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  1. #1
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    Lightbulb crazy 3rd-world idea: aircon from small fridge



    Hello esteemed refrigeration engineers,

    I have an interesting MacGyver-style problem
    relating to refrigeration and air condtioning,
    and would like to dip into this incredible pool
    of theoretical and practical knowledge to
    see if it can...somehow...be made to work.

    BUT WAIT...READ ON BEFORE YOU RESPOND...

    In order to avoid triggering certain
    understandable and very reasonable instincts
    that you have, I need to set the scene first...

    Imagine for a moment that you are suddenly
    transported from your modern, highly professional
    world of precise measurements, refined,
    specifically optimized-for-purpose design,
    unbelievably thorough and conservative safety
    analysis, and high expectations for performance
    and efficiency, into a third world backwater where
    even the most basic resources such as refrigerators,
    aircon units, refrigerant, and spare parts are scarce
    luxuries.

    Picture yourself in a world where a 7000 BTU
    window aircon unit costs 6 months of a family's
    wages and is therefore unthinkable for them.

    In this world, everywhere you look, the locals
    have devised fiendishly clever means of keeping
    their old equipment working, and adapting old
    equipment to effectively do things no engineer ever
    imagined it to do. In this world, there are NO
    inspectors, NO liability lawsuits, and
    absolutely NO expectation that any technology
    will work for any significant length of time; instead,
    there is enormous gratitude any time any technology
    can be adapted to help people for any period
    of time.

    I live in a place like this in a backwater of
    rural Northern Thailand.

    My observation here is that aircon units in
    the 7000 BTU range which eat 600W of power
    cost upwards of $500, while used (but working)
    small 80-200 W fridges regularly cost $25.
    I have not seen any cheaper aircon solutions.
    I have not seen any evaporative/swamp
    coolers at all (presumably because they don't
    work at all in the humid climate).

    Many locals seek a way to cool one small room.

    My question is:

    If you only had access to small fridges and wanted
    to cool your room, how would you go about it?

    How can one rip apart a fridge and MacGyver it up,
    perhaps with an electric fan, into a device to cool
    the air? Is there a better way to do this?

    What are the theoretical issues of this? Is there
    anything fundementally different about a fridge's
    compressor/refrigerant/condenser specs compared
    with those of an air conditioning unit, other than
    simply the BTUs, that would prevent this from
    working? If a small fridge's compressor were
    running all day instead of intermittently,
    would it burn out?

    What about mechanical and practical issues?
    I am assuming (correct me if I'm wrong) that
    the condenser coil would have to end up outside
    the room, while the evaporator coil (or freezer
    tray!) would have to be inside the room with
    warm air blowing through it. After disassembling
    the fridge, can its coils and tubes be "bent" into
    some appropriate shape without causing those
    coils to break or lose their proper charge? Or, is
    there a way to do it on a typical small fridge without
    bending the copper tubing?

    There are some local repair shops here which can
    work on fridges, but "local" means a 4 hour bus ride
    away, and "repair" is primitive at best. If AT ALL
    possible,we are looking for a procedure that a non-
    fridgie can do. If it takes a LOT of labor, that is
    NO problem--labor is almost free. If it takes a lot
    of troubleshooting and trial and error, no problem.
    If it takes any specialized expensive equipment, it is
    instantly out of range.

    All the fridges I have seen use R12 and are of the
    "hermetic (the motor & mechanical parts are sealed
    within the case)" type, not belt-drive. I can provide
    a typical photo of the compressor setup if it will help,
    and I will be happy to research any other data points
    you need. I am not a fridgie so please explain any
    stats that you need.

    Remember--LOW expectations. Anything you can
    provide, any little improvement, will be met with
    nothing but appreciation, for the alternative is
    nothing at all.

    Let me give you some perspective: when you
    have a flat tire here, you pull over to the local
    "ba yang," where some old guy fires up a tiny
    concrete cooking barbeque (the same one he
    uses to make super-tasty barbequed pork
    satay), heats up a chunk of rubber from someone
    else's old tire in a homemade iron press tool
    resembling a nutcracker, clamps and melts the
    "patch" into your tube with satisfying hiss,
    you pay up to 10 baht (25 cents US), and you're
    off for another few weeks/days before it happens
    again. Some people patch their tubes 10-20 times
    before they feel it's necessary (or can afford)
    to replace them. They are grateful that
    "ba yang" are so ubiquitous and helpful.

    Looking forward to some great ideas, or at least
    some clear explanations of the limits of the idea!

    Thanks!



  2. #2
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    Re: crazy 3rd-world idea: aircon from small fridge

    I suspect your question is a good one, but you have over-explained your dillemma.

    Copper can be bent.
    A refrigerator can condition air.

    Having explained your environment, you can ask a specific question and get some good answers.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Having explained your environment, you can ask a specific question and get some good answers.
    Well, these are my specific questions from the post:

    How can one rip apart a fridge and MacGyver it up,
    perhaps with an electric fan, into a device to cool
    the air? Is there a better way to do this?

    What are the theoretical issues of this? Is there
    anything fundementally different about a fridge's
    compressor/refrigerant/condenser specs compared
    with those of an air conditioning unit, other than
    simply the BTUs, that would prevent this from
    working? If a small fridge's compressor were
    running all day instead of intermittently,
    would it burn out?

    What about mechanical and practical issues?
    I am assuming (correct me if I'm wrong) that
    the condenser coil would have to end up outside
    the room, while the evaporator coil (or freezer
    tray!) would have to be inside the room with
    warm air blowing through it. After disassembling
    the fridge, can its coils and tubes be "bent" into
    some appropriate shape without causing those
    coils to break or lose their proper charge? Or, is
    there a way to do it on a typical small fridge without
    bending the copper tubing?
    I am appealing to the experience of folks here
    to find problems with and suggest a design for
    this MacGyver task. Your post is a start!
    You said:

    Copper can be bent.
    A refrigerator can condition air.
    Does the first part mean that one should be able
    to (carefully) bend the copper tubing of an
    already-charged fridge without causing it to
    discharge or otherwise break?

    Does the second part mean that the answer to
    my question is "no, there is no difference"?

    Are my assumptions about the placement
    of the two coils correct? Is there another way
    to do it that might be easier and involve
    less tweaking of the original fridge?

    As to the mechanical/practical issues, I am looking
    for specific suggestions about how to rig up a
    disassembled fridge to make it a good air cooler.
    Since I am not a specialist in this area, possibilities
    that are obvious to you might not be obvious
    to me. For example, there could be many ways to
    blow air through -- a fan behind the freezer tray,
    unwind the evaporator coil and wind it around the
    grille of a fan, place a fan in front of the freezer
    tray and have it suck air, etc... I'll bet there's some
    easier, better way that I have not even considered.
    Maybe there's even some way that involves
    minimal disassembly of the fridge.

