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  • Latest in efficient cooling?

    Wondering if there's been any advances in cooling tech for cold rooms and glycol chillers? I've got a 12'x38' cold room that is very well insulated and will need two-zone cooling (one for primary (50s-60s F) and one for conditioning/finished beer storage (34 F)), as well as potential stand alone cooling for jacketed fermenters down the road. Biggest concern in the cold room is moisture control. I just want to avoid the old-skool electricity black hole version of chilling - there's gotta be something pushing the efficiency envelope out there...

    PS - Anyone with ideas on how to incorporate geothermal into the mix? My brewery building is heated and cooled with a 5-ton geothermal unit and if I could figure out how to run lines to an exchanger in the cold room, at the very least to pre-chill glycol? Or is it a case of too complicated for the $$?
    Last edited by BeerBoy; 05-31-2009, 08:21 AM.

  • #2
    Lots of questions here. First, it sounds as if you will have separate temperature rooms in your cold storage for fermentation/conditioning tanks? If so, then you'd be transferring your recently fermented beer from one side to the other--from fermenters to conditioning tanks? And all your beers will have the same fermentation temperature? You will know, of course, that differing the fermentation temperatures is an easy way to gain a different taste/aroma profile from your beer and avoid a characteristic "house taste". And you will not have the luxury of raising the temperature for a diacetyl rest on a single tank--if need be. If your tanks are over about 15 bbl, then the volume/surface area ratio could produce warm zones in your tank during fermentation. It might be hard for an air cooled tank to convect/conduct this heat out from the bulk of fermenting green beer and into your cold room. As well, your wort heat exchanger should be sized so that the cooled wort is cold room temperature as well, otherwise the warmer wort may warm the room--and the other tanks. Placement of your tanks will also likely inject some fermentation temperature differences in the mix. Those in a corner will have a different fermentation temperature profile than those in the center of the cold room. In short, it will be difficult to nail an exact fermentation temperature. On the other hand--this isn't absolutely necessary if it is a consistent, repeatable temperature profile. (I think there's too much emphasis on being exact rather than consistent) Then there's cleaning--you're committing to cleaning, acid washing, and sterilizing in sub-optimal temperatures. And in many states, you are not allowed a cold room drain due to health concerns of some sort. Makes it even harder to rinse and wash tanks.

    Not to put you off from following your plan, I just thought I'd throw some typical reasons why this is not done more often. Now if I understand your setup, on to your questions: Down the road you should have a separate glycol loop with a dedicated compressor and chiller. Don't put all your eggs in one basket with a single cooling source. Second, moisture will control itself. There will need to be a drain pan under your evaporator fan coil unit. Your air will be humidity-tempered to the dew point of the set temperature--more or less. The water will be removed by the pan drain. Although it does take lots of energy to remove this water vapor as liquid, the old skool way is the only way I know of to do this. Otherwise, keep liquids out of the cold room. Kinda hard when you're cleaning tanks.

    As far as efficiencies go, some compressors are a tad more efficient than others, that's true. But you have to balance that with the long term cost of ownership--these same efficient compressors have a reputation for not lasting long. You'll have to do the math for your situation. And the last question about geothermal; are you referring to a pumped water heat pump? If you have a large, cool reservoir of heat sink, then you probably could run the warm section of your cold room with that alone. But the efficiency of these units goes way down when you try to cool to low temperatures. For a tank farm run on glycol, your glycol return temperature should be quite low--lower than a heat pump can cool efficiently. The larger the difference between your heat sink and your load, the less efficient it will be. So I don't think you could include a heat pump in your glycol loop.

    The real answers to your particular setup would best be answered by a refrigeration pro. Jim at Pro Refrigeration might be able to chime in now and set me straight where I've misspoken. I appreciate your wanting to keep electrical costs down. Where I am, we pay $0.42/kW*hr for power. I'd love to hear how I could lower costs. I already keep my coils clean, check for correct glycol mix (more is NOT better), situate my condenser unit in a relatively cool location, and do all those first-tier things you're supposed to do. Please share what you learn. Good luck and Cheers!
    Phillip Kelm--Palau Brewing Company Manager--

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    • #3
      A couple things I have found to help, first, be sure that the condensate drain doesn't just drip where it will need to be re-evaporated...drain it outside the cold box.
      Second, it seems the major electricity use in a cold box is not the compressor, but the fans. I replaced my 8 fan unit with a unique more efficient single fan unit and had better cooling and less electricity usage. These units are likely not made anymore, but based on this, my next thought is to wire most of the fans on my other box with a relay from the refrigerant solenoid (they would only run when the refrigerant was circulating). This would allow a bit of air circulation all the time, yet the heavy electricity demand would only be on when necessary. If the box had dairy products of something very temp critical, this could not be as wise as if it held more stable beer.
      For mold control, I have found eliminating malt dust to be quite important, as well as using the colder refrigerant vs warmer glycol for the box cooling. Better sealing of the door is also critical if in a high humidity area.
      Last edited by Moonlight; 06-02-2009, 03:04 AM.

