Miny Cascade : Budget Dual 1/2hp

[n00b 0f l337]

So recently I had a few asks for a low budget cascade. Now normally those two terms can't be fit in the same sentence. Inherently, they are not low budget.
But sometimes exceptions can be made. And normally that requires a bit of sacrifice. But sometimes, just sometimes, you luck out :p

So, a miny cascade project. Dual 1/2hp 39R131F's from Rechi Precision.
Short toppers, and they run a bit hot, but they've never shown me less than there full 1/2hp :p
Condenser comes from a Copeland condensing unit (have about 20 of these things laying about, so time to use them).
Desuperheater is my new miny condensers, just under the dimensions of a 120mm fan, they're absolutely midgetish! Fitting a 120mm Panaflo 12G12L fan for good air flow with mid range noise.
Foam stack is the preinsulation first cuts for the 10 Plate HX. Which will be "bound" and insulated.

3ft flex line, Evaporator to be determined, and HPCO on the way.

The entire unit will most likely be cased in aluminum extrusion and acrylic/sheet metal to give it a solid indestructible approach. And of course I have a few other upgrades that can be fitted if the budget opens up a bit.

As for refrigerant,

R507a, R23 will be used.
Although not many builders can get their hands on R23 due to cost, I have a 10lb cylinder to be used, and it is much more ideal than trying to muscle R1150 to condense.
The goal will be about -70C, a solid dry ice range temperature, at the flick of a switch Of course unloaded will go lower for Spi etc giving that mid range bencher many are looking for to replace clumsy pots.

Hope you all enjoy this build as much as I do, I expect to be done with construction when the final parts arrive by next week (tuesdayish) and tune in the week after.

No owner on this one, so it might just go up for sale or just become a light weight show case.

[before]

Good luck mate

So recently I had a few asks for a low budget cascade. Now normally those two terms can't be fit in the same sentence. Inherently, they are not low budget.

Well said.

[-cyclone-]

Quite interesting build especially concerning I'm going to try my best at building smth similar soon -)
n00b could you please give us some specs of that rotaries? Unfortunately found nothing :/

[n00b 0f l337]

52xx btuh 1/2hp Rechi. The specs on these might as well not exist. Finding the right run cap will be hard since I've found 3 conflicting numbers, will try them all after tuning and see which produces lowest power draw.

Progressing well, made the HX "box" from my favorite pink substance, and slot fitted the brazed and pressure tested plate HX. Using the mill I traced the ports and backside ridge into the foam. Snaps together, 3" thick, 10" tall, 5" wide. What a format.

Enjoy. Evap ordered from Ron. And searching up the HPCO now. I have some valve mount ones, but I raelly have grown to dislike them. Getting a stable long term seal can be a pain or just a general fight. Tho I could rip one off the 3 stager...

[teyber]

Looks good!

You should get weird with it if this has no purpose... one day im going make a overpowered inefficient beverage chiller..
a co2 cascade drink chiller would be cheap and score some big points with friends on those muggy nj summer days

[e-Killer]

Subcribed, i have two exact Rechi´s, now find where i can get R23, or im tihinking on blend of 410/CO2 402a/CO2, with Captube instead of txv for lowering the cost.

[n00b 0f l337]

Next one will be QA075's most likely. Similar size, bit taller, but I've heard they're a tiny bit quieter.
This will be running captube, put 6' 6" of .031 on stage one (which is about to come out of vacuum with 10 psi of r290 and then a full charge of r507a), then I guess she'll sit for the week as I'll plumb the second stage as far as I can go and order up some of the aluminum extrusion.

Could be done with TXV, but it's unnecessary if your goal is for a single load.
Over a large range of loads, sure it can be useful, but it's more of a way to get perfect tuning without having to know how to tune

[n00b 0f l337]

I'd recommend against R410a or R402a with these, they already run way to hot. I'm using r290 for oil, r507a primary, and already considering swapping to r134a if it'll do the r23.
As to some updates, first stage done, just need to tune when second stage is finished and ready for it. But we have frost! Amazingly she's quite quiet. Certainly can here it, but if you push down lightly on the HX box to muffle the vibration, there's not much but air flow noise. And speaking of that, this condenser setup's quite nice. I'm glad I went with the 13W motor on the fan.

I purchased a Supco vac gauge on ebay a while back, an old style one when my digital crapper out. It was sold as is, but at $25 it was hard to pass up. Even had a bidding war for it. But, I called Supco when I got it, told them I had purchased it second hand and wasn't sure if it was in Calibration.

They said send it over, so I did. They even paid return shipping. Recalibrated, all good now. Talk about great service, it's an old model, nothing close to there new stuff even.

