Well, I have frost....

[RussC]

Well, I don't have pics, but I've torn the system apart.....why.......

I have a system leak. The leak is very minor, so I didn't find it right away. With R134a, the system pressure was ~50psi static. At that pressure, it wouldn't leak. With porpane and static pressures of 95psi, it would leak out at ~1.5psi/hr untill it reached ~60psi.

I believe it was on the suction side, as the system ran ~15hrs fine with no capacity loss under load. But, leave it set, pressure dropped. That tells me when it's running, and the suction side pressure is very low, no leak. But, in static conditions, low side pressure is much higher, and leak.

Anyway, I think I found the bad braze. I wanted to redo the system anyway with a desuperheater, so I have that going right now. I'll make the entire low side 5/16" tube, like the original water fountain. Plus, a new filter/drier and use dentured alcy instead of water in the resivor. I'll get some initial pics up tomorrow.

RussC

[SexyMF]

Harking back to the heat load from your pump. You are saying 30/40 (75%) of the energy used to power the pump is wasted i.e. the pump is only 25% efficient. Give the brand some more credit!

As for your pressure drops perhaps you are not taking into account the compressor and refrigerant cooling down.

[RussC]

OK,
Im not sure what the efficiency of a electric motor is? If I have some spare time over the holidays, I'll take a look.

On the leak, I believe there is a leak. If you look at the PT charts, Propane at 21c is 127psi, R134a is 69psi. Its nearly double. At room temp, the same weight charge is ~2x the pressure. So, I monitored it for 2 days. After ~3hrs the charge stabilized ~18c at 93psi. After 24hrs, it was 62psi. Thats a leak.

RussC

Harking back to the heat load from your pump. You are saying 30/40 (75%) of the energy used to power the pump is wasted i.e. the pump is only 25% efficient. Give the brand some more credit!

As for your pressure drops perhaps you are not taking into account the compressor and refrigerant cooling down.

[SexyMF]

I concur.

[RussC]

OK,
Tore system apart. cut new base, just screwed old base to wood pcs. Im going to 5/16" copper for the evap. Im not going to have a superheater after the evap. I figured I'll put the extra coils in the evap for more cooling.


the system redo will have this large desuperheater. I'll put a fan on it also, but thats later


And the entire layout with larger drier.


I hope to have it all brazed up pretty quick. Will be using 72" of 0.031cap instead of the 58" I had.

RussC

[SexyMF]

I use 2 coils of 5/16". Also, good upgrade to the filter/dryer

[RussC]

OK,
Got the system brazed. Here is the layout


Next, as I get better at brazing, captube splice...sweet


Im also getting the feel for compression fittings. Ive got a good feel for how much to tighten. They didn't need any adjustment, and the system has held vac for 6hrs now. Let it go overnight, then fill and test in the morning



RussC

[SexyMF]

I stripped my board back down to it's original state. I have finished my testing. I've learned heaps and are now tracking down a Danfoss NL11F compressor because mine is just to loud. Also, the motherboard is difficult to insulate (not much clear area around the socket). I may jump up to direct-die cooling using a chilly1 block.

I'm keen to see how your new setup goes.

[Malachia]

can i ask you what liquid you used to go under 0C? thx!

[RussC]

anti-freeze and water. 50/50 split is good for -35c. 75/25 is good for -85c.

RussC

can i ask you what liquid you used to go under 0C? thx!

[Malachia]

what kind of anti-freeze? the one that you use in cars or another kind?

[Blaster]

anti-freeze and water. 50/50 split is good for -35c. 75/25 is good for -85c.

RussC

wow where u get that antifreeze ?? i can only get glycol here, in which the freezing point is -25ºC, in its pure state

[johann]

Some antifreeze is already mixed up with water but I foun that normal undiluted car antifreeze in a 50/50 ratio does about -30c without freezing and 66/33 gives about -40c without freezing.

It does get thick though... Pump needs to be strong at these temps.

Realistically in a average chiller liquid temps are not below -30c so 50/50 works good

[RussC]

This info is right on the Prestone Antifreeze 1 gallon container. Thats were I got it. I wouldn't try to run a 75/25 mix at -85c, it would be so thick, it probably wouldn't pump much, unless you have a STOUT pump.

Johann is right, it does thicken, But wont freeze. Your better off using alcohol/antifreeze mix. But, you need a air tight resevoir to hold the alcy from evaporating out.

RussC

wow where u get that antifreeze ?? i can only get glycol here, in which the freezing point is -25ºC, in its pure state

[Vex]

how far u got with the rebuild now?

[RussC]

Ya,
Its been a while. Im also working other jobs to pay the rent. I have some pics to post tomorrow, but haven't done much. Im completely re-doing the resivoir

RussC

how far u got with the rebuild now?

[SexyMF]

My mix of about 60/40 started to ice up at -50C.

[RussC]

Ok,
Got the new pics.

First, I scraped the old resivor and starting a build on another....


The res will be inside this PVC tube. This will be easy to insulate. All will get glued together and the compression fittings will mount the 1/2" ID tube.

Wrapped 5/16" copper as small as I could get them and fit into the 3" pipe. There will be two sections, one inside the other..


I still need to braze the bottom together, then install in the pipe, glue it all together then braze into the system and test. Im getting the pump tomorrow, but will not get to work on the system till well after the holidays. I then may have to go to the semi-conductor fab near Sacramento to work on a chiller for the wafer etchers we build. So I may not get back to this project for 2 weeks.

Happy Holidays,
RussC

[Vex]

looking good so far, that res looks mint..i look forward to seeing it finished

happy holidays to you too!

[[XC] mysticmerlin]

Well? I have the same water fountain and am watching this very close to see what you get out of it. I don't know wether to go DD or Chilled and can't wait to see it.

[[XC] mysticmerlin]

Bump you up. What did you get out of this or did you give up?
I am talking with chilly1 about a DD head now. Still like the idea of the chiller though.

[epion2985]

update?

[predator500]

Looking good cannt wait to see update

[Xeon th MG Pony]

12-23-2005, 12:00 AM <<< He's probly long since gon working in the feild or life

[epion2985]

working...