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Solar AC
Need THOUGHTS on a Solar air conditioner NON-Electric ??? | |
Ok this is my brilliant idea to use the concentration of solar HEAT specifically to motivate freon, now it may sound totally luney to use heat to make cool , but it is no less lunacy the efficiency of solar collectors to make electricity.
With solar you have a lot of HEAT, and the application of that
heat is going to be the most efficient.
Off topic example:
Its the same thing as why in heck does someone use Electricity For Heating, to cause heat with electricity you have to SHORT out the electrical line, seems very inefficient to me, when gas loves to burn and make heat.
So logially if you use the heat of solar energy to make steam or hot water or something that uses the HEAT aspect of it, it is very efficient.
But i live in california, and we have reduced consumption of power to a bare minimum, as we have to pay 20+cents per kilowatt when using more . after reducing the consumption to a minimum, the air conditioner itself is one of the Hugest power consumers, this heat pump also is very inneficent causing even more heat on the exterior of the house, even more than is "Heat Pumped" out of the house, so using a concentration of solar energy to heat freon which moves it to the expander inside the house, would take the Hottest times sun and make the house cool WHEN NEEDED.
Now i know your all saying this just isnt possible, how would heating something, make it cooler???
Well that is why this idea is a QUESTION not a finished though, for eons there have been propane refrigerators in mobile homes, how does this technology work?
i know freon can be expanded and move from heating, but i dont know how it is "checkballed" for movement to the expander, or how it is resivored.
The modern motorized freon movement system is very simple, pump freon with motor, how would i make one that moved freon via concentrated heat ??
I will be looking foreward to any ideas anyone has to put this into a testing capacity (small),
I realize it isnt for everyone, but i need air conditioning for my job doing video, and it is the largest consumer of energy here.
time to engage brain :-)
Vid_Pro
Energy FAQ
http://www.phact.or...skeptic/frenfaq.htm
Some good Q&A on solar-powered heat engines about halfway down the page [Dog Ed, Sep 04 2001, last modified Oct 21 2004]
Gas Refrigerator
http://www.mainerec...inegas/mgas02.shtml
I'm thinking that this would work similarly to a gas powered refrigerator. I couldn't find a description of how they work, so here's the next best thing. [mwburden, Sep 04 2001, last modified Oct 21 2004]
solar hvac in sacramento
http://www.hvacrnew...orials/2001greg.htm
do a 'net search on "solar hvac" and you will find many links. [mihali, Sep 04 2001, last modified Oct 21 2004]
How a propane Fridge works
http://www.betterpr...er_how_it_works.htm
Or doesnt, some say that in hot times ice cream melts in LP freezers, also as you can see it is actually HEATING up some place, my idea is to take the heat already there. [Vid_Pro, Sep 04 2001, last modified Oct 21 2004]
NREL Sand Diego Solar Availability Stats
http://rredc.nrel.g...book/sum2/23188.txt
[FloridaManatee, Oct 04 2004, last modified Oct 21 2004]
Typical Energy Requirements
http://www.mid.org/...ric/applian2002.htm
[FloridaManatee, Oct 04 2004, last modified Oct 21 2004]
solar cooling industrial
http://www.solel.com
the factory is on next hill from my village... [pashute, Oct 04 2004]
and another solar cooling solution
http://www.sunergy.se
And by the way UnaBu, trees Are ACs. Google for TREE COOLING RESEARCH [pashute, Oct 04 2004]
[link]
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And to add to that, i could have 4 more solar "tanks of freon, so as the sun moved from the appropriate collection area it strikes one of the 4 tanks the expansion is used to move the collection mirror assembly back into position. |
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if the propane refrigeration systems require Cycling, then as the freon made it to the right pressure the collector becomes covered by a single mirror (using the freon pressure again) stopping the heat going to it and therby cycling the unit. |
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Hello, Vid_Pro. I'd have to actually research this, 'cause I'm not an HVAC pro, but doesn't real air conditioning use a heck of a lot of energy recompressing the freon? I'm not sure you can extract that much energy from sunlight (or heat generated by sunlight). If it were possible in a cost-effective manner society would have gone solar long ago. |
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That said, I think you might be able to cut some from your AC bill. If you used photovoltaics to run a small water pump and a fan you might be able to design a solar-powered swamp cooler that would lower your workspace temperature quite a bit, leaving less work for the AC. I guess a swamp cooler adds a lot of moisture to the air, and you might not want that... |
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For tinkering purposes, call around to junkyards and HVAC shops to find an old air conditioner core or two. If you smear the fittings with an adhesive/sealant (Goop, by Eclectic Products, is one brand) then you can use hose clamps and a cheap garden hose to run water or whatever through the core (at pressures less than 70 psi or so, anyway) and test various ad-hoc setups. |
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You might look into the cooling strategy that the State of Arizona highway department uses for their roadside rest areas (beginning in about the mid-1980s). I remember seeing one of the sites, and the concept sounds crazy, but it works: The site has a tower of galvanized sheet steel, set up under the shade of an awning and positioned over the doorway. Apparently the shade encourages condensation (even in a desert climate), the water seeps down through filters made of corrugated paper, and the wind moving through the tower evaporates the water, which (because of its rapid expansion) cools whatever's next to it. Apparently the unit has no moving parts. Beyond that, I'm not up on how it works precisely (sorry), but I remember being pleasantly stunned by its functional elegance. (I just hope I reported it right.) |
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thanks for the link DogEd.
