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Frogwatch 02-20-2014 09:05 PM

Solar powered cooling
 
Boats got plenty of sunlight and a huge heat sink below em. How do we use that for cooling? Check out something from about 100 yrs ago called a Crosley "Iceyball". It used evaporation and condensation of ammonia to produce ice and it was regenerated by heating on a burner. Replace said burner with a solar concentrator and Voila, ice from the sun. However, I dont like the idea of ammonia on a small boat so....................Zeolites.
Zeolites when dry absorb water vapor like mad giving off heat. Use the heat to regenerate another zeolite container. When it absorbs water vapor, it causes cooling of the water reservoir producing ice.
AS I really dont need ice on my small boat, I wonder if this could be used to cool my boat. It would certainly de-humidify incoming air and running the air over ice it produced would cool it. Regeneration would need to be supplemented with a solar concentrator.
OK, lets go further.........after considerable checking of the patent office, I suggest, zeolite aided desalination. Two separate zeolite containers so one can regenerate the other. A salt water reservoir connected to the zeolite containers. The humidity captured is fresh water. it can be driven off the zeolite by heating and recondensed via the cooling produced by the evaporation in the salt reservoir.
Turns out that reverse Osmosis is more energy efficient than any form of distillation except we have nearly unlimited sunlight.
Thoughts?

SimonV 02-20-2014 10:53 PM

I have no idea but it sounds good, why has it not been produced before? What are the down sides?

ccriders 02-20-2014 11:05 PM

Re: Solar powered cooling
 
I've never seen a zeolite, so sounds like FM to me. But then, I've never seen an electron either.
John

guitarguy56 02-20-2014 11:33 PM

Re: Solar powered cooling
 
Zeolite is a crystal and is used in removing ammonia in fresh and marine aquariums. I used to use it but now I use a protein skimmer to remove wastes from the saltwater before it causes algal blooms.
You are right that after absorbing water it can be heated to release steam and this steam can be used for various uses but you need 'heat' besides the high heat from hot temperate zones or use heat from the engine exhaust...

Heating and refrigeration:

Zeolites can be used as solar thermal collectors and for adsorption refrigeration. In these applications, their high heat of adsorption and ability to hydrate and dehydrate while maintaining structural stability is exploited. This hygroscopic property coupled with an inherent exothermic (energy releasing) reaction when transitioning from a dehydrated to a hydrated form make natural zeolites useful in harvesting waste heat and solar heat energy.

Here is one you might want to read up on...

http://www.bine.info/fileadmin/conte..._internetx.pdf

Torch 02-20-2014 11:35 PM

Re: Solar powered cooling
 
I'm not familiar with Zeolites and their properties. It's an intriguing idea, how large would these containers need to be?

guitarguy56 02-20-2014 11:56 PM

Re: Solar powered cooling
 
At $275 plus change... I would try to find a way to make something like this work on a small boat... it's cheap and can cool a small cabin well. Would work well at shore power, small enough to store away when not needed and it could vent through a dorade or port window. A plus is the dehumidifier and some have heating capabilities.

http://www.compactappliance.com/Kold...r_Conditioners

RichH 02-21-2014 12:41 AM

Re: Solar powered cooling
 
The downside to zeolites (chiefly activated alumina) is the HIGH energy needed for regeneration - 'roasting' the zeolite 'bed' for 8 hours at 350F, plus cool down. The alternative is 'pressure swing' zeolite regeneration using a partial diverted flow of produced dehydrated gas/air (-40 dewpoint) but which consumes even more energy overall than 'heat swing' methods. The question is from where will you generate the power to operate the 60-100 psi needed for this zeolite regeneration to be accomplished in the 8 hours? Cant generate the pressure - no problem if you can wait 8 days for regeneration.

Sorry, but the 'compactness' of fossil fuels (gasoline @ 22-24000 Btu/pound or ~114,000 BTU/gallon) running a simple 2000 watt generator plus 'capacitance starter' powering a ~6000 BTU AC unit is still 'light years' ahead in efficiency and operating cost for cooling a boat.
To run an equivalent 'solar' installation for 6000BTU (100BTU/min) you'd need a panel output of 1700+ watts .... about 5 square meters (~55 sq. ft) of solar panels, something much beyond the entire surface area of the typical sailboat, ...... of course only to be run between 10AM to 3 PM on bright sunny days.
Got a small barge you can tow along to hold all those solar panels?

Actually a direct fired propane driven system, such as used in the 1930s is still viable and very efficient using one of the modern environmentally less damaging 'freons', instead of ammonia. Bring your mortgage application when you consider propane/CNG driven cooling, and then expect a routine monthly EPA inspection and mega-hassling.

Nothing in life is free.

Not to 'knock you down' on inspiration; but, the use a zeolites for sub-cooling simply wont 'do it', although they can reduce the uncomfortable 'humidity'. So, keep your thoughts, and keep trying !!!!

;-)

deltaten 02-21-2014 09:17 AM

Re: Solar powered cooling
 
Going a bit tangential; but what about the old, camper shell ammonia reefers?
I seemta recall that they took no power..were all gravity/ambient temp operated??
A co-worker had an old truck camper with what appeared to be an ice chest. Some old fella tuned him into what-was-what and all he needed was to turn it upside-down for a few days and it worked again!

Am I wrong in that rememberance? Is there suchan animal? I *know* there's propane-heated reefers....lotsa Amish and RV dealers about here ;) If ther'd be a no power/heat unit; that would be tthe cat's cojones:D

capta 02-21-2014 02:18 PM

Re: Solar powered cooling
 
Quote:

Originally Posted by deltaten (Post 1443186)
Going a bit tangential; but what about the old, camper shell ammonia reefers?
I seemta recall that they took no power..were all gravity/ambient temp operated??
A co-worker had an old truck camper with what appeared to be an ice chest. Some old fella tuned him into what-was-what and all he needed was to turn it upside-down for a few days and it worked again!

Am I wrong in that rememberance? Is there suchan animal? I *know* there's propane-heated reefers....lotsa Amish and RV dealers about here ;) If ther'd be a no power/heat unit; that would be tthe cat's cojones:D

As mentioned above, ammonia was a pretty common refrigerant at one time. I ran a refer ship that had ammonia refrigeration and it was very efficient, but extremely dangerous.
I doubt that I'd want it in my boat, even in a self contained unit.
The best refrigeration system I've ever had was a propane refrigerator. Very inexpensive to buy, completely self contained (no cooling pump) maintenance free and it burned EXACTLY 20# of propane every 30 days. It was on a trimaran, which of course didn't heel much, but it functioned perfectly, even in the roughest of weather, deep sea. I would go back to it if I thought it would work on a monohull, but I doubt that it would. I do not understand why every room-a-ran out there does not use propane refrigeration. A shame indeed.

Torch 02-21-2014 04:07 PM

Re: Solar powered cooling
 
would the dehumidifier provide potable water? Is so, that would be a dual benefit.


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