    My post hopes to get the engineers here
    thinking about a free-form design problem,
    as opposed to being a request for specific
    data on a formula or material property.

    Unfortunately, that means I can't give you
    super-specific questions as you may
    have hoped.

    Fortunately, free-form design is by far
    the most fun aspect of engineering!
    Hope that's okay for this forum.

    Thanks again.

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    Re: crazy 3rd-world idea: aircon from small fridge

    If you take great great care at dismantling it you can extract the whole cooling unit as one peice.

    Secondly insulate the chosen room very very well

    Set the condencer and comdressor where it will have much air flow perhaps even a fan

    gently bend the tubes into a air handler of any sort into the room of coice after this insulate it heavily.

    It will take it a long time to reach a cold tem in said room and will make the system work hard so cooling the compressor as much as possible will be wise.

    I my self made a water cooled air handler out of an old fridge evap and a larg card boad box that I ran tap water through the coil! works well at both dehumidifying anf cooling the small place

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    Re: crazy 3rd-world idea: aircon from small fridge

    Hi lsemprini

    The copper tubeing should be able to be bent with care without too much problem. Work slowly and gently.

    The evaporator section may be made from two sheets of aluminium pressed together into the shape of the ice box. Bending or straightening this may cause a breakage so be very, very careful.

    Thinking sideways for a minute..... if you can get the icebox section out of the fridge in one piece - good.

    Place it inside a well insulated box so that it becomes a small freezer box on its own. Now fit a fan to one end of the box, with a hole in the box, and an opening at the other end to let the cooled air out. Does that make sense to you? - Its's easier to draw than to write!!

    You may need to add some baffles of some kind to keep the air against the coldest part of the coil.

    Regarding the compressor; it should be able to run 24 hours a day without problem providing - it needs to be kept as cool as possible. An electric fan is good but obviously cost more to run. So, clamp some cooling fins to the compressor body, fit it inside a tube of some sort which is open at top and bottom. This will then act as a chimney using the natural draft effect to move cooling air over the compressor body.

    How are we doing so far?
    Brian - Newton Abbot, Devon, UK
    Retired March 2015

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    Re: crazy 3rd-world idea: aircon from small fridge

    Problem I see, 7000 BTU = 2000 W and is small, very small for a window unit, especially in humid climates and in poor or non-isolated rooms.

    So, a small fridge has perhaps a capacity of 150 W, so you need 10 fridges to do the job.

    It's like a Norway guy tries to heat his house with a lighter or a match.

    Don't forget also that the climate is very humid, so you will have a lot of latent heat to remove before the air wants to cool, or in other words, before you will notice a noticeable temperature drop.

    Second, the condenser was designed to handle a load on the evaporator of +/- 0°C (32°F). You will blow air over it much, much warmer. Can the compressor handle this and especially, can the condenser handle this very high load, again, in a very hot climate.

    Another problem, most of the evaporators of the cheap units are inside the covering, just behind the inner walls. These are mostly foamed in the isolation of the cabinet.

    If it's a plate evaporator, then it will be very difficult to bend it in another shape without leaking because the tubes are pressed in the plates.

    What's your job over there anyway because you write fluent English which seems strange for me.
    I was in your country in 1999 or 2000 to visit the factory of Mitsubishi Electric. (Phuket, Patong, Phi-Phi, Bangkok as far as I can remember)
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: crazy 3rd-world idea: aircon from small fridge

    How are we doing so far?
    Great! These are the just the kind of ideas
    I was hoping for. Thanks MG Pony and
    Brian_UK.

    Your description of the "small freezer box" makes
    sense but can you give me a little more detail on
    what you mean by:

    The evaporator section may be made from two sheets of aluminium pressed together into the shape of the ice box. Bending or straightening this may cause a breakage so be very, very careful.
    Do you mean aluminum foil or sheet material?
    By 'pressed together' do you mean that the
    two sheets sandwich the evaporator coil
    or something else? Having trouble picturing
    this.

    Regarding the compressor; it should be able to run 24 hours a day without problem providing - it needs to be kept as cool as possible. An electric fan is good but obviously cost more to run. So, clamp some cooling fins to the compressor body, fit it inside a tube of some sort which is open at top and bottom. This will then act as a chimney using the natural draft effect to move cooling air over the compressor body.
    MG Pony also mentioned water cooling the condenser
    coils.

    Here are my questions on this:

    From your posts, it sounds like you think the
    compressor might actually overheat and break if,
    say, the the compressor and condenser coils
    were just hanging out a window, open
    to the (warm to hot) outside air and slight breeze,
    but without any additional form of cooling
    such as a fan or water. Have I understood
    that correctly, or did you just mean that the
    system won't cool very well but the compressor
    is not likely to break? I'd like to get a sense
    of how 'tough' a compressor is and what causes
    it to break.

    I wonder if there might be some way to jerry
    rig the fridge's thermostat to make the
    compressor run all the time unless it reaches
    a dangerous temperature range?

    Next question is more theoretical:

    The fridge itself is already using the compression
    and expansion of a refrigerant to move heat to
    the condenser coils.

    You have suggested further refinements such
    as an outside fan or water stream to help the
    condenser shed heat.

    My question is: are these strictly additive?

    In other words, let's say the fridge by itself
    can cool the 90F air down to 70F. Then let's
    say I start cool water flowing over the condenser
    coils.

    Will the cooling power of the water REPLACE
    the work done by the condenser/refrigerant
    or ADD to it? Should I expect to get air that's
    still about 70F or much cooler than 70F?

    Put another way, will the compression and
    expansion of the refrigerant material add
    and subtract a certain number of degrees
    from the air temperature regardless of what
    the air temperature is (e.g. 90F -> 70F
    or 60 F -> 40F), or does the refrigerant
    have a narrow operating range, outside
    of which it is not able to further cool
    the air?

    Thanks much!

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    Re: crazy 3rd-world idea: aircon from small fridge

    Wow, this forum sure has a lot of moderators

    Thanks Peter_1, these are good points.

    As far as the capacity, I agree it's a long shot
    but I'll probably try to make one prototype just
    to see. Thanks for the calculations.

    I don't understand the theory well enough
    to know: if the system is underpowered to
    that extent, is it likely to cool the air
    extremely slowly or not at all?

    Quote Originally Posted by Peter_1
    Another problem, most of the evaporators of the cheap units are inside the covering, just behind the inner walls. These are mostly foamed in the isolation of the cabinet.
    Previously I had assumed that the entire evaporator
    coil of small fridges was wrapped around the freezer
    tray, as opposed to there being more parts to the
    evaporator coil elsewhere such as inside the
    fridge walls. I will have to check out some
    local units (with freezer trays) to see which way
    they are designed.

