ECI 33+ (3 Stage Cascade)

[NoL]

Sorry I'm still rusty on my Deutsche, so this will be in English for a while.
Feel free to post in German, I will try and translate to help me learn.

I wanted to share with you my current cascade project.


So here's some autocad!

ECI 33+
Expected Project Start Date: June 1st
Expected Completion Date: Unknown
Part Acquisition: 60% Inventory, 40% To be Ordered

Estimated Temperature: <-- Ha like I&#039;d tell you that









UPDATE JUNE12th.

Little update.
Got home today, gotta start unpacking a huge amount of stuff from school. But, ran down stairs, and threw some crap on the table.
Hope you enjoy.



Some fairly sloppy grinding and heavy red krylon paint later,



A milling machine! Richard got it into the workshop on this dolley of his. I was scared watching this thing jump up and down with each step. (Had to underinflate the tires on the dolley to take 300lbs safely)

Welding up a new work table, mainly for the project, but also for the milling machine.
Then we can start plotting the cage





Table 1 done. Milling machine going on up tomorrow.



Winch + ceiling beam = Mill on Table!
I&#039;m happy it made it, table seems more then okay, but conducts vibration a bit much.
Going to get some more MDF under it, get it all bolted down. And then figure out why the spindle ain&#039;t spinnin!



Everything moved over, so time to start laying out parts.
Might have a lead on the condenser I&#039;d like for this, so the front is a little empty.
Compressors that seem ”used” are working pulls from my own personal cascade that well, I built and never got around to finishing. So they&#039;re brand new still.

Layout time.

Brazed the first suction stem on compressor numero uno. It&#039;s nice to do them like this, since they&#039;ll shoot straight up to the heat exchanger coils. Nice and easy to insulate.





Heat exchanger time.
You can never have enough copper.

Making some fitting attachments.
Cleaned and shined;


Survey says...
OIL SEPARATORS!

[PhilippF]

Ain´t these oilseps a bit *em* heavy?

And I am not completely sure if the HX can be built exactly the way you have drawn it (you wnt to use 90 degree elbows on the outer shell?).

But nice project What gases do you intent to use?

Regards,

Philipp

[Patrickclouds]

you are using to capillary pipes into the evap.
one for hotgas ? i can´t realy recognize it on the pictures.

how are the datas of your rotarys? ccm?

what dimensions of the hole unit are you planning?

good luck

[NoL]

Thank you! Finally an active phase forum with RESPONSIVE people!
Yep, the oil sep&#039;s are a bit heavy. A bit over the top really, but Zerol 150 seems to test better with it.
And built that way? Easy. 3/16” pipe in 3/8” pipe bends nicely in my pipe bender.

R402a/R1150/R14 (Little left, if not R1150)

1/8” Tubes to evaporator, CPEV&#039;s on all stages.
And yep, one is hot gas bypass, linked after a solenoid and secondary oil separator.

First and second stage are 20cc, third is 14cc.
Dimensions are looking like 18” by 30” by 20” (W, L, H)

[august123]

Awesome project
I like your CAD with every pipe inside.
But first stage rotary looks a little small for loads beyond 200watts?

[Moc]

With your compressors I would use R404A/R23/R14 because the first and second stage has the same displacement/power. Your first stage will not give good enough temps to condense R1150 with healthy high side pressures. And most of all, R23 makes cold enough temps to condense R14!

Also I don&#039;t understand why you want to use a CPEV in the first stage... A TEV would make it much more simple, calculate the correct nozzle with the Danfoss Tool and you hardly have any problems.
There are also TEVs for R23 made by Danfoss. August123 uses one in his 4 stage and is - as far as I heard it - quite happy with it.

Did you understand how a CPEV and TEV works?
Am I allowed to ask why you didn&#039;t posted that in XS?

[NoL]

Oh I know TXV&#039;s, I even have some electronic expansion valves sitting around. I don&#039;t like the lack of adjustability past the superheat screw. I&#039;d rather dial it in manually with a CPEV. Removes errors.
I wish I had R23, or R170, but I don&#039;t. Luckily, I&#039;ve worked with less and had no issues. Most likely will end up providing an SLHX on the first stage. Certainly helps with a CPEV.
This isn&#039;t my first 3 stager
But all great suggestions, thank you.

