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Pipsqueak

Pipsqueak


duplicate post

On 7/31/2015 at 11:12 PM, TonyC said:

 

 

Somehow this post got posted twice so I'll edit the second one with some more useful information.  

 

I remember reading somewhere in this thread where somebody was asking how long you run the freeze cycle with pre-frozen food.  

 

I have my chest freezer set to -12F, and I usually let the freeze dryer cool for an hour before I put the frozen food in.  After I load the food in I wait another half hour to start the drying process. I've had a lot of cycles that the total time between pulling one batch out and starting the drying cycle on the next is around 2 hours.  I'm running mine in a cold garage, so it cools down pretty quickly.  If you have yours in a warm room it would probably take a little longer.  Obviously things like ice cream and marshmallows you would want to let the freeze cycle run longer.  

 

When I'm ready to start the drying cycle, I open the door, remove the insulator, and check the temperature of the food on the trays with an infrared thermometer.  As long as it's below -10F I start the dry cycle.

 

A side note for TonyC, have you ever thought about attaching a mirror to each side of the tray rack to reflect the radiant heat back in to the trays?  I've looked at some mirror finish stainless on ebay, and it looks like you could do it for about $40.   Not sure if it's worth a try or not.  I would think it would let you get more water out in a cycle because the radiant heat wouldn't be warming the ice on the chamber walls.  Just a thought....

Pipsqueak

Pipsqueak

On 7/31/2015 at 11:12 PM, TonyC said:

 

Here is my first pass on a Vapor Trap... it is an old whole house water filter that I modified.  It failed to reduce the moisture in the oil...  I'm in the process of modifying it to catch and suspend the moisture in the container long enough for desiccant beads to absorb the water.  The air flow comes into the inlet, down the central pipe to the bottom of the screen and filters up through the beads and out the top.

 

I know this was like forever ago, but I thought I would respond anyway.  I haven't been on much in a while, I only run my freeze dryer in the winter.  

So I think you'll find it's a lot harder to remove water vapor from a vacuum than just using desiccant, as the vacuum will just pull the water out of the desiccant.  The only way I know to filter the water vapor out would be a cold trap.  They usually use liquid nitrogen or dry ice to keep the temperature low enough that all the water condenses out.  Obviously you would need a supply of the liquid nitrogen or dry ice that would probably not be cost effective for most of us.  

http://www.bestvaluevacs.com/coldtrap.html

The other option to get that cold would be to use a cryocooler and build a cold trap around it.  It could be done, but would be pretty expensive.  I've been watching some electronics on ebay that have cryocoolers in them, but the cheapest I've seen is around $600.  Still not a cheap option, but you wouldn't need dry ice or liquid nitrogen to feed it.

http://www.ebay.com/sch/i.html?_odkw=superfilter&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H1.Xsuperconductor+superfilter.TRS1&_nkw=superconductor+superfilter&_sacat=0

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