Steve Lusardi wrote:
That is really good info....... thank you. I think you are correct about
keeping the systems separate. Combining them will create far too much
complexity.
Absolutely. This will NEVER work with any efficiency. You'd
need to have suction throttling valves on the air cond
evaporators, or the'd raise the suction pressure preventing the
freezer from ever getting cold. Suction throttling valves are
used in cars to prevent freezing the evaporator, but having very
heavy throttling will MASSIVELY reduce compressor capacity.
You'd end up using a 10 Hp compressor to get 1/2 Hp worth of
comfort air conditioning - it would be a collosal disaster.

They actually make DIFFERENT compressors for different
temperature differentials, or expressing it a different way,
specific suction pressures. For many refrigerants that are used
in different services, like R-22, you will find low, medium and
high-pressure compressors, meant for freezer, refrigerator and
air cond use, respectively. If you use a low-pressure
compressor for AC, it will overload due to the much higher
volume of gas pouring into it. If you use a high-pressure
compressor for a freezer, it will not develop rated power as it
is not getting as much gas in as it was designed for.
I have made the same observation of cold plate performance that
you have, but I think that is because of the use of brine as the storage
medium for a freezer applications. Its state change is far too warm to be
efficient. There are far better solutions for cold storage capacity, hence,
the -40 degree requirement.
Don't confuse freezing temperature with heat capacity. They are
totally different. You want the most heat of solidification per
volume, but maybe most H.O.S. by weight should suffice.

Jon