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      • #4
        If you have a multiple fan unit, the evap is designed to operate with all fans running. Check the seals on the door to the walk-in and caution employees not to leave the door open while loading.unloading the cold box. The condensate definately should be plumbed out of the walk-in and insure any liquid containing vessel stored in the cold box is sealed. Cooling units do not start cooling the air until the moisture is removed so this is extremely important in cutting costs.

        Some walk-in boxes are built directly on the concrete flooring of the brewery, pub or kitchen. This can be a signicant source of moisture. Insure it is properly sealed.

        Good Luck!!

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        • #5
          If it is efficiency that you are after, you will probably be better going with a direct expansion cold room. Utilizing glycol for your cold room basically is adding a layer in the cooling process: refrigerant\glycol\cold room, we are using refrigerant to cool the glycol, then the glycol to cool the room. For best efficiency, you'd be better off cooling the cold room directly with refrigerant.

          One advantage of using glycol for your cold room cooling is really found when you have a large glycol load in the brewery. I generally recommend customers only consider glycol cooling for their cold room when they have a dual circuit chiller system with redundancy and of course, surplus capacity. Another advantage is more environmental with the elimination of refrigerant lines being ran into the brewery, and operating with an overall smaller total refrigerant charge. This can also lead to significantly reduce installation costs. Also as gitchegumee explains, is very rare to see a cold room utilized for fermentation control. We often see the cold rooms housing the conditioning tanks but just about every project I've been directly involved with has had insulated and jacketed fermentation tanks.

          The biggest developments recently with efficiency on glycol chiller systems, at least the systems we produce, is the introduction of variable frequency drives, electronic expansion valves, microprocessor controllers, and overall sound equipment design. Variable frequency drives modulate the speed of the motor based on the demand, for example we will install VFD on our glycol pumps to maintain a constant pressure on the supply line at all times. As the number of tanks that are calling for cooling increase and decrease, the pump speed will adjust accordingly only running at the minimum speed required. Variable frequency drives are also starting to be used on the compressors.

          Another efficiency idea is to reclaim the heat that is discharged from the condenser. Heat exchangers can be added to all refrigeration systems that will use the heat from the compressor discharge to preheat their hot water, heat rooms, etc. You can often recover as much as 50% of the heat generated by your system.

          I'm personally not real familiar with the ground source systems. I'd suggest consulting with the contractor that installed your system for ideas.

          I hope this information has been somewhat helpful. Good luck going forward.

          Jim

          Pro Refrigeration Inc.

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          • #6
            Originally posted by BeerBoy
            PS - Anyone with ideas on how to incorporate geothermal into the mix? My brewery building is heated and cooled with a 5-ton geothermal unit and if I could figure out how to run lines to an exchanger in the cold room, at the very least to pre-chill glycol? Or is it a case of too complicated for the $$?
            Tying into another system to pre chill your glycol will just add load to that system. The heat has to be removed and that requires more work. The return lines to the compressor may be cool but generally, on a hermetically sealed compressor that is used to cool the motor. There are plenty of ideas out there about robbing cooling from the cold room evap fan discharge stream for a glycol system out in the brewery but that just adds heat load to the cold room compressor section causing it to work harder and longer.

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            • #7
              ambient air to cool glycol

              Thanks Scott, great points that reminded me of some other cool stuff we are doing in some of the colder regions (like Minneapolis, Denver). On these systems we are mounting ambient air to glycol heat exchangers (these heat exchangers look like the units mounted in your cold room) outside at the chiller unit, but instead of using the glycol to cool the air, we are using the colder ambient air to pre-chill the glycol before returning to the chiller tank. Obviously you need an ambient climate that spends a good deal of time below your glycol return temp to take advantage of- but the results have been pretty exciting.

              Jim

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