Principles of refrigeration. Advanced level bodging help required

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

    I’d have thought the guts of an old fridge would be your best option – that is after all designed to do a job much like the one you’re trying to do. No experience in bodging fridges though, and one thing that springs to mind is the presence of dodgy chemicals.

    Though I’m mainly just ticking – intrigued to see suggestions from the real bodge merchants.

    Gary_M
    Member

    Be very careful messing about with chiller compressors – toxic fumes and pressurised gases.

    cynic-al
    Member

    SPeaking ap a bodging expert my answer would be yes

    RealMan
    Member

    Stick an old freezer down there, leave the door open.

    stumpy01
    Member

    Main problem would be taking the gubbins of a fridge & fitting it into your space without having to re-do all the pipework & stuff (which would mean dealing with all the refrigerant & stuff).

    Peltier would work but you’d need a meaty one for that size & they are very power hungry.

    Just wondering if you could get some car a/c parts from a scrappy, plumb it all in & get a garage to recharge it. Is the equipment they use mobile or not?
    Something like these people:

    Cool Car Air Conditioning – Air Con Recharge, Service & Repair

    Not cheap though using car parts I wouldn’t have thought, bearing in mind a new compressor for my air con was about £400.

    Premier Icon Stoner
    Subscriber

    eBay prices for car compressors and condensers was pretty much ruling it out.

    Is fridge coolant pressurised then?

    If I could tear open an old ridge and extract the condenser/compressor and pipework in one, I reckon I could fit it either side of the panel (cold side/hot side)

    Premier Icon geoffj
    Subscriber

    A couple of elements out of electric cool boxes fastened into the top?

    Premier Icon Stoner
    Subscriber

    A couple of elements out of electric cool boxes fastened into the top?

    not cheap…and Id need quite a few….

    Premier Icon aracer
    Subscriber

    Is fridge coolant pressurised then?

    What do you think “compressor” means? 🙄

    Premier Icon Stoner
    Subscriber

    aracer:

    Thermostat Range – 18-32*c
    and
    Power Consumption – 890W

    Id need 14degC. Id probably want to control it with a basic switch though. so could bodge an external one…

    Premier Icon Stoner
    Subscriber

    What do you think “compressor” means?

    haha.
    Is it under pressure when the compressor isnt on though?

    RealMan
    Member

    Compressor?

    I ‘ardly know ‘er!

    Premier Icon geoffj
    Subscriber

    Radiator fitted into the back of the wine store plumbed into a pumped circuit which passes through an old fridge located at the side of the store. Controlled by a stat, natch.

    Well you said you wanted bodged! There is the potential to neaten it up by using a small 3-way caravan fridge.

    http://www.ebay.co.uk/itm/Electrolux-RA122F-Fridge-240v-Caravan-Tent-Awning-/300590634034

    Premier Icon Stoner
    Subscriber

    Originally I was going to install some spare underfloor heating pipe around the inside of the store, and then use a bilge pump to pump water from a rainwater harvest storage tank in the ground around the pipe…..

    …but in the end I didnt bother with the rainwater storage tank, so I have no heat sink, otherwise, thats what Id still do.

    Premier Icon aracer
    Subscriber

    Or how about cutting a fridge shaped hold in the side and mounting a fridge in it – don’t forget to leave the door open!

    Premier Icon geoffj
    Subscriber

    so I have no heat sink

    The underfloor circuit in the rest of the house?

    Premier Icon Stoner
    Subscriber

    Or how about cutting a fridge shaped hold in the side and mounting a fridge in it – don’t forget to leave the door open

    thats closer to where my brains going…

    Premier Icon Stoner
    Subscriber

    The underfloor circuit in the rest of the house?

    no realistic way of connecting to it, and if air temp in summer is 20degs in the house its not going to help.

    Underground water should remain around 11-15degrees all year.

    Premier Icon aracer
    Subscriber

    There are of course more traditional methods
    http://en.wikipedia.org/wiki/Icehouse_(building)

    Premier Icon Stoner
    Subscriber

    got snow?

    Premier Icon geoffj
    Subscriber

    Ok, so how about digging a trench outside somewhere. Below a metre, the temp remains constant at 7 degrees (ish). Sink a coil and pump through that?

    Premier Icon Stoner
    Subscriber

    Ok, so how about digging a trench outside somewhere. Below a metre,

    No. because Im lazy.
    Id imagine also unless its quite a big hole, energy being pumped into the sink may be arriving faster than it can dissipate in the ground.

    Premier Icon aracer
    Subscriber

    got snow?

    I’m guessing you have a freezer to generate ice packs.

    Premier Icon Stoner
    Subscriber

    My wine store needs cooling. It’s smoothing out temperature fluctuations, but it’s getting to hot during heat waves.

    Id like something based around 12v DC so that I can use solar/SLA battery, although 240v is possible.

    What approach would you take?

    The store is an insulated “box” of about 2m3. The walls are foil backed 40mm polyurethane foam panels (like Celotex/kingspan) so really easy to cut/drill for ducting or pipework.

