Just Chillin Cascade

[{.bLanK} GoD]

good idea {.bLanK} GoD for the fine tuning idea.
Its also good to see ppl using HPCO on both stages
Will you use a thermostat in this cascade to control second stage?
Question, why have you insulated the Expansion tank?.
Your meant to have a long length of capillary line to the expansion tank and braze it in to the 2nd stage suction line near the compressor

I hope they refunded you your money after making you sit the wrong test to get ethylene

I will use some sort of control to look after the second stage, at the very least I have the old G-froster X here I could use, wont give me an evap readout tho.
I'm thinking of either getting a K-type G-froster or a Carel controller, i'm leaning towards the Carel controller, twice the price tho.

I have insulated the expansion tank as it seconds as an accumulator. An accumulator I realize isn't needed as if any liquid ethylene getting past the evap is going to vaporize well before it gets in the compressor. But I figure by increasing the low side volume I should be able to get a lower low side pressure.

Luckily that course was %100 funded by the government. I wonder if I'm that lucky with the right course this time?

EDIT:I just realized,

Your meant to have a long length of capillary line to the expansion tank and braze it in to the 2nd stage suction line near the compressor

If it's on the low side like that it's still low side volume so would achieve the same thing, except it wouldn't have to be insulated right?
Thinking about it now, the only thing I can think of that would hinder my performance the way it is, is that expansion tank absorbing more heat through the insulation, the insulation is about 25mm thick though.

[n00b 0f l337]

Well also you have a lot more gas at start up in the loop, so greater work on the compressor. Attached via a metering device think of it like the system is way undercharged, turns on so easily, then sucks the rest of gas in to optimal charge.

[kayl]

That’s good to hear the course was %100 funded by the government


An expansion tank serves 2 purposes
1- To lower your static pressure
2- decrease you high side pressure when system first starts. It does this by slowly releasing refrigerant from the expansion tank via capillary line. Once all the gas is out of the expansion tank the pressure inside will be the same as the suction line not effecting the system.

By the looks of things you have rotary compressors on both stages and they have their own accumulator so an additional accumulator isnt needed.
Personally i prefer to use an adjustable thermostat to control the second stage. I place the bulb of the thermostat on the 1st stages suction line 30-40cm before the compressor and adjust it to come on and turn off when its at a certain point. Load testing with something like 300-350W on the cpu head will tell you what temp to set it at.
I also have a switch on both stages. Turn both switches on and once the first stage is to temp second stage starts automatically. If pressure ever gets too high the HPCO kills power to the second stage, and like wise if something goes wrong with the first stage (ie too warm), second stage turns off.
I have a switch on second stage to turn that on and off if cpu cold bugs or need to change cpu leaving the first stage running for qucik turn on of second stage when need.
Doing it this way there is no need a fancy expensive controller. Just need something to display temps If you want something to control the PC and display temps the Gfroster XE2 is perfect.

[{.bLanK} GoD]

Well now that makes perfect sense. I will cut it out and re-do it.
Not having the expansion tank insulated will give me more room to insulate the shut off valves.

[{.bLanK} GoD]

Picked up a 30m roll of 0.08mm (0.031") capillary tube and a 1/2" vibration damper for the 2nd stage suction line. (not evap flex, that's due in a couple of weeks).
And there's also a 5/8" Cu 90° bend that will go on the end of the evap flex line to connect to the suction shut off valve.


Just about finished piping.
Just need to add another 1/4" access port to the 2nd stage suction, remote mount my access ports and that's it.
Put some pressure in the 2nd stage tonight, but got about 200psi of N2 in it before running out.
Low side gauges are disconnected temporarily so I can pump it up to 400psi ish without blowing up the low side gauges.
Also changed how I had the expansion tank connected to the 2nd stage. Now it's Tee'ed into the suction via 1.5m of 0.8mm (0.031").

[{.bLanK} GoD]

Ethylene arrived today
Along with the Hydrogen regulator with higher outlet pressure gauge and the 3/8" x 36" flexible suction hose.

