Ref. R-1150

[jan willem]

Hello I'm new here,

I have a question i have to design a 2 stage cascade system i have to cool 25 liters methanool to -100gr Celcius.
for the 1stage i whant to use a 21cc Danfoss compressor with R-410 and for the 2 stage i also use a 21 cc danfoss with R-1150 or R-508b.
I whant to now wich Ref. is better and wich oil i have to use for the second stage.
Is there somebody who can help me.

[US Iceman]

Hi Jan,

For your first question you sure picked a good one to start with.

R-1150 (ethylene) is a hydrocarbon so if you use this as the cascade refrigerant do you have to plan on explosion proof wiring and electrical devices? I am not familar with your safety codes, but you do need to verify the requirements if you use ethylene.

To see which refrigerant is best, look at the mass and volume flows that are needed in your operating conditions. Ideally you want low mass and volume flows to keep the compressor small. But since you are looking at a 21cc displacement compressor, the cooling loads cannot be too high.

I have only worked on one or two ethylene systems, but the oil should be selected on the pour point and the miscibility t o ensure sufficient viscosity at the desired operating conditions.

I have no experience with R-508b so I'm afraid I will not be much help on that refrigerant.

[jan willem]

US iceman tks for you answer, The standard installation we make goes to -80C in the second stage we use R-508b mixed with R-404a and a liitle bit of N-penthaan for the oil.
My Costumer asked me if i can make the installation to -100C so i looked on the internet for information so i saw that some people used R-1150 in the second stage, so i came on this forum. This kind of questions i can not ask on the dutch forum i can not get there a serius answer(sorry if my englisch is not correct)

jan willem

[US Iceman]

Ethylene will