PM me (Not sure this forum has that, I bet it does) Moc, I&#039;d rather not throw things out in public chat.

[Patrickclouds]

i agree with moc´s opinion about the compressor of the first stage.
try it and if it doesn´t work you can still switch to r170 or r23

hope to see more pics soon

[Moc]

Oh I know TXV&#039;s, I even have some electronic expansion valves sitting around. I don&#039;t like the lack of adjustability past the superheat screw. I&#039;d rather dial it in manually with a CPEV. Removes errors.
I wish I had R23, or R170, but I don&#039;t. Luckily, I&#039;ve worked with less and had no issues. Most likely will end up providing an SLHX on the first stage. Certainly helps with a CPEV.
This isn&#039;t my first 3 stager
But all great suggestions, thank you.

PM me (Not sure this forum has that, I bet it does) Moc, I&#039;d rather not throw things out in public chat.

Hey Nol
Seems like we have some different opinions there. I love TEVs for its selfadjustability. Normally you don&#039;t even have to use the superheat screw (because Danfoss cabilbrates it in the factory at the needed 7K superheat... ). A TEV makes the pulldown quite fast, changes to variating load, and I never had real problems with them.

What are the reasons for you to say that a SLHX helps with a CPEV?

[NoL]

I&#039;m not sure why, I just dislike that I have no real say, and that it all comes down to a clamp on the suction. I&#039;d rather bring it into adjustment for different ranges of load.
A SLHX helps with a TXV as well, but I&#039;ve found more so with a CPEV, as increasing the pressure on the low side then results in a colder CPEV as well.
Just the adjustment becomes ”better”
If the CPEV&#039;s fail, I will switch to TXV&#039;s, without a doubt.

[NoL]

Creating heat exchanger 1.

My method involves 5 ft long steel beams and clamps.

Clamp the tubes straight as possible.

And try.

When your looking down a 20ft long barrel though, things get interesting.
This took 3 days.

[NoL]

And bent on up.
20” by 12”. 4 loops or so tall.
Should be adequate heat exchange. And nice and easy to insulate, I hope.

[DerMalle]

Nice bent-work.

[NoL]

Thank you
Now to make the CPEV&#039;s line up nicely.
2 Down.
One HX to go.

[UnRockStar]

CPEV in First Stage?

[Moc]

Jep, ich habs ihm auch schon gesagt das das ne schlechte Idee ist. Er meint das würde Probleme vermeiden, weil mans ja selber einstellen könnte .

[Patrickclouds]

clean work

[Moc]

Yes, the HX is really perfect! Keep this level on .
Do you habe any plans how you want to mount the HXs? Please do lay it just on the rotarys .

[UnRockStar]

die AEVs wirken eher nachteilig auf den kreislauf.

zwar hab ich eine konstante temperatur aber die Kälteleistung schwangt.

Was macht das AEV:

Es Hält den Saugdruck und somit die Saugtemperatur Konstant.

habe ich eine geringe last muss das AEV viel einspritzen um den druck zu halten. da nur wenig Kältemittel verdampft und so der druck nicht ansteigt.


Kommt jetzt aber last kann schlagartig viel Kältemittel verdampfen.
jetzt Re gelt das AEV z u und spritzt weniger ein um den druck Konstant zu halten.


Es Verhält sich also genau umgekehrt wie es ideal wäre.


Es funktioniert evt aber es ist keine gescheite lösung da finde ich Kapillarrohr ja noch besser.

[NoL]

die AEVs wirken eher nachteilig auf den kreislauf.

zwar hab ich eine konstante temperatur aber die Kälteleistung schwangt.

Was macht das AEV:

Es Hält den Saugdruck und somit die Saugtemperatur Konstant.

habe ich eine geringe last muss das AEV viel einspritzen um den druck zu halten. da nur wenig Kältemittel verdampft und so der druck nicht ansteigt.


Kommt jetzt aber last kann schlagartig viel Kältemittel verdampfen.
jetzt Re gelt das AEV z u und spritzt weniger ein um den druck Konstant zu halten.


Es Verhält sich also genau umgekehrt wie es ideal wäre.


