I've started testing. At least in a preliminary fashion.
http://youtu.be/3x4yionNB6k
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I've started testing. At least in a preliminary fashion.
http://youtu.be/3x4yionNB6k
Newbie alert.... The discharge and liquid lines are very hot. This seems to signify a problem, but I'm not sure what that problem is. The system is pulling down fine, but I know the compressor shouldn't be getting that hot. The stable running pressure on the suction line is 60PSI, which is a bit north of what I expected. Do I need to make adjustments to the TXV???
How hot? Those can run upto 110C.
And sounds like the pump is simply cavitating on some air.
i don't want to sound like a :banana::banana::banana::banana: but could you please hold your camera horizontally next time :rolleyes:
It stands to reason that I realized that and will undoubtedly make amends with the next video... hehe :p:Quote:
i don't want to sound like a :banana::banana::banana::banana: but could you please hold your camera horizontally next time
The pump may be cavitating, and surely the next time I fill the system I'll see if I can do something about it... However, usually these things work themselves out. The system was running for considerable time. There were no changes. In fact it got worse.Quote:
Originally Posted by n00b 0f l337
The system stabilized some, but I couldn't get the system to even frost on the suction line. It stabilized at 40PSI at the suction line give or take. The TXV outlet went as low as 24F but no lower. The return gas was ~10 degrees warmer. Its pretty clear that I'm getting good heat transfer. The system pulled from 74 to 50 degrees in about 10 minutes. So pump flow isn't an issue. The condenser pump did well. No leaks there and the condenser water was balmy at the least. Didn't even peak 80 degrees.
Condenser pressure was 190-205 PSI at the most, and suction pressure was ~38-44 PSI at the most. The Sight Glass was not completely full, however as I have added charge the suction pressure rises and stays that way. I'm reluctant to add charge further until I have a good sense of what I'm doing.
The coldest I got the water was 30F. It then hovered between 30 - 31 F. So I'm on the right track.
I will say, the discharge line temp came down after I added charge. Clearly there wasn't enough refrigerant coming back. Anyways, help is appreciated. :)
P.S. I was having a ball out there today.... hehe
Any help? :)
I have a distinct feeling that I'm undercharged. Superheat is considerable given the pressure at the suction line being at 40PSI and the temp above freezing. However, every time I add charge the suction pressure rises and it does not go down...
Do I need to significantly change the setting on the TXV regarding the superheat? I have a feeling its doing some excessive hunting. Again, might just be my experience level with charging...
I think I may have a solution for my pump cavitation problem. I've done some additional research and I agree that it appears to be a cavitation issue. I'm likely going to have to redesign the pump discharge to be a vertical system with a bleed valve. Currently it is a horizontal discharge and that may be causing the pump some difficulty in removing air bubbles. I'm still curious as to why the first fill didn't produce this problem.
I wonder if the glycol (being somewhat viscous) caused a vapor barrier behind the impeller that caused an internal air bubble that couldn't force its way out. Sort of the way soapy water forms a bubble. Once I filled, at static pressure it could have been enough to maintain itself in that tiny space. Once running the bubble couldn't be ejected. It might have settled at the top of the volute and stayed... Which is odd... Of course, that is all just a supposition... Either way, it seems to be cavitation.
You can also prime the pump manually with.... another pump. Basically buy a small pump and use it to pump fluid into the main pump before filling the system.
I could, but that's difficult given the setup... Maybe Fill it backwards???
I feel kind of dumb... I forgot to insulate the TXV Bulb. I should probably do that before making any assumptions about charge... I will examine the location of the bulb as well just to make sure its in a good position and nice and snug.
Edit: I did also have a nice long conversation with some folks around here. One of the HVAC Techs gave me some good pointers. Helped me understand the TXV operation a little better. Aside from insulating the bulb, I'll make the adjustments this Saturday.
Then its round 2!
Today is the big day! >=)
Here's to hoping I get this thing down to 0F!
Bad news. My impeller is busted.
