dodgson said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

Direct the moist air into a room with a dehumidifier.

He wants to recycle the wetness from the dehumidifier.

Attach a pipe to the bottom of the water collection tank in the dehumidifier then.

Alternatively ask Steven Wright if he has a solution.

The Rev Dodgson said:

roughbarked said:

The Rev Dodgson said:

Direct the moist air into a room with a dehumidifier.

He wants to recycle the wetness from the dehumidifier.

Attach a pipe to the bottom of the water collection tank in the dehumidifier then.

Alternatively ask Steven Wright if he has a solution.

:)

roughbarked said:

The Rev Dodgson said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

Direct the moist air into a room with a dehumidifier.

He wants to recycle the wetness from the dehumidifier.

No, I want to collect the water and use it for some agricultural purpose in another greenhouse nearby. The main purpose is to harvest freshwater, the salt is a bonus by-product.

There’s lots of parts of the country that have salty groundwater and plenty of sunshine.

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

I know this one. I used to manage a large timber operation in the SW where had 4 very large timber drying kilns. They were just a huge insulated building with a row of fans for moving the air, a couple of household water heaters for warming the interior, and two very large refrigeration units running outside, but with one entire wall of the building full of cold/condensation coils. Below the coils was a rain gutter to collect the water and drain it through a 25mm hose fitting outside into a ditch. The was a control box on the outside to monitor everything, and I was running the whole operation. If you have any specific questions, pop them in.

party_pants said:

roughbarked said:

The Rev Dodgson said:

Direct the moist air into a room with a dehumidifier.

He wants to recycle the wetness from the dehumidifier.

No, I want to collect the water and use it for some agricultural purpose in another greenhouse nearby. The main purpose is to harvest freshwater, the salt is a bonus by-product.

There’s lots of parts of the country that have salty groundwater and plenty of sunshine.

We get what you want to do.

A dehumidifier removes the water from the air. In essence condensation wasn’t such a bad answer because it can do the same thing.
Where to put it and how to channel the water are just positional errors, if you like.

Kingy said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

I know this one. I used to manage a large timber operation in the SW where had 4 very large timber drying kilns. They were just a huge insulated building with a row of fans for moving the air, a couple of household water heaters for warming the interior, and two very large refrigeration units running outside, but with one entire wall of the building full of cold/condensation coils. Below the coils was a rain gutter to collect the water and drain it through a 25mm hose fitting outside into a ditch. The was a control box on the outside to monitor everything, and I was running the whole operation. If you have any specific questions, pop them in.

:) It is perfect. Insert cold and water condenses.

Kingy said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

I know this one. I used to manage a large timber operation in the SW where had 4 very large timber drying kilns. They were just a huge insulated building with a row of fans for moving the air, a couple of household water heaters for warming the interior, and two very large refrigeration units running outside, but with one entire wall of the building full of cold/condensation coils. Below the coils was a rain gutter to collect the water and drain it through a 25mm hose fitting outside into a ditch. The was a control box on the outside to monitor everything, and I was running the whole operation. If you have any specific questions, pop them in.

*one entire wall inside the building…

Kingy said:

Kingy said:

party_pants said:

Hopefully a quick question.

Let’s say I have a salt evaporation pond. Pretty simple to operate, fill it with salty water, let the sun evaporate the water away and eventually you are left with a layer of salt.

Now let’s say I build a large glasshouse (plastichouse?) over the top of my pond, so that the warm humid air can be captured and funneled away.

What’s the best way to extract the moisture from the air? I am not talking about boiling the water, so we are not working with steam as such, just warmish humid air. Is it down to cooling the air below the dew point? Are there any other methods that might work on a large scale?

(assume cost is not a consideration for now)

I know this one. I used to manage a large timber operation in the SW where had 4 very large timber drying kilns. They were just a huge insulated building with a row of fans for moving the air, a couple of household water heaters for warming the interior, and two very large refrigeration units running outside, but with one entire wall of the building full of cold/condensation coils. Below the coils was a rain gutter to collect the water and drain it through a 25mm hose fitting outside into a ditch. The was a control box on the outside to monitor everything, and I was running the whole operation. If you have any specific questions, pop them in.

*one entire wall inside the building…

You did say, LARGE.

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inputs
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture, free of impurities.

fixed

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

A condensation plate. As was said, drips into collection and is piped away by gravity to maybe a small pump if you need it.

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

party_pants said:

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inputs
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture, free of impurities.

fixed

Simple. Try putting a dish of salty water inside a plastic bottle. Allow the sides of the plastic bottle to drip into a collection.

Boris said:

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

my last post said that.

roughbarked said:

Kingy said:

Kingy said:

I know this one. I used to manage a large timber operation in the SW where had 4 very large timber drying kilns. They were just a huge insulated building with a row of fans for moving the air, a couple of household water heaters for warming the interior, and two very large refrigeration units running outside, but with one entire wall of the building full of cold/condensation coils. Below the coils was a rain gutter to collect the water and drain it through a 25mm hose fitting outside into a ditch. The was a control box on the outside to monitor everything, and I was running the whole operation. If you have any specific questions, pop them in.