    Quote Originally Posted by Peter_1
    Second, the condenser was designed to handle a load on the evaporator of +/- 0°C (32°F). You will blow air over it much, much warmer. Can the compressor handle this and especially, can the condenser handle this very high load, again, in a very hot climate.
    Hey, that's my question .


    What's your job over there anyway because you write fluent English which seems strange for me.
    I was in your country in 1999 or 2000 to visit the factory of Mitsubishi Electric. (Phuket, Patong, Phi-Phi, Bangkok as far as I can remember)
    I am a software engineer by training and escaped
    the US for a bizarre but rewarding life in the Thai
    countryside. I am hoping that I can act as an
    (albeit non-expert) bridge of knowledge because
    anything I find out here I can convey to the
    local non-English-speaking technicians/monkey
    wrench types in the Thai language.

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    Re: crazy 3rd-world idea: aircon from small fridge

    I did this about 20 years ago when I'd just started as an apprentice. I got hold of an evaporative air cooler, the type that you fill with water or ice, gutted it & fitted a domestic fridge compressor, wound quarter tube inside a tube with a small fan on the end for the condenser with a hose that ran outside to exhaust the warm air & fitted a small evaportor in front of the existing cooler fan. It didn't work. As Peter said the compressor, condenser etc. need to to be sized for the job. A domestic fridge compressor is way too small.
    The only other way I can think of doing it using a domestic fridge compressor is to cool a large amount of water overnight (do you get cheaper overnight electricity where you are?) & then circulate that cooled water through some sort of heat exchanger with a fan during the day.
    Noah had to leave the dinosaurs behind as they would've sunk the boat.

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    Re: crazy 3rd-world idea: aircon from small fridge

    You realize you can use propan as a refrigerant? If you got a bunch of compressers and hook them paralell and us a mix of R600a & R-290 and then use a water chiller set up like Fill said.

    It can chill a room but it must be massively insulated and will take a loooooong time to cool, but once cooled it will make a nice temperary retreat from the heat.

    What I put in the picture there is get three fridge compressors make a large condencer that can be air cooled, then couple some fridge evaps togeather and use any type of silver bering plumbing solder. Thing will be horidly inaefficeint by most terms but will work, use propane and isobutane as the refrigerant to charge it fifty fifty mix by weight as this will be easier for you. Use a fourth compressor to vacuum the system out and break the vacuum with propane , do that a fiew times over.

    So for that all you need is 4 empty fridges, buntch of 3/8th pipe and 1/4 pipe, a drill, with 3/8 and 1/4th bits, tourtch, solder, pipe cutter, flare tool or punch (To widen tubes for soldering in odd ways), propane & butane, and lots of insulation or a mud brick room with 4foot thick walls and some more reading to learn the rest.
    Last edited by The MG Pony; 09-11-2007 at 08:01 PM.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Oh and hook like three cap tubes in peralel to increas the net flow for higher capacity.

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    Re: crazy 3rd-world idea: aircon from small fridge

    It's amazing how we take things for granted over this side of the world.

    Best of luck Isemprini and I hope it works out for you.
    If it was easy everyone would do it.

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    Exclamation Re: crazy 3rd-world idea: aircon from small fridge

    Be VERY CAREFUL about using propane or butane PLEASE.

    Things can go BANG if you make a mistake.

    Also a few points on refrigeration equipment that you may or may not know so apologies if I am repeating stuff to you.

    Inside the system must be dry, that means no air or moisture. Moisture will kill a compressor quickly, it will also block up thin pipes with ice, so, you don't want moisture.

    If you do break open a system then beware of the gas. It shouldn't hurt you directly but R12, R22 etc together with a flame will produce phosgene gas and that HURTS BIG TIME.

    NEVER put oxygen inside a system, it will mix with the oil inside and EXPLODE, it really will, no joke.

    Ideal situation is:-

    With system empty, use low pressure nitrogen bled through the pipework whenever you are brazing (soldering) a joint together. This will stop the formation of scale/oxides inside the pipe.

    Nitrogen at higher pressure can be used to pressure test the system after all the bits are stuck together.

    Release the nitrogen pressure and evacuate the system, yeah right he says... If you haven't got a vacuum pump then you could use a spare compressor to suck out any air/moisture from the system.

    With the system under a vacuum you can then add your refrigerant back into the system.

    Sorry to do this but a bit of Health and Safety was required before we go much further i think.

    Cheers
    Brian - Newton Abbot, Devon, UK
    Retired March 2015

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    Re: crazy 3rd-world idea: aircon from small fridge

    The fridge refrigeration system is a low temp system. I don't suggest using it for a high temp application (directly cooling the air) - the compressor will cr*p.

    Get a barrel of water and insert the evaporator into the water in order to form ice. recirculate the (cold) water from the barrel through some copper pipes (or a coil that you should be able to find from a gutted aircon) with a recirc pump. blow a fan over the cooled coils with the circulating cooled water running through it.

    That would be the most effective use of your fridge to cool air.

    First of all, for proper occupied space conditions - a 45degF coil is typical for 75degF at 55% relative humidty (comfortable). Any colder than that - your are wasting capacity on latent work (removal of water from air).

    Do what I say - and you may have some success. You can let the unit run overnight when the conditioned air is not needed, building up an ice bank, and essentially storing the energy. I don't know if the machine will keep up without stored ice, but you can double the capacity of the machine if you only need it to cool 12 hours a day - triple it if you need it only 8 hours a day - quadruple it if you need it only 6 hours a day, etc - by storing the work in frozen water when the need to cool air is not present.

    Do you have a water well on your property? Perhaps that water is cold - you can recirc that.

    Cheers!
    Last edited by herefishy; 09-05-2006 at 12:02 AM.

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    Re: crazy 3rd-world idea: aircon from small fridge

    OH!

    and if you're really good - you will adjust the freeze point of the (water) solution with antifreeze, glycol, or salt to lower the melt point of the water to about 10F - that would give you better coil tempertures - you might adjust the freeze point of the system in order to maximize the efficiency of the system without sacrificing capacity by obtaining unnecessarily low freezing temps.

    Good Luck!

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    Re: crazy 3rd-world idea: aircon from small fridge

    As we are knocking ideas around.What about using a Normal compressor fridge but wind the discharge pipe through a domestic Ammonia absorption Fridge were the heater normally fits, to get some free cooling.Hold on! I'm Off to the patent office.

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    Re: crazy 3rd-world idea: aircon from small fridge

    I think the idea of storing "cold" as ice and circulating it when needed is the best idea.