I found out what was going on. The pump wasn't cavitating at all. In fact, it was pumping very well and self priming as designed. The pump suction was nothing short of impressive. Unfortunately, that means I can't refill my system without expending a ridiculous amount of effort when I have to drain it again. The bushing somehow broke off of the impeller and thus I need a new one. :(
Well I did fill the thing back up. I'm going to buy a new impeller. The bushing is missing (obviously broken off). So the impeller slides forward. It doesn't make that noise when I run it dry. It only happens when its got fluid; and glycol isn't enough to give the pump motor any problem (it made it with water last time I ran it too). In the meantime I'm testing. I've almost got the right charge inside. The TXV is better behaving now that I've added some charge. Its pulling down very quickly... In fact while I was adding charge it cut off and pumped down. :p:
Not quite there with the charge yet, but getting close.
It appears that i have somewhere between 3.5 - 4.5 lbs of charge. <--- It could be less, but I just didn't take a beginning cylinder weight. :( The URI website says the shipping weight is 32 pounds, but I don't know that I can trust that.
I'm done for the week, but some very promising results. The return gas got itself down to 11 degrees at the lowest. I didn't get any shots because I was busy baby sitting a few things. Unfortunately, with both pumps running and a the other odds and ends I was blowing the garage circuit a few times. The compressor is likely drawing around 10 amps. So that leaves 5 for the two pumps, solenoids, and fans.
After consideration, I believe the activation of the two solenoids connected to the power relay are causing the trip. It happens about 10 minutes after starting (coincidentally the time setting for the delay). I've got to find a way to plug into a separate circuit, or I'll never be able to test the bloody thing through a full cycle.
I relocated the TXV bulb to the evaporator outlet, and my sight glass is now clear. My biggest concern is with how much refrigerant is in the system. My receiver has a 3lb holding charge capacity. The system probably contains slightly more than that, but of course it isn't all in the receiver.
Bottom line, next week will mean the final adjustments.
Superheat = ~17F (Might have to do with my tweaking the TXV last week, will make minor adjustments)
Sub Cooling = ~10F (Right on target.)
Suction Pressure - 35-37PSI
Discahrge Pressure - 310PSI (This is likely high due to the incorrectly adjusted TXV, or I may have to remove some charge. I'm betting on the former.)
Lowest Fluid Temp so far = 30F (Dang circuit breaker. Who places a 15 amp circuit in a garage? Seriously. 20 Amp please?)
I will have to get a new impeller, but in the meantime all is good. :)
So what do y'all experienced folk think? Should I worry about that high discharge pressure? Or is that just due to the heat of compression due to higher superheat? (Which I can adjust).
I gotta say, this worked out perfectly. It actually works as designed. No real tuning nightmare, just pure unadulterated bliss. I never felt so excited in my life! :) Well, at least as far as accomplishments go... :p
New Impeller is in hand. Lets see if we can't get down to temp this weekend!
Friday : Replace Impeller and run system checks and build heat exchange coil (minor job).
Saturday : Take system to minimum design temperature!
I'm excited. No more setbacks this time. Just run it! >=)
I like your plans, then on Sun. you can chill a cpu.:yepp:
Well, I could.... but the next phase is actually building the enclosure, then getting the parts. So that's a bit off... :p
One thing at a time :)
Impeller changed. Bushing busted. New seal as well.
http://imageshack.us/a/img842/7224/vaim.jpg
In continuing my investigation, I have made an additional discovery. Upon taking apart the pump once more when I changed the impeller I neglected to remove the rubber seal that was in there. Somehow my idiot brain thought that it was part of the pump. However, this orange seal was in place.
This is not a design seal. This seal is too thick, and as a result, the gap between the thrust washer and the front of the pump meant that the impeller would always rock as it spun. Evidently, the micro vibrations that resulted probably caused the breakage of the impeller bushing. Although this seal created a single millimeter gap between the volute sealing surface and the pump housing, it is enough to cause the impeller to shudder.
It is my conclusion that the guy I got it had to replace parts just as I have had to do. That is probably what lead him to sell it. It wasn't that old when I bought it. I got quite a steal. ;) I am willing to bet that he started having problems when he switched to the new seal.
Tomorrow I will be able to FINALLY run the dang thing without all that noise. ^_^
http://imageshack.us/a/img197/1973/wry1.jpg
Looks good Stew !
Glad you got that pump problem sorted out :)
Will post temps after dessert. Its taking a while to pull down, but that was because of some issues that I had. A bit of adjustment and it looks good.
The only problem is the pressure at start-up. Its meant for low temp applications, so when it is working with...say... 63 degree coolant, then the high side pressure spikes quite a lot. It gets as high as 375PSI. That said, pressure normalizes over time and we're at 250PSI and ~25PSI. That changes as the coolant gets colder. Pretty normal, but man its taking a while.
