Water cooled Air

[Scriblerus the Philosophe]

My dad used to use a swamp cooler when he had an apartment. It worked pretty well. But our humidity is usually >30%, so that's why.

Buy some of those bamboo window shades and put 'em over the windows. They are fabulous. Also, there's a type of screen that's very effective at blocking the sun. We have some on the backdoor. Keep plants near the entrances.

[Sibling Zono (anon1mat0)]

Your system can be effective at cooling a small space, like the immediate area around a chair, or a very small room.

Which is my intention. I'm perfectly aware of the limitations, and the intention is to use it on my den during the day (when I'm home alone). In the evenings is cooler so I may be able to avoid turning the AC on until it's too hot.

Heat has to go somewhere.

I guess the suggestion would be to replace the water from the reservoir with cold water if it becomes warm (as it should) otherwise I would expect the cooler (reservoir) to delay it's radiation.

[Aphos]

The second type puts the evaporation completely outside.  It's quite simple, really, and works very well.

You  _can_ "roll your own" easily enough.  The heat added by the pump is minimal, if you use a small pump.   A car radiator would work for the inside unit, provided you had a catch-basin under it.  The cooled water should hopefully get cool enough to help reduce your inside humidity, which will collect on the cool radiator.  You'll either need to periodically dump the catch basin, or plumb it to the outside.   The amount won't be all that much.

But for the rest.  You'll need tubing, a pump, and some sort of cooling tower.  Home-made ones work well enough.   This must be outside. 

This sound close to what I have in mind, except for the 'outside' part:

As a proof of concept, while explaining it to a relative we did a base experiment using a small fan, an empty sodacan box and a few soda cans out from the fridge, using the box as a duct and placing the cool cans inside and checking the temperature of the air before and after and there is a drop in temperature, plus a slight level of dehumidification.

Have in mind that I'm not looking to a fully automated system, so I don't care if I have to put ice in the box every 2 hours. Also my relative suggested using a portable cooler as a reservoir (which makes a lot of sense).

As I remember, Zono's in a condo, so outside is probably not available, unless it's a patio home situation.

Indeed. BTW the honeycomb shades are nice!

I have my doubts about you being able to save money with this system.  The problem is that your freezer works pretty much the same as an AC unit, except the heat it is dumping is into your house rather than outside.  So the heat you have removed from the ice is just being transfered into the air inside the house, which you are then transferring back into the ice...round and round.

So to get any gain, you are going to have to put your freezer outside or in the garage...which is going to decrease its efficiency because the ambient air will be warmer.

Also, while I am not sure of the figures (it has been a long time since I took Thermo) I think you are going to have to use a LOT of ice to get much effect.

[The Meromorph]

That's actually the measure commonly used to size A/C units.
For a 2400 sq foot house - 4.5 tons of Ice a day.
For a 1200 sq foot house - 2 to 3 tons of Ice a day...

[Aggie]

This thread has got me jumping around wikipedia...   I have come to the conclusion that I should take a stab at jury-rigging a misting system for the patio this summer.  Even if I don't achieve flash evaporation, it'll be good for the plants.

[Sibling Zono (anon1mat0)]

I have my doubts about you being able to save money with this system.  The problem is that your freezer works pretty much the same as an AC unit, except the heat it is dumping is into your house rather than outside.  So the heat you have removed from the ice is just being transfered into the air inside the house, which you are then transferring back into the ice...round and round.

So to get any gain, you are going to have to put your freezer outside or in the garage...which is going to decrease its efficiency because the ambient air will be warmer.

Which is why it would be used in a different (and closed) room.

That's actually the measure commonly used to size A/C units.
For a 2400 sq foot house - 4.5 tons of Ice a day.
For a 1200 sq foot house - 2 to 3 tons of Ice a day...

Mmm... which scaling would mean that for the 100sqf room I want to cool I would need aprox 160kg of ice, although I imagine that it would mean a frosty 60F (or less) with such a system. If I can get it to 75-80F and dehumidifies the room I would be more than happy.

Again I'm not planing to replace my central AC unit, much less with the fridge!

[Griffin NoName]

This thread has got me jumping around wikipedia...   

   

It's much more fun jumping around Facebook 

[Sibling Chatty]

OK, the latent nerd in me is wondering about a window installed unit of Peltier junctions...could be reversed for winter as well.

Guys?

[Bob in a quantum-state-of-faith]

OK, the latent nerd in me is wondering about a window installed unit of Peltier junctions...could be reversed for winter as well.

Guys?

PK junctions are efficient, but they are expensive and very small.

For anything large enough to cool an entire room?  You'd need a huge array-- I'd guess 6 foot by 6 foot wouldn't be too big.

They work well for spot applications, and even tiny little fridges (2 cubic feet).  I don't think they'd be very viable.