[killermiller]

Do you lease the cylinder or did you buy it?

[{.bLanK} GoD]

Yes it is leased.
I don't even know what it all cost exactly yet.
Goes onto the firms BOC account and then billed to my personal staff account. (which is basically trade price interest free hire purchase)

[teyber]

nice!

How much does a decent hydrogen regulator run?

Smart, you tied down that bottle very well! What purpose does the folded towel under it have?

Regards

[kayl]

very nice, good to see ya finally got some ethylene, all tht hard work paid off
Good to see the bottle bolted to the wall and fire extinguisher near by.

[{.bLanK} GoD]

How much does a decent hydrogen regulator run?

Do you mean cost?

Smart, you tied down that bottle very well! What purpose does the folded towel under it have?

Regards

The floor where the bottle sits is not flat, the towel is there to stop it rolling sideways at all and bashing my spanky new regulator.

very nice, good to see ya finally got some ethylene, all tht hard work paid off
Good to see the bottle bolted to the wall and fire extinguisher near by.

And there is another fire extinguisher on the other side of the garage.

More pics!

Kayl Block and lineset closeup, about to get hot.


A little fugly but she's all good.


Lapped and pressure tested.


@Kayl, I had to file a couple of notches into your enclosure to be able to get the C clip through when removing.


Wiring is temporarily done, and lineset is connected to the service valves.


ZOMG perfect vacume! (batteries went flat)


Inspector says its all good.

[{.bLanK} GoD]

So First stage is gassed up, second stage is on last vacume now, when I get home from work tomorrow, I plan to charge it with Ethylene.

[n00b 0f l337]

Good work man, seriously
Is it just me or do I spot a bunch of flares vs brazing on normal pipes, any preference? seems your introducing more chances of leaking in the long run. Also, how are the gauges held on? And of course, what gray stuff is sealing those gauges in.

[{.bLanK} GoD]

This is my first cascade, I plan to learn heaps more while building and tuning it.
I half expect to have to change things around, I have given it heaps of room to make it easier to get in and change anything if I have to. Flares don't leak if they are done right. Just a few reasons why I went nuts on the flares. Hahaha, pun intended.
The gauges are attached by unscrewing the two screws holding the gauge shell, two holes in a piece of 16 gauge galv and the screws put through and back into the gauge shell. Simple.
Grey stuff sealing the gauges in? If you mean the bluey grey stuff sealing the permanently mounted gauges in, it is "Higheside Chemicals INC, "Leak Lock"" It's what we use at work, it's a refrigeration grade thread sealant/thread locker.

[Big SturL]

You are definitely one of my favourite builders - always so clean and proper! Waiting in excitement for some results

[before]

Great pipe work... really amazing.

[tiborrr]

Amazingly clean pipe work, now let's all hope it will reward Blank God with some nice -110°C idle temperatures.

[{.bLanK} GoD]

Thanks guys.
First test run went good.

All unloaded so far, I'll crack out the load tester tomorrow.

1st stage gas = R410a
2nd stage gas = R1150
Ambiant = 14°C
HX temp = -38°C
Evap temp = -100°C
1st stage low pressure = 3psi
1st stage high pressure = 205psi
2nd stage low pressure = 1psi
2nd stage high pressure = 255psi
TXV orifice = X0 approx 1 turn open
2nd stage cap tube = 0.031" @ 2.6m
1st stage gas charge = 500 grams initial + 100 - 150 grams approx
2nd stage gas charge = 130 grams



Pretty happy so far, still have to get a load under it and spend some time tuning it.
I am probably going to need another expansion tank for the second stage, static pressure is at 350psi atm (and hasn't warmed up fully yet either ) and probably stuffed the low side gauge by now
And I have a crap load of insulating still to do.
I'll be busy to have it ready for L3.