What is normal pull down time for most? I'm on 2 hours from 65F. Its down to ~15F now. 25 degrees per hour. Not bad? I just don't have a comparison to benchmark against, hehehe.
7F.... That is the lowest value of the day. :)
There are some spots I need to insulate a bit better. However, flow gets a bit low when it gets down that far. I suspect a bit of slush may have been forming during the off cycle because I turned the pump off for a bit. Either that or it formed at some point during operation. Or it might just be the viscosity of the solution. Perhaps it was just because the liquid was so thick that it didn't move much once discharged... LOL
I am at a loss as to what you will be using this for if it takes 2 hours to get this rolling. Yes I get it's for a PC but do you plan on leaving this on for very long periods of time ?Quote:
Originally Posted by Stewie007
Well, it might be a flow issue. I ran it through a pretty restrictive coil to test. It took longer than usual. Guess you arent so eager to see it work anymore huh :p: hehe
Still working out the kinks. Flow was dreadfully low. Have to find out why. It pulled down to 8 degrees far faster the first time.
Of course I am Stewie, I love these things :)
Flow was probably from restriction and fluid becoming very viscous.
Partly, but it wasnt as big of a problem the first time around. So, there was something I did a bit differently. At 20 degrees viscosity should be around 50 cps... at 8F it would be around 65 to 70. Olive oil is around 85 and this pump would handle that,
So, I agree that restriction is the likely culprit. But I am unsure why it differed the first time around.
This sort of changes the whole dimension of the project. Restriction is proving to be a problem. Water blocks are, by design, are restrictive.
What type of block,then, do we utilize for this to be effective? :)
http://www.enzotechnology.com/vga_ib.htm#
This one was recommended by someone a while ago, and I also like it. Looks like it isn't very restrictive same with their CPU blocks. The problem is, do you think it will fit a 7900 Radeon or a 290/280?
http://www.enzotechnology.com/scw_reva.htm#
I like this as well. Looks like I might be able to back order it... Its AM2... but isn't that pretty much the same socket retention mechanism as the AM3/3+?
How little flow are you getting?
Alarmingly little. The pump suction appears adequate, and the outlet is pushing pressure out. However its so low that the reservoir appeared to be still. It screams blockage to me. I am going to negate the coil next week and see if that makes a difference.
Coil could have frozen up?
It shouldn't have. Its a 50/50 Glycol mix. But if it got slushy, that would plug the restrictive coil. I am going to test with a wide open system next week, but when its finally running with a computer... I'll have a strainer inline.
The problem is, I don't know if I turned off the pump when it was below freezing or not. I think that I did. And that probably caused my problem. But I can't verify it. We'll see next week.
I wonder if I overcharged the system. What is the normal amount of frost that should form on the accumulator? Can I assume that with a return gas temp of 0F (even with superheat) that its pretty normal for the accumulator to have a nice layer of snow on it?? :)
The biggest indicator to me, though, is that if I have the TXV adjusted up just slightly, the start up pressure is ridiculous and I have to shut it off to protect the compressor. If I adjust the TXV down a bit, it alleviates the condition at start up and superheat appeared to be normal. Later in system operation, the pressure will fall to a more acceptable level.
Is this just because of the higher load at start up? OR do you think I'm overcharged?
Edit: I'm just gonna have to reset the TXV setting and see. Its obviously off because I didn't know what I was doing at the start. :p:
Also, I wonder if this GPU block will fit most modern cards? Seems to be a perfect choice.
http://koolance.com/gpu-200-video-ca...et-water-block
Got some results to post later :)
Apparently my favorite phrase of the day is ".....to be expected...." LOL. I should make the videos more time neutral. Doesn't make much sense to make a video and then post it 5 hours later as if I just made it :p:
Anyways... I've done some testing and I think the system is pretty much ready for the enclosure. It will be a few weeks before I can take care of that given the holidays. Still not where it needs to be reservoir temp wise. Given the difficulty keeping flow rates up that is the main reason why the temperature change slows to a virtual crawl. Its still pumping pretty fast at that point, I confirmed that by shutting the valve and watched the bubbles flow. Needless to say they were moving fast. So maybe not such a big deal. Anyways, first video... then second one in a few.
http://youtu.be/n_0a7MsujcM
I used my temperature probe to get a shot of the outlet temp from the chiller. This is the coldest temp I took, and it was right before I had to close up shop for the day. That is about an 7* Delta T. If I ran it for long enough, I could hit 5F, but considering that I'm hitting 10 in a little less than 1.5 hours time from 65F or so that's not bad. I'm going to do some additional tweaking the week after next (won't be here next weekend). However, in all likelihood I can probably add a booster pump to help increase the head pressure capabilities in order to boost the flow through the evaporator.
