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  • Cooling efficiency

    Hi everyone.

    We have a Glycol chilling system that pumps out 30% glycol at about 22F. We are aiming to chill our tanks to 32-34F. We find that temperatures fall until about 38F then often stick there. The chiller seems to be working fine, so we think there may be a problem in the heat transfer between the beer and the cooling panels in the vessels.

    One time we dry hopped at about 38F and the temperature fell quickly to 34F. One theory is that the direction of convection changes at about 38F and so momentum of cooling is lost. Another is that a thin film of ice can build up leading to ineffective heat transfer. Has anyone else come across this and how did you solve it? Would some agitation of the beer (like with the dry hopping action) at 38F kick the last phase of cooling into action?

    Cheers!

    Robert

  • #2
    Your evaporator can be expected to be 5-8 deg. cooler than your glycol set point, so you need to add more glycol--to a freezing point of less than ~15 F to prevent your evaporator from icing.

    I'm sure Jim will jump in on this, but most chillers are built to operate most efficiently at around 28 F. As you go lower, you lose cooling efficiency rapidly.

    And, yes, you will have problems with ice accumulating inside the fermenter and considerably lowering the heat transfer rate to the glycol. We used to run our glycol at 22 F, and experienced all these problems--including increased gravities/ABVs due to loss of water to ice. We're now running at the recommended 28 F, and the problems are gone.
    Timm Turrentine

    Brewerywright,
    Terminal Gravity Brewing,
    Enterprise. Oregon.

    Comment


    • #3
      I agree that you might actually try increasing the temperature set point (26-28 F) as it's likely that as you're approaching 38 F you are building up an ice layer and hindering the HX. If at the higher temperature you are still not achieving the desired performance, it might be an issue resolved by increasing the glycol flow to increase the Heat Exchange efficiency through the jacket. This could be determined by taking readings across the jacket inlet and outlets to determine how much heat is being removed.

      Good Luck,

      Jim

      Pro Chiller Systems
      Prochiller.com
      jimvgjr@prorefrigeration.com

      Comment


      • #4
        Thanks guys. We are rather caught between chilling at a higher temp to avoid ice and running cold enough to reach target temps. Our vessels each have two cooling panels, one lower than the other. If we can't get this sorted then one option is to move/replace these. Any thoughts on optimal cooling panel design? Cheers!

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        • #5
          I guess by "panel" you mean jacket. If so, using the highest jacket that is completely covered by product will help prevent stratification within the vessel. We have vessels with up to 3 jackets, and generally use only the highest, or sometimes the middle and highest. The cone jacket is used only for final clarifying after crashing, and not always then. When filling with warm wort, we turn the jackets on as they are covered, starting with the lowest, and closing the lower ones after the vessel is filled.
          Timm Turrentine

          Brewerywright,
          Terminal Gravity Brewing,
          Enterprise. Oregon.

          Comment

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