Dehumidifier from a walk-in freezer unit?

makeitshine2

I have 2 each 1-1/2 ton refrigeration units for a walk-in freezer. I would like to build a dehumidifation kiln to dry lumber. Each unit would freeze an 8' x 10' freezer to -20 degrees.

How hard would it be to use a freezer compressor and condensor as a dehumidifier? How would it work?

Thanks for your help!

Bill

russ_watters

Welcome to PF.

The difficulty here is that the temperatures generated at each coil are largely a function of the physical properties of the refrigeration system: the refrigerant, its pressure and the compression ratio. As a result, your evaporator is going to "want" to be at -30 or so and it will be very hard for you to keep it from frosting over.

makeitshine2

Russ,

The condensor for a freezer has heat strips built-in and will run a defrost cycle as programmed. Would this be enough?

I also have a condensor that is refrigeration. (for a walk-in refrigerator) Perhaps I could match that with the compressor unit!

Thank You,
Bill

russ_watters

What is the operating temperature of this "kiln" going to be? It would be a balancing act, but it may be possible for this to work if you have enough airflow and temperature to keep the leaving refrigerant temperature high and the condensation from getting too cold. You'll want to strike a balance, having little enough airflow that it gets cooled enough to condense water but enough airflow that it doesn't freeze the water on the coils.

Are you using this system as the only source of heat/dehumidification for the system? Ie, are you using the condenser heat to warm the "kiln" while using the evaporator to dehumidify it?

A periodic defrost cycle would certainly help.

Whatever parts you use, do you have access to the operating points of the cycle, meaning the design pressures? That would help a lot in figuring out how to make the performace work.