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RE: [carfree_cities] Re: Carfree: editorial comment & donation info

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  • Matt Thyer
    Great explanation Joel, I d suggest that a benchmark of refrigeration efficiency could be the simple Cubic space cooled/KWHr consumed. This would result in a
    Message 1 of 2 , Dec 11, 2008
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      Great explanation Joel,

      I'd suggest that a benchmark of refrigeration efficiency could be the simple
      Cubic space cooled/KWHr consumed. This would result in a nondimensional
      coefficient that could be used to compare as apples-to-apples a variety of
      refrigeration systems.


      Matt Thyer

      From: carfree_cities@yahoogroups.com [mailto:carfree_cities@yahoogroups.com]
      On Behalf Of J.H. Crawford
      Sent: Thursday, December 11, 2008 12:45 PM
      To: carfree_cities@yahoogroups.com
      Subject: [carfree_cities] Re: Carfree: editorial comment & donation info

      Hi All,

      I had the following note from a reader of Carfree Times
      that I thought was worth responding to on the list:

      >A comment on your long editorial - you wandered far from your apparent
      domain of expertise and diluted your consistent message. A minor but telling
      point, old refrigerators are far less efficient in operation than modern
      ones. That is, old fridges consume far more power in cooling the same
      volume. So the increase in size aside, new fridges are far more efficient.

      That is not actually correct. A little industrial history here.

      In the early days, General Electric, the company in question here,
      was run by electrical engineers like my grandfather who had as
      their goal the efficient design and manufacture of good electrical
      equipment. After about 1960, the company was undoubtedly run by
      marketers, MBAs, and lawyers who did not have an engineering
      background and whose focus was on profitability, not efficient,
      long-lasting products (which actually reduced sales for the company).
      Soon after the change, GE was embroiled in price-fixing accusations
      and some of its executives even spent time in jail. (That was
      back in the days when white-collar crime was actually considered

      Efficient electro-magnetic equipment requires adequate amounts
      of iron and copper. Inefficient equipment is lighter and cheaper
      but loses more energy to heat. Since the compressor motor actually
      runs in the coolant stream, its losses are energy wasted twice:
      first in the electrical losses and then in the heat losses that
      must be removed from the coolant.

      After about 1960, GE started to make insulation thinner
      (to increase the size of the cool box and to reduce costs).
      This resulted in condensation on the outer surfaces of the box.
      This problem was handled by building HEATING coils into the
      outer part of the shell, to evaporate the condensation.
      This, of course, warms the very box we are trying to cool,
      while itself consuming electricity.

      Finally, auto-defrost was added. In the early days, this was
      just auto-defrost in the refrigerator part. That can be achieved
      by allowing the evaporator coils to warm to the temperature of
      the fridge, about +5 degrees C. The ice melts and the water runs
      down the coils and is led out of the box. When auto-defrost is
      added to the freezer compartment, life is much more complex.
      I believe that a number of different schemes have been used to
      accomplish this. All of them involve introducing heat at the
      coils, which in normal operation are always below freezing.
      All auto-defrost freezers are by their nature inefficient.

      What has happened in recent years is that manufacturers,
      under pressure from the public and the government, have
      somewhat improved the efficiency of their products, probably
      in the main simply by improving insulation and door seals.
      Perhaps some modest efficiency improvements were also
      introduced into the compressor motor, and maybe the
      heat-exchanger coils were lengthened, which improves efficiency.

      However, I am reasonably certain that the most efficient
      frost-free models use quite a lot more electricity than
      the original refrigerators from the 1920s, none of which
      were frost-free. These refrigerators were, of course, quite
      small internally compared to today's monsters, so this is
      not really an apples-and-apples comparison. But as seen
      by the kilowatt-hour meter, I'd be willing to bet that
      the fridges from 1925 used less electricity than any
      auto-defrost electric refrigerator. I'd love to use one
      of these antiques myself.

      One final footnote: when I needed a really quiet refrigerator
      in 1986 (because I was going to be sleeping right next to it),
      I went out and bought a 1958-vintage GE fridge. You could
      hardly hear it run.



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