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Pool Volume Chiller Calculations

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  • Pool Volume Chiller Calculations

    Hi all,
    I want to know about the calculations to design chiller for brew process , these kind of chillers have the condensator unit (compressor, condensator and evaporator ) , commonly the evaporator is a cupper pipe which is submerged in a insolated stainless pool with a blend of water + Glycol (commonly 50%). Chiller also has a 1/2 HP pump that drives the glycol and water from the pool to the fermenter jacket (which solenoid is activated) in order to cool the beer.
    So I followed this post: https://bvthermal.com/how-to-size-a-brewery-chiller/ to calculate the power ,with that information I made an excel sheet where I entered the value of the total volume of wort that I need to cool in 18 hours (which is the normal time ) from 75F to 34F and the excel calculates the condensator unit power (in BTU/hr) that I need using the formule of heat ( C = Q /(m × ΔT)) . That method looks great and excel works perfect.
    Nonetheless ,I want to calculate the volume of the chiller's pool, (as I mentioned is an insulated stainless box). Is there any information to get some formula to that purpose?
    In other words what I want to model has these variables (input and output)
    inputs:
    -Volume of Beer to be cooled (in lb or Liters),
    -Final Temperature
    -Initial Temperature
    -Pull down (crash) Time


    Outputs
    -Power of Unit compressor (BTU/hr) . Current I have this value.
    -Volume of Chiller Pool .(m3 or liters)
    -Large of the Evaporator Pipe.

    attached the excel that I did and some photos of the chiller that I am talking about in this link https://we.tl/t-elnsrfhnj0


    Thanks in advance.
    Walter​
    Attached Files
    5 files sent via WeTransfer, the simplest way to send your files around the world

  • #2
    Designing a chiller system for a brewery involves several critical factors, including sizing the chiller unit, calculating the volume of the chiller’s pool, and determining the evaporator pipe size. Let’s break down each aspect:
    1. Chiller Sizing:
      • You’ve already calculated the compressor power (BTU/hr) using the heat transfer formula: (Q = m \cdot C \cdot \Delta T), where:
        • (Q) is the heat load (energy needed to cool the beer).
        • (m) is the mass of the beer (volume × density).
        • (C) is the specific heat capacity of beer.
        • (\Delta T) is the temperature difference (initial temperature - final temperature).
      • This step is crucial, and it seems you’ve handled it well using your Excel sheet and the information from the post you mentioned.
    2. Volume of Chiller Pool:
      • Calculating the volume of the chiller’s pool (the insulated stainless box) involves considering the total heat exchange required during the cooling process.
      • The pool contains a blend of water and glycol (usually 50% glycol).
      • To estimate the pool volume, follow these steps:
        1. Determine the total heat load (energy needed to cool the beer) based on the mass of the beer and the temperature difference.
        2. Divide the total heat load by the heat transfer coefficient (U-value) for the pool. The U-value accounts for the heat exchange efficiency between the beer and the pool.
        3. The U-value depends on the insulation quality, the material of the pool, and the design.
        4. Once you have the U-value, calculate the pool volume using the formula: (Q = U \cdot A \cdot \Delta T), where:
          • (Q) is the total heat load.
          • (A) is the surface area of the pool (including the evaporator pipe).
          • (\Delta T) is the temperature difference (initial temperature - final temperature).
        5. The pool volume will be the volume of the water-glycol mixture.
    3. Evaporator Pipe Size:
      • The evaporator pipe (usually made of copper) is submerged in the pool to facilitate heat exchange.
      • The pipe size affects the efficiency of heat transfer.
      • Consider the following factors:
        • Flow Rate: The flow rate of the glycol-water mixture through the evaporator pipe affects cooling efficiency. Ensure sufficient flow for effective heat exchange.
        • Pipe Diameter: Larger pipe diameters allow better heat transfer. Smaller pipes may lead to higher pressure drops.
        • Length: The length of the evaporator pipe depends on the pool dimensions and the desired cooling capacity.
        • Insulation: Proper insulation around the evaporator pipe minimizes heat loss to the surroundings.

    Remember that these calculations involve both engineering principles and practical experience.

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