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  • Out Side Cold air to Walk-in

    In need of advice and suppliers for system to bring in Cold winter air to the storage cooler. Unit houses all hops, bottled and kegged product.
    Also serves as the dispensing of product to taproom. Temperature at night drops to the mid 20's. looking to shut down condenser unit for at least 12 hrs.
    Just an energy cost cutting idea. Who has one on a small scale..? Our cooler is 18' X 25'.

    Lance
    Tonopah Brewing
    lancejergensen@gmail.com
    775.997.6411

  • #2
    Economizing - Free Cooling

    IN a perfect world you might calculate the CFM of air needed at that temp and so forth, but truthfully you can probably hack this kind of thing on smaller scales and make it work.
    I have something similar on the books.
    Essentially you need a fan drive to bring air in and a relief damper to allow the room not to pressurize and to exchange, all of this on thermostatic control.
    You could used something as simple and cheap for your fan drive as a dry evap cooler.
    I would have motorized dampers in and out.
    Control wise you will break your switch leg to your LLSV on your refrigeration system when the economizer set point is active on outdoor air temp.
    The control wiring will be simple. One or 2 relays and an outdoor air thermostat will do it. You should be able to run your entire outside air induction array on one circuit supplied for the ampacity of your fan drive. This will run dampers, controls and all. You will also need a separate box thermostat to tell the system when to cool and when to cycle off.
    You will need to take a stab at the CFM you want to run which will determine the inlet and outlet duct sizes. These need to be placed for optimum air flow through the box.
    For large liquid loads as such, I don't see that the math needs to be perfect
    Last edited by Starcat; 02-01-2015, 08:33 AM.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

    Comment


    • #3
      Hi Lance,

      Free-aire makes a system for just what you are looking for. Here is their link:
      http://freeaire.com/how-it-works/

      Comment


      • #4
        I built a system for this several years ago. It works great. We use two fans, one for evac, one for pressure, to keep the air pressure in the cooler balanced. The electronics cost me about $20. I can find the schematics if you're interested and handy with a soldering iron. I have ours set to a differential of about 5 degrees F, which works very well here (NE Oregon, ~4,000 ft elev). We get nearly free cooling for 9 months of the year or better.

        The Freeaire systems look great to me. If they had been around when I built mine, I probably wouldn't have built it.
        Timm Turrentine

        Brewerywright,
        Terminal Gravity Brewing,
        Enterprise. Oregon.

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        • #5
          +1 on freeaire. we have it, works well.

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          • #6
            Tgtimm, I would be interested in that schematic if ar all possible. I have talked with freeaire butbi think their system and controls are a little much for my small application.
            Thanks
            Andy

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            • #7
              Originally posted by Crosley View Post
              Tgtimm, I would be interested in that schematic if ar all possible. I have talked with freeaire butbi think their system and controls are a little much for my small application.
              Thanks
              Andy
              Mind sharing what their costs were?


              Brian

              Comment


              • #8
                I didn't actually get up to having them work up a quote for me, but from my discussions with their sales rep their system is very intricate and involved (control panel, multiple fans and blowers) and they do not just sell individual components, but complete systems.
                My walk in is only 10x18 so I think this would just be overkill.

                Comment


                • #9
                  20 years of experience with outside air refrigeration.

                  As the inventor of the Freeaire® refrigeration system, I have been involved with many free cooling systems in breweries and other types of refrigerated warehouses for many years. I have found that every situation is unique, but that almost every cooler of your cooler's size in a northern latitude or high elevation can benefit from using outside air. Accessibility to an outside wall, the climate, electricity rates, the size of the compressor system that is cooling the space when the weather is not cold, and the existence of utility rebates are just some of the variables that go into the decision to add an outside air system. Such a system should be combined with high-efficiency evaporator fan motors and evaporator fan control to run the evaporator fans less often or at reduced speed, which are efficiency measures that apply to coolers in any climate.

                  I can be reached at richard@mv3momentum.com or 617-658-4414.

                  Richard Travers

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                  • #10
                    Hey everyone, I just need to offer a counter-argument against doing this. Nothing against Freeaire or anyone else doing this but I've been involved in similar installations that turned out horrible. What you are talking about is essentially outside air economizing. Its very common in the north for air-conditioning systems but when you are talking cooler temperatures, the savings goes away.

                    Some issues to think about:

                    1. How many hours will this actually work? - Yeah, it feels like all of winter is a long, cold freeze but look at the data and determine how many hours you will really be below your temperature set point. Look for "bin weather data" or search for TMY3 data for your location and you can count the number of hours there are when your system could potentially work.

                    2. Do you really need cooling during those hours anyway? - Notice that most of the hours when you could run the outside air economizer are in the middle of the night and early morning. When is your refrigeration system running? Look at the loads on the cooler: transmission through the walls, warm product coming in and infiltration when the door opens. If its cool enough to do outside air economizing, there will be very little transmission load unless the cooler is inside a heated building. If the viable hours are late at night and you aren't moving warm product in or opening the door, there would be very little reason to run the refrigeration system anyway.

                    3. How much could you save? - Even if your refrigeration system was running extensively during those viable hours, you need to check your electric rates and your system's operation. Many of you will be on a time-of-use electric rate from the utility. This means your cheapest electricity probably is purchased in the night hours. So your payback is extended because you wouldn't have been paying that much anyway. Likewise, when it is cool out your refrigeration system doesn't have to work as hard to reject the heat. This is especially true if your system can float the head pressure (discharge pressure) down when outdoor air is cool.

