Date:         Wed, 14 Sep 94 16:08:24 -0700
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         riclvw@deety.radiology.arizona.edu
Subject:      Re: kooltrons (was Re: STAT...) 

sstones wrote:

>Also, they do not have plumbing, They have no moving parts at all.  Yes I 
>didn't beleive it at first either but appearantly it used Some sort of 
>wonderful new semiconductor to transfer heat from the inside out or vice 
>versa.

Actually, the Koolatron and other similar coolers use Peltier devices,
which are not really now or semiconductors. Here is an excerpt on the 
Peltier effect from my Growler's CD-rom encyclopedia:

  Copyright - 1992 Grolier Electronic Publishing, Inc.

  thermoelectricity...

  Peltier Effect.
  ... the Peltier effect only occurs at the junction of
  dissimilar materials when electric current flows. Heat, called 
  the Peltier heat, is either emitted or absorbed at the junction, 
  depending on the direction of current flow. This effect was 
  discovered by the French physicist Jean C. A. Peltier in 1834. 
  Once again the basic nature of the effect was misunderstood; 
  Peltier believed that he had discovered a violation of Ohm's law. 
  In 1838, Heinrich Lenz demonstrated the true nature of this 
  effect when he used a bismuth-antimony junction and froze a drop 
  of water when passing electric current in one direction 
  (absorbing heat) and then melted the drop by reversing the 
  current (emitting heat).

    
  Principle.
  In the Peltier effect a net motion exists, and thus the charges 
  transport energy. The energy associated with each charge differs 
  in the two materials. When a charge moves from one material to 
  the other, at the junction it emits or absorbs this difference in 
  energy and causes the Peltier effect. 

  Uses.
  The Peltier effect is used in refrigeration and heating; a modern 
  single-stage Peltier cooler can reduce temperatures to nearly 70 
  C degrees (125 F degrees) below room temperature. In comparison 
  to more conventional systems, Peltier coolers have the advantages 
  of very local heat transfer (occurring only at the junction) and 
  no moving parts; however, they also have the disadvantages of 
  lower efficiencies and higher costs.

  Numerous special circumstances have justified the use of a 
  Peltier cooler. Important factors are its durability, resulting 
  from the absence of moving parts, and its versatility--by 
  reversing the current direction, it can be changed from a cooling 
  to a heating system. A number of electronic systems require very 
  local cooling or heating to obtain optimum performance; Peltier 
  systems are ideal in these instances and have been used with 
  transistors, lasers, microwave amplifiers, and light detectors. 
  Peltier coolers have also been used to maintain biological 
  samples during periods of storage and transfer. The largest 
  Peltier-effect systems built so far are air conditioners used on 
  U.S. Navy submarines.

So, now you know more than you wanted. :-P

A thermoelectric cooler is not much use here in Aridzona
during the summer, but neither is my ammonia cycle refrigerator
that came with my Weekender. I usually just load it up with ice.

Rich.

riclam@deety.radiology.arizona.edu