[VAC] Re: refrig

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

I went to the sunfrost web page this morning, linked from
www.homepower.com. I think it was www.sunfrost.com. The 19 cu ft
refrigerator takes 63 ah per day at 90°F ambient. They claim. The 4
cubic foot takes 13 as refrigerator alone, 16 with ice cube tray. It
won't begin to fit my Caravel, its 32" wide and 35" high, 27" deep.
There's LOTS of insulation there. My several year old Sunelco catalog
showed the components available separately, or the compressor, and
plumbing all assembled for installation in a custom cabinet. I've no
current Sunelco catalog, though there was a link from Home Power
Magazine's site. Used to be there was a 12 volt compressor or two in the
W.W. Grainger catalog too, but I don't find it in my most recent one
dating from 1996. A great deal of the efficiency of the Sunfrost comes
from lots of insulation. Consumer's Reports tests which included a
strict schedule of door opening to simulate normal use was not as
optimistic about energy savings as Sunfrost. That test was several years
ago. Sunfrost didn't appreciate the result.

If one could supplement the gas units with a second cooling coil and a
12 volt compressor, one might gain the best of both worlds. Propane use
for boondocking, and electric use for traveling and when on AC power. I
think the relative energy inefficiency of the absorption process
precludes running it on 12 volts for any extended period whether while
traveling or from batteries and solar panels. In the meantime, my picnic
cooler and some bagged ice will have to do. I'm sure that modern foamed
insulation will be far more effective than the original relatively thin
fiberglass insulation also.

Gerald J.