I've never worked on a refrigeration system before, but why WOULDN'T this work? I've got a friend who does plumbing so he has most of the pipe bending and fitting tools I'd need.
Obviously excluding the fact that it isn't time or money efficient compared to buying one prebuilt. I have a feeling there's some major flaws with my design but I don't know enough to spot them.
DESU I'm probably not going to do this in case I fuck up the seals and asphyxiate myself.
I'm not a fridgie, but that seems legit to me. Why not mount the hanger for the evaporator assembly between the fans though? It's dead space anyway in terms of airflow and will make for a much more compact unit.
"Digital thermostat + Display" = some sort of remote controller?
I've got a digital thermostat that runs off 240V and has a 240V relay controlled by some kind of microcontroler with a thermister. Basically it just lets me set a temperature range (HiLo or LoHi) with a digital readout rather than relying on the analogue thermostat.
I originally bought it to put in a fridge that was misbehaving, but now I've just got it laying around.
The odd offset design for the window unit is to minimize the length the pipes have to be and the distance the window has to be open.
If I lengthen the pipes too much I'll need more refrigerant, which I can't buy because it's old school HFC. Changing the volume of the system will probably also change the performance although I could mitigate the change in volume by using a different diameter pipe.
do you already have any components? the design seems fine but the details are in the physical characteristics. what size evaporator? what size condenser? what size compressor? Are your condenser fans sized correctly to maintain an adequate high side pressure? why are you running 24v fans when you have 240v supplied? are your evap fans sized to maintain proper suction pressure and superheat?
also, you don't need a 'moisture trap'. they are used mostly on refrigeration systems and not necessary on AC.
i would also have a separate control circuit. run all your inductive loads through a relay/contactor.
The diagram on the left is the air conditioner I currently have, it's not very effective because it draws air for the evaporator from inside the room and although the exhaust is piped out the window I suspect negative pressure in the room is drawing hot air back in. The control circuits are all from that, the digital thermostat is a component I have laying around. The angle steel is also what I have laying around.
Obviously the simplest way to fix the problem would be to use a second hose for intake and pump air into it with some fans to prevent flow restriction. (and that's probably what I'm going to end up doing), but this is a cool idea I came up with and I'm interested to see if it could work.
I have six of the 24V fans which I harvested from a discarded elevator power supply, the 24V power supply is from the same chassis. They push a lot of pressure since they were on a radiator, but I'm not 100% sure if they blow as much as the blower fan inside the portable AC. My plan was to point my IR thermometer at the radiators while it was running to see if the temperature was above the super critical point.
The existing evaporator fan is some kind of blower type fan although I suppose it should work if I stick it out the window as well.
I'm not sure if there is a moisture trap, but there's some kind of cylinder next to the compressor on the low pressure liquid side and I'm not sure what it is.
Is this a mod of an existing portable a/c unit? Or are you designing/building from scratch?
If it's the latter, consider putting the compressor outside for less noise. Like a ductless room a/c, but hanging in the window. The only parts that need to be inside are the indoor fans and evaporator. In fact, a good starting point might be to acquire components for a ductless system and build from there.
Not a bad idea for a variation on a window a/c unit. Doesn't block the view and hangs below the window like a planter box.
It's a mod of an existing unit, although building one from scratch would be a fun project too.
I already have all the components I need, the only problem is figuring out how to work with refrigerant gasses and making sure I get the math right for the thermodynamics (which I'm pretty much learning from scratch).
If I can build this without altering the lengths of the tubing I figure I can just recharge it with the same gas I took out of it and it should work without having to do any calculations...
Having the compressor outside would be ideal for noise reduction, but I'm not sure how that will work with regards to protecting it from the elements.
Oh, existing aircon is a Dimplex DAC-12005, a single hose indoor unit.
One of the hurdles is that I can't find any schematics for the unit I'm modding, so I'm just working on what I can see when I take it apart. So I don't know how much gas is in it, the volume of the system, or the details of the radiators. I can tell they're serpentine type and the dimensions, but obviously that's not the whole story.
The problem is that you WILL lose gas. Even if you use a reclaimer and reclaim everything from the system, you will still lose some just in the hoses and the problem is those units are critically charged meaning they won't work properly without the proper charge. They are not listed on the units because they aren't meant to be repaired. So if you don't have access to r407c then you can forget it. you could also use r22 although thats probably harder to come by and more expensive.
also, you seem to have your coiling naming backwards. the cold one that sits inside is the evaporator and the hot one that (ideally) sits outside is the condenser.
i used to have a stand up type AC in one of my apartments. it too took inside air and blew it outside for exhaust. the pipe was attached to a flat panel that sat in a window frame so i just make another hole in it and ran another pipe to the inlet of the condenser fan and used a box to go from the round pipe to the square inlet. it worked nicely. i also ended up insulating the exhaust pipe as it would radiate heat back into the room.
otherwise just build a unit from scratch.
Yeah, I'll probably end up doing the the two hose system. That was my original plan, before I went all autistic on it.
Where would I find parts to make one from scratch, out of interest? Harvesting broken AC units off craigslist? I've seen a few radiators at the local scrap yard but I think plugging holes would be be a big fraught. Buying the parts new... I suppose I could look for appliance replacement parts although I'll probably end up spending a lot that way.
It would be hard to find the parts. In that size range parts aren't as modular as bigger stuff. You would be best off just buying a ductless split system. Otherwise you would have to scrounge parts from other systems I guess.
Alright, I can solve the refrigerant problem, I've some cheap/broken portable AC units on ebay which I can harvest refrigerant from and sell as scrap.
I've also got a possible lead on an expert to consult on this. My friend knows a guy who installs custom refrigeration systems on boats. If I can get him on board with this I'm sure it'll solve most of my problems.
As promised, here is a poorly stitched panorama of my workbench.