"Cascade refrigeration"

[magnum]

Hello everyone,

I am new here but need some help. I have been out of the refrigeration field for several years doing controls. I just recently have been asked to design to different types of refrigeration systems the first one is a auto cascade that fits inside a 12" square frame that is being used to cool a 6"x8" ceramic dry block down to a -70C or cooler at ambient temps from 65 deg to 90 deg.

The second is a cascade system to fit in a 19"x26"x13" cabinet. Used to cool down 5-6 liters of methanol in a flask to a -70C or cooler at ambient temps from 65 deg to 90 deg. Both of these cabinet sizes are no yet set in stone. I don’t know what refrigerants are out there any more, and what type of improvements have been done in these type of systems in the last several years? Example types of air-cooled condensers, metering devices, heat exchangers ect.

Any help would be appreciated

Thanks,

Magnum

[The MG Pony]

http://www.xtremesystems.org/forums/...d.php?t=144007

Look there.