Es funktioniert evt aber es ist keine gescheite lösung da finde ich Kapillarrohr ja noch besser.

I agree, I really do.
I might still got TXV. But I&#039;d also like to be able to go colder with lower loads. More so then a TXV would allow. These CPEV&#039;s also actually are adjustable when cold, so on the fly is possible. The price is also what really makes me turn to them first. 7 euros a pop.

[Moc]

die AEVs wirken eher nachteilig auf den kreislauf.
zwar hab ich eine konstante temperatur aber die Kälteleistung schwangt.
Was macht das AEV:
Es Hält den Saugdruck und somit die Saugtemperatur Konstant.
habe ich eine geringe last muss das AEV viel einspritzen um den druck zu halten. da nur wenig Kältemittel verdampft und so der druck nicht ansteigt.
Kommt jetzt aber last kann schlagartig viel Kältemittel verdampfen.
jetzt Re gelt das AEV z u und spritzt weniger ein um den druck Konstant zu halten.
Es Verhält sich also genau umgekehrt wie es ideal wäre.
Es funktioniert evt aber es ist keine gescheite lösung da finde ich Kapillarrohr ja noch besser.

@Unrock
Ja mir schon klar... ihm aber nicht.
Ich übersetz ihm mal:
@Nol
I&#039;ll try to translate it for you and add a bit.

With a CPEV you have always the same suction pressure but not the same cooling power.
How works a CPEV?
It keeps the suction pressure= suction temperature (as far as the cooling power is able to...) constant.
If you set it to your maximal load, you have floodback when the second stage is unloaded...
When you don&#039;t have full load on the second stage, the temps could be better and so on...
Thats why a TEV is wonderful... gives you always the best. Of course you have some peaks cause its not so quickly reacting but always better than CPEV (in a stage with an HX).

Unrockstar explained it more technical:
If you have a small load, the CPEV has to inject a lot of refrigerant to keep the pressure high(/at value you set it) but there is just a little refrigerant that can boil. Next, you create some load and every refrigerant boils off... the pressure rises and the CPEV closes... but to hold the load, it needs the massflow.

It react in the oppostite way you want.
Even a captube would be better because with load, the suctin pressure rises, the compressor has more to do, the high side pressure rises because the condensor has more work and because of the higher pressure, more refrigerant goes through the captube.

I hope you understand everything (my english or refrigeration-specific, if you have any questions, feel free to ask.

[Moc]

I agree, I really do.
I might still got TXV. But I&#039;d also like to be able to go colder with lower loads. More so then a TXV would allow. These CPEV&#039;s also actually are adjustable when cold, so on the fly is possible. The price is also what really makes me turn to them first. 7 euros a pop.

Oh, now I was to slow... takes always much time to answer in english .
Here in Germany we don&#039;t give much on half-loaded tempertures. Of course you can get some nice temperatures when you close the CPEVs... but that doesn&#039;t count. -120@250W and a nice pipework, thats what we want to see! :banane:

[NoL]

Well let me show you just that
(Actually I want a bit colder!)
The other thing is though, with a constant suction pressure, you keep constant high side pressure on the following stage. TXV will result in a varying high side pressure.
I no doubtedly understand that. You&#039;d also be surprised how hard it is to find a good TXV around here.

[NoL]

Second heat exchanger rolled, CPEV&#039;s tested played. Nice and up front. They will be ”separately” insulated in their own little sealed box.

Now thats sexy. And under 3 inches tall.

[Moc]

Perhaps you would be surprised how hard it is to find a good CPEV here ....
Many people buy their TEVs (here in Germany) super cheap from Ebay (new)....sometimes cheaper han 10€/piece (always Danfoss here).

The other thing is though, with a constant suction pressure, you keep constant high side pressure on the following stage. TXV will result in a varying high side pressure.

BUT: A TEV will give you in most times the best temps (different load,ambient temp,compressor temps) which -if you think on the next stage- will give you always the lowest high side pressure. That is good for your compressor and temps (but not if you use a CPEV in the second stage )....
And normally there is no problem in varying HSP because 1) it doesn&#039;t vary much 2) the next stage should be able to work with slightly changed settings (e.g if you use a TEV or caputube ).

Okay... lets close the CPEV discussion, its so hard for me...

Looks great .