Cooler Condenser

[10fingers]

I was trying to think up a way to keep my distillation condenser cooler when I came up with the idea of running the cooling water through a refrigeration condenser. I have a dehumidifier which I think might work. It is basically a small refrigerator, and it's small and portable. A freezer would work better but it would not be convenient.
Dehumidifiers require a couple of modifications to get the temp. of the evap coil as low as possible. They are designed to shut off when they get too cold so that the moisture which condenses on the coil does not freeze. Also, the condenser coil and the evaporator coil are mounted on a metal frame which will draw cold away from the evaporator. So the evap coil has to be cut away from the frame, a water container needs to be built around the evap coil and insulated.
The cooling water for the distillation is then pumped through this container. I have a small waterpump that I'm going to mount directly to the dehumidifier so that it is a closed loop. You can add auto antifreze to the water. Also I can put my vacuum aspirator onto the output of the pump. I should draw a better vacuum with the colder water. I think I can get the water temp down to 10 or 15 degrees F. One problem with the closed loop though is if you are evacuating something corrosive it's going to contaminate the cooling water, but you can either put some kind of trap on it or have a valve to open the closed loop and run tap water through it and into a drain.
When I get this contraption done I will have a limitless cold water supply and a vacuum system all in the size of a dehumidifier.

[Boomer]

Why not use a drink cooler from a bar? There are compact on-the counter coolers with 8 litre tanks of glycol water, with the evaporator coil built into the tank walls. Inside the tank is a stirrer and a stainless pipe coil for the drink (coke, beer etc) to be cooled during dispense. All you need is connect the pump + tubing!

These also come with integrated pump for re-circulating the glycol water (e.g. to cool the dispense valve), you don't even need ANY external equipment except for the tubing to the column and back! :)

Bigger units have a 90l tank with 50 pounds of ice frozen to the walls as thermal reserve. Inside the tank is a stainless pressure vessel for carbonating the drinks. Imagine converting this to a (continuous) NG plant!!!
2200 watts of cooling power plus 50 pounds of ice reserve in case of a runaway … :D

[10fingers]

That sounds like a good idea. But right now I have a dehumidifier that I got for nothing.

[newdle]

refridgeration loops don't turn off to prevent the coils from freezing.

They stop because the compressor is not designed to run continously. Go look at any standard air compressor/gas compressor and you will see it has instructions of how long it can be run for before it must be switched off for a certain time.

Meaning, if you untweak the compressor to run all the time, to keep the coil cold, your compressor will die in about a day or two, i reckon.

Speaking of which, this has been a pet hate for me for a while. So if anyone knows of a type of continous compressor in the same form as refridgerators please drop me a PM.

[Boomer]

The ones I described ARE rated for continuous operation. No bar can afford to stop selling drinks to give the compressor some rest! :p

Also, decent fridges also have no-rest compressors. If some Alaskan shoots an elk in summer and puts 300 pounds of meat in an empty freezer, it will run over a day before all is frozen.

Plus, my mums fridge (not mine, damnit) even has a "boost switch" that bridges the thermostat if it is newly filled. The manual tells you to switch it off the other day if all inside is below -21C.

BTW efficiency is best if it runs continuously - every cycle the pressure has to build up, the it equalized through the capillary tube in stand-by. Only after pressure build-up can the unit pump some heat.

[Anthony]

Fridges and freezers will run continuously. Sometimes people use the fast-freeze/thermostat over-ride switch and then forget about it. The applicance usually lasts a couple of years in that condition before the compressor fails.

Also, computer overclockers who improvise phase-change coolers from fridge compressors run them continuously.

[10fingers]

Thanks for pointing out that potential problem Newdle. A dehumidifier is a little different than a fridge or freezer though. The air from the room is blown through the cooling condenser so that the moisture in the air condenses on it. If it were to get too cold and freeze then the air would not be able to pass through.
I haven't messed with this idea for awhile but when I get back to it I will let it run for a couple of days before I spend a lot of time making modifications to it. Also, I have been trying to scrounge up a good freezer compressor unit, I think it will give me colder temperatures than a dehumidifier.

[VX]

How about getting a bucket of ice water, and a small pond pump... a tiney one (or any other low capacity pump) Then simply top upthe ice in the bucket of water, and run the pump from the bucket to make a closed system. i.e. ice water goes from bucket, through pump.. is pumped through condensor and then back into ice bucket.

If you need cooler temperatures than this you could use ice, salt water.... If cooler temperatures still are needed you would need to invest in a suitably chemical resistant pump to alow various sluries to be used. i.e methanol/CO2, Ethylene glycol/ CO2 etc

This works well and is the method that i use..