That said, it doesn't take as long to get the temps down after first run. so I'm not too concerned.
One concern that I have is that for some reason, the solenoid remains party energized after the system is deactivated. It causes a pressure bleed that won't allow the system to stay off. Very concerning....
http://imageshack.us/a/img833/5142/6uhi.jpg
Are you still using that copper coil being heated by a camp stove as a load to test ?
That's a fair bit hotter then a CPU I would think so it should cool down much faster with a normal 300watt load.
No load, just pull down. The stove was for a known heat load and it served its purpose hehe
I sm going to do alot of folding type stuff though, so that will produce some heat. But thats no worry... I am getting 100 degree condensing temps. So we're talking more capacity than the chips can put out.
Rough estimate at 1500+ watts based on specs of the compressor. Actual unknown, but I ran some calculations on that data and that gave me a general idea.
Edit: I will probably have to remove some charge from the unit. I may have overdone it. Still, with temps down to ~5F that isn't that bad. Of course, that's after the chiller and not in the reservoir. The viscosity of PPG is just not going to allow the big flow rates. Ethylene Glycol would have been better, but I chose PPG for a reason. It does put out high pressure.
I was thinking of these chilled water loops as well the last few days.
I just thought about it again today, wondering if 180 proof vodka would work well as the fluid.
Instead of water and other things to keep ec down.
One can't legally distill, but you could always buy something close enough to 100% :).
Thought about acetone and methanol but both are a hazard, while ethanol isn't so much (still flammable though).
Better then probably hydrogen peroxide or rubbing alcohol.
Hydrogen peroxide would oxidize stuff as soon as it hits silver probably.
I found tubing that handles sub zero, but pumps are a problem.
I don't really wanna use a metal pump either.
Edit:
I just found this it was interesting:
http://www.overclockers.com/data-on-...-watercooling/
Sorry I don't mean to derail your thread dude.
It's just something I just became interested in too :).
Windshield wiper fliud I think uses 10% methanol, I would never use methanol though.
Well, I was figuring that I might have this thing around for a while and if a little munchkin comes into the picture, I don't want any accidents to turn fatal. PPG is a pretty reliable fluid, though.
I got a good idea of how well the flow was going when my time delay kicked in and the slightly warmer water in the coil above discharged into the reservoir. It was by chance that I took the makeshift cover off to see a wave of warmer water hit the cold solution. It dispersed into the water quite quickly. So I think my pump is getting decent enough flow. Its just tough to get that temperature change once you're temperature differential sinks so low. I may have to recover some charge so that I can close the valve up a little bit to get the pressure, and thus the temperature inside the evaporator down.
I have been dancing around the option of adding a booster pump after the evaporator. I have to do some research on that first, though. It is a no no to run two dissimilar pumps in parallel, but not so much to run them in series. I just have to figure out what type of difference is acceptable. It would help to have a second pump adding flow to help turn over the temp in the reservoir more quickly. The system would be allowed to continue down to the 0F in a more expedient manner.
One thing I can say about these Ryton volutes... they insulate well. Won't have to add much insulation to the pump for condensation. It barely condenses moisture at 10F fluid temperature.
Well, some major changes to report. Although I haven't done much lately, I have learned that Polypropylene will be a superior choice to Ryton. Therefore, I will be acquiring a Polypropylene Volute for the existing pump, and the second pump (should it be needed) will have the Polypropylene housing. Big Flub-up on my part. It'll be fine for testing, but once that's complete, the volute will be replaced.
The engineer I spoke to with the manufacturer advised that Ryton becomes brittle at low temperatures. I could use it, but I would have to be absolutely sure that the plumbing doesn't apply stress to the volute.
I was able to find a TE-5-MD Pump motor on Ebay with the motor drive magnet. All I need is the pump head. The MD-SC variety is about $140 bucks. So if the second pump is needed, I've got a source for an identical pump.