it kinda proves my point everyone trying to tranduce everything, transducers are so inneficient, i think if i can apply the principals of gas expansion to this project, i can take all that nasty energy OUT of my house :-) instead fo trying to run a poor efficency generator off of the movement of the gasses |
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yes it takes many amps to run the blasted electical freon pump i think the thing uses more power than 20 100w light bulbs now even without the added power use of the fan, luckily the house is highly insulated, and it isnt on for very long at any one time. |
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solor pannels operating the AC would be 5-12% efficient and it would take full coverage of the roof + to actually RUN an ac unit off of them 20-30,000 worth of electrical solar pannels + batteries and etc etc. |
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problem with solor pannels they dont last much longer than 5 years, an all metal tank and copper lines & chrome reflectors would last much longer. |
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i am willing to dedicate a 15foot round area to solar collection, i wonder how many BTU that would give me as a heating unit about 200 square feet of sun |
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swamp coolers are not an option in this case, video doesnt like them, also i have seen a few homes taken over by various elements due to high internal moisture. |
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WhatsBruin
how you explaind that system is totally understandable, aparentally even in the shade they have achieved condensation of water on the cooler plates , reading that is very interesting. |
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whatsbruin: it's called 'evaporative cooling'. many desert communities use it. |
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vid_pro: your ac unit uses "more power than 20 100w light bulbs" = 2 kilowatts. if you run it for an hour, at "20+ cents per kilowatt(hour, i'm assuming)" it costs you 40 cents? how does this affect your business? if your house is "higly insulated" and you ac isn't on for "very long" then your yearly cost to run the ac would be much less than the cost of covering your roof in solar panels (although many of us would agree that people living in the "sunshine areas" should be using solar power). |
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btw, solar hvac is already in use in sacramento. see link. |
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Una Bubba
Relative humidity here is not that high as we are not coastal actually we are inland just enough to have some of the highest highs and lowest lows.
the guage reads 40% relative humidity, but freon ac units reduce this even more, so i can get internal down to 30-35% relative, video storage is best at 40% and down. swamp coolers can raise reletive humidity to 60%+ |
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PeterSealy
were using the new lesser volitility freon in all of our vehicules now, i truely believe that relative to its volitility it is as enviromentally negative as the illegal kind. |
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Straight Ammonia used in propane fridges doesnt sound like an enviromental gift either :-)
hopefully any of this is a closed system just like your cars :-)
cars suffer from to many rubber seals and to much movement of the engine, so they naturally will leak more often, the houses i have been in have held thier freon for many more years. |
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Mihali
the ac unit when on is 6x the total consumption of the entire house, everything in the house is on motion sencors, all heat is gas powered, florescent throughout, all of the video equiptment running over 20 machines + two computers use a total of 500W.
Yearly costs for energy are now 1800$
reducing to smaller amounts over baseline would save $1000 of that per year, as baseline power usage is only 6c per KW. these figures include the 20% reduction from last year which were presentally getting a refund on.
as far as COST, we have already output VAST costs in florescent and led lighting, efficient monitors and refrigeration, motion sencors. all of it has eventually paid off.
if i used the power at WILL like i want to use it, we would be looking at 300-500$ energy bills right now per month, as some of my neighbors probably already do.
the house is a 6 bedroom |
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some of it is the Principal of paying for something that you never have own or get an advantage from, that is Business :-)
2-4$ per day, is a car payment add it up. |
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Elendilmir
the trees were wiped off the face of the ground to develop the areas housing, the Psudo replacement trees they installed after are trying the best they can, but it will be a few more years, Buying a good tree and installing it is 5-10,000$ each. |
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ALL
the idea here is that photovoltaic isnt efficient or inexpencive yet, and transducers are inefficient also, with thier inefficiencies output as heat usually, sure the present AC unit isnt on for long at a time, but we also have to suffer at times , myself i enjoy the heat, but the older people want the ac on, and the video would prefer it on.
