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6592RE: [hreg] Solar powered A/C

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  • Kevin Conlin
    Jul 10, 2007
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      Hi Paul,  I believe your assessment of using tap water is correct, the water in Houston is too hard and you will have mineral deposits which will slow the heat transfer.  Using the condensate seems like a good idea if there is enough of it, might present an interesting plumbing challenge!  Good luck!

       

      Kevin

       

       

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      Solarcraft, Inc.

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      From: Paul Archer [mailto:tigger@...]
      Sent: Tuesday, July 10, 2007 6:52 AM
      To: Houston RE Group
      Subject: RE: [hreg] Solar powered A/C

       

      Thanks for the responses.
      I had thought about putting some sort of sprayer on my condensing coils, but
      I've been afraid that the water would have too many impurities which would
      end up on the coils. Now if I could divert the condensation from the cooling
      coils (which is naturally distilled, of course), then that might help...

      Paul

      Yesterday, Kevin Conlin wrote:

      > Hi Paul, I'm afraid that's over my head. I'm familiar with the technology,
      > but can't explain it chemically, perhaps one of the smarter engineers can
      > explain it. The absorbtion chillers do not have conventional compressors,
      > the heat is used to drive a chemical process using lithium bromide where I
      > think it is vaporized, then used to absorb heat as the reaction reverses.
      It
      > is a chemical phase change process, not a vapor/compression process.
      >
      >
      >
      > With regard to using water to cool the Freon in a conventional AC unit, I
      > think those do exist, they are called de-superheaters and they make
      domestic
      > hot water by pre-cooling the Freon before it enters the coils. The problem
      > is there is more hot water than the household can use, so it's effect is
      > limited. A Houston AC generates more hot water than even a swimming pool
      can
      > absorb, even using spray bars for night time cooling, a NASA engineer
      tried
      > it some years ago, and as he put it, he had the largest crab-boil in
      > Houston!
      >
      >
      >
      > Sorry I don't have time to Google any of this, I'm just getting back from
      > vacation to several hundred e-mails and going from memory.
      >
      >
      >
      > Kevin
      >
      >
      >
      > _____
      >
      > From: Paul Archer [mailto:tigger@...]
      > Sent: Monday, July 09, 2007 9:31 PM
      > To: hreg@yahoogroups. com
      > Subject: RE: [hreg] Solar powered A/C
      >
      >
      >
      > Kevin, you seem pretty well versed on the subject, so perhaps you can
      answer
      >
      > this question for me: (why) is the heat from the A/C itself not used in
      the
      > process? It seems to me that you could take cold (well, cool) water and
      run
      > it through a heat exchanger with the condenser coils (or whatever passes
      for
      >
      > condenser coils in an absorbtion unit), and then on to the solar
      collectors,
      >
      > for a gain in efficiency. Or is there something I'm missing with that?
      >
      > Paul
      >
      > 9:24pm, Kevin Conlin wrote:
      >
      >> Hi Folks, I believe the solar powered system in the Caribbean was a
      solar
      >> thermal absorbtion chiller. There have been several attempts to do
      this,
      >> usually using a commercial absorbtion chiller that uses solar hot
      water
      > from
      >> evacuated tube collectors as either a pre-heat with natural gas final
      >> heater, or using the chiller at lower efficiencies with lower temp
      solar
      >> water. The absorbtion chillers are a very proven and extremely
      reliable
      >> process generally designed to use waste heat or stream in the low
      200'sF.
      >> They are known to run for 50 years or more as they have very few
      moving
      >> parts and very low energy consumption, most of which runs pumps. They
      are
      >> mostly found in large factories or plants, I remember seeing a large
      one
      > at
      >> a Procter & Gamble paper plant that used waste heat from a
      cogeneration
      >> turbine. The plant maintenance crew loved it because it ran so quiet
      and
      >> smooth, and never required attention. Unfortunately, this process is
      not
      >> scaled small enough for residential use, I think the smallest units
      are 20
      >> tons, but with lower evacuated tube collectors coming out of China, it
      may
      >> be practical for commercial scale systems.
      >>
      >>
      >>
      >> There was one system at NASA over 20 years ago, but like most demo
      > projects,
      >> it was very expensive, over engineered and under built. There was also
      a
      >> home builder here on Houston that offered solar AC in the late 70's,
      >> Morgan-Barnhart was their name, and they used tracking solar thermal
      > trough
      >> concentrators mounted on the roof. (Nice aesthetics!) They also
      failed,
      >> due to various mechanical and other problems, as well as the
      relatively
      > poor
      >> and often cloudy solar resource here in Houston during the summer.
      > Tracking
      >> collectors are better suited to cloudless regimes like west Texas, NM,
      AZ
      >> etc..
      >>
      >>
      >>
      >> I believe there are some residential systems being offered in Japan,
      but I
      >> have no first hand knowledge of them. Solar A/C has long been one of
      the
