Question: What's the difference between an autocascade and a non?
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Question: What's the difference between an autocascade and a non?
Autocascade 2 or more stages of cooling one compressor, cascade 2 or more stages of cooling 2 or more compressors. Each stage has it's own compressor.
Being the noob that I am, I knew that an autocascade is to do with different refrigerants in one loop with one compressor, but how exactly does it work.
Just being curious.
Love your work btw
every forum that has a propper phase change part has people talking about 'Chilly1'
Are you showing your evapdesigns to everyone who wishes to know, or do you keep them for yourself?
grtz
(edit: sry didn't read the begin of the topic :rolleyes: )
http://www.teampuss.com/berkut/autokas.jpg
In my opinion: the ultimate CO2 cascade design.
Why do you have both the CO2 and R290 going to the evap? Is it to stop the liquid co2 forming dry ice?
R290 flushes CO2 dry ice from the feed line and heat up the capilary tube outlet (if we can talk about heating up @ -50C temps :D)
The evaporator is filled with dry ice flowing in R290. Dry ice evaporates cooling the evaporator, R290 flows further to the HX. There it evaporates cooling the inner surface of the HX. No compressor floodback.
http://www.teampuss.com/berkut/AUTOCASCADE/2/2.jpg
Here is a pic of the HX to show how it works.
sorry for asking but what is the hx's purpose? and what does hx stand for?
that is a cool design there you have some good ideas there berkut for subliming c02.
hey do you have access to r1150, i would love to see you use that.
for the r290 capillary tube to the evap is that on a hand tap or constant?
that is a very good idea. so in the end you use r290 adn c02 not r22 anymore.
Hey Berkut can you label the hx, im confused because theres 3 inlets, I thought there was supposed to be 2 (1 for evaporating r290, 1 for condensing co2). Do you have any idea about a cap tube length for the r290 heating the end of the CO2 cap tube?
edit: I found out the middle is a the suction line, cool. It's like combining the hx and suction line hx into one.
edit2: do you use an oil separator or have you found that all the oil stays with the r290?
Are you using only one filter drier at the liquid line?
random questions:-
1. whats a filter for? - pardon me for being a dumba$$ ;)
2. some drawings shown here have systems whereby oil returns back to the compressor, whereas some dont; why is this?
p.s
i knew what a single stage does and a cascade, but i had no idea about auto cascades until chilly1's post explainig it - thanks man, your already a legend (even tho you aint dead! ;))
1) filters are to catch water and small bits of debris (filter/drier)
2) The systems where oil returns to the commpressor use an oil separator to separate out the oil right after the compressor, so it doesnt freeze in the evap. Some autocascades dont need this because the oil tends to remain with the lower pressure refrigerant.
hope that helps
how do you know when to use it?????Quote:
Originally Posted by gkiing
If your low stage refrigerant is one that doesn't carry oil very well (r22,r507,r404a) then use it, and if it carrys oil exceptionally well (like r290) then you dont use it.
R22 does carry oil quite well. and so does R402. R507 and 404 and the HFC's carry polyolester well but not mineral oil.
Yes, phase separator can be also a oil separator, so oil fly with low pressure gas
(R290, R22, R404a, R507 etc.)
And again yes, berkut's test autocascade have only one filter, before phase separator
ahh, thats straightened it out,
thanx guys ;)
When I was using r22 with mineral oil I had problems with the oil return, I had to add at least 10% propane to get it to work properly.Quote:
Originally Posted by chilly1
I dont have any experience with 402, but 404a and 507 seem to work better with a bit of propane to help with the oil.
So does it mean that if your using 404a or 507 as a low pressure refrigerant on an autocascade you dont need an oil sep because they carry the oil well eneough? I thought r290 was the only exception where you may not need one.
If you use Poly oil yes, if there is mineral oil use a little propane at least 2 % for R22 R290 on mineral or poly oil it is fine.
Excuse me for asking but I understand all your drawings and explanations except for the part where you mentionned more than one refrigerant such as r290 AND CO2 I`m confused as to where the CO2 comes into the equation, what is it`s purpose, do you need to run 2 different refrigerants if so how? Forgive the n00b questions...
THANKS
the two refrigerants evaporate/condense at different temperatures so you can seperate them out. as they enter the phase separator the 290 is a liquid the co2 is a gas. the liquid 290 is put into one side of the heat exchanger where it is allowed to boil (be reducing the pressure) cooling the heat exchanger down, the co2 gas goes in the other part of the heat exchanger still at high pressure where it its cooled so it condenses into a liquid. the liquid co2 goes to the evaporater on the cpu/gpu etc where it is allowed to boil cooling the evaporater down. both the 290 and co2 are now returned to the compressor. this just allows you to condense co2 at much lower pressure than if you tried condensing it at room temperatures.
What are the proportions of the mixture CO2 to propane 1:1 ?
And another question, when filling the system with a refrigerant what pressure should it be pumped up to?
Berkut... Just dont forget to add in a small Accumilator or you might end up flushing out the compressor oil on start up.
Thats why I used Hotgas to maintain Evap Pressure.
if ya get the gas charge right with correct metering devices first and second stage ya dont need anything to flush evap of ice it sorta does itself.
On an autocascade? Interesting..Quote:
Originally Posted by kayl
and for cascade aswell, last nigh benching c02 casacade didnt show any signs of blocks like with last cascade. i think is amount of r290 in there and keeping second stage pressure low ie lots of r290. my high side pressure at load is about 160psigQuote:
Originally Posted by gkiing