Dehumidifier from a walk-in freezer unit?

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    Dehumidifier Unit
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Discussion Overview

The discussion revolves around the feasibility of repurposing refrigeration units from a walk-in freezer to create a dehumidification kiln for drying lumber. Participants explore the operational challenges and considerations involved in adapting these systems for a different application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Bill inquires about the difficulty of using freezer compressors and condensers as dehumidifiers and seeks clarification on how the system would function.
  • One participant notes that the temperatures at the coils are determined by the refrigeration system's physical properties, suggesting that maintaining appropriate temperatures without frosting could be challenging.
  • Bill mentions the presence of built-in heat strips and a defrost cycle in the freezer condenser, questioning whether this would be sufficient for the dehumidification process.
  • Another participant asks about the operating temperature of the kiln, indicating that achieving a balance between airflow and temperature is crucial for effective dehumidification without freezing the water on the coils.
  • There is a suggestion that using the condenser heat to warm the kiln while the evaporator dehumidifies could be a viable approach, contingent on the system's design pressures and operating points.
  • Participants discuss the importance of airflow management to ensure effective condensation without freezing issues.

Areas of Agreement / Disagreement

Participants express varying opinions on the feasibility and operational challenges of using refrigeration units for dehumidification. No consensus is reached on the best approach or the effectiveness of the proposed methods.

Contextual Notes

Participants highlight the need for specific operating points and design pressures to better understand the performance of the refrigeration system in this new application. There are unresolved questions regarding the balance of temperature and airflow necessary for effective operation.

makeitshine2
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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
 
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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.
 
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
 
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.
 

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