    Now, this thread reminded me of the time when someone in Survivor (a video system benchmark) improvised an evaporative "A/C" by using an empty coconut shell to fetch water from a nearby lake and pouring the water on themselves. Then they either relied on the wind or used some object as a makeshift fan.
    "If Hannah was an air handler, I would be a condensing unit so I could open her TXV and pump my refrigerant through her coils." - a HVAC friend of mine

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    Re: crazy 3rd-world idea: aircon from small fridge

    third world ,i understand the meaning. In most of our countryside,AC is a foreign language. In summer,it's very happy if have a electric fan. In winter, burn something to keep the essential temp. So the "free cooling "is worthy of endeavour to offer to 3rd world. I've heard that someone uses well water to cool room which consumes very little energy,it's not a bad idea. In some area, water evaporative cooler can offer cooing air for room AC. There is no real"free cooling" ,it depends what you pay for it Develop proper tech for 3rd world is a great work.

    regards
    LC
    I hear...I forget;I see...I remember;I do...I understand

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    Re: crazy 3rd-world idea: aircon from small fridge

    Hi,

    Here in the other side of the 3rd world we do not do crazy ideas like that.

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    Re: crazy 3rd-world idea: aircon from small fridge

    What about dig a deep well with pourus walls insert an air duct to just above the water.Use a fan to draw the air from the bottom.The wicking effect and evaporation of the pourus walls will produce cooling. Or with an outer pipe led on its side sealed at both ends with a water feed filled with water.An Inner pourus pipe Draw the air though it for evaporation.

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    Re: crazy 3rd-world idea: aircon from small fridge

    These are all great ideas! Keep 'em coming!

    Here are some thoughts I have on ideas I saw
    above, both the air-cooling and water-cooling
    ones:

    Butane and Recharging

    I myself will definitely be sticking to the options
    that don't involve silver soldering, recharging
    the refigerant, etc...but I can certainly pass on
    any ideas in that category to any folks here
    who actually have tanks of nitrogen, torches,
    etc!

    Blowing Air Through the Evaporator Coils

    In the category of cooling the air directly with
    the fridge's evaporator, many of you are
    doubtful that the amount of cooling offered
    would be at all useful (or that the compressor
    would die if it were). Fair enough.

    It occurred to me that it's not actually
    that hard to try and could be done without
    disassembling the fridge at all. Refining
    ideas from 2 posters above, one could:

    1. take a typical cube-shape dorm fridge
    that has a freezer tray,
    2. place it in a window with the
    condenser coil and compressor sticking
    outside
    3. seal the whole window area around the
    fridge (as well as the rest of the room!)
    4. remove the door of the fridge
    5. replace the door with a thick, door-sized
    piece of wood, sealed around the edge of the
    fridge opening with weatherstripping or
    the rubber gasket from the original door.
    the piece of wood has one hole (say 4 in diameter)
    about where the freezer cabinet is, and one hole
    (say 4 in diameter) lower down.
    6. blow the warm air from the room into the top
    hole (e.g. with a short corrugated duct pipe going
    up near the ceiling, and a blower)
    7. place some sort of baffle inside the fridge
    that forces that air to move over the freezer
    tray before it can escape out the lower hole.
    perhaps augment the freezer tray with
    fins (gee just like the 50s).
    8. theoretically cool air will come out the
    bottom hole.
    9. theoretically the compressor will be
    running continuously
    10. see if the compressor gets very hot and
    if so rig up some kind of air or water cooling
    mechanism outside.

    This method has the advantage that we don't
    have to take apart the fridge, and we can take
    advantage of the fridge walls' insulating properties
    to keep the outside heat out.

    This method also gets around the problem one
    poster mentioned--that many cheap fridges have
    some of their evaporator coils embedded in the
    fridge wall and are hard to get out.

    Freezing Water with the Evaporator Coils

    In the category of using the fridge to cool
    water and then blowing air over copper tubes
    or a grille full of the cool water, a similar,
    slight refinement of an above idea occurred:

    1. start with any fridge that has a freezer tray
    2. place it in a window with the
    condenser coil and compressor sticking
    outside
    3. seal the whole window area around the
    fridge (as well as the rest of the room!)
    4. find the largest bucket you can that fits
    inside the fridge
    5. fill the bucket with water [optional: put
    in antifreeze, glycol, or salt for better chillin']
    6. place the bucket inside the fridge such that
    the freezer tray is submerged in the water.
    this may involve slightly bending the freezer
    try and evaporator coils wrapping the freezer tray,
    or finding a wacky-shaped bucket.
    7. now rig up a small circulation pump that pumps
    water out of the bucket, sneaks through the
    insulation of the fridge door, leads to
    a copper coil or grille attached to the front
    of a fan sitting right on top of the fridge,
    and then sneaks back through the
    fridge insulation to empty back into the bucket.

    This is essentially a fridge-powered version of
    this very funny college-dorm budget aircon unit:

    http://www.eng.uwaterloo.ca/~gmilburn/ac/

    The advantage of this is, again, there is no
    need to disassemble the fridge (much ) and
    we can use the fridge's insulation to perhaps
    keep the ice cold longer if we intend to
    "store up ice" overnight and then use it
    the next day.

    One slight problem might be if the entire bucket
    freezes and there is no water to circulate!

    Why is the water-based solution better?

    There is a more general matter though that
    I was hoping the engineers here could explain:

    At an intuitive level there's something odd about
    the water-based solution: assume for the moment
    that we do NOT store up ice when it's cool
    out, and only run the system when it's hot out.

    It seems like any time we add more mechanism
    between the evaporator coils and our air, we're
    just going to add heat and waste potential cooling
    (from 2nd law of thermodynamics). If the
    compressor would die if we tried to blow warm air
    past the evaporator coils, then that means
    either a. the compressor would ALSO die with
    our water-based solution, or b. our water-based
    solution must cool much less effectively than
    blowing the air right over the evaporator coils.

    Have I missed something here? Is there something
    magical about going via water/ice that makes
    the water-based solution overall more effective?
    Something about the operating temperature ranges
    of the components involved? I'd like to understand
    this better.

    Does the water-based solution ONLY make sense
    if we also take into account the ability to
    "store up cold" overnight? Or would it offer benefits
    over an air-based solution in either case?

    Wells, underground tubes, and thermal mass

    As to using the thermal mass of the ground
    to cool (e.g. via a well or underground pipes),
    yes I have also considered that and of course
    it's always good not to require electricity for
    cooling! Some, but not all, folks around here do
    have wells.

    I hadn't pursued that avenue much because
    I was assuming that the cooling ability
    of well water would always be significantly
    less than that of a fridge (which in turn
    would be significantly less than a real aircon
    unit), but please correct me if I am wrong
    there!

    --

    Thanks again, keep the cool ideas coming!

