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Thread: understanding refrigeration

  1. #1
    Join Date
    Aug 2004
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    pacific northwest
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    4

    understanding refrigeration

    I have seen glycol chillers described by horsepower and by tons. What is being referred to by a "4 ton glycol chiller"? Is that the weight of the chiller itself? Also, if I am trying to determine what size glycol chiller I will need, should I be more concearned about horsepower or tons? In a nutshell, I need to chill six 7bbl tanks. Also, should a 200 sq. ft. walk in be a separate chilling system?

  2. #2
    Join Date
    Mar 2003
    Location
    Nashville
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    823
    A ton of refrigeration is 12,000 btu/hr, if I remember right. A 4 ton would probably be a 5 hp chiller or so.

    I would go with a different refrigeration system for your cooler, makes it less complicated and a cold room manufacturer could give you an exact quote.
    Linus Hall
    Yazoo Brewing
    Nashville, TN
    [url]www.yazoobrew.com[/url]

  3. #3
    Join Date
    Dec 2004
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    Mukilteo, WA
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    Hi Charles,

    Basically, the "Tons" specification of a refrigeration system (generally the compressor/condensor side) is derived from the old days and is a comparison to the cooling effect of ice. I believe this was how much cooling capacity you got from 2,000 lbs of ice melting over a 24 hour period. It equates to 12,000 BTU/hr of cooling capacity, or 288,000 BTUs/day.

    A BTU (British Thermal Unit) is the energy required to cool or heat 1 Lb of water by 1 Degree F. There is an equation between BTUs and horsepower, and that is 1hp = 2,546 BTU/hr. As I stated before, there is also a relationship between refrigeration tons and BTUs, and that is BTU/hr capacity = refrigeration tons x 12,000. To equate refrigeration tons and horsepower, it is Hp = refrigeration tons x 4.716.

    These, of course, are all calculations used for sizing and equating, and your milage may vary based on road conditions.

    Example: A 3 hp compressor assembly will produce about .636 tons of refrigeration, or be able to remove about 7,638 BTUs/hr of heat from your system.

    Why do we use "tons of refrigeration"? I dunno...........it seems a little antiquated to me............kinda like measuring people's weight in "stones" or similar. The real deal in all this is BTUs/hr and horspower. Based on some rudimentary calculations, you can approximate your heat load based on how much heat is generated during fermenation, how fast you want to "crash" a tank (drop its temperature), and how low you want to go temperature wise. There's a few other considerations in there, but using those, to calculate BTUs/hr, and deriving your horsepower, which the sizes the motor(s), which will then give you your electrical requirement.

  4. #4
    Join Date
    Dec 2004
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    Mukilteo, WA
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    299
    Hey, Jeff............great write-up, Buddy.

  5. #5
    Join Date
    Oct 2003
    Location
    Pittsburgh, PA
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    My two cents: Once you figure out what you need, spend a few buck more to oversize the unit. Fermentation will be your likely equipment bottleneck as you grow, and it's nice to have the extra cooling capacity.

    Scott

  6. #6
    Join Date
    Dec 2002
    Location
    San Carlos, CA, USA
    Posts
    40

    Absorption Chiller vs. Compressor Chiller?

    Since we are on the topic of chillers, does anyone have experience with absorption type chillers? I came across one... and had never heard of one before. What are the differences? Do they have the same end result?

  7. #7
    Join Date
    Dec 2002
    Location
    San Carlos, CA, USA
    Posts
    40

    re: absorption chillers

    My local Trane outfit has a 5 ton absorption chiller for $1500. It's brand new...they had it sitting in the warehouse and didn't know what it was. Do you think it's a good option?

    Jeff,

    No I didn't buy the 7 ton chiller... The shipment date pushed out to mid-January and he wasn't able to provide any specifications on the unit. So, I need one sooner and I'm not really comfortable about buying a chiller without specs..

    Chris

  8. #8
    Join Date
    Dec 2002
    Location
    San Carlos, CA, USA
    Posts
    40

    re: absorption chiller

    well it looks like this model of absorption chiller only goes down to 37 F. http://www.robur.it/gestione/immagin...ec-sheet_b.pdf

    I may use it in a series with another chiller.

    Absorption technology seems to be very cool. There are absorption units that will go down to the correct temp., but they are very $$$$.

    thanks for input.

    anyway...still looking for a 7 ton chiller...

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