Nice going russell, ive been afk. Ill try to get some more couples out to you today, looks like you need them :D
]JR[
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Nice going russell, ive been afk. Ill try to get some more couples out to you today, looks like you need them :D
]JR[
Hmmmmm... In order to minimize static pressure, as well as the operating high side pressure, we need to minimize the amount of R23 in the system, so everything which contains liquid R23 should be as small and as short as possible, but not small enough to restrict the flow.
In other words, it would be preferable to have the R23 cap tube connected directly to the outlet of the heat exchanger, or at the very least minimize everything between the heat exchanger and the cap tube. I would put the drier in the R290 liquid line, and there is no need for a sightglass in the R23 circuit.
Captain Cascade, jump in here anytime. This is all theoretical for me. I have never seen an autocascade... LOL
Thanks for the advice gary. Yes you are right on all counts, the captube is brazed into the 1/4" tube coming out the heat exchanger, it's as short as I could make it. I have a sight glass on the R290 exit on the phase separator and the drier just after that
Is the R290 circuit using a TXV or a cap tube?
A cap tube :D
Its 120" of 0.031" cap tube. The low stage uses 130" from what I remember. Im running the system on the computer to get a heat load, im waiting for things to stabilise. This is what the numbers look like at the moment.
R23
SST: -65ºC (1.4barg, 20psi)
Evap Temp 2 inches from exit: -55ºC
SCT: -10ºC (18barg, 261psi)
R290
SST: -20ºC (1.4barg, 20psi)
Evap Temp 1 inch from exit: 15ºC
SCT: 55ºC (18barg, 261psi)
Condensor Outlet: 25ºC
Air in:23ºC
Air Out:26ºC
The processor should be putting out around 68 watts.
It looks to me like the system needs a little more R290. The exit temp should be closer to the SST. I would add a little until the exit temp is about -10C.
This beast just guzzles the propane, I cant seem to shift the exit temps for the propane evap. I will keep trying. Softly, softly, catchee monkey :D
I added some more R290 and the exit temp went up a degree. So SST is -20ºC and Evap exit is 17ºC.
A little at a time and wait in between is the best way.
Is the sight glass full?
Here are a some pics the pipework, hold down and the entire setup, trying to pass the time waiting for the beast to balance out.
http://www.russellpetrie.plus.com/im...ade/autoc4.jpg
http://www.russellpetrie.plus.com/im...ade/autoc5.jpg
http://www.russellpetrie.plus.com/im...ade/autoc6.jpg
If the sightglass is full but the evap isn't fully flooded, this would indicate that the cap tube is too restrictive.
I had a feeling you were going to say that. I've put a lot of propane into this, and I have no real way to recover it. I have empty propane cylinders, about 1 litre in size but im pretty sure they are non refillable. I've got (or had :)) 4.5kg R23 to play with so thats not that big a deal. You've gotta do what you gotta do. I was thinking about cutting off 12" of tube, is that about right? When I go to recharge it, is there methodology to this? eg R23 first then propane or what? Maybe the captain can help us on that one. My thoughts on it were to add a little R23 so there is something to run around the vapour side of the phase separator, then start pumping in the R290.
An little observation on the sight glass, before it had some bubbles running through or was 95% full. Now its completely full with no bubbles what so ever.
Is the exit temp coming down?
Its hard to tell, its not moving significantly, its hovering around 15ºC. Its at 14.8ºC now. I'll give it another little squirt and see what happens. Although my cpu temps have dropped 2ºC so thats a plus.
What are all of the temps and pressures?
I just added a squirt of propane, so i will let it settle and then report back :) Somehow I knew you were going to ask me that. :D
You should give us the full list every time you post.
I have got my 2 thermocouples (supplied by ]JR[, thanks) secured to the 2 evap exits. I have 1 more thermocouple but its a probe type ( stainless steel rod 3-4mm dia) and takes a little while to react. I can easilly give you the evap exit temps, saturated temps and pressures. I've got the probe set up on the condensor air in, and I have a little LCD thermometer monitoring the air out temps. I know there are more to take, condensor in/out compressor in/out, do we really need them at this time?
Thats 15mins since last gas charge. Here is the list so far.
R23
Evap Exit: -52ºC ( i let a little out to make room for more R290)
SST: -65ºC (1.5barg, 22psi)
SCT: -13ºC (16barg, 232psi)
R290
Evap Exit: 15ºC
SST: -19ºC (1.5barg, 22psi)
SCT: 50ºC (16barg, 232psi)
Air in: 22ºC
Air out: 26ºC
The more temps, the clearer the picture, but whatever temps you can provide. I think you have the most important ones covered. It all helps.
Thats what I was thinking in my head. Just after I posted the list. My cpu temp dropped 1 degree again.
You should not have let any out. The R23 was just about right. If anything, it could have used just a little bit more.
I will give it alittle taste of R23, but will keep an eye on those pressures as it can fairly shift them.
We want the difference between the R23 SST and exit temp to be about 5-10C. The pressures will be whatever they will be.