07-30-16, 02:58 PM | #51 |
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The issue with adsorption chillers is initial costs and serviceability. If you go with a net metering scheme then it really doesn't make sense. If you are fully off-grid an absorption chiller might make sense, also if you had a good source of waste heat. It's a good idea, but the cost of PV and A/C equipment is so cheap that it's hard to justify. If you were to size a system you would likely have an oversupply of heat during the swing seasons along with a daily under supply of heat during the evening and morning. While PV won't have the peak efficiency as thermal collectors they produce usable power during "lean" heat times. PV still won't match the ultimate efficiency of solar thermal but PV producing more usable power and its price point makes solar thermal hard to justify.
The other point of serviceability, you'd be forced to use a commercial service firm if it breaks (or DIY), as a residential customer you would be a low priority for them if they would even talk to you. DIY might be fine for us but it would not be for the vast majority of homeowners. This for DIYers makes access to the knowledge base more difficult, and makes parts and components more expensive. |
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07-30-16, 04:56 PM | #52 |
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Really good info! I am looking into this now. I really wouldn't be that hard, if would for sure have to be DIY, but a large solar collector that is used for heating in the winter now doesn't have to not be used in the summer, you could use the extra to power a refrigeration cycle.
OR could you directly heat the propane (refrigerant) in a homemade high pressure solar collector with a check valve allowing flow only in the discharge direction? Would that create flow? I KNOW you could get it hot enough to make huge pressure differences.
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07-30-16, 09:28 PM | #53 | ||
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Quote:
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07-30-16, 11:03 PM | #54 |
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The hard part of that idea is creating suction. in a window-style phase change air conditioner, the compressor creates suction as well as high pressure. The suction is necessary to force a low evaporation temperature.
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07-31-16, 05:36 AM | #55 |
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Yeah, I was thinking something along the lines of a thermosphion.
The hardest design "area" is the suction port of the solar collector. Some how the pressure tank/solar collector must be at a pressure LESS than the suction pressure coming out of the evap. Or it must be FORCED into to solar collector with a pump. I'm thinking maybe 2 tanks, One can be the solar collector itself, the other right before the solar collector with a compressor stuck in between the two. The sun hit the solar collector cause the thermosphion to start and the unit runs until the pressures are equal (a safe psi shut off) then the compressor is run forcing the gas into the solar collector again..... I'll make some drawing.
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07-31-16, 11:56 AM | #56 |
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The thing with the thing you ponder is the "icy ball" cooler. Spent material is regenerated with heat and the high-temp, high-pressure gas is captured in a closed container. This container is either sealed and removed, or a valve is closed, when the heat source is removed. The pressure and temp of the sealed container drops, and the container becomes a "Heat vacuum" until all of the captured gas evaporates.
The next step in improving the process is eliminating moving parts. This is the Einstein Refrigerator design, which was the driving idea behind the RV fridge. They absolutely work, and last like the Energizer bunny. No moving parts in the refrigeration circuit, all it needs is a heat source above 150-175 degF to boil the weak solution. Various solutions can be used, the two most common are are anhydrous ammonia or lithium bromide and water. A third material is used to reduce the partial pressure of the working solution. This can be hydrogen, butane, propane, freon, etc. When building a DIY unit, the refrigerant circuit is evacuated and the vacuum is broken with this third material (just like a heat pump). The working solution is pumped in afterwards, so there is no non-condensing gas in the system. There you have it, run it like you stole it. The problem here is in the details. How much of what to charge the system with is important. As with the other technologies in this industry, details are well known inside the circle, but not easy to find outside it. Also, ammonia and lithium chloride/bromide are highly corrosive, so copper and brass fittings are not appropriate. Would-be innovators have been running into the regulation wall associated with underwriting and safety requirements, and most have not produced a unit that could be mass-produced or copied easily. Any members with experience in this realm of ammonia or lithium bromide chiller/freezer operation, please chime in here with details. There is an abundance of "eager beavers" posting sparse tidbits of design and fab data on the net, but not really anything resembling complete plans or parameters to begin with. I can think of no better place to aggregate this subject and help the "makers" out there get a heads up to begin assembling monsters in garages and shops at large. As always, pats on the back rule over financial rewards. Last edited by jeff5may; 08-02-16 at 09:27 AM.. Reason: grammar |
07-31-16, 12:10 PM | #57 |
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I am googling the terms you mentioned. I have access to a multitude of parts. And this really seems like an awesome idea. I am all for building and testing a unit, and tweeking the needed solution. A solar collector can easily hit 200F+.
https://en.wikipedia.org/wiki/Einstein_refrigerator https://en.wikipedia.org/wiki/Icyball https://en.m.wikipedia.org/wiki/Absorption_refrigerator http://peswiki.com/directory:closed-...mmonia-turbine http://www.fieldlines.com/index.php?topic=130778.0
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08-02-16, 10:19 AM | #58 |
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I found a really thorough article on an icy-ball style unit, abbreviated SAAR, done as a senior ME design project. The document includes a wealth of practical information, as well as a survey of the dominant intermittent solar refrigeration processes. It is obvious the prototype worked, as the team published charts and graphs describing operating data under typical observed conditions.
http://www.solaripedia.com/files/1113.pdf Another site to see is Energy concepts and the ISAAC system. Be sure to surf around, as the info is scattered on the site (like most commercial pages). http://www.energy-concepts.com/_page..._ice_maker.htm Here is a STEVEN build, with pics and bill of materials: http://www.free-energy-info.com/P13.pdf |
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08-02-16, 02:48 PM | #59 |
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Thanks for the links Jeff, those would for sure be more simple.
I have access to one of those large (12' diameter) smooth surface satellite dishes that I though of coating with mirror tape and building a solar tracker for. Other than needing flexible hoses to follow the tracking dish the design would be able the same. This is the perfect "grid down" way to keep things cold. I am still really struggling with the design of this whole thing, it was simple enough to just look at a hvac unit and put in parts where I needed them. There are not many examples to just look through..... But once i get over the learn curve I think I can do this rather quickly. http://crosleyautoclub.com/IcyBall/crosley_icyball.html http://www.motherearthnews.com/diy/a...z75sozgoe.aspx http://blog.modernmechanix.com/refri...-solar-energy/
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שְׁמַע יִשְׂרָאֵל ה' אֱלֹהֵינוּ ה' אֶחָד Last edited by MEMPHIS91; 08-03-16 at 09:16 PM.. |
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