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Thread: understanding refrigeration

  1. #1
    Join Date
    Aug 2004
    Location
    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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    812
    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
    Location
    Mukilteo, WA
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    302
    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
    Location
    Mukilteo, WA
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    302
    Hey, Jeff............great write-up, Buddy.

  5. #5
    Join Date
    Oct 2003
    Location
    Pittsburgh, PA
    Posts
    405
    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
    38

    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
    38

    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
    38

    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...

  9. #9
    Join Date
    Aug 2005
    Location
    Phoenixville, PA
    Posts
    17

    Pop quiz

    OK Guys,
    Get out your calculators. I have to replace a [2-separate] fermentor and bright+ Glycol system and am looking for units on thermal load and configurations. My math is horrible.

    System 1 Use and load
    Fv1-20bbl
    Fv2-20bbl
    Fv3-5 40bbl (3)
    2nd stage on 2phase heat exc.

    System 2 Use and load
    Fv6 40bbl
    5- 20bbl bbt’s (5)
    2-40bbl bbt’s (2)
    And a big, ugly 60bbl bbt
    Also:
    300 ft. of trunk lines from bbt’s to our “matrix fridge” which serves our 65 taps through 2 1-ton water-cooled Banner units

    Although I know what I think I need to accommodate the loads, and I think my math and reasoning is correct, the HVAC guys in my area have no experience with multi-differential loads and want to sell me twice what I think I need, which is; 2- 3HP/ton units for a cooling of 600,00 BTU’s/hr total (300k ea.) We want 2, to split the load in the event of breakdown.

    Food for thought,
    We have 2- 300 gallon reservoirs running 20% ppglycol, and brew 2x./week in winter and 4x/week in summer.

    Any advice will be helpful to me and to others in the future
    Thanks in advance,
    -Firey

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