[Dualist]

Quite interesting build especially concerning I'm going to try my best at building smth similar soon -)
n00b could you please give us some specs of that rotaries? Unfortunately found nothing :/

http://www.rechi.com/en/web_en_produ...efrigerantId=1


What wattage are you aiming for.?

[n00b 0f l337]

Hey Dualist, your a good reminder, I'll pop over to Benchtec as well see what you all are up to

I want 250-300W load. Temperature won't bother me. It'll beat a single stage anyway I charge it.
But, it should show me -65 to -70C.

[n00b 0f l337]

What a good day, even found a HPCO lurking around while I cleaned.

[RussC]

Nice,
Whats the small radiator for?

RussC

[n00b 0f l337]

Desuperheater, it's important when you aren't sure if you have room to spare. Also, no oil separator. I've replaced the oil with Zerol 150, and don't think I'll be operating below -80C.

[n00b 0f l337]

Who likes updates, I like updates!



Most of the second stage brazed in, such a tight fit. And could barely braze it up without heat on the first stage, but wet paper towels work out great. Slight amount of heat got to the insulation of box, but it just deflected and melted away a quarter of an inch, now I can slot the pipe insulation in better! (Yay )

We also have a date and trial time for this thing, Dumo would like a crack at it, but OCF is having there forum party and I think this will debut there.

So three weeks. Enough time? Damn right.

Enjoy the shot, I'll add in the HPCO later today when I finish pondering where I'll fit it, and then at this point we are just waiting on that evaporator to show up from Runmc.

[runmc]

Nice clean work Adam Keep it up. I really hope this works for you.

[Bobsama]

Very nice on these. What's the cost to build?

[n00b 0f l337]

Decently high for "budget". Can't cheap out though, and I'm putting in a Yellow jacket 4ft stainless steel flex, Kayl evaporator and mount, full electric and auto starting setup.

[n00b 0f l337]

Big thanks to Runmc. Purchased an evaporator/mount on Monday, hear on Wednesday in the afternoon.
Could not be better And if he was, he'd have to fend off the women more then I'm sure he has to.

[tiborrr]

250-300W is not enough nowadays. Aim for 350+ albeit with higher temperatures. This cascade should pull 350W @ -75°C w/o issues on R-1150 and TEV on 1st stage.

[n00b 0f l337]

While I can agree that I will have to push for more than 300W.
I cannot agree that a TEV and r1150 will get you anywhere near that.
We are talking about 5200 btuh rotarys here. There is no chance of holding a heavy load at the evaporator and keeping a HX below -30C.

[tiborrr]

I'm running 2x MP14FB (1/2hp pistons) and using Piotres' 54mm evap with 2.5m 0.9mm. Cascade holds leaky GTX470 @ ~1100MHz through Heaven benchmark, which is equivalent to about ~ 350W @ -79°C (-81°C after it recovers). Probe stuck to filter/drier on the 2nd stage right after HX shows around -26°C (19-20bar loaded). The key is not to use too much restriction on ethylene stage, otherwise you'll have to charge too much of this high pressure gas which will eventually bring your first stage to it's knees.

With low restriction and smaller amount of R-1150 on 2nd you'll be able to hold 350W on first at decent temperatures. Yes, your idle temps will not be super duper low (perhaps not even sub -100°C - like mine, idles around -98°C w/o anything attached to it), but you'll be able to hold high load.

[n00b 0f l337]

There's the big difference though. You have 14cc. I have 7cc. These are quite small compressors, and I just don't think it will be possible. I have r23 and that'll be a bit easier, but I also don't find 19-20 bars of pressure acceptable. If this goes to a customer, I want my HPCO set at 300 and normal load between 2 and 250 psi on the high side. These rotarys would cook otherwise.

Maybe on the next one I'll see what r170/r1150 can do, but I just don't see it being viable here.

[n00b 0f l337]

Extrusion case in the making, baseplate is .09" white painted aluminum plate, and panels are .04" white painted. Bought a bunch of black oxide screw caps for the outside, should look purdy.
Tomorrow the last bits for the case should show up.

[RussC]

Nice, 80/20, we use that stuff for frames for our etchers.

RussC

[n00b 0f l337]

Actually not 8020, I found a better provider who would do custom cuts for free at slightly better than 8020 prices. Also, 1010 channels are normally just slightly too tight for the square of a carriage bolt (1/4-20), but he was willing to run a reeming tool down each channel on each piece as well to widen em up just a hair for me. No charge on that as well. So what can I say, had to go with him.

8020 makes good stuff though, and their brackets are nice and premade. But you are always better off cutting your own if you can