  22. #22
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    Re: crazy 3rd-world idea: aircon from small fridge

    When you are cooling a mass of water overnight you are basically storing energy in the water, the same as storage heating but in reverse (ok guys I know you've actually removed energy from the water but this makes it easier to understand). The domestic fridge compressor is not powerful enough to cool the air directly (it will a tiny amount but not enough to cool a room sufficiently) but it can slowly cool an amount of water given time (overnight). That stored energy can then be used during the day by running the cooled water through a fan-assisted heat exchanger by day when it's needed. As someone else said you could make it even more efficient by using glycol & cooling it below the freezing point of water. That way it would still be fluid & be able to be circulated & yet be colder than using just chilled water alone.

    Quote Originally Posted by lsemprini
    These are all great ideas! Keep 'em coming!

    Here are some thoughts I have on ideas I saw
    above, both the air-cooling and water-cooling
    ones:

    Butane and Recharging

    I myself will definitely be sticking to the options
    that don't involve silver soldering, recharging
    the refigerant, etc...but I can certainly pass on
    any ideas in that category to any folks here
    who actually have tanks of nitrogen, torches,
    etc!

    Blowing Air Through the Evaporator Coils

    In the category of cooling the air directly with
    the fridge's evaporator, many of you are
    doubtful that the amount of cooling offered
    would be at all useful (or that the compressor
    would die if it were). Fair enough.

    It occurred to me that it's not actually
    that hard to try and could be done without
    disassembling the fridge at all. Refining
    ideas from 2 posters above, one could:

    1. take a typical cube-shape dorm fridge
    that has a freezer tray,
    2. place it in a window with the
    condenser coil and compressor sticking
    outside
    3. seal the whole window area around the
    fridge (as well as the rest of the room!)
    4. remove the door of the fridge
    5. replace the door with a thick, door-sized
    piece of wood, sealed around the edge of the
    fridge opening with weatherstripping or
    the rubber gasket from the original door.
    the piece of wood has one hole (say 4 in diameter)
    about where the freezer cabinet is, and one hole
    (say 4 in diameter) lower down.
    6. blow the warm air from the room into the top
    hole (e.g. with a short corrugated duct pipe going
    up near the ceiling, and a blower)
    7. place some sort of baffle inside the fridge
    that forces that air to move over the freezer
    tray before it can escape out the lower hole.
    perhaps augment the freezer tray with
    fins (gee just like the 50s).
    8. theoretically cool air will come out the
    bottom hole.
    9. theoretically the compressor will be
    running continuously
    10. see if the compressor gets very hot and
    if so rig up some kind of air or water cooling
    mechanism outside.

    This method has the advantage that we don't
    have to take apart the fridge, and we can take
    advantage of the fridge walls' insulating properties
    to keep the outside heat out.

    This method also gets around the problem one
    poster mentioned--that many cheap fridges have
    some of their evaporator coils embedded in the
    fridge wall and are hard to get out.

    Freezing Water with the Evaporator Coils

    In the category of using the fridge to cool
    water and then blowing air over copper tubes
    or a grille full of the cool water, a similar,
    slight refinement of an above idea occurred:

    1. start with any fridge that has a freezer tray
    2. place it in a window with the
    condenser coil and compressor sticking
    outside
    3. seal the whole window area around the
    fridge (as well as the rest of the room!)
    4. find the largest bucket you can that fits
    inside the fridge
    5. fill the bucket with water [optional: put
    in antifreeze, glycol, or salt for better chillin']
    6. place the bucket inside the fridge such that
    the freezer tray is submerged in the water.
    this may involve slightly bending the freezer
    try and evaporator coils wrapping the freezer tray,
    or finding a wacky-shaped bucket.
    7. now rig up a small circulation pump that pumps
    water out of the bucket, sneaks through the
    insulation of the fridge door, leads to
    a copper coil or grille attached to the front
    of a fan sitting right on top of the fridge,
    and then sneaks back through the
    fridge insulation to empty back into the bucket.

    This is essentially a fridge-powered version of
    this very funny college-dorm budget aircon unit:

    http://www.eng.uwaterloo.ca/~gmilburn/ac/

    The advantage of this is, again, there is no
    need to disassemble the fridge (much ) and
    we can use the fridge's insulation to perhaps
    keep the ice cold longer if we intend to
    "store up ice" overnight and then use it
    the next day.

    One slight problem might be if the entire bucket
    freezes and there is no water to circulate!

    Why is the water-based solution better?

    There is a more general matter though that
    I was hoping the engineers here could explain:

    At an intuitive level there's something odd about
    the water-based solution: assume for the moment
    that we do NOT store up ice when it's cool
    out, and only run the system when it's hot out.

    It seems like any time we add more mechanism
    between the evaporator coils and our air, we're
    just going to add heat and waste potential cooling
    (from 2nd law of thermodynamics). If the
    compressor would die if we tried to blow warm air
    past the evaporator coils, then that means
    either a. the compressor would ALSO die with
    our water-based solution, or b. our water-based
    solution must cool much less effectively than
    blowing the air right over the evaporator coils.

    Have I missed something here? Is there something
    magical about going via water/ice that makes
    the water-based solution overall more effective?
    Something about the operating temperature ranges
    of the components involved? I'd like to understand
    this better.

    Does the water-based solution ONLY make sense
    if we also take into account the ability to
    "store up cold" overnight? Or would it offer benefits
    over an air-based solution in either case?

    Wells, underground tubes, and thermal mass

    As to using the thermal mass of the ground
    to cool (e.g. via a well or underground pipes),
    yes I have also considered that and of course
    it's always good not to require electricity for
    cooling! Some, but not all, folks around here do
    have wells.

    I hadn't pursued that avenue much because
    I was assuming that the cooling ability
    of well water would always be significantly
    less than that of a fridge (which in turn
    would be significantly less than a real aircon
    unit), but please correct me if I am wrong
    there!

    --

    Thanks again, keep the cool ideas coming!
    Last edited by phil68; 09-05-2006 at 05:11 PM.
    Noah had to leave the dinosaurs behind as they would've sunk the boat.

  23. #23
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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by lsemprini
    I was assuming that the cooling ability
    of well water would always be significantly
    less than that of a fridge (which in turn
    would be significantly less than a real aircon
    unit), but please correct me if I am wrong
    there!

    --

    Thanks again, keep the cool ideas coming!

    if the well water is <45degF - that is what you are looking for - ideal.

  24. #24
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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by herefishy
    if the well water is <45degF - that is what you are looking for - ideal.
    Herefishy, we did some drills and the temperature from 10m (30 ft) till 30 m (100 ft) is almost the same in teh wole world: 12°C (55°F), but still usefull for cooling.
    Make some holes and insert copper pipes in it and circulate on it with a pump through a coil.

