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  1. #1
    Join Date
    Apr 2019
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    Fridg, Freezer, AC combo?

    I build "green" energy efficient homes. I am looking for the possibility of combining several needs into one solution. The needs are as follows:


    Custom super-insulated kitchen refrigerator/freezer cabinet with separate (unified?) compressor/controller.

    A sizable in-ground freezer, super insulated, with large thermal mass, similar to the old fashioned ice houses, that used winter ice cut from lakes, that kept ice through summer before modern technology. Except in this case, in winter, in this northern climate it could use outdoor air to freeze the thermal mass, and for warmer conditions have some conventional compressor freezing available.

    The home envelope is extremely efficient so very little if any ac will ever be needed, but it is good to have some available. It is the same for heat. With passive solar and thermal mass very little heat is needed. I am not clear how outdoor air filtering and exchange for the tight building envelope as well as heat exchange would fit in, if any of this can be combined at all.

    It would seem to me like a four zone system.
    1. Kitchen freezer
    2. Kitchen Refrigerator
    3. Walk-in freezer
    4. House with ac and heat and preferably outdoor air filtration, and heat exchange.

    Is there anything existing that could manage all this in one system? With customization? Would the costs be far higher that just using separate more traditional systems? Would someone be able to help with a customized system, or would I have to start my own company and develop it at great cost?

  2. #2
    Join Date
    Oct 2011
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    Chicagoland Area
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    If "one" solutions fails, all 4 fail. Is that acceptable to the end user? The current offering of high, medium, and low temp compressors have different compression ratios and different motor cooling requirements. Not to mention, many of the current refrigerants are on the chopping block, I don't see it as a feasible solution today. Maybe in the near future, with vfd driven compressors and blowers, and liquid injection, there may be a cost effective solution, but not today.
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  3. #3
    Join Date
    Feb 2010
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    On the water but near the hood
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    It doesn't matter if you can engineer and build a system like you describe. The problem is that the industry doesn't have enough qualified people, broadly available, who could understand it's complexities when something eventually goes wrong. We simply have more qualified people retiring than potentially qualified people entering the trade.

    Until you can solve that, your idea will remain just that, an idea.

  4. #4
    Join Date
    Jul 2000
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    Guayaquil, EC
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    Such ideas of building a super-efficient refrigerator and freezer are intriguing until one considers how very efficient and reliable quality home appliances are today. It would be very difficult to match or better them with anything one could cobble together from scratch.

    As for the walk-in freezer, I question that approach primarily from the standpoint that a walk-in inherently is not a very efficient because there's a lot of wasted volume to allow passage and access. The extra volume leads to increased exposed wall area and heat gain. A good chest type freezer is by far the most practical and efficient. It may not be as convenient, but then having an underground freezer vault isn't exactly handy or convenient either.

  5. #5
    Join Date
    Jul 2002
    Location
    Chariton, Iowa
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    Study and possibly reconsider the phase change (gas to liquid) to phase change (liquid to solid) system for freezing the thermal mass, unless the condenser heat will help heat the structure. Remember that gas to liquid phase change refrigeration is a reverse Rankine cycle.

    With Rankine the larger the temperature difference between hot and cold the more heat energy gets converted to usable energy instead of just flowing from hot to cold.

    Since refrigeration is the opposite the higher the temp difference the more energy you have to put in to move a given volume of heat energy from cold to hot.

    If making the ice causes a larger temp difference than simple DX comfort cooling with a 45 evaporating temp then you lose energy wise.

    This is the reason those "make an A/C from a cooler filled with ice and a fan" ideas clogging up Pinterest Etc. are so dumb.

    Some of the best ice makers are 60 kWh per ton of ice, and a 12 EER (for easy math being 1kW and 12k BTU per hour) A/C is 24 kWh per ton of cooling.

    That's 2.5x the energy to freeze and remelt ice instead of DX cooling. This despite A/C being rated at 95 F condenser air ambient and ice makers at 90 F

    Also the simple fact that trying to make a single refrigerant circuit handle comfort cooling at said 45 evaporating temp and freezer duty at a below 0 F evaporating temp possibly at the same time won't end well efficiency wise.

  6. #6
    Join Date
    Jan 2004
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    I think the system your talking about would cost more than the rest of the house would.
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  7. #7
    Join Date
    May 2006
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    the way houses of today are built your right

  8. #8
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    Aug 2016
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    San Diego
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    Yes but it would be interesting to see it accomplished. It would need one hell of a control system constantly monitoring pressures and temps along with controlling valves.

    Maybe something along the lines of a whole house VRF. But 410, which VRFs use, isn't very good for medium or low temp. So if you were to come up with a system that used a refrigerant that works for refrigeration as well as comfort cooling, it should in theory work. Of the top of my head the only refrigerant that comes to mind would maybe be 22. Granted in 2019 there are so many other refrigerants that there is one out there that would work that I'm just not thinking of.

    Quote Originally Posted by beenthere View Post
    I think the system your talking about would cost more than the rest of the house would.

  9. #9
    Join Date
    Aug 2002
    Location
    Southold, NY
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    Supermarkets do it all the time!

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  11. #10
    Join Date
    Oct 2014
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    Columbus, Ohio
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    I've thought about this sort of setup for a while. The fact is, the benefits are too small at such a small scale. As pecsmg said, supermarkets do stuff like this all the time, but it's on a much larger scale and there is significant opportunity for efficiency gains.

    In my opinion, something like this could be done if the various home appliances could have water-cooled condensers that could be plumbed into a central heat-management system. The common denominator of a water connection would allow you to share heat between many things: Freezer, refrigerator, ice maker, HVAC system, geothermal heat pump with heat recovery, domestic water pre-heat, etc.

    But as btuhack said, it would be difficult or impossible to find people to work on it when it inevitably breaks down, as all mechanical things do eventually. If you did find someone, they would cost a fortune.

  12. #11
    Join Date
    Apr 2003
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    St. Louis
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    Ice is 32* that being said 0* or colder freezer has to be cooled with refrigerant. So if there is a 2 ton cooling, 1/2 ton refrigeration load need a 3 ton freezer unit to cool the freezer and make ice to circulate chilled water for refrigeration and comfort cooling. Go with geothermal for comfort cooling ,heating and some hot water and solar water heater. Let the refrigeration be stand alone. Putting all systems together with any one problem could take down the whole system. The more complicated a system is the harder to find someone that understands it.

  13. #12
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    Quote Originally Posted by pecmsg View Post
    Supermarkets do it all the time!
    Supermarkets use a separate A/C from the refrigeration equipment.
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  14. #13
    Join Date
    Jan 2010
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    Quote Originally Posted by beenthere View Post
    Supermarkets use a separate A/C from the refrigeration equipment.
    Not always now.....I have seen several high temp cooling applications piped right off a CO2 rack.

    Sent from my SM-G965W using Tapatalk

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