    Im not sure a Peltier device approach is going to be sufficient, so am looking at compressor/condenser approach.

    Would an old fridge be usable for parts? or car air conditioning unit? or perhaps a dehumidifier (I have one sitting idle)

    bodgers, I need you.

    Here’s the problem:

    wrecker
    Member

    Fridge gas isn’t toxic. The ozone layer doesn’t like it very much though.
    I don’t think you’ll get something based around a 12V supply.
    14degC SP is out of the range of a split system too. I don’t think you’d have a lot of joy with the guts of an old fridge either, I reckon you’re looking at about 1kW of cooling and you will probably have problems with the evap coil icing up. Not an easy one TBH.
    Perhaps evaporative cooling (adiabatic)? Water supply on a float valve, basic stat operating the fan?

    TooTall
    Member

    75 ft of 6″ pipe laid out at a 2m depth in the garden. Small stack at the other end, small 12 or 24V fan drawing air along pipe. Cools air to approx 55 deg F and pushes it in to your storage area. Can be run mains or from a single solar panel.

    Premier Icon Stoner
    Subscriber

    is that proven tech that tootall? got any links?

    Premier Icon Smudger666
    Subscriber

    Stoner

    Skimmed the thread and will give it some thought but FYI pressure on the ‘high pressure’ side of a heat pump/fridge can be 16-20 Bar from memory depending on the refrigerant used. Take care with any ‘bodging’!

    Premier Icon geoffj
    Subscriber

    75 ft of 6″ pipe laid out at a 2m depth in the garden. Small stack at the other end, small 12 or 24V fan drawing air along pipe. Cools air to approx 55 deg F and pushes it in to your storage area. Can be run mains or from a single solar panel.

    Won’t that dry it out? Iirc you want cOnstant humidty too?

    Premier Icon wonny j
    Subscriber

    I think you’re looking at the problem the wrong way around.

    You need more thermal mass not refrigeration. Unfortunately your shed is a lightweight structure so heats up quickly for a given heat input (like sunshine on the roof).

    Wine cellars are normally underground and have lots of exposed stone/earth so have a very high thermal mass or thermal inertia.

    Increasing the thermal of the shed walls might be more effective…. lots of flagstones or breeze blocks on the inside of the insulation might do the trick

    Premier Icon Stoner
    Subscriber

    The shed is insulated wonny.
    The store is a second layer of insulation.

    Premier Icon Stoner
    Subscriber

    How about a water cooler and a water circuit inside the store.
    http://www.ebay.co.uk/itm/Blue-Grey-Premier-Water-Cooler-37cm-x-31cm-x-111cm-/110732345672

    Just need a small lemonade bottle header, a 12v inline pump, and a relay switch to turn the water cooler on at the same time as the pump.

    http://www.solarproject.co.uk/page2.html

    He maybe right. There is a reason why wine is often kept in caves and cellars. Ours stays cool whatever the weather just 1-2m below ground level in a stone cellar.

    What about heading down?

    Junkyard
    Member

    like too talls idea but as wonny notes the issue is the shed overheating.

    Can you surround the wine rack with heavy stone as a thermal sink and then close it off , from the rest of the shed somehow? like an old fashioned larder?
    Perhaps wet it on the outside so evaporation will further cool it?
    Can you not just dig a hole in the floor and build a cellar underneath?

    Premier Icon Stoner
    Subscriber

    stone inside the shed wont really help as it will just add to temperature buffering not cooling. The cellar heat sink thing is being underground where ground temp is always low and acts as a permanently regenerating heat sink.

    Im trying to avoid digging more holes, so electrical cooling is the preferred solution at the moment. Adding thermal mass inside the insulated envelope and cooling that would help.

    Elfinsafety
    Member

    Just put it in Scotland and it will remain cool all year round.

    Swelper
    Member

    Is it a cellar kind of arrangement (wine open to the atmosphere) or does the wine store cabinet have a door on it ?

    My understanding is that Refrigeration systems are designed in terms of compressor size v’s refrigerant = temp output. Bodging something up would compromise any efficiency and cooling effects, though saying that over engineering would be the way forward, for example 2 x compressors and increasing the path of refrigerant. Or putting in a large ish fridge unit.

    A small chiller unit would be ideal if you can live with 220 / 240v

    http://www.ebay.co.uk/itm/Cold-Room-Condenser-Compressor-Refrigeration-Unit-/110735108058?pt=UK_BOI_Restaurant_RL&hash=item19c853a7da#ht_500wt_1156

    Premier Icon sturmey
    Subscriber

    Smudger your right about the pressures when running, but even when static the pressure in the system evens out about 5 bar assuming R134a refrigerant A lot higher if 404 but that would be over kill. I trialed a Penguin refrigeration unit that would have done the job a couple of years ago. Basicaly it was a 12 volt scroll compressor and small condensing set with fan mounted on a plate then piped to what can only be described as a thin radiator to which we blew a fan across to distribute the cooling. We found it very efficient and low consumption.

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