Need help with a little Cold Box

[skoot61]

I'm building a Cold Box.
I took the cold (freezer) unit out of a mini fridge and am going to mount it in the bottom of a cold box I built, so I can keep extra kegs cold and try some lagering.
I'm going to blow air over the freezer unit, channel it up a tube in the corner of the box so the cold air comes out the top and settles in the compartment.
I KNOW! why don't I just use an old chest freezer! Because I dimensioned it to fit 3 buckets or 2 buckets & 3 cornies, etc,... Plus it'll look much nicer then an old freezer.
Two Questions -

1. Should I Pull or Push air across the freezer unit?

2. I would like to attach some copper fins to the freezer unit to increase cold surface area. Can I screw into the flat portions of the unit, as long as I stay away from the raised tube lines or does coolant run thru the flat portions as well?

[captain carrot]

I'm not sure what your freezer unit looks like but I'm guessing it's rectangular like the one's sitting above the top shelf in a mini fridge. If you want to increase the cold transfer I would cut and stack copper pipe inside the freezer cavity and blow the air through the pipes. Ducting the air flow from the fan to the freezer cavity will help also. A slower speed fan would probably help too. I would use damp rid or something similar to keep frost from forming on the freezer unit. Post pictures! I bought a mini fridge at a garage sale and am looking for ideas. Good Luck!

[skoot61]

Thank captain. What's "damp rid".
I've been taking pics and will post my project.

[Bugeater]

Thank captain. What's "damp rid".
I've been taking pics and will post my project.

You can get this stuff at almost any hardware store, WalMart, etc.

It is a desiccant that soaks up the humidity in the air inside your fridge. Just open the carton and set it in there.

Wayne

[SacoDeToro]

I keep a jar of Damprid in my chest freezer. It works great. You can also buy refil cartons, which is nice.

[skoot61]

Got some "Damp Rid". I have a freezer unit on the bottom of my cold box, that I blow cold air from it to the main chamber. Should I put the DampRid in the freezer part or the main chamber?

[Brewgyver]

Put the Damp Rid in the main box. When you open the main box to change kegs, etc, humid air will enter and condense on cold surfaces.

As to increasing the HEAT transfer area of the evaporator, you can add small finned aluminum heat sinks. I would not advise you to drill or screw into any portion of the evaporator, but you probably could do it safely on the flats, which are themselves only extending the heat transfer area from the evap tubes. Keep the enclosure around the evap as small as possible, while still leaving it accessible for defrosting.