Principles of refrigeration. Advanced level bodging help required

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  • Principles of refrigeration. Advanced level bodging help required
  • Premier Icon stevomcd
    Subscriber

    geoffj’s solution is probably the best bodge mentioned so far. A very large barrel of rainwater might even do the job as a heat sink rather than having it pass through an electric fridge.

    Put a zigzag of pipework behind your wine store. Copper would be best, but the stuff you get for solar thermal heating doesn’t look like copper, so whatever that stuff is would probably work well enough. Run this through a pump (not much power required) and into a large coil of pipe dropped into a big rainwater barrel kept in a shady place. if you can partially bury it, even better.

    Ideally, stick some basic controls on the pump so that it only operates during the day, or for 10 minutes every hour, or whenever the temperature gets too high.

    A really bodgy bodge might just be to have the aforementioned big rainwater barrel, drop a submersible pump into it, run water through a coil behind your wine, then drop it back into the barrel. This would definitely have to be run on some kind of timer or thermostat.

    Might work, might not. Don’t know if a rainwater barrel would have enough thermal mass. Insulate the barrel as much as possible.

    EDIT: I’d suggest that bodging it from an old fridge is a non-starter. Getting hold of the extra coolant required is probably going to be a pain and you’d have to massively extend everything so that the heat could be dumped outside. Otherwise, it would be equivalent to having a fridge with an open door, which over time just makes the whole room warmer, az any ful kno.

    Premier Icon CHB
    Subscriber

    Stoner, my dad was a refridgeration engineer, so I grew up with it.
    The ideal thing would be the kit out of an old commercial fridge freezer as they are configured for blown air.
    The pressure in a fridge/freezer is NOT dangerous. I have seen hundreds of systems punctured and pipes cut off systems and its no worse than letting down a road bike tyre (or Fox Shock!).

    Compressors have a fill pipe. This is normally braized close at the factory, so if you want to refil then you firstly have to fit a fill valve.

    The heat exchanger on the back of the fridge is low pressure and is relatively easy on most to take off, braize on extensions and relocate.
    Most donor fridge freezers have the internal heat exchanger (the bit that gets cold) integral to the shell of the cabinet, so you might struggle to find an internal heat exchanger.

    Hope this helps!

    IF it was me then I would buy a 300 quid air conditioning unit instead.

    Premier Icon CHB
    Subscriber

    Oh and not sure what gasses are used these days (20 years since my dad did it). Used to be Freon, that was not dangerous (except for Ozone!)unless it went near a naked flame. The combustion product is phosgene gas, not nice stuff.

    Wonder how much of the ozone hole was my dads fault.

    Premier Icon Stoner
    Subscriber

    cheers CHB. That all sounds wonderfully complicated, so Im tending to the pumped water circuit as fridge circuits sound a hassle.

    So do we think a jacket wrapped water butt full of water with a coil of underfloor heating pipe (got loads left over) through it and then via a 12v pump and zigazagged down the back of the box might do it?

    just need a thermostat and timer controller.

    Premier Icon sturmey
    Subscriber

    Most of the gases these days arent ozone depleting CHB I remember freon and guys messing with it while brazing for a laugh 😯 I have also seen engineers cracking bottles of refrigerant off and directing it on to cans of coke to chill them down before drinking in summer. The water method seems to favourite I think you may need to wrap the coil quite close and round the sides as well to make it as efficient as possible and a small amount of air circulation wouldn’t do any harm.

    Premier Icon CHB
    Subscriber

    Basically Stoner, you are building a big fat wonderfully Heath Robinson version of this:

    Zalman Reserator 1 V2 and Fan Kit

    Can we all pop round for a glass of Chateau Latour?

    Premier Icon stevomcd
    Subscriber

    If I had the time, the inclination, or the ability to recall 10-year-old engineering classes, I would do the sums for you… I may get bored enough at some point, but I’m sure someone who’s more up-to-date than me will get there first!

    Premier Icon Stoner
    Subscriber

    I shall start collecting the bits I need then

    No Latour, but a few nice Savennieres.

    Cheers for all the help guys.

    Premier Icon geoffj
    Subscriber

    As an addition, you could increase the thermal mass of the store iteself, by putting a pond in below the wine racking – say a foot deep?

    Reminds of some trouble they had at Edinburgh Botanic Gardens when they drained one of the ponds inside one of the glass houses. They couldn’t get the temp regulation right for ages afterwards 😐 – dopey gets!

    wrecker
    Member

    Chb is talking about the R12 gas which was fun when brazing! Also the only gasses which are non ozone depleting are ammonia and propane, the rest are subject to the f-gas regulations.
    Basically, you will get some cooling effect from what youre trying i dont think that you’ll be able to hit 14degC with it though. Assuming ground temp of 12degC and a rough deltaT of 6K, you’ll be looking at 18degC IF the system is sized correctly. I reckon that, at the flow rates you’ll get off small pump and the thermodynamic qualities of water that the indoor coil you’ll need would be huge particularly without a fan.
    If you do bastardise a fridge, you’ll need a line tap valve for the compressor stub, a turbo torch, some gas, manifold gauges and preferably some oxygen free nitrogen, a vacuum pump; it goes on.

    TooTall
    Member

    Stoner – a lot of Passivhaus air systems are based on air intake heat exchangers:

    =http://www.passivhaustech.com/archive/wordpress/04/2011/air-intake-ground-source-heat-exchanger

    Useful passive cooling info

    I was in a shelter in the Mojave Desert last week – 118F air temp outside. There were 3 double ducts about 40′ long feeding into a box in the corner that was running a 4A 24V solar-powered fan. Air temp inside was about 78-80F and this was only achieved through air-ground heat exchanging in the ducts. It has been working like that for 18 months!

    wrecker
    Member

    That second link has evaporative cooling as mentioned in my earlier post, which is the manner in which tootalls original idea works also.

    Premier Icon wonny j
    Subscriber

    Stoner, as you’ve already found out you can insulate all you like and the space will still heat up if it’s an enclosed space. You need more thermal mass like exposed stone, concrete or brick, (high density materilas) . A big barrel of water will help in that way as well.

    Premier Icon Stoner
    Subscriber

    thanks for all the links etc.

    will read up and come up with a feasible design based on the space, layout and resources I have.

    EDIT: BTW wonny, the slab in there is about 6-12″ thick concrete (uninsulated) about 150sq ft. Its a massive bit of thermal mass.

    It was made with the (larger than expected!) balance load from a floor slab fill for the barn

    TooTall
    Member

    My original suggestion isn’t evporative cooling – it is using the duct in the ground as a heat exchanger.

    wrecker
    Member

    If you’re blowing air over water, the water will evaporate and provide cooling ( providing the rh isn’t too high). That’s evaporative cooling.

    TooTall
    Member

    wrecker – I can’t see that I mentioned water once. I mention pipes, fan and air. I know what evaporative cooling is thank you very much.

    iDave
    Member

    I would have thought that the most obvious solution is to have a temperature alarm ‘thingy’, and when the temp is too high, it auto-posts on STW annoucing a party at Casa Stoner? The reduced number of full bottles in the store will help the other bottles calm down a bit.

    Premier Icon miketually
    Subscriber

    I’m a simpleton, but… Could you replace the racking with something with more thermal mass? A ‘shelf’ of stone or slate every few rows?

Viewing 19 posts - 41 through 59 (of 59 total)

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