Author Topic: Alternative Energy Cooling Systems  (Read 7867 times)

Offline flippydidit

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #30 on: November 17, 2012, 01:28:13 AM »
Part of the solution comes from the creation of large blocks of ice (to be stored in the "icehouse" section of the box).  As nightfall is generally the shortest part of the day, and is typically cooler (variable depending on location), the ice should be more than sufficient to provide continuous temperature reduction.

Sounds great on paper anyway!
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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #31 on: November 29, 2012, 07:42:35 PM »
I've thought about solar powered ammonia absorbsion method as well, it's been used in RV refrigerators for years.
Yes, there is a finite amount of ammonia & hydrogen used in these, but if kept outside the home and used to cool an intermediary circulated water tank....
Would add zero cost cooling supplement on hot sunny days and/or heat sink for a more efficient heat exchanger system with normal central air type systems.

Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #32 on: December 01, 2012, 08:36:02 AM »
An intermediate loop to cool water adds complexity and reduces efficiency, Oink.  If you're planning on then transitioning to cool air (like we're used to).  If you use the cool water to cool the concrete floor, or the walls, then it would be OK, I think.

If you're going to have the main unit outside the home, cool air can still exit the unit and go into the home.  You just need to insulate the outside unit.  It could be done.

The troubles with ammonia are why I am an advocate of using the Water-Bromide system.

Offline tkrabec

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #33 on: December 01, 2012, 10:10:41 AM »
why not just get a standard AC compressor, swap out the Motor for an Engine & power that off bio gas?  The other other blowers and such could be powered off Electrical or even large belts driven off the motor powering the compressor.

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Offline GomerPile

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #34 on: December 07, 2012, 02:14:21 PM »
I have looked into the AC thing for my off-grid house.  I decided to go with assloads of insulation, a small variable speed AC unit, and a small generator.  In hot weather you cool the place down and the insulation keeps it that way!  Remains to be seen how well that works.  I only have 30-60 cooling days per year in my location and my place is 350sf.

Another option I will play with at some point is using earth tubes to suck cool out of the ground to cool my place off.  Neat part is that it would provide partial heating in the winter.

Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #35 on: December 08, 2012, 09:36:10 AM »
I have looked into the AC thing for my off-grid house.  I decided to go with assloads of insulation, a small variable speed AC unit, and a small generator.  In hot weather you cool the place down and the insulation keeps it that way!  Remains to be seen how well that works.  I only have 30-60 cooling days per year in my location and my place is 350sf.

Another option I will play with at some point is using earth tubes to suck cool out of the ground to cool my place off.  Neat part is that it would provide partial heating in the winter.

Gomer, when it gets hot next summer, can you come back to this thread (hopefully not dead yet) and give us a report?  There is more than one way to skin this cat.

Offline Jeremy Downing

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #36 on: December 10, 2012, 07:15:28 AM »
I have looked into the AC thing for my off-grid house.  I decided to go with assloads of insulation, a small variable speed AC unit, and a small generator.  In hot weather you cool the place down and the insulation keeps it that way!  Remains to be seen how well that works.  I only have 30-60 cooling days per year in my location and my place is 350sf.

Another option I will play with at some point is using earth tubes to suck cool out of the ground to cool my place off.  Neat part is that it would provide partial heating in the winter.

This is a problem near and dear to my heart.  I love the south, but the heat can be dangerous at times.  In my opinion, the best solution for this is an earth-integrated home.  Four feet of soil and plants on the roof and a couple of walls and I suspect cooling will not be an issue.  Oh, and no electricity required for this solution.  The hobbits knew what they were doing.  :)

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Offline GomerPile

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #37 on: December 10, 2012, 09:27:48 AM »
Will do!

@Jeremy
I agree with the earth integrated home idea.  There is a place in my town that has 3 sides in the ground and their cooling problems are very minor and only on the hottest days.


Gomer, when it gets hot next summer, can you come back to this thread (hopefully not dead yet) and give us a report?  There is more than one way to skin this cat.

Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #38 on: December 10, 2012, 10:34:08 AM »
Awesomeness over the weekend: I found out that a friend who has a farm and lets me shoot out there has a GEOTHERMAL heating/cooling system! 

The system uses two wells (220 ft deep here in NC) and it's a closed-loop system; i.e., well water never enters the system, it only cools/heats the pipes.  The geothermal system pre-heats/pre-cools for his normal HVAC system.