    This will work better then a fridghe (which will never work)
    You asked: what will be the effect with the fridge...well...temperature in teh room will perhaps drop from 35°C(95°F) to 34.7°C (94.5°F)
    Does it cool?
    But, you will feel some cold coming out the fridge but the effect on the room will be zero. And I think it even won't drop, it will only dry a little bit.
    First thing you have to do if you only have a small capacity available is isolate the place very, very good.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  25. #25
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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by Peter_1
    Herefishy, we did some drills and the temperature from 10m (30 ft) till 30 m (100 ft) is almost the same in teh wole world: 12°C (55°F), but still usefull for cooling.
    Make some holes and insert copper pipes in it and circulate on it with a pump through a coil.

    This will work better then a fridghe (which will never work)
    Interesting.

    Can you make an estimate of how the temperature
    changes between the surface and 10m in a tropical
    climate? I wonder what the benefit in terms of
    degrees is for each additional meter that we dig down
    (and 2 meters of pipe that we purchase)? Is it
    roughly linear from the surface air temperature down
    to 12C at 10m?

    The reason I ask is: the cost of the pipe starts
    to possibly be relevant because for some reason,
    copper pipe here is crazy expensive (USD $1.32 per
    meter ($0.40/foot) for 10mm (3/8") od pipe) as
    opposed to about $0.38/meter for uPVC pipe.
    Galvanized is also much less than copper but I didn't
    check the price recently. I think the reason is
    that nobody has public natural gas or public potable
    water service here, so nobody has any reason to use
    copper pipe except for the "rich folk" with aircon!

    What other materials would work nearly as well
    as copper pipe? I can go check the price
    for them.

    How much worse would uPVC be than copper pipe?

  26. #26
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    Re: crazy 3rd-world idea: aircon from small fridge

    Ah, and here's question #2 about the undeground
    pipes:

    It's more of a construction question than an
    engineering question.

    Anyone have any good suggestions on how to dig a
    10m+ deep hole, big enough to fit two pipes side
    by side, without special drilling equipment?

    For those people who do not have existing
    wells, or whose wells are too shallow, I believe
    that the cost of renting out the customized
    well-finding and well-digging machines which
    periodically pass through town would be
    prohibitive.

    I am assuming, but haven't actually confirmed,
    that the technique of manually pounding some
    object like a metal pipe into the ground will not
    work after you get a few meters deep. But maybe
    there's some simple trick I don't know of to
    make this work.

    I haven't asked any locals here about this yet;
    for all I know they might have some cool
    technique involving bamboo and a coke can
    But I thought I'd ask the engineers as well.

  27. #27
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    Re: crazy 3rd-world idea: aircon from small fridge

    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: crazy 3rd-world idea: aircon from small fridge

    It's a bit more complex than that.You will have to go down to 10m with any pipe plastic would be best.Then at 10m you would need a coil of good thermal transfer pipe like copper.This will allow the warm water to tranfer it's heat before returning to the surface.If it was straight up and down the water would cool on the way down and warm up on the way up with no net effect.

  29. #29
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    Re: crazy 3rd-world idea: aircon from small fridge

    The size of the coil would depend on the amount of cooling you would require.Also other factors would be the heat transfer.The poorer the heat transfer of the ground or coil material the longer the pipe must be.If the ground around was pourus it may be posible to pump the water out the ground at the water table.Run that through a coil in the room and then dump the waste water into another hole or fields to return it to the water table some distance away.Try getting the temp of the water that comes from your nearest well and see if it is lower than ambiant it should be at least 5C lower to be any good.Would the well run dry if you tried to pump water out at a flow rate that the water leaving the room coil was equal to the room temp and let the waste run into another well metres away?You could experiment with two holes a distance apart down to the water table with a gravel filled trench running between to let the water flow.Cover the gravel with normal soil.pump water from one hole.let the waste down the other allow the water to flow underground through the gravel,cooling as it moves along underground, to be pumped up again.

  30. #30
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    Re: crazy 3rd-world idea: aircon from small fridge

    A Fresnel (pronounced fr-nl - or - FRAY-NEL) lens could help you to prevent pumping the guts out of that little compressor. All it takes is a little sunshine, caution, and experimenting. I can tell you where to get them for nothing.

    Email me some rough sketches of the rooms floor plan, with window dimensions and height off the ground, position of where magnetic north is at and the nearest city and I can then do some work in Rhino and possibly come up with some inexpensive solutions to use solar heat as your friend. You can move fluids with heat. Both Air and Liquids are Fluids.

    This is very do-able. Gosh, it makes me which I could get to Bangkok.

  31. #31
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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by cryptojoe
    A Fresnel (pronounced fr-nl - or - FRAY-NEL) lens could help you to prevent pumping the guts out of that little compressor. All it takes is a little sunshine, caution, and experimenting. I can tell you where to get them for nothing.

    Email me some rough sketches of the rooms floor plan, with window dimensions and height off the ground, position of where magnetic north is at and the nearest city and I can then do some work in Rhino and possibly come up with some inexpensive solutions to use solar heat as your friend. You can move fluids with heat. Both Air and Liquids are Fluids.

    This is very do-able. Gosh, it makes me which I could get to Bangkok.
    sounds intriguing!

    in general, how can one use the heat of the
    sun to cool (other than lots of expensive solar
    electricity panels which not even the rich folk
    can afford here)? what would one use the
    fresnel for? something to do with boiling water?

    this is potentially for many folks here in this
    mountainous region of northern Thailand
    including cities such as Mae Hong Son,
    Soppong, Pai, and Mae Malai.

    These cities are hard to find with Google Maps!

    Pai is at 19.3167N,+98.4500E, altitide 1597 feet.

    http://maps.google.com/maps?f=q&hl=e...99993&t=h&om=1

    for starters you could just assume some idealised,
    simple room/window conditions, to give us some
    idea of what you have in mind.

  32. #32
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    Re: crazy 3rd-world idea: aircon from small fridge

    Cryptojoe,there are some naturelaws you can't change which excists since the beginning of earth.
    But I'm eager to learn and listen.
    Because your idea is patented, provide us the the patent number and we can have a look.

    You ran out of DVD's, why not post a free link on the net

    Looked onc to your artist site, well...very nice made.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  33. #33
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    Re: crazy 3rd-world idea: aircon from small fridge

    Okay, when you turn on an AC unit some form of a pump comes on to produce pressure on a fluid. Pressure and temperature rise at a constant rate to one another. This is why it takes less electricity to cook using a pressure cooker.

    Here's an experiment you can try to prove this. Its a little trick I learned in the Army as a combat engineer which also proves that the suns core is ice.

    If you can still find a clean, metal 55 gallon drum/barrel, put a case of Pepsi or Beer in the bottom of the drum. Fill it to about 20 Centimeters from the top with water.