On the other hand, if you can get a bunch second-hand (they tend to be quite expensive) for free or cheap, then putting huge heat sinks on them.... let's see how would you do it?

Okay, two rectangular tubes, side-by-side.  One for air coming in, the other for air going out.  Put a fan on each, just to be sure (they WILL fail if they overheat). Put the junctions in the common wall of the tubes, with heat-sink fins going into each tube.  Test each, and ensure the heat is going to the tube-going-out.    Room air out, picks up heat from heatsinks and exits the building.  Outside air comes in, looses heat and goes into the building.  Filters at each end.   

An array big enough would consume quite a bit of juice, though.  I wonder if it would be more or less than a very, very small  room A/C unit?

[Griffin NoName]

The one I bought http://www.heatbusters.com/easifit/products/all-products/unico-star-85-heating-cooling does cool or heat..... and has no outside unit... what you get is what you see... but it wouldn't solve the cost element - or at least I suspect it wouldn't.... but maybe worth investigating how it works.

[Sibling Lambicus the Toluous]

Just thinking... my gut feeling says that in the middle of a Florida summer, a dehumidifier might be more effective than an evaporative cooling device.  It wouldn't reduce the actual ambient temperature, but by reducing humidity, it would improve your body's ability to evaporate heat away itself.  Effectively, it should reduce the humidex/"feels like" temperature.

Another part of my gut says that a normal freon-or-similar-based system is probably going to give you the biggest cool-for-the-buck of any active system.  Is it a viable option to just close the vents in the unoccupied rooms (and either switch the A/C system on & off manually, or wire in a switch to a second thermostat in the room you're in), or to get a small window air conditioner for the one room you need cooled?

I find that leaving all the windows closed except for one room on the main floor and one room upstairs creates a nice amount of breeze by natural convection... though the stack effect up the stairwell probably helps a fair bit.  Are you on one level or two?

[Sibling Zono (anon1mat0)]

I'm on a condo on a 3rd floor.

What I have in mind should work as a dehumidifier (and it is NOT an evaporative cooler), in fact it should work better as a dehumidifier than a cooler unit in itself.

Lastly, a typical (small) AC window unit uses 125V*15A=1850Watts. My main AC unit uses from 4KW to 5KW. For comparison the tower fan I have besides me uses 42W, double that for a ceiling fan at high speed (~80-100W). If my power usage is 200W I would be using 9 times less electricity than a window unit and 25 times less than my main unit.

Again, why cool the whole house when I spend most of the time in one room? And I don't need it to be chilled, just enough to be bearable.

[Aggie]

The one caveat I can think of is that you won't actually be using 'already spent' energy to make the ice.  Placing 'warm' materials (such as liquid water) into the freezer will make the freezer run harder (if not, it'd raise the temperature of everything else in order to cool the water). 

Still might be a net reduction in energy, but you'd need to hook some kind of a power meter up to the freezer to check how the usage changes when you are making ice.


(I've wondered if it might be efficient to run this sort of air-conditioning using good ol' winter-frozen ice, stored in an underground cistern or an ice shed bored into a hillside.  Mero's numbers seem to indicate otherwise - up here it's probably better to simply send the cooling circuit into the ground where it stays close to 4^o Celcius)

[Sibling Zono (anon1mat0)]

The one caveat I can think of is that you won't actually be using 'already spent' energy to make the ice.  Placing 'warm' materials (such as liquid water) into the freezer will make the freezer run harder (if not, it'd raise the temperature of everything else in order to cool the water). 

Still might be a net reduction in energy, but you'd need to hook some kind of a power meter up to the freezer to check how the usage changes when you are making ice.

I imagine there will be a hike in energy use from the fridge but not a very significant one. A typical fridge uses ~400W, a 100W hike would still be on target.

(I've wondered if it might be efficient to run this sort of air-conditioning using good ol' winter-frozen ice, stored in an underground cistern or an ice shed bored into a hillside.  Mero's numbers seem to indicate otherwise - up here it's probably better to simply send the cooling circuit into the ground where it stays close to 4^o Celcius)

If I lived in a house with permafrost under it...  

[Aggie]

I imagine there will be a hike in energy use from the fridge but not a very significant one. A typical fridge uses ~400W, a 100W hike would still be on target.

You could probably run a quick calculation based on the mass of water you think you'll need and the temperature drop necessary.  The energy used for cooling still has to come from somewhere, but for the small space you need to cool it may be just fine.

Given that you will be able to get quicker freeze times out of containers with high surface areas, you could build an ultra-low tech system simply by placing a number of cold packs (ziplock bags filled with water, then frozen while laying flat on baking sheets work too) on a wire rack or shelf and blowing a fan past them.  No need for a pump or radiator.