RE: The Refrigerator

["Thomas L. Fors" <tom@epocha.com>]

I don't know how you feel about modifying your brand new refrigerator, but
if you can remove the evaporator and get it in the bucket of water, it
should improve things quite a bit.

--Tom

> -----Original Message-----
> From: Tom Droege [mailto:droege@wwa.com]
> Sent: Friday, October 23, 1998 4:54 PM
> To: tass@wwa.com
> Subject: The Refrigerator
>
>
> I have been running the refrigerator since noon with a waste basket in it
> full of water.  With 57.2# of water it is cooling 2.6 degrees per hour.  I
> figure that this is 148 Btu per hour or 43 watts.  What a bummer.
>  I had to
> guess which sized refrigerator to buy.  All I could do was to
> estimate what
> the losses would be for a 5.6 cu ft. small student refrigerator.
>  But I do
> note that it is hard to couple the cooling to the water.  The air
> temperature in the fridge might be quite a bit cooler.
>
> Those of you that want to use an old refrigerator for this
> purpose would be
> advised to get the biggest old klunker that you can find.  Possibly I
> should have bought a freezer.  It would have not cost much more.
>
> You say I should have asked for the "pumping capacity" of the refrigerator
> before I bought it?  Ha!  Consumer products don't have
> specifications these
> days.  All they tell you is that this model will use $28 worth of
> electricity a year at $0.0867 per kilowatt hour.   I did a guess
> from this,
> but was off by a factor of two or so in how much heat it would pump.
>
> I had hoped to be able to use the "Little Giant" submersible pump that I
> have just because it is the easiest thing to do.   The problem with this
> type of pump is that it's heat goes into the tank.  It will
> probably use up
> most of the 43 watts available.  Sigh!   But at least I will be
> able to get
> a noise test done at low temperature with this set up.   I will
> just run it
> all night to cool down the water and do a test in the morning.
>
> Boy, I don't know how they sell these things to students.   It
> would take 4
> hours to cool a case of beer.  Well, I guess it would keep up with one
> student.  A personal beer cooler.  But it would be worthless in a frat
> house.
>
> I note that I could match this $200 (plus shipping) refrigerator with 4
> small thermoelectric (@ $10ea) devices.  I am thinking of just plastering
> some TEC on the frame of the telescope.  There is lots of area,
> and warming
> the whole telescope body would reduce problems with dew.  Serious
> astronomers will be horrified that I am thinking of heating the telescope.
> But we need only 7 second seeing.  Should be hard to do this much
> damage by
> heating things up a few degrees.
>
> Just waiting for the screams of horror.
>
> Tom Droege
>