Oil distrubution problem with a evap, how to fix?

[Henry.]

Hi folks!

Have just built a waterchiller that worked really great at first startup and a evap to this to cool 800W later on. But when i had a "little" problem due to a kinked PVC water tube where the effect of this eventually resulted in a ruptured copper tube in the evap due to frosen water so was i forced to open it up and then saw that there were quite some oil in the bottom of it.

It was very good that this problem occurred because when i saw the oil i then of course realized that oil distribution in this evap could be a real problem since i dont think that the oil in any way could follow the gas up trough suction that are 9" from bottom of a tube.

I really want to have this design since i have made several things to it so how could i in a simple manner as possible fix so that the oil could be sucked back to the comp? If possible that is..

The refgas will of course be a liquid at bottom and that shouldnt be sucked back in unless its only very little which then doesnt matter but i dont really have any ideas left for this.

The water outlet and inlet are on the bottom but i didnt painted that neither the coil.

[icecube51]

you have to give us more detailed info on the design, the refrig you are using, the desired icewater temp, some kw's on evap, condensor , compressor....... diam of tubing, lengt of tubing, how is the expantion regulated?? tev, txv, eev??

you got homework...

Ice

[Brian_UK]

Can you not use a suction tube similar to that used in a suction accumulator.

They use a 'U' tube with an open end at the top, to remove vapour, and have a small hole at the bottom of the U to suck the oil from the bottom of the container.

http://t0.gstatic.com/images?q=tbn:3lpQES8PCt6qmM:http://www.concord-ent.com/images/suction.JPG

[Henry.]

Brian_UK: hmm yes that semm interesting and might be an option, only searched for oil separators before with no real luck. But almost the entire evap will be full of boiling refrigerant and will the oil really settle at bottom in that case?

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The pic on the evap is because when i posted this thread i thought i maybe could do something with the evap to get the oil back in some way but just couldnt figure out how. You normally prevent oil into the evap by using an oil separator before the evap and right after the comp i guess, have i realized now.
So now instead i only need a design of a quite good and efficient oil separator i can build my self so no oil get into the evap or if it now work a suction tube similar to the one in a suction accumulator.

I have read that copperwool in a tube are used in homebuilt cascade systems to prevent oil into the captubes but im not really into how these are built and how oil would be transferred back to the comp and i havent found any pictures or any info on how efficient they are but i guess they are quite efficient so the captube wont be clogged with frozen oil.
　

iceqube51: Didnt thought the things you mention would be needed therefore the lack of it. But now when im only need a oil separator design or similar this is not needed anymore i guess? But i can mention those i know anyway just in case or just for general info:
　

Desired water temperature: around 15C.

Gas: bbq R290, that what i can get my hands on here.

KW on the evap: I have built it after a qualified guess and to what i guess should be enough to handle 800 - 1000W an dhave ebough time to chill the water down but i only know when its time for a full system test. I did a test with only 350W before with no problem: about 1/8 gallon of circulated water heated to 65C (to really push the system) and 5 min after system start it had went down to 12.6C and still going down quite fast. Good or poor i dont know but its totally fine with me and seem ok at least so far and this with a not really optimized system.

Condenser: whatever it is i guess its a little to small for the full test of 800W later on but i have no numbers but its not an efficient one with aluminium ribs and copper tubing but all is iron but i wont use this anyway in the real system.

I have a modern one that with aluminium and copper tubes and it measurements are 8" high 10" wide and 3" thick but i doupt this could handle 800W? It would be really good if it could because i have fans and all that to it. Otherwise i have a bigger one but thats really an evap but its almost twice as big so that will do if this can be used as condenser with its much wider tubes in it that condensers have. I cant run the system again due to a ruptured tube in the evap due to ice in it because a pump stopped pumping so i will rebuild it later today i hope but its a lot of work.

Compressor: the one in the test system i use now i dont know because the sign have been scraped of but i know it should cope with the power. The compressor im going to use later on in the permanent system is a SC15D that is way more then needed for 800W at 15C but i dont have a smaller one that can cope with 800W so until i might find a little smaller one this will be used.

Since the system will be constantly loaded with around 700 - 800W so is it only regulated with a captube guesstimated by Dancap. I cant get hold of TXV:s or similar so this was one of several i have been salvage and i was so lucky that one had the exact size Dancap recommended.