He has seen huge improvements to his heating (electric) and cooling bills.

I am going to learn all I can about this system.  Maybe it will help us when we prototype our reversible cooling system, Nate.

Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #39 on: December 10, 2012, 10:35:46 AM »
Nate (flippydiddit), you might want to ask the moderator for a name change for this thread, so people can find it easier.

I suggest something like "Alternative Energy Cooling Systems" or something like that.

Offline Mexican_Hippie

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #40 on: December 10, 2012, 12:46:37 PM »
Awesomeness over the weekend: I found out that a friend who has a farm and lets me shoot out there has a GEOTHERMAL heating/cooling system! 

The system uses two wells (220 ft deep here in NC) and it's a closed-loop system; i.e., well water never enters the system, it only cools/heats the pipes.  The geothermal system pre-heats/pre-cools for his normal HVAC system.

He has seen huge improvements to his heating (electric) and cooling bills.

I am going to learn all I can about this system.  Maybe it will help us when we prototype our reversible cooling system, Nate.

I definitely want to hear about that.

Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #41 on: December 18, 2012, 11:52:26 AM »
Another solar-powered ice maker.  This one uses ammonia absorption, and is a reversible cycle like we've been talking about here (not a continuous cooling cycle).

http://www.wired.com/wiredscience/2008/11/solar-rig-bring/

Offline inconel710

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #42 on: December 18, 2012, 02:28:45 PM »
Wow - I haven't thought about Lithium Bromide systems since Navy Machinist Mate "A" School.  Here's the Navy's rate training manual that includes LiBr systems:

http://books.google.com/books?id=U3meFxPQt2oC&q=bromide
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Offline backwoods_engineer

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #43 on: December 20, 2012, 10:44:35 AM »
Wow - I haven't thought about Lithium Bromide systems since Navy Machinist Mate "A" School.  Here's the Navy's rate training manual that includes LiBr systems:

http://books.google.com/books?id=U3meFxPQt2oC&q=bromide

Thanks, inconel.  (Nice metal to name your nic after  :D)

Do you have experience maintaining those systems?  Would you be willing to give us some advice on a prototype?

Offline inconel710

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #44 on: December 20, 2012, 03:16:24 PM »
Sorry, only exposure was "A" school book lernin!  Only refrigerant plants I personally saw were Freon cycles.  I do remember the old salts would sometimes pine for the older, simpler bromide plants, but that's about it.
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Offline flippydidit

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #45 on: January 01, 2013, 03:40:58 AM »
Nate (flippydiddit), you might want to ask the moderator for a name change for this thread, so people can find it easier.

I suggest something like "Alternative Energy Cooling Systems" or something like that.

Moderators, I'd like to request a title change to this thread.  Backwoods_Engineer made a great point.  Could we have the title changed to "Alternative Energy Cooling Systems"?  Thank you!
Nate
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"One of these centuries, the brutes, private or public, who believe that they can rule their betters by force, will learn the lesson of what happens when brute force encounters mind and force."
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Offline flippydidit

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Re: Alternative Energy Cooling Systems
« Reply #46 on: January 22, 2013, 10:30:40 PM »
Backwoods_Engineer, I read the article you posted about the one developed for South America.  It was fairly vague, and the link they provided to the design was broken.

Tell me more about the Lithium-Bromide or Bromide-Water system you're in favor of.  I'm not familiar with the pros or cons for those.  I'm not a chemist and usually rely on my chemist friend down here.  He's the one that said the ammonia system I drew up was very workable.

In other news, I'm working on getting an insulated 40ft. shipping container to start with.  I wanted to start with a 20ft. container, but the 40ft. kind of fell into my lap.  As long as my plans continue undisturbed, we should be able to build this system while I'm home in April.  We'll have the supplies, and the funding to do a complete build without interruption.  Hopefully before that starts we've worked out different design ideas and picked one that will work best.

Let me know your thoughts!
Nate
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"One of these centuries, the brutes, private or public, who believe that they can rule their betters by force, will learn the lesson of what happens when brute force encounters mind and force."
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Offline backwoods_engineer

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Re: Alternative Energy Cooling Systems
« Reply #47 on: January 24, 2013, 03:34:12 PM »
Benefits of Lithium Bromide/Water system over Ammonia/Water:

- No ammonia to leak
- No hydrogen required in system
- Hot-side temperatures closer to what could be achieved in home solar heating panel
- Cold-side temperatures compatible with well-based cooling
- Can be run in "batch" mode as opposed to continuous loop; ammonia water requires some tricks to do this (see IcyBall)

LiBr isn't as efficient as the Ammonia system, though.