*one entire wall inside the building…

You did say, LARGE.

I had no trouble driving around inside with a 6m pack of timber on the forklift. It took a week to stack, 2-3 months to dry, and a week to empty each one.

At one point, the owner had promised the dry timber to the client earlier than I could get it dry. He told me to turn up the heat, I told him no, you can’t do that without damaging the timber. He waited until I knocked off on a Friday, and turned it up anyway. I came in Monday morning to find steam roiling out from tiny little gaps in the doors and checked the control box to find out what had happened.

The entire kiln load of premium timber for flooring had been turned into propellers, canoes, ski jumps and matchsticks. Utterly fucked all of it. I rang him up to tell him what had happened. He didn’t admit it for weeks. I resigned not long after.

Boris said:

party_pants said:

dv said:

Since you aren’t concerned about cost, what are our parameters? Best in what way? Smallest energy input? Smallest plant space?

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

party_pants said:

Boris said:

party_pants said:

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

pipe it into underground tunnels which would be cooler.

party_pants said:

Boris said:

party_pants said:

Simplest, easy to operate,
not overly dependent on high tech or exotic inouts
least production of pollution and other negative externalities,
cleanest and safest water for drinking or agriculture free of impurities.

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

Arts said:

party_pants said:

Boris said:

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground running along the plastic and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

fixed

Arts said:

party_pants said:

Boris said:

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

points for practicality. :)

Arts said:

party_pants said:

Boris said:

won’t the plastic covering collect the condensation? this is how the early miners in Kal got drinking water.

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

That’s an idea.

Have a large concrete trough in the middle which just sits there full of salty water. During the day it freshwater evaporates. At night it cools and condenses on some sort of cool surface, water collects and feeds into some sort of drip irrigation system going to the plants. So long as it does not get too hot for the plants during the day.

party_pants said:

Arts said:

party_pants said:

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

That’s an idea.

Have a large concrete trough in the middle which just sits there full of salty water. During the day it freshwater evaporates. At night it cools and condenses on some sort of cool surface, water collects and feeds into some sort of drip irrigation system going to the plants. So long as it does not get too hot for the plants during the day.

The plants can be shaded.

party_pants said:

Arts said:

party_pants said:

No doubt it would collect some of it. Maybe that could be designed with an internal gutter system.

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

That’s an idea.

Have a large concrete trough in the middle which just sits there full of salty water. During the day it freshwater evaporates. At night it cools and condenses on some sort of cool surface, water collects and feeds into some sort of drip irrigation system going to the plants. So long as it does not get too hot for the plants during the day.

my FIL has plastic chains from his roof gutters to ground gutters that lead to his surrounding garden.. the water simply moves along the chains.. it’s pretty clever. and no unsightly down pipes

We will assume “Best” is the best balance of expedience and cost.

I would suspect a decent budget could build a large glass hothouse with chimney, hot humid air rises up the chimney and sucks in the dry outside air.
The brine could be poured over matting and the crystals harvested regularly, rather than in a batch process.

The rising air could power turbines to run the pumps, and there may even be an excess and the water could easily be condensed out and potentially used for agriculture.

A big financial outlay, but I think it would be effective.

Dark Orange said:

We will assume “Best” is the best balance of expedience and cost.

I would suspect a decent budget could build a large glass hothouse with chimney, hot humid air rises up the chimney and sucks in the dry outside air.
The brine could be poured over matting and the crystals harvested regularly, rather than in a batch process.

The rising air could power turbines to run the pumps, and there may even be an excess and the water could easily be condensed out and potentially used for agriculture.

A big financial outlay, but I think it would be effective.

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

Arts said:

party_pants said:

Arts said:

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

That’s an idea.

Have a large concrete trough in the middle which just sits there full of salty water. During the day it freshwater evaporates. At night it cools and condenses on some sort of cool surface, water collects and feeds into some sort of drip irrigation system going to the plants. So long as it does not get too hot for the plants during the day.

my FIL has plastic chains from his roof gutters to ground gutters that lead to his surrounding garden.. the water simply moves along the chains.. it’s pretty clever. and no unsightly down pipes

He’s a clever lad.

Dark Orange said:

Dark Orange said:

We will assume “Best” is the best balance of expedience and cost.

I would suspect a decent budget could build a large glass hothouse with chimney, hot humid air rises up the chimney and sucks in the dry outside air.
The brine could be poured over matting and the crystals harvested regularly, rather than in a batch process.

The rising air could power turbines to run the pumps, and there may even be an excess and the water could easily be condensed out and potentially used for agriculture.

A big financial outlay, but I think it would be effective.

