My new Liquid cooled SS, and Where is the problem?!

[DXB750]

Hi,

Compressor: Danfoss SC21CL
Captube : 0.036, 245cm
Condensor: plate HX 20 plates





At first I only used the R507, but the cooling performance was not as good!
I then used a mixture R507+Propane The result was as follows ..

UNLOADED



LOADED 250watt,



I could not make the cold stable for more than that!, Because I want 280 watts or more..
What do you advise me? And what do you think is the maximum load can I do with this unit?

Thanks,

[Buckeye]

From my little bit of experence charging these I would say you need more gas.

I believe it works like this.
Light load of gas = colder unloaded temps, warmer loaded temps
Heavier load of gas = warmer unloaded temps, but better loaded temps

You are warming 24c in temps at only 250watts. I would say charge to 300watts to -36c.
Unloaded temps mean nothing really. It's all about the load it can handle, tune for that and the unloaded temps will fall where it does.

Not sure how the water cooling system holds up tho.
Not sure how that gas mix will work either.

But I am sure more experenced builders can give better feed back here.

[tiborrr]

Low side in vacuum and 107PSI high side in load? That's 7bar. You seem to have undercharged unit.

If more charge doesn't help then shorten the cap tube a bit more to ~ 220mm and try again.

[Jack]

tiborrr, as far as I can see DXB750 has at load a 18,1 psi (1,24 bar) low side and a 269 psi (18,5 bar) high side.
107 is the high side temperature in Fahrenheit.

Anyway, I would suggest a shorter captube as well.

[tiborrr]

Darn, can't read those fancy manifolds.

Ergo, start trimming your cap tube!

[DXB750]

Thank you all guys, and I will do your advice ..

Now I've replaced the evaporator and the suction line, Because the Previous suction line exposure to some of the damage in the braid!



Of course, can not leave it that way, especially with the propane more than 10%...

suction line, 100cm, 1/2" :



http://www.hosecraftusa.com/model/SB...ded_Metal_Hose

evaporator, with 9 feet of cap tube... At first I will use only R507 with 9 feet, and if it was not as it should I will add propane, and shortened capillary tube to 220cm



http://www.piotres.com/?go=5,suction...zed_evaporator,

Also I did a new Accumulator, 2" of diameter and 5" height, former Accumulator is somewhat large, height 6.5"



Now I finished the Vacuum and will inform you the results later...



Thanks =)

[Jack]

You will trap oil in that style of accumulator, it will collect at the bottom.

An inline accumulator would be better, for example like this one here:
http://i190.photobucket.com/albums/z...s/DSCF7369.jpg

[DXB750]

You will trap oil in that style of accumulator, it will collect at the bottom.

An inline accumulator would be better, for example like this one here:
http://i190.photobucket.com/albums/z...s/DSCF7369.jpg

I want to put it in a vertical, because that fits the internal measurements of the case. About the oil to avoid the trap of what you think of this design is it appropriate? Or that it will also return the liquid to the compressor?

Untitled-1.jpg

Thank you,

[sdumper]

Why not use a 10 inch by 1inch copper tube with copper brillo stuffed inside as an accumulator. It will serve your needs well and avoids any chance of oil not returning.

Or 5 inch by 2inch since you already have 2 inch diameter...Its what I use in SS and it works perfectly.

[wdrzal]

The orange tube on the accumulator should only extend through the top just down past the top of the U tube. Where the U is on the tube there should be a small orfice hole facing up for oil return. About 1/16" should do. Any liquid refrigerant that passes through that orfice will boil off .

What are the sub-cooling numbers ????, and water/intake to water/out of the radiator when you run the unit. My concern is that radiator is not rejecting enough heat limiting performance.

[wdrzal]

Forgot to change flow direction. Haven't figured out how to remove pic and replace it yet.

This is how a accumulator looks on the inside.

[n00b 0f l337]

Looks like the in's and out's are reversed.


EDIT: Right on time, now it's good.

[DXB750]

Why not use a 10 inch by 1inch copper tube with copper brillo stuffed inside as an accumulator. It will serve your needs well and avoids any chance of oil not returning.

Or 5 inch by 2inch since you already have 2 inch diameter...Its what I use in SS and it works perfectly.

I will use 5"×2" vertical, because that is the appropriate measure so I can put this unit in the "Extended Ascension CYO-CASE" and the exploitation of the rest of the free space for other things...
Of course I will put into consideration the use of copper brillo

Thank you

[DXB750]

Forgot to change flow direction. Haven't figured out how to remove pic and replace it yet.

This is how a accumulator looks on the inside.

Ok, now I understand how I can made the accumulator
And I will add to the copper brillo for more reserve..

About the temperature numbers from HX with 250W loaded "Old Evap & Suction line" but I have taken to read the water temperature of the surface tubes in the heat exchanger, because I did not use a sensors on the water hoses!

Water :
in = 24,7C
out = 24,8C

Refrigerant :
in = 44C
out = 25,5C

ambient = 23,6C

Thank you very much wdrzal,

[DXB750]

Capillary tube 0.036 , 220cm
R507+Propane ~ 70/30

The new accumulator has been proposed above,



I've added an additional Radiator 2x120mm.



Unloaded = -45,5C
280Watts = -28,2C
Ambient = 24,7C



But I think the high pressure must be less than 280PSI!!

[Xeon th MG Pony]

On your accumulator you need a pin hole on the very bottom of the U bend to facilitate oil return, other wise over time it will just fill up with oil and fail to act as a accumulator, that and you needn't the copper wool, a simple deflector on the in tube to guide the refrigerant to hit the walls of the shell

[DXB750]

I did as suggested "wdrzal" and I made ​​the U bend more down so can be retrieved more of the oil, and I added some oil equivalent the lost in the former accumulator...

I do not understand very well what you mean by this:

a simple deflector on the in tube to guide the refrigerant to hit the walls of the shell

Can you explain more?

Thank you,

[DXB750]

And what you think is the maximum high pressure is Appropriate and safe in the event of run 24/7 ?!

[Xeon th MG Pony]

You want the pin hole to be on the bottom of the U bend, the gas velocity will create a venturi effect returning the oil to the compressor at a metered amount that will be safe. Other wise it will build up reducing the over all volume of the accumulator.

And as a second thought wrap as much cap tube around it as well and utilize any left over liquid refrigerant to sub-cool the cap!

[DXB750]

Thank you for this information and advice Pony..

[DXB750]

Today I added a little of the refrigerant, and left run it about 6 hours with 300watts....

302Watts = -30,6C
Ambient = 26,5C
HP = +300PSI < I think it needs a Monster Radiator!

[Xeon th MG Pony]

Try it on a waste water circuit and see what that does, your main gas to water exchanger should be good, it is the secondary conversion that is probably killing your heat rejection

[DXB750]

I previously tried to change the pump speed of 1 to 5, but was the best stability at 4....
Temperature of the liquid before entering the heat exchanger is 35,4C, and room temperature 26,5 to 26,8C !!
I could not take the real temperature of the liquid after leaving the heat exchanger!



Refrigerant with 302watt :
In = ~ 95C
Out = 32,4C

[Nosfer@tu]

Amazing build
Looking forward to reading more

[sdumper]

Agreed very cool build.