Offline nkawtg

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Re: Alternative Energy Cooling Systems
« Reply #48 on: January 24, 2013, 05:06:50 PM »
Lithium Bromide is hazardous though. Refer to the MSDS:
http://www.sciencelab.com/msds.php?msdsId=9927560
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Offline mangyhyena

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Re: Alternative Energy Cooling Systems
« Reply #49 on: February 23, 2013, 01:59:24 PM »
What about using homemade methane to run an absorbsion chiller?  What size digester would it take to make enough methane to supply that, do you all suppose?  Maybe use the methane to run it on hot nights?

Not directly solar powered, but inline with the spirit of free fuel, it could be used as an active backup for the solar air conditioner, and the methane can fuel other things as well.

Offline backwoods_engineer

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Re: Alternative Energy Cooling Systems
« Reply #50 on: February 23, 2013, 02:21:45 PM »
Interesting thermal-mass air-cool thread going on elsewhere that may be relevant to this project:

http://thesurvivalpodcast.com/forum/index.php?topic=41274.0;topicseen

Offline mangyhyena

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #51 on: February 23, 2013, 04:58:01 PM »
When I was designing a house five years ago I came upon the idea of a solar powered ammonia absorption air conditioner. There are some models available for residential use, but they rely on electricity or gas to heat the ammonia.

It's a small amount of ammonia, which if there is a leak it can be quickly mitigated with water.

You will need to come up with solution for night time use.

Does anyone have a link to a residential absorption air conditioner that uses gas?  I'd like to see the specs and try to figure out if a residential sized methane digester or two could supply enough fuel to power an air conditioner that runs on gas.  Refrigeration (absorption type) & air conditioning sans the grid or fossil fuel would be really nice.

Offline dhvsfan

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Re: Alternative Energy Cooling Systems
« Reply #52 on: May 16, 2013, 11:37:24 PM »
Not sure if this will help you but you can go to www.roburusa.com.

From their webpage:

Integrated solutions for
 Heating, Cooling and DHW production
 with Absorption Heat Pumps
 fired by Natural gas + Renewable energy:

Offline Insidious

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Re: Alternative Energy Cooling Systems
« Reply #53 on: May 17, 2013, 12:49:13 PM »
I didn't see links for..
The Einstein refrigerator
or
some modern updates


The selling point on this design is that even though efficiency is low.. it has no moving parts, and the ammonia is permanently sealed inside the unit. So in theory you could build one that would still be cooling away 100 years from now..

 :)

From a safety standpoint.. how about putting the mechanism over an in ground pond/tank of water in a ground depression?


The whole entropy thing is a bitch.. its easy to release or lose energy (heat) but hard to store/remove it (cool).
« Last Edit: May 17, 2013, 01:08:37 PM by Insidious »
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Offline GomerPile

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Re: I'm going to piss Jack Spirko off! Heehee.
« Reply #54 on: July 10, 2013, 12:41:11 PM »
Report on cooling the Bodega (www.tinyhomebuilding.com).  Its not 100% done yet, but I am working inside with nasty heat and humidity outside (90's).

I installed a 5000btu window air conditioner that I pickes up at Lowes for $119.  It runs off a Honda EU2000i generator without any trouble at all.  At this point the walls are at R39 and  the roof is at R58.  Its 14x18 feet inside with a loft and 15ft ceiling over half the area.  All the inside walls are covered in drywall and in the processing of being mudded (man I hate drywall work).

I ran the AC for about 4 hours one day and had the place feeling like an ice box.  The upstairs loft was much hotter than the first floor...I hope to even things out with a ceiling fan.  The next morning, it was still noticeably colder than the outside air temp.  I did not feel the need to run AC again until 2-3 in the afternoon.

Based on my very unscientific testing, I think this is going to work out very nicely.

Gomer, when it gets hot next summer, can you come back to this thread (hopefully not dead yet) and give us a report?  There is more than one way to skin this cat.