[Clemmaster]

Shorten the 2nd stage captube there's apparently too much restriction (130gr :/)

Very nice build

[before]

Or maybe try to get a little lower 1st temp. Play a bit more with the TXV (if possible?). -38C looks a bit 'hot' IMHO.

BTW R410A ins't the easiest refrigerant to use, is it?

[tim-]

r410 is no problem to use as long as you have work out pressures and temperatures

[DagoDuck]

Very nice work, indeed! Probably I would change the orifice against a 00. Perhaps another refrigerant in the first stage would be also the better solution. Where do you get the suction hose?

[{.bLanK} GoD]

Strapped the load tester on yesterday and fired her up again.
ATM she will hold only about 70w @ -90°C, any more load and the ass drops out and temps go up a lot.
First thing I need is another expansion tank, static pressure in the second stage got to 390 psi before i vented enough ethylene to bring it down substantially. Venting Ethylene is not illegal, but it is very flammable, so was done with the garage door wide open and electrical equipment isolated. i.e. garage door opener. Ethylene smells a lot like acetylene.
I could also loose the desuperheater, as that is taking up a lot of high side volume and would give me the same effect as another expansion tank by not needing as much gas in the system to fill the desuperheater.
I read that the oil separator does a pretty good job by itself desuperheating the hot gas. Discharge out from the oil separator is stone cold, and the discharge from the compressor is about 40 - 50°C max.
So i reckon I might loose the desuperheater.
My 2nd stage low side gauge is reading 5-10psi higher than it should due to it being over pressurized Gonna need a new one before i can do any accurate tuning.
It's going to have to be able to hold at least 200-250w below DIce temps before I will be fully happy with it. But I am stoked with it hitting -100°C
In the mean time i need to insulate a crap load of pipes, that needs to be done before tuning properly as well.
Oh and btw, she ain't quiet be any stretch of imaginationland, lol. If I build a case for it later down the track, it'll need sound dampening material.

I agree 1st stage isn't cold enough yet.
I have a bunch of orifices to try if I need to, R507 was the alternative if R410a was unsuccessful.
The suction line I purchased from "Refrigeration Engineers" (R.E's) was not cheap but nice and long and pressure rated to 1000psi.
I have 4-5 probes to monitor while tuning, i might go buy another dual probe meter to assist, it sux ass to have to keep changing probes back and forth.
1-evap
2-2nd stage suction
3-HX
4-1st stage suction
5-load tester

I also need to know, am I looking for a 2nd stage super temp similar to a SS or the first stage? with the unloaded -100 shot, 2nd stage suction was about -10C.
I am also thinking I need to move the HX probe, it's currently on the liquid line between the TXV and HX, as close as I could possibly get it to the HX, Think I need to open the HX insulation and mount it on the HX itself.

[{.bLanK} GoD]

Another problem I think i may have is the length of my ethylene liquid line.
Can anyone confirm it is waaaay to long?
And better off using a smaller spun filter/dryer?
If I substantially lower the liquid line volume, the expansion tank I have might be sufficient?
Edited this pic to show ethylene liquid line length.

[{.bLanK} GoD]

Not long after my last post I noticed a moderate safety design flaw. My bad
I wasn't going to mention it like I bet a lot of people do, but If other people can also learn from my mistakes, all the better.

Expansion tanks are suppose to expand aren't they? lol


The 2,5/8" Cu caps were flat originally, the highest pressures both stages saw was 400psi under pressure testing which has bulged the ends of the expansion tank and the accumulator I made.
It could have quite possibly taken another 400 psi to rupture either tank, but after seeing the bulging, it gave me an uneasy feeling so they were both removed and scrapped.

So I went and purchased two new accumulators, one for the first stage and the other for the expansion tank on the second stage.
Also received a crap load more K-type thermocouples, new low side gauges, fittings, and a smaller filter/dryer for the second stage liquid line.


You can also see I have a small heat trace wrapped around the accumulator.
In the suppliers book it mentioned

When using accumulator with suction temp lower than -18°C, a heater should be used to ensure oil return

I am unsure as to whether I will need it or not, but it's there wrapped around the accumulator (under the insulation) if I decide I do need to use it.