The ineficiency of the electric heat pump actually is adding heat to the external enviroment way beyond the heat it removes from the house, so you could say that everyones ac units are just heating everyones air, the more they turn them on the hotter the air around the houses gets, the more they turn them on, sounds like a Stupid Loop. |
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even if a ammonia gas exchange unit had to be on all the time the sun was out, because it isnt as efficient as the Power Sucker a well done system could run continuously when the sun was out. |
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Your solar panels should last considerably longer than five years; they commonly have twenty year warranties. Some '60s ones are still powering satellites, IIRC. |
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Failing swamp coolers, I think pumping air through a pipe sunk deep into the ground would be your best bet. |
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hello_c has a point--some installations use the ground as a heat sink (better to use groundwater, but in your area I'm not sure that's possible). |
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But back to your main idea, using solar heat to drive a compressive cooling system: go for it. I can't quite visualize what you're design might be, but take a look at Stirling engines--a websearch on the term should turn up lots of sites. They run off heat differential and have been prototyped for commercial power generation but found wanting for some reason, I think cost-to-output ratio. Again, though, you'd be running the engine to power a conventional air conditioner, although through a direct linkage rather than generating electricity. |
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I've always wondered if you could put reflective Mylar on the inside of one of those big old-fashioned satellite dishes and make one heck of a solar concentrator. Could you get it hot enough at the focus to heat a boiler for a small steam engine? |
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None of this is really what you're after, is it. Sorry. I can't seem to get my mind around a way to harness the expansion of gas/liquid on the roof to directly cool the building without having all the compressors and tubing of a conventional AC unit. |
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[greetings and thanks to mihali for "evaporative cooling"]
It seems that what we're after here is a site-specific solution that not only finds a way to move warm air and cool air around but also tailors the building to (1) its work functions and (2) its thermodynamic environment. Maybe looking at the building itself as a total system (like a ship) would help. |
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If Vid_Pro's company can ease the HVAC load by changing some other aspect of the building (say, insulation or earth-sheltering), the modified building might eventually reach a point where existing solar-electric power systems could handle a significant part of its HVAC needs. Whether that could be done quickly enough or cost-effectively is another question. |
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Is there some way that you could combine certain requirements of the work (say, shelter from electromagnetic disruption of the video process and product) with the need to keep the interior shielded from excessive heat? |
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that would be totally cool, use the sun to move the gasses and the ground to cool the gasses prior to expansion.
but i bet the expansion has to be done gravity based as the propane fridges are all with the heat remover at the top and the expansion tubes lower than that. |
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and i am not putting a electric pump in or it would defeat the purpose of the idea, add bearings and everything. |
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which would mean the heat exchanger would have to be on the roof, as the expansion tubes now are in the attic. |
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there must be easier ways |
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What the warrenty is on fly by nite photovoltaic solar cells sellers doesnt have anything to do with the realistic time that solar cells have lasted in real situations, if people started replacing them in 5-10 years based on warrenties from the solar companies, they would just fold and reform, like anyone selling stuff that doesnt last. |
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<depressing factoid>Electrical solar panels take more energy to manufacture than they will ever give off in their lifetime.</depressing factoid> |
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RayfordSteele: Are you kidding? That is depressing. |
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bris, nope. True story.