Offline flippydidit

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Re: Alternative Energy Cooling Systems
« Reply #55 on: May 25, 2014, 07:56:25 AM »
Backwoods_engineer,

It's been a while since I've gotten back to this thread, and I was wondering if you'd put any thought into this project since then.  To update you, I've acquired a standard 20ft. shipping container.  Since I posted this thread as a reference in another thread, I figured I should try to get back onto this project.  Currently my job allows me to use any of the equipment on my off time.  It's a full-service machine shop, so I can fabricate any parts that we can't purchase.  Let me know your thoughts.
Nate
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CEO and Founder of PermEscapes
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"One of these centuries, the brutes, private or public, who believe that they can rule their betters by force, will learn the lesson of what happens when brute force encounters mind and force."
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Offline IKN

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Re: Alternative Energy Cooling Systems
« Reply #56 on: May 26, 2014, 09:59:16 AM »
Been a while since I've visited this thread as well. How goes the project ?
If still in the planning phase, here's a couple more thoughts.
Lithium Bromide absorbtion, although a viable option, has a few issues. The submarine I served on in the Navy had a Lithium Bromide refrigeration machine that I was trained on and operated so I know what I'm talking about.
The principle that a Lithium Bromide system uses is that water boils at a lower temperature under vacuum. It uses water as the refrigerant unlike an ammonia based system that uses ammonia as the refrigerant.
The issues:
1 cubic foot of liquid water at atmosperic pressure when boiled expands to 7000+ cubic feet of steam at atmosperic pressure. Since Lithium Bromide absorbtion systems use water as the refrigerant by absorbing heat into the water and boiling it under vacuum, the volume of space needed for the "chiller" section is rather large even though the Lithium Bromide solution is adsorbing the "steam" to maitain the vacuum, so to speak.
Lithium Bromide systems also require pumps. A vacuum pump to remove all the air, a refrigeant pump (water), and a bromide solution pump. Pumps require elctricity to operate though, admittedly, not as much as a normal hosehold A/C compressor for a comperable sized system.
The water/Lithium Bromide solution ratio is critical as well. Too much and the Lithium Bromide salts will come out of solution and rock up the system. Too little and it won't adsorb the "steam" enough to maintain the vacuum.
While Lithium Bromide systems work well, they require a lot of monitoring, maintenance, and a steady heat source.
On the other hand, an ammonia based system requires a heat source and a heat sink to operate. No pumps, no monitoring, no fuss.
If anyone would like a more detailed description of how a Lithium Bromide system works or an Ammonia based one, let me know.
BTW, what was the TSP episode you refered to in the original post ? I haven't heard it yet and would like to give it a listen.

Offline buenijo

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Re: Alternative Energy Cooling Systems
« Reply #57 on: July 18, 2014, 10:46:39 AM »
In many podcasts Jack states that solar powered air conditioning just isn't cost-effective/plausible/possible.  Well I didn't start off this apocalyptic science project to tweak his ear.  That's just the way it's heading.

I disagree. In fact, I have zero doubt that a/c can be powered by photovoltaics. There are many ways to go about this to optimize the results. In any case, a large PV array is necessary. Since the panels themselves are a lot cheaper than even the recent past, then it's a cost effective alternative in the off grid setting. The "secret" is to operate a/c primarily as an opportunity load on a large PV array to lessen or eliminate battery discharge. A small a/c unit can be operated directly off a battery after solar hours, but the bulk of the cooling load should be met while a large array is generating. Also, there are highly efficient a/c units out there that do particularly well. These include the split ductless "inverter" drive units with variable compressor speeds. These also have almost no motor surge current, so small inverters power these units nicely. They can operate at a wide range of cooling outputs with highest efficiency achieved at the low cooling loads which is ideal for when one desires to operate at night with battery power - but the same unit can show high cooling rates when the power from an array is available. There is also potential in hacked systems including assembling a DC a/c unit using a DC motor and automotive a/c compressor with fan coil units. That's an advanced, DIY project, but it's not rocket science. In that case, it could be a practical possibility and even cost effective if one can do away with an inverter and operate a brushed DC motor without a controller (direct battery power via relay).

Offline buenijo

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Re: Alternative Energy Cooling Systems
« Reply #58 on: July 18, 2014, 11:12:07 AM »
Folks, I recommend you stay away from lithium bromide. The main problem is its corrosive nature. Also, it's not easy to devise a good absorber using this substance. I know because I built a very small test unit using the stuff.