    Now find some old used motor oil nobody wants, enough to fill the rest of the barrel another 10cm or sop (its not an exact science experiment). Now put about 1 cm of gasoline on the top, and carefully set the gasoline on fire in a safe manner, like a long stick with a rag and lighter fluid on it.

    The gasoline will set the very high octane motor oil ablaze. This will take awhile so, sit back and watch, making sure nothing else catches fire.

    After it stops burning, reach down to the bottom and grab one of the drinks. You will notice it is ice cold, and should frost right over. Hurry and open it or else it may freeze!.

    How did that happen???

    Gasoline burns at a lower temperature, therefore it is a lower octane than motor oil. The motor oil then super heats the top of the water it is floating on, causing it to boil. As the steam is released into the oil, hydrogen and oxygen separate and feeds to fire even more.

    As the water rapidly evaporates, it gives off the latent energy stored in it. Heat is energy. The lack of energy is cold. So as the water gives off its stored energy (heat) the bottom of the water becomes cold.

    I'm sure there are very complicated or even simpler ways to describe this action. but even if you do not do this experiment, it simply describes how nature tries to balance things out, first by giving off the stored energy in your warm water (before you started the fire) and the reaction at the bottom of the barrel as the energy is sucked out of it.

    This is a simple demonstration of "Hot Side - Cold Side" principle of AC.

    Now, once you get a good grip on how to use heat, you can use this same principle to cool your home. There is a cooling effect to evaporating water. But it is limited to the relative humidity of the ambient air. In humid climates an air-conditioning unit cools in two ways, one by the cold air itself, the other by removing water from the air.

    If you need energy at the cheapest price available, always remember the term "Solar Thermal Dynamics."

    Does you community have a public library? If so, find if they have a book on Air Conditioning/Refrigeration they are both the same. If you understand why they work, you will better understand how to make the energy we call heat, work for you instead of against you.

    Also remember that one of the best places to find the parts you need for refrigeration can be found in the automobile junk yard. Compressors, collectors, condensers, tubing, orifice, its all there just waiting to be cobbled back together and given a second life, to be liberated and resurrected.

  34. #34
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    Re: crazy 3rd-world idea: aircon from small fridge

    I have got to try that at my next BBQ

  35. #35
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    Re: crazy 3rd-world idea: aircon from small fridge

    Ive just stumbled on this thread, very interesting..........

  36. #36
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    Re: crazy 3rd-world idea: aircon from small fridge

    Be warned Andy, I don't want your wife coming back and suing me if you blow yourself up. If you've ever deep fried anything and put water into oil and watch as it hydrogenates (makes snapping and popping sounds) stand back!!! Its not an exact science, its crude but it works.

    Mind you, the first time I did it was under the directions of a man 5 years older than me and fresh back from Viet Nam (right over there in Siam, that is next to Thailand). We didn't take out a tape measure and the last time I did this was way back in 1979 at the ripe old age 21, so, use caution. It does work for Texas Lone Star in the Long Neck bottle, but my proportions may be off a tad.

    As my attorney might (meaning I ain't practicing law without a license) say; "This information is provided for entertainment purposes only"

    ROFLMAO!!!!

  37. #37
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    Re: crazy 3rd-world idea: aircon from small fridge

    Hi,

    Quote Originally Posted by Peter_1
    Cryptojoe,there are some naturelaws you can't change which excists since the beginning of earth.
    But I'm eager to learn and listen.
    Because your idea is patented, provide us the the patent number and we can have a look.

    You ran out of DVD's, why not post a free link on the net

    Looked onc to your artist site, well...very nice made.
    For those reading this thread who are now
    as confused as me, Peter_1 was referring to
    this thread:

    http://www.refrigeration-engineer.co...ead.php?t=4706

    where cryptojoe introduces himself and says:

    I really don't want to be known as a Professional Inventor, inventors are like starving artists. Being on the back side of forty, disabled, ill health and so forth, I need a way to keep patents, copyrights on works and inventions; so, I formed a Nevada LLC (Limited Liability Company) with my wife and I as the principles.

    I call it Dynamic Earth because I deal primarily in Solar Thermal Dynamics. PV Cells will never pay for themselves as long as nothing more than 14% efficiency can ever be reached.

    I've produced an animated video I called "Energy Through Resource Reclamation." I'm running low on DVD's and will need to get another batch made up soon. I'll be sure to make some kind of an announcement when they become available again.
    cryptojoe, if you send me one DVD I can make an
    internet streamable movie file for you, which
    you can host on your website.

    in the meantime, after tempting us with that,
    what more can you tell us about a technique that
    might work in this remote environment?

  38. #38
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    Re: crazy 3rd-world idea: aircon from small fridge

    OK I understand,I'll stick to a fridge so I won't lose my eye brows . I can just see a fireman throwing cans of beer into a petrol fire somewhere before they put it out so they could have a chilled beer after.:-)

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    Re: crazy 3rd-world idea: aircon from small fridge

    You are miserably wrong on solar cells, now days the repay rate is oft less then ten years total energy is not only fully returned but continue to return 100% pollution free energy. I put too much energy in researching solar cells to allow such a claim.

    Links >
    Search terms "Solar Cell payback Data"
    Links:

    - http://en.wikipedia.org/wiki/Solar_cell (Basic explanation of current data )
    - http://www.csudh.edu/oliver/smt310-...n/pvpayback.htm < Dead link
    - http://www.ecotopia.com/apollo2/knapp/PVEPBTPaper.pdf (Download of PDF) < Works
    - http://www.ecotopia.com/apollo2/pvepbtne.htm < Works
    - http://www.greenbiz.com/news/news_t...FTOKEN=97796295 < Dead

    I really don't want to be known as a Professional Inventor, inventors are like starving artists. Being on the back side of forty, disabled, ill health and so forth, I need a way to keep patents, copyrights on works and inventions; so, I formed a Nevada LLC (Limited Liability Company) with my wife and I as the principles.

    I call it Dynamic Earth because I deal primarily in Solar Thermal Dynamics. PV Cells will never pay for themselves as long as nothing more than 14% efficiency can ever be reached.

    I've produced an animated video I called "Energy Through Resource Reclamation." I'm running low on DVD's and will need to get another batch made up soon. I'll be sure to make some kind of an announcement when they become available again.

    As for the barrel Idea it makes sense and when I have the time I will test it and will post the results

    Fixed quote = Upper part of peragraph got omited
    Last edited by The MG Pony; 13-05-2006 at 10:40 AM.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Have solar cell reached more than 14% efficiency? If so, this is a very recent development, and I stand corrected. I often forget about the recent rises in electrical prices which I suspect may have allot to do with lowered costs, unless production of PV's has increased.