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

A plastic bottle does the same thing.

roughbarked said:

Dark Orange said:

Dark Orange said:

We will assume “Best” is the best balance of expedience and cost.

I would suspect a decent budget could build a large glass hothouse with chimney, hot humid air rises up the chimney and sucks in the dry outside air.
The brine could be poured over matting and the crystals harvested regularly, rather than in a batch process.

The rising air could power turbines to run the pumps, and there may even be an excess and the water could easily be condensed out and potentially used for agriculture.

A big financial outlay, but I think it would be effective.

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

A plastic bottle does the same thing.

That article is from 2014.

About that time they were set to be the next big thing in Australia, and a start-up company raised a lot of money on the stock exchange.

What happened to that money, I don’t know, but the investors don’t have anything to show for it.

I presume these towers don’t work that well in practice.

The Rev Dodgson said:

roughbarked said:

Dark Orange said:

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

A plastic bottle does the same thing.

That article is from 2014.

About that time they were set to be the next big thing in Australia, and a start-up company raised a lot of money on the stock exchange.

What happened to that money, I don’t know, but the investors don’t have anything to show for it.

I presume these towers don’t work that well in practice.

Engineering is hard :)

The Rev Dodgson said:

roughbarked said:

Dark Orange said:

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

A plastic bottle does the same thing.

That article is from 2014.

About that time they were set to be the next big thing in Australia, and a start-up company raised a lot of money on the stock exchange.

What happened to that money, I don’t know, but the investors don’t have anything to show for it.

I presume these towers don’t work that well in practice.

Over-engineered, I believe, is the term?

roughbarked said:

The Rev Dodgson said:

roughbarked said:

A plastic bottle does the same thing.

That article is from 2014.

About that time they were set to be the next big thing in Australia, and a start-up company raised a lot of money on the stock exchange.

What happened to that money, I don’t know, but the investors don’t have anything to show for it.

I presume these towers don’t work that well in practice.

Over-engineered, I believe, is the term?

Not necessarily.

It may well be that the systems proposed at development stage were grossly under-engineered.

For instance, the sort of person who understands the enginnering behind hot air flowing up a tower might well not have a clue on what is involved in making a very tall tower stand up under high winds.

And vice-versa of course :)

Arts said:

party_pants said:

Arts said:

just let it drip to the ground and plant stuff on the outside of the plastic that you want to eat or grow for other purposes.. you’d probs have to contain the salt in some sort of try but you’d need that anyway..

That’s an idea.

Have a large concrete trough in the middle which just sits there full of salty water. During the day it freshwater evaporates. At night it cools and condenses on some sort of cool surface, water collects and feeds into some sort of drip irrigation system going to the plants. So long as it does not get too hot for the plants during the day.

my FIL has plastic chains from his roof gutters to ground gutters that lead to his surrounding garden.. the water simply moves along the chains.. it’s pretty clever. and no unsightly down pipes

I like the idea of rain chains. Apparently a lot of people use them in Port Fairy. I have one that is little terracotta owls, but it broke some years ago and I haven’t got around to rethreading it and putting it up. They are a Japanese thing. There are some beautiful ones available.

https://rainchains.com.au/

Dark Orange said:

Dark Orange said:

We will assume “Best” is the best balance of expedience and cost.

I would suspect a decent budget could build a large glass hothouse with chimney, hot humid air rises up the chimney and sucks in the dry outside air.
The brine could be poured over matting and the crystals harvested regularly, rather than in a batch process.

The rising air could power turbines to run the pumps, and there may even be an excess and the water could easily be condensed out and potentially used for agriculture.

A big financial outlay, but I think it would be effective.

https://www.nationalgeographic.com/history/article/140416-solar-updraft-towers-convert-hot-air-to-energy

A close colleague at CSIRO was working on that. He was calculating how much extra air could be carried aloft by the current, gaining extra energy from a high bypass configuration similar to that used to increase power from jet engines.

As with everything in Australia, you need a lot of water to run it. And we don’t have a lot of spare water except near the coast. I had thought of covering one of those huge salt-production pans in South Australia with a greenhouse.

By the way, you’re asking the exact right question. Efficient dehumidification is the key to making this system viable. My first thought would be a nanoscale-pore counter-current heat exchanger. Maximise the surface area involved in the heat transfer. This is superb for gas to gas heat exchange, the pores could actually be much smaller than a micron in diameter and operating in parallel could give a heat transfer rate per unit volume thousands of times better than the best currently existing heat exchangers. I even envisaged/invented a rapid nanoscale manufacturing method (akin to how steel car doors are produced in giant presses but scaled down to the nanoscale) for these heat exchangers.

With the nanoscale heat exchanger operating massively parallel, you can only cool it down to just above the dew-point. Then a second cooling method suchy as bubbling through cold water does the actual; dehumidification.

The energy lost in the cooling to above dew-point is regained by heating the air coming into the solar funnel. mollwollfumble patent pending.