                    4. Are there any dangers? - If you are bringing in outside air, you need to make sure you are filtering it to prevent insects, dirt, debris, pollen, etc. You won't be able to stop moisture or odors, though. I was involved in a refrigerated warehouse that tried this but they were sucking in diesel fumes from the loading dock so they put in HEPA filters. That ended up boosting the fan hp so high, it cost more than if they just ran the compressors at a low head pressure. Then there is also the danger of bringing in air that is too cool and you start freezing product. I'm sure the commercially available systems have that built into their control software but something rigged up by Bubba-Joe-Bob and Sons refrigeration may forget that detail.

                    Just keep in mind that nothing is free. Look into reducing parasitic loads (door heat, left on lights), compressor sequencing, tightening up the door, ECM motors, etc. before this step.

                    Comment


                    • #11
                      Dan--if I might speak as a "Bubba", I'll say that our system works quite well. At 4,000' elevation and 45 degrees north, we certainly are well below our cooler temp of 40F for at least 9 months/year--and this is most of the day. Even in summer, most nights are below 40F for at least 5-6 hours. I did use a limiting thermostat to keep from over-cooling, and when it gets particularly nasty out and we start to get low temps in the cooler, I simply switch the inside and outside sensors so the unit brings in warmer air when possible.

                      True, I'm running about 10 amps of fan motors, so it isn't free, but compared to running a 24 hp chiller compressor, it does seem to be a savings. Besides, our chiller pulls a heavy load, so reducing that at all is a plus.

                      Unfortunately, our power bill is nearly incomprehensible to a "Bubba", so I can't really give solid numbers for before/after.

                      As for the air quality problems, did I mention we're at 4,000' and 45 north in a remote, mountainous area? To quote The Talking Heads, "Some people tell me not to worry about the air...."

                      Aside from all else, designing and building the system was fun and educational.
                      Timm Turrentine

                      Brewerywright,
                      Terminal Gravity Brewing,
                      Enterprise. Oregon.

                      Comment


                      • #12
                        Since I just had to look them up, here are the schematics and some pics of my "Bubba Cooling" economizer: https://www.flickr.com/photos/chesni...7624442589753/

                        Of course, you'll have to add a couple of fans--exhaust and intake--and a suitable contactor or SSRL to turn them on and off. Total cost for the controller should be > $20 if you build it yourself. Add a thermostat to keep the cooler from getting too cool.

                        This is for you to use, not to sell--FreeAire would likely have problems with that. I can trace the design to prove it's original--with a little help from my friends at dicovercircuits.com .

                        I still have many parts to build several of these if anyone is interested.
                        Timm Turrentine

                        Brewerywright,
                        Terminal Gravity Brewing,
                        Enterprise. Oregon.

                        Comment


                        • #13
                          Bubba Timm...seriously awesome. From what I can tell, you did it right and you have the weather to make it pay off. That's just not the case for most people. Fortunatly for you, we don't all live in Oregon.

                          On those cool nights, do you overcool a bit to help you hold temperature for "free" through the day? There are also some phase change materials (wax basically) that can be set to freeeze/thaw at whatever temperature you want to give you a little more capacity. Basically you would solidify them at night using the outside air and then they thaw during the day to take up heat but at 40F or whatever temperature you want instead of freezing like water.

                          On your chiller, are you also running a water side economizer? Instead of running the compressor, whenever its 10F below your glycol/chilled water set point, you can run it out to a fluid cooler/dry cooler to get "free" cooling. Its pretty common with computer server cooling applications and industrial systems but I haven't seen enough in breweries.

                          Anyway, I just wanted to make sure the devil's advocate side was out there. I've seen systems where the thermostat fails open and freezing air is brought in. I've seen it where it fails open on a hot day and so much hot air is brought in the compressors are overloaded and product is lost. I've seen health inspectors freak out at the thought of outside air being brought into a cooler. I've seen systems installed by major contractors/design firms that should know better be a complete disaster.

                          Comment


                          • #14
                            Dan--our cooler is usually filled floor-to-ceiling and front-to-back with product--lots of thermal mass to buffer the temperatures. We do run the economizer down to about 30F when the temps allow--by experience, we don't have any freezing problems until about 23F.

                            We've given some thought to a "wet-side" economizer, but our space is very limited, so we haven't actually done anything yet.
                            Timm Turrentine

                            Brewerywright,
                            Terminal Gravity Brewing,
                            Enterprise. Oregon.

                            Comment


                            • #15
                              Originally posted by TGTimm View Post
                              Dan--our cooler is usually filled floor-to-ceiling and front-to-back with product--lots of thermal mass to buffer the temperatures. We do run the economizer down to about 30F when the temps allow--by experience, we don't have any freezing problems until about 23F.

                              We've given some thought to a "wet-side" economizer, but our space is very limited, so we haven't actually done anything yet.
                              In the refrigerated warehouse industry we refer to that as passive shifting or passive thermal storage. The idea is to over cool everything at night and leave the refrigeration system off during the day. If you have a time-of-use electrical rate, which means electricity price goes up during the day when demand is up, it is very advantageous if you can leave the refrigeration system off all day until you get into the off-peak (night) time prices. A large mass of product helps you out. It will keep the temperature pretty stable throughout the day.

                              With beer, temperature fluctuation is fine. As you watch the temperature, remember you are looking at air temperature. The beer will be a few degrees behind. Other food products (e.g. most dairy, especially ice cream, meat, frozen peas) suffer extreme quality loss from fluctuation.

                              Space...if you aren't limited by budget, space is the second most valuable commodity. Look into it. Someone may be able to find you space. Also, check to see if your electric utility will give rebate $$ for energy efficiency upgrades.

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