    Don't get me wrong, I use solar cells to trickle charge my electric lawn mower. I am in the process of changing over many of my ambient lights to LED's which draw little power compared to a conventional bulb and could run my LED's, but the cost of the battery systems is a large drawback.

    Sorry for going way off topic and hijacking the thread.

    I'll check the links and give you many thanx for the reference materials.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by cryptojoe
    A Fresnel (pronounced fr-nl - or - FRAY-NEL) lens could help you to prevent pumping the guts out of that little compressor. All it takes is a little sunshine, caution, and experimenting. I can tell you where to get them for nothing.

    Email me some rough sketches of the rooms floor plan, with window dimensions and height off the ground, position of where magnetic north is at and the nearest city and I can then do some work in Rhino and possibly come up with some inexpensive solutions to use solar heat as your friend. You can move fluids with heat. Both Air and Liquids are Fluids.

    This is very do-able. Gosh, it makes me which I could get to Bangkok.
    So anyway, do continue cryptojoe --

    How can one use a fresnel lens plus the
    property from the barrel experiment to cool
    a house?

    Are you envisioning some kind of clear
    tube where the fresnel is used to boil
    water at one end?

    Let us know, thanks...

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    Re: crazy 3rd-world idea: aircon from small fridge

    (Solar cells have gotten to 26% and some rather insanely expensive ones have gotten 36% or so)


    Sorry for the lack of info guys twas insanely tired.

    36% is max theoretical Ideal situation with the current high end cells, not very applicable to this discussions context

    How ever the 26% is the Current high end applicable Cell rate, IE it is usable for the home owner.

    So in the end: 26% In Field use and currently mass manufactured

    36% Space and or Highly optimized situations and in the lab using the very tip of high end technology
    Last edited by The MG Pony; 13-05-2006 at 08:48 PM.

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    Re: crazy 3rd-world idea: aircon from small fridge

    "Are you envisioning some kind of clear tube where the fresnel is used to boil water at one end?"

    No, no! The barrel thing I discussed was meant to demonstrate the Hot End/Cold End principle, how cooling can be produced by very crude means.

    The reason for telling you about the Fresnel Lens was because I'm certain that you can find them manufactured over there relatively cheaply. You may even be able to pick them up used for nothing if you can find a television repair shop nearby.

    If you had a Fresnel Lens like the ones used in big screen projection television sets or the smaller ones used in flat screen TVs, you could set up a passive solar heater to assist in heating up the hot/high pressure side of your refrigeration unit and relieve some of the work on your compressor, thereby reducing your total electric consumption for the unit as well.

    Provided you supplied your snail-mail address in your reply to me, I will be sending a book written by a man who assisted an impoverished man and his family in Haiti to make a portable refrigeration unit mostly from scrap materials, that he now uses to make ice, and, thereby, make an income to support his family with.

    As I mentioned in my reply to your email, I am married to a Korean woman I met while serving inside the DMZ between the north and the south. I fully comprehend the poverty of a third world nation.

    However, compared to Haiti, Thailand is a paradise. At least you have a stable government, and currency.

    So, make sure to give me that reply with snail mail address, and you can expect some information you can sink your teeth into. You never know, if you are determined and work hard, you could wind up becoming a mogul of sorts in your own community. By asking questions here, you are definitely on the right track.

    When stationed in Korea as an Engineer, we had a motto that went like this:

    "We the willing, lead by the unknowing; doing the impossible, for the ungrateful; have done so much, with so little, we can calculate the day when we shall be able to do positively anything with absolutely nothing."

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    Re: crazy 3rd-world idea: aircon from small fridge

    Quote Originally Posted by cryptojoe
    "We the willing, lead by the unknowing; doing the impossible, for the ungrateful; have done so much, with so little, we can calculate the day when we shall be able to do positively anything with absolutely nothing."
    Sounds like the last contract I bid for

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    Re: crazy 3rd-world idea: aircon from small fridge

    It also sounds like an ex-bosses opinion of what we should have been able to accomplish in R&D.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Roflmao!!!

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    Re: crazy 3rd-world idea: aircon from small fridge

    It may be more efficient to go to the comercial equipment junk yard and find a few large machines which has been discarded and build one good one. If your lucky you may be able to find a fully working split system which someone has thrown out because the computer is unserviceable. The compressor and fans can simply be connected straight to the power supply.

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    Re: crazy 3rd-world idea: aircon from small fridge

    Friends,there could be another way of reducing the load on the fridge.
    I live in Thailand for last 6 months.Most of the people in places like SriRacha put on the air con for sleeping in the night.During the day it is mostly the table fan or padestal fan.

    Third world homes are not built for coling or heating.So let us not cool the whole building instad cool the sleeping place.If one can use the insulated cover instead of Mosquito net ,the space is reduced to let us say 6 X 5X 4 ft a volume of 120 cft.Typically in tropics the one tonne air con handles a 1200 cft room and two occupants.So we need a system 10 times smaller for the bed.say 120 btu/hr .The refrigerator will do the trick

    I have designed an AC bed for an indian TV show it may be aired in about two to three months.
    There is no need to cool tons of brick and mortar ,when all you need is removing less than 400 btu per hour (two peple sleeping)

    I am planning to offer the product as a "head borad Air Con"containing refrigeration system using automotive components and a refrigeration compressorhere in thailand ,it will cost less than damaging a fridge and experimening.May be made as akit that people can assemble DIY

    I am using an air to air heat exchanger to bring in fresh air and reduce the internal load by heat recovery
    Last edited by Darshi; 17-06-2006 at 03:52 AM.

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    Re: crazy 3rd-world idea: aircon from small fridge

    head borad Air Con"containing refrigeration
    Head board air conditioning strikes me as ingenious, Darshi. I would love to see some pictures or sketches of it someday. What automotive parts are you going to use, the evaporator and condenser?

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    Re: crazy 3rd-world idea: aircon from small fridge

    As a frequent visitor to Korat province (visiting again shortly after my visit to China even more shortly)I am well aware of the technologie problems and also the heat. Domestic fridges generally have a small, low starting torque motor due to the low evaporating temperatures of most domestic fridges.Trying to run this at high evap temperatures will eventually overload the motor. Rather than revamp a fridge to do what it was not designed to do.I would look at another method. Maybe putting a watertank in the fridge attached to a simple coil and fan with a pump, using the refrigerator to build a large icebank overnight and then recirculating water through the tank and coil to produce cooling.The cool condensate could be piped back to the tank to offset evaporation in the tank and therby reducing the cooling time needed to cool ambient water. Reinsulating the fridge with some cheaper local source EG saw or of granulated rice husks? maybe would reduce heat transmission through the cabinet and increase unit efficiency as would limiting air ingress and water vapourization. This will decrease the latent load and increase sensible heat transfer. Obviously the fridge would need to operate as as a freezer.

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