      >> holy grail's in the industry, it seems like a practical compromise
      using
      >> proven technologies would be a solar driven geothermal system.
      >>
      >>
      >>
      >> That's all I can recall from memory, it would be great if someone
      would
      >> commercialize the technology and do it right, after all, they've been
      >> working on it for 30 years!
      >>
      >>
      >>
      >> Kevin
      >>
      >>
      >>
      >> _____
      >>
      >> From: evelyn sardina [mailto:evelynsardi na@
      > <mailto:evelynsardi na%40yahoo. com> yahoo.com]
      >> Sent: Monday, July 09, 2007 5:53 PM
      >> To: hreg@yahoogroups. <mailto:hreg% 40yahoogroups. com>
      com
      >> Subject: Re: [hreg] Solar powered A/C
      >>
      >>
      >>
      >> A freind just got back form Costa Rica. He brought back a picture of a
      > long
      >> black hose that sits on top of a roof in a work house in the farm
      where he
      >> stayed. It provided all the hot water needs for the shed. It was
      rolled up
      >> in many layers and was just sitting on top of the roof. I think it was
      > tied
      >> to the roof. I asked him to email to the group but he unsuscribed. It
      >> seems to me we make things that have simple solutions simply too
      >> complicated. I am not suggesting a hose on top of our houses but a
      > tankless
      >> water heater or solar water heater?
      >>
      >> Ariel Thomann <ajthomann@pol. <mailto:ajthomann% 40pol.net>
      net> wrote:
      >>
      >> I had lunch last week with a friend whose family still lives in the
      island
      >> of
      >> Dominique. As I understood it, all (new?) houses there must harvest
      >> rainwater
      >> and use photovoltaics on their roofs. Sorry, I have no details.
      >>
      >> Ariel
      >> - We are all Human beings here together. We have to help one another,
      > since
      >> otherwise there is NO ONE who will help.
      >> - All countries need a NO REGRETS strategic energy policy. Think ahead
      7
      >> generations.
      >> ------------ --------- --------- ------
      >>
      >>> Hey Steven:
      >>>
      >>> I recall about 10 (maybe more?) years ago hearing about a hotel in
      the
      >>> Caribbean using solar a/c, but I didn't hear anything more about
      it. It
      >>> seems like we would hear more about it if it were successful.
      However, my
      >>> cynical side makes me wonder if information is being suppressed. I
      would
      >> also
      >>> be very interested in more information. I wonder what effect scale
      has on
      >>> such a system. i.e. Would it be suitable for residential use. It
      bothers
      >> me
      >>> to hear our a/c sucking up energy all summer long (but not enough
      to turn
      >> it
      >>> off & sweat).
      >>>
      >>> Welcome to the group.
      >>>
      >>> Henry
      >>>
      >>> Steven M <marzolian@yahoo. <mailto:marzolian% 40yahoo.com>
      com> wrote:
      >>> Greetings, all.
      >>>
      >>> I was raised in Venezuela, where it's no hotter than Houston but
      it lasts
      >> all
      >>> year round :-). Both there and in Texas, I have often
      >>> thought of all the energy being used just to keep things cool
      indoors.
      >>> Wouldn't it be better if there was an A/C system that sat on the
      roof and
      >>> worked better the hotter it got?
      >>>
      >>> Years later, on the first day of my first class in thermodynamics,
      the
      >>> professor asked us to write down briefly what we knew about the
      >>> subject, and what we hoped to learn. Alas, the class didn't give
      me any
      >> easy
      >>> answers to that question, but I'm still interested,
      >>> especially with our electric rate hikes here in Houston the past
      >>> couple of years.
      >>>
      >>> Then, a few weeks ago I saw an article about a solar-powered
      >>> airconditioner. It was not just solar cells connected to a
      >>> conventional (Freon-type) unit, and it's not a "swamp
      cooler", but there
      >>> wasn't enough information to understand how it works.
      >>>
      >>> I once read somewhere that the Houston metro area has the largest
      >>> concentration of A/C devices in the world. Don't know if it's
      true, but
      > it
      >>> makes sense. We're so big, our electric rates are so high, and
      it's so
      >> hot,
      >>> that if those systems make sense anywhere, it would be here. Or
      would it?
      >>>
      >>> Yesterday I went went looking online. There are lots of proposals
      out
      >> there,
      >>> but I didn't find any local contractors, nor any aystems that seem
      to be
      >>> available as immediate replacements for conventional A/C.
      >>>
      >>> Does anyone have any thoughts or information about the status of
      solar
      >>> powered air conditioners? Is there any likelihood that they'll be
      more
      >>> practical any time soon?
      >>>
      >>> Steven Marzuola
      >>>
      >>>
      >>>
      >>>
      >>
      >>
      >>
      >>
      >>
      >> _____
      >>
      >> 8:00? 8:25? 8:40? Find a flick in no time
      >> with theYahoo! Search movie showtime shortcut.
      >>
      >>
      >>
      >>
      >
      > ------------ --------- --------- --------- ----
      > "Looking down the barrel of a loaded gun...
      > Just to see where the bullets come from!"
      > --Screaming Blue Messiahs--
      > ------------ --------- --------- --------- ----
      >
      >
      >
      >

      ------------ --------- --------- --------- --------- --------- -
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      "How do you do that, then?" Terry Pratchett
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