The weird things you learn as a former solar car team member... |
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I'd use sunlight to heat water. Then use turbines to turn the steam into electricity. Cheaper and easier. |
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Hope I'm using this right. Thinking of using solar power to generate steam to turn a turbine - why not use solar power to heat something that evaporates at a lower temperature in a closed loop? Say, an alcohol? Would that be cheaper per watt than solar cells? |
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welcome, kallisti. is this not your field of expertise then? try a category more to your taste and I suggest you read the help page to your left under meta. |
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Yes I believe it could be done,first you will have to raise the pressure to say 150# heat ,wind powered pump etc,then this will have to be connected to a thermastic expansion valve sized for the tonnage you want,this will be run into your evaporator acoil ,after this it will have to go to some type of condensor, fan cooled ,water cooled then it must go to a container, this is where it gets to be a problem,now you have to somehow get this gas back into the first container or maybe the way to do this is to switch your heat source to this container, and by useing check valves or three way valve to isolate the freon switching the freon flow back to your expansion valve .this will have to alternate in order to keep a constant flow of freon and you will have to have safety pressure valves to release pressure to a seperate enclosed tank if need arises! |
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Here's a "free after initial cost ($$ & back-breaking work)" air conditioning system. Obtain as many "heat-exchangers" as you need (one room or whole house), (used car radiators w/attached 12 volt electric fans work great), copper water pipe, 12 volt water pump, solar electric system (panels, batteries, etc.), shovel. Install the radiators where cool air is needed (each room or in your existing HVAC system if you want to use the 120 volt fan). Run the copper water pipe from the radiators to the pump to outside. Now this is where it gets fun. Bury the water pipe underground to take advantage of the constant cool underground temperature. (How low you go and how much buried water pipe you should install depends upon your area and water table. Where I live, I hit ground water at 3-4 feet. You can bury your pipe in dry ground, but you'll need more pipe in the ground.) Once complete, you should have a simple circuit for the water to follow; from pump to underground pipe (ground absorbs heat and cools water) back into house to radiators (radiators absorb heat and fans blow cool air) to pump. With this system, you'll NEVER have to deal w/freon in your home. It always works. If you run out of 12 volt battery power, just run a wire to your car for pump & fan power. And you can tell those tree huggers that you are "greener" than they are! |
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Referring back to [Vid_Pro]'s original challenge: Yes something could be achieved. |
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It is difficult to drive a gas compressor with minimal physical or electrical transduction. This necessitates a chemical chiller or an evaporative system. There are commercial, but gas-fired systems on the market, but these use gas and electricity, respectively. Both systems are feasible on a home build-basis. |
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Chillers require a reagent, such as a bromide or nitrate, which could be dried out in the sun, under a transparent cover and when water is introduced, it cools rapidly. The drawback is the use of chemicals (and the FBI wondering why so much nitrate is being delivered to the suburbs). |
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Evaporative water coolers work well, using cooling from the evaporative process. The disadvantage is that you are at the mercy of the dew point and wind velocity. |
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Which to build? A chiller is potentially more ambitious, but is a great solution if you work during the day but want to chill the house in the evening. A passive evaporative systems would be my choice if the environmental factors suitable, the cooling requirements were modest and viewed as a bonus, rather than a necessity. |
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Also, be prepared to accept a very large collector array. The NREL's data (link) shows San Diego's average solar energy availability in the hottest months (April-September) is 6.3 kWh/m2/day for a flat panel collector. An efficient A/C will use about 2kWh per hour(link). At about 8 hours per day usage, that's about 16kWh per day. Assuming a conversion efficiency of an arbitary 10%, you will need around 25m3 per A/C. |
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I personally think it is a great Idea to convert Solar (Light) energy to Heat energy that could be used in refrigeration and Cooling systems(A/C). this can be very efficient in countries where there there is plenty of sunshine at least 300 days out of the 365 days. Basically we need to heat the freon by concentrating the light energy in such a way that the temperature (heat) is suffecient to compress the freon inside the closed loop system. The real challenge is that optimising the amount of light incident on the reflectors so that we can get the maximum heat consentrated on the tube. I guess we can achive this by motorizing the mirrors so that the focal length can be maintained to achieve maximum efficiency. I was also thinking if the tubes can be embedded on a black body material such as granite that not only absorbs heat but also retain heat (like an electrical capacitor) to deal with the variance in light intensity (due to cloud passing) etc. The efficiency of this system will depend on the following factors
1. The quality of mirrors (reflectors) and their placement in the system
2. The ability to maintain constant temperature across the length of the tubes and maximum heat transfer to the tubes. |
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The real important factor is the cost to build such an equipment. I feel if we all put our heads together this might turn out to be a low cost marketable product. I dis agree with many that it may not be economically feasible to many a computer was costing $200,000 40 years ago but we now have a decent computer for under $800. So it is not immposible and I srongly feel it is doable. |
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I strongly feel this system will be environmentally safe and also has the potential to save electicity. |
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I hope nobody minds, but I'm going to sidestep the entire debate and give [VP] some practical solutions. |
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1) Shade your A/C. You would be surprised how much more efficient you unit will become in the shade.
2) If that's not enough, use evaporative cooling. Rig a pump and water source to spray water directly on the coils while in operation. It will cost you some in water but will save a lot on electricity.
3) Improve your envelope. Make sure you have good overhangs on all windows (>2'). Install reflective roofing. Get double-pane, low-e windows (and install them correctly). Install weather stripping.
