Re: refrigerator

[brian whatcott <inet@intellisys.net>]

At 10:34 5/12/98 +0200, you wrote:
....
> I quoted for fun the situation I found when I browsed through thirty years
of 
> American Journal Physics and twenty years of The Physics Teacher. The best 
> article I found was one from 1979 where the experiment for measuring
efficinecy 
> of refrigerator was described. .... I wanted to show that it is 
> quite hard to find simple data about working cycle of a real refrigerator
like 
> what is material which is needed for isolation and the gas which expands
etc... 

> Dr. Mojca Cepic

Thank you for responding so quickly. I think I have a clearer understanding
of your position now. The two topics you mention above are quite 'trendy'
in this country. But US concerns are not necessarily your concerns.

 Let me explain.
Popular and efficient materials for fridge insulation are expanded
polystyrene and foam polyurethane. You are possibly familiar with the
sheets of the former material which provide excellent insulation when used
as house wall insulation.

 But there is a concern that  manufacturing processes may release chlorine
compounds into the upper atmosphere which are noted to erode the tenuous ozone
layer so that reported cases of skin cancer are already rising world-wide.

 The most popular refrigerant until the last decade has been called 'Freon'.
 This is a chlorofluorocarbon compound which is particularly effective in
destroying ozone by all accounts. This wonderful product, a US invention,
has become the victim of its success. 

The automobile airconditioners which formerly used this material would
sooner or later leak and the huge US auto accessories business responded
with small cans of freon to 'refresh' these air conditioners.
This product sold by the millions...

 It is now legislated that fridges must be pumped out and the refrigerant
recovered to storage. Moreover, certain refrigerants are no longer to be
produced here.

 On the somewhat related topic of global warming, the US is a somewhat
bashful bride in the union of international efforts to decrease so called
'greenhouse gas' production. (CO2, Methane etc.)

 Leading technical details on the Freon gases are to be found in references
like the Handbooks of Chemistry, CRC Handbook of Chemistry & Physics and so
on.

I hope this note has been more helpful to you. You are aware of the need to
'keep digging', so I invite you to ask for more detailed aspects.
Sincerely
Brian Whatcott