Fridge uses cold outside air to cut energy costs
On WorldChanging, Alex Steffen gives a briefing on the Freeaire System, which pipes in cold external air when available to cut energy bills.
"...designed to provide such free cooling for walk-in coolers, freezers and cold storage warehouses. The system utilizes an electronic controller to finely tune the operation of standard refrigeration equipment, and this controller simply monitors the outdoor temperature and desired temperature settings and stops refrigerator evaporator fans when not needed, which also reduces the compressor's refrigeration load. Proper airflow is maintained when the evaporator fans switch off by operating one or more energy-efficient circulating fans.LinkRoughly half the electricity consumed by a typical convenience store is used for refrigeration. The Freeaire System is designed to save energy year-round by allowing refrigeration equipment for a walk-in cooler or freezer to run only as much as it has to. Once the system is installed, evaporator fans typically operate 50 to 75% less often, and reach-in door heaters operate 90% less frequently. Condensing units also usually experience a 10 to 20% reduction in operations. Moreover, a Freeaire System saving 20,000 kilowatt-hours annually can prevent 40,000 pounds of CO2 from being emitted to the atmosphere.
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Gratifying to know that technology can use cold air to reduce energy costs .
The trouble is though that politicians use hot air to raise them !
Cldnn Jm
http://www.cldnn-cmmnt.cm
For the win: they should ensure that any waste heat from the unit is reclaimed and used to heat the air in the store/restaurant/whatever where the unit resides (since, if it's cold outside, the conditioned spaces will have some kind of heater on anyway).
This is generally true for a "cooling" units: they don't "create" cold: they merely move heat around (and generate a little more heat as they operate due to friction).
For those of us in cold climates, these advanced devices are called "garages" or "back porches" and are commonly in use from three to seven months of the year. The portable version, often referred to as a "car trunk" is capable of storing frozen foods for long periods in multiple locations, as well as keeping sweaty gym clothes from decomposing.
I've wondered why this idea has taken this long. I've worked at restaurants all of my life and always thought it weird that in the winter time I'd walk (freezing!) from my car into a warm restaurant, then down to the basement into the walk-in cooler that was pumping out its own heat.
I told a friend a few months ago about this awesome idea I had of using air vented from outdoors, controlled by an electronic thermostat, to help cool grocery store freezers on cold days, and he looked at me like I was crazy.
Who's laughing now, buster?
Theodore Taylor did some research on "ice ponds" that would do for A/C what this trick does for refrigeration.
An office building would set up on the edge of a parking lot a big swimming pool like structure. Ice and snow would be plowed into it. At the end of winter it would be covered over. When A/C season swings around, the pond would be used as a heat sink, greatly decreasing electrical demand.
not the "curve of binding energy" Ted Taylor?
Using cold outside air in coolers/freezers does not work. First, the unit would have to be against an outside wall. Then think of what is outside that wall...diesel/gasoline exhaust? Dumpsters? Mold? Back alley smells? And you want to bring that directly into a place where you store food? No, you do not.
You have to filter that air. Now the fan motor has to be sized large enough to push through all that filter, which uses more energy than the refrigeration system does because of the cool outside air, provided it is a built up system that rejects heat to the outdoors (think supermarket) instead of the indoor space (think domestic refrigerators).
If you really want "free cooling", go with Thinkerer's garage idea.
As for the other ideas, all heat (or cold) can be recovered. Its just a matter of what capital cost you are willing to pay to do it.
I've often wondered why we don't put the heat exchanger portion of refrigerators outdoors, like we do with air conditioners. It would seem to be a win regardless of season -- in the winter, heat exchange ought to be rather efficient (much greater delta-t) leading to running the compressor less. You do give up some of the waste heat but I bet it's still a net win. In the summer, at least you're not pumping more heat into your already hot house (if like me you don't have air conditioning) or into a house that you subsequently cool with a second cooling system (your air conditioner).
I suppose the simplest form of this idea would comprise a massive wall cut-out to allow the back of the fridge to be outdoors. Seems rather unappealing though.
I think the advantages over the "garage" system (which I also use, well actually I prefer the "screened-in porch" variety) are self-evident.
JGS: The reason we don't is because it would increase the cost of the fridge from around $800-$1k up to the cost of most central A/C units ($3k - $4k). The units would have to be much beefier to handle the low condensing temperatures of winter, too. If you read your owner's manual, it usually warns against using in a space below 50F.
#7: Yes, that's the one.
The ice pond research is described in one of Freeman Dyson's books. Taylor was leading a team of Princeton students.
hey, ever read Dyson's son's biography? The Starship and the Canoe?
@Bucky #8.
You don't have to filter the outside air if you use an air/air heat exchanger. That would allow the outside air to cool the inside air while keeping them separate.
I think most manufacturers of walk-in coolers walk-in cooler are in favor of any new green technology that is promising. Unfortunately, until the costs come down, most retailers and foodservice operators will never be able to justify the expense.
geothermal heat exchangers. Heat AND A/c