I recommend you all look into adsorption systems using water as the refrigerant and solid adsorbents like silica gel and zeolites. While these present serious difficulties as well, there is no problem whatever with corrosion. The main problem there is the high heat exchanger surface required to cool the adsorbent while it's adsorbing the water vapor, and heating the adsorbent during regeneration. Commercial units are using conventional finned copper heat exchangers by packing them with small beads of the material. I think a unit with a low cooling capacity and operating for long periods can work well and be fairly simple, but I do NOT recommend solar as a heat source. I think a biomass furnace used to generate steam might work - or even better using the steam exhausted from a steam engine to drive the unit to get electricity and cooling (and use the steam for heat during winter months).

I did brief testing on a small lithium bromide unit I assembled from scratch - I did this just to answer questions - it was not a useful unit. What I found that should interest anyone who wants to go this route is that establishing and maintaining a high vacuum on a small system is not terribly difficult. A trick I found was to use steam to help displace the air when drawing vacuum. So, I was able to pull out virtually all the air with a crappy vacuum pump by first putting hot water in the system, then drawing down the system at a low point since water vapor is less dense than air. It worked perfectly. I was able to chill the water to 30F (lower than freezing since I probably had some salt in the water that lowered it freezing point). In other words, there was a near perfect vacuum in the system even though I used a vacuum pump that can't get anywhere near that.

Now, ammonia is VERY promising for this application. However, getting that to work with a low temperature heat source is a lot MORE difficult than other systems. If someone is dead set on using solar heat as the driving energy, then go with silica gel/water adsorption. The best feature of ammonia is the ease in making the absorber, and one doesn't have to deal with a vacuum. It's possible to use a water column as the absorber where the evaporator connects to the base to bubble ammonia vapor into the column. As long as the water is kept cool, then it will work. A continually operating system used to maintain a modest capacity does not require much ammonia. Seriously, just a gallon or so will work. What is needed is a pressure pump to force the ammonia water solution from the absorber through a heat exchanger tubing coil placed in the furnace. The solution is partially vaporized, then pushed into the separator. The ammonia vapor leaves through the top of the separator and into the condenser, turns to liquid, then moves to the evaporator via the expansion valve. The weak ammonia water solution in the separator leaves at the base, should be used to preheat the rich ammonia water solution leaving the absorber, then the now cool water enters the absorber to take in the ammonia vapor from the evaporator. Note that with a high temperature heat source, it's possible to have a unit run without electricity by using the high pressure ammonia vapor from the separator to drive a micro expansion engine to force the pressure pump - however, it makes more sense to just use a small dc motor for very small units. NOTE: Can't use copper with ammonia - use steel tubing - use aluminum for the evaporator.

NOTE: I posted this primarily for interest. I think small vapor compression units are the way to go for off grid space cooling, and photovoltaics makes sense in most settings. A wood fueled absorption/adsorption cooling system might be practical if designed for a low cooling capacity and run for long periods, but the development costs would most likely be prohibitive. I'd like to see it, but I decided I'm not willing to risk the resources in its development.
« Last Edit: July 18, 2014, 11:24:03 AM by buenijo »

Offline buenijo

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Re: Alternative Energy Cooling Systems
« Reply #59 on: July 18, 2014, 12:00:24 PM »
Also, while I'm on the topic of off grid cooling systems, then I'll mention another possible approach. I've looked into wood gasification a great deal. The main problem with these is the fuel processing required. There is also the problem of low efficiency in the engine system at low outputs. The only practical system I've considered has to be a fairly large system operated at a high output. If the system can use fairly large wood chunks, and see high efficiency approaching 20% overall (20% of wood lower heating value converted to shaft work), then I think the following can work. The idea is to use the engine to drive several compressors directly to chill a large store of water contained in an insulated tank. The evaporator should be contained within and surrounded by a water/glycol solution. Containers of water should be placed within. The idea is that the evaporator chilled the water/glycol which does not freeze to avoid insulating the evaporator, then the water/glycol is indirectly heated by the water contained in the small containers. Eventually the water freezes, then the engine is shut down. The water/glycol remains cold as long as the water is not thawed. Yeah, this is an elaborate system, and I'm not necessarily advocating it - just pointing out another viable approach.

Of course, one might also use a highly efficient small Diesel engine to do the same, but I assumed the desire is to get away from commercial fuel sources. The COP of this kind of system would probably be around 2.5 - 3 if properly set up, and would benefit greatly from water cooling the condenser. It might also be operated at night when temperatures are cooler to help in cooling the condenser.