4) Reduce energy use inside. Any electricity used inside will be pumping heat inside. Use fluorescent bulbs. |
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It's much cheaper to reduce electrical use than install PV panels. |
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Now, back to the main issue. Yes, it's possible to achieve what you are aiming at. I think you'll find that you will need a lot of area of solar collectors and a good heat sink (such as a cooling tower or ground source cooling) to make it work. |
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I am new here and have been following your discussions. I will be going
back to school next year and spend 2-3 year only on solar powered ac and
refrigeration. |
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As worldengineer has said, rather prevent heat entering your house than
trying hard to remove it - the old saying : prevention is better that cure! |
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On solar refrigeration, look at these links |
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www.suntimes.co.za/2002/08/11/news/news17.asp
www.eta-awards.co.za/bradley.htm |
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www.monash.edu.au/pubs/eureka/Eureka_95/fridge.html |
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For those of you who like playing around with stuff like this, go to
www.knowledgepublications.com and buy the ebook "Sunshine to Dollars"
by Steven Harris. Its very practical and GREAT! |
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I see 3 methods to power the pump: (1) Use a stirling engien and conect it to a piston pump, (2) Hit a ( or a row ) of small tanks with 2 one way valves attached -
>_> - with the concentrated sunlight ( in on/off phazes - heat it up, gas goes into cooling-off loops, cools to *ambient*, goes through small hole (pressure goes down, temp goes down), goes into heating-up coils (cools house), reenters pump (because pressure is lower)) (3) put a expansion chamber around the pump, insulate from pump, "shoot" expansion chamber (perferable because it dose not heat pumped gas as much - smaller cool-off coils) |
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Or use a heat excanger with a swamp cooler - cool the air, have it flow over sheet of metal, have air flow over sheat of metal on other side ( inside ) ( heat goes into cold air ). |
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On the prime point of using heat to create cool, certainly such things are possible. But is it ecconomical? |
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Some methods stated above use an expander of some kind to react to being heated. The resulting mechanical force would in turn run a pump for ac or a fan for evap. But the effiency would be a ratio of the heat put to use, compared to the heat moved to effect cooling. |
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Hmmm, a jet engine is kind of like that. But is kind of unitised. Just a thought...back to my point. |
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Considering the source heat itself as free, well OK, then we have to look to the cost of setting all this stuff up. So how much do you save on power bills, putting all the investment needed to make a system work, and consider it's only good during daylight hours..? |
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I'll give you the thought that a viable wide use of solar will help drive the price of other sources downward. I consider that a hidden benefit of solar. |
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If you can come up with an AC augmentation-solar unit for less than $300 per room. People may well buy AC one room at a time. If it sells well, it's use may well keep our society liveable for an additonal 50 years! |
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Use a portable AC unit, close the door. No need to cool 6 bedroom house for your video work. A 1kW unit can handle 450sqft easily. |
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If you must go geek, use thermal reflective paint in the room to better retain your bought 'coolth'. |
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You'd need to cover your entire
building's roof to even get near to the
amount of energy required to power an
AC sufficient enough to cool down your
room. Besides having to reshingle your
roof, you'd have to be willing to dish
out thousands and thousands of dollars
for the solar panels that have only
enough capability to power one AC.
Also, you'd have to figure out how to
store that energy you've collected
during the day so you would be able to
use it at night. You figure out how to
get enough energy without covering
your roof in solar panels, how not to
spend thousands on a single AC unit,
and how to store solar energy, then I
think you've got a winner! |
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the answer, to me, seems obvious given the information you have posed, and your requirements. |
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hope you are still around to read this and give it a try, and prove me a dumbass. |
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you said you get the highest highs and the lowest lows? well, why not put those lows to work? |
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just install a huge water tank, or a few smaller ones, in your yard, and insulate them as best you can. |
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fill 'em up and try this: run two plumbing loops from the tanks, both returning water in a closed cycle. the first loop goes to a large radiator mounted outside (maybe from a truck), and the second goes into your home to a smaller radiator. both radiators have fans attached to draw air through them. |
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at night, run the outside loop to chill the liquid, as cold as you can get it (off peak rates are a bonus). |
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during the day, use the cool liquid to absorb heat from within your home. |
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nothing fancy, but i bet in an area with temperatures extremes, like yours, it would work well. |
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just as an aside, you could also build a thermal accumulator using rocks/metal/whatever, and duct air rather than using a water loop, but i think water would work best. |
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