Principles of refrigeration. Advanced level bodging help required
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.Posted 6 years agostumpy01Member
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:
Not cheap though using car parts I wouldn’t have thought, bearing in mind a new compressor for my air con was about £400.Posted 6 years ago
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)Posted 6 years ago
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.Posted 6 years ago
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.Posted 6 years ago
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:Posted 6 years ago
Fridge gas isn’t toxic. The ozone layer doesn’t like it very much though.Posted 6 years ago
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?
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?Posted 6 years agowonny jSubscriber
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 trickPosted 6 years ago
How about a water cooler and a water circuit inside the store.
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.Posted 6 years agoJunkyardMember
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?Posted 6 years ago
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?
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.Posted 6 years agoSwelperMember
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 / 240vPosted 6 years agosturmeySubscriber
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.Posted 6 years ago
The topic ‘Principles of refrigeration. Advanced level bodging help required’ is closed to new replies.