As I suspected, and confirmed by kayl, my 1150 liquid line was way too long, I removed this much.


Replaced the big filter with a wee one and relocated the 1150 liquid line service valve. Decided I didn't want a sight glass as well, don't really need it and you can barely see anything in there when it's covered in frost.


She's had a good ten hours odd thrashing over the last two days. Yesterday I replaced the R410a with R507 with much better results. Lower pressures all round, lower temps all round, lower current draw all round and lower 1st stage static by over 50psi.

R507+R1150
0.031" Cap @ 2.5m

225w Load after One hour.
1st Low = 21 psi
1st High = 175 psi
2nd Low = 20 psi
2nd High = 303 psi
Evap = -72.6°C
HX = -24.1°C
1st Suction = -10.6°C
2nd Suction = -29.1°C
Load tester = -63.4°C
Ambient = 18.4°C
1st Compressor current = 1.6 Amps
2nd Compressor current = 1.8 Amps
Total Current = 3.7 Amps

200w 10 minutes after 225w test.
1st Low = 19 psi
1st High = 170 psi
2nd Low = 15 psi
2nd High =282 psi
Evap = -79.1°C
HX = -26.6°C
1st Suction = -17.9°C
2nd Suction = -28.0°C
Load tester = -70.6°C
Ambient = 18.1
1st Compressor current = 1.6 Amps
2nd Compressor current = 1.7 Amps
Total Current = 3.6 Amps

150w 10 minutes after 200w test.
1st Low = 15 psi
1st High = 160 psi
2nd Low = 9 psi
2nd High = 253 psi
Evap = -87.8°C
HX = -30.4°C
1st Suction = -22.4°C
2nd Suction = -25.4°C
Load tester = -81.8°C
Ambient = 18.0°C
1st Compressor current = 1.55 Amps
2nd Compressor current = 1.6 Amps
Total Current = 3.4 Amps

100w 10 minutes after 150w test.
1st Low = 12 psi
1st High = 155 psi
2nd Low = 6 psi
2nd High = 237 psi
Evap = -93.0°C
HX = -32.6°C
1st Suction = -24.5°C
2nd Suction = -28.3°C
Load tester = -89.0°C
Ambient = 18.0°C
1st Compressor current = 1.5 Amps
2nd Compressor current = 1.55 Amps
Total Current = 3.35 Amps

70w 10 minutes after 100w test.
1st Low = 11 psi
1st High = 150 psi
2nd Low = 4 psi
2nd High = 229 psi
Evap = -96.2°C
HX = -33.8°C
1st Suction = -25.3°C
2nd Suction = -31.5°C
Load tester = -93.0°C
Ambient = 17.9°C
1st Compressor current = 1.5 Amps
2nd Compressor current = 1.5 Amps
Total Current = 3.3 Amps

No Load 10 minutes after 70w test.
1st Low = 10 psi
1st High = 150 psi
2nd Low = 1 psi
2nd High = 219 psi
Evap = -99.1°C
HX = -35.2°C
1st Suction = -25.9°C
2nd Suction = -30.7°C
Load tester = -96.6°C
Ambient = 17.9°C
1st Compressor current = 1.5 Amps
2nd Compressor current = 1.5 Amps
Total Current = 3.25 Amps

No load shot.


So far I am pretty happy with it. She really likes the 100-150w mark, I might try shortening the cap tube again, (not before L3 this weekend tho) see if she can hold a 200w load slightly lower. But I am pretty much on par with what I wanted in my first post.

It will be a strong colder than DIce phase cooler.

I am very happy with the power usage, A little over 850w
I still have the wiring to do properly, a little more insulation and a thermostat to control the second stage.

Did I say a little more insulation? lol


And a nice high res shot of the frosty load tester.
Geez, I'm glad that's not high voltage running through that load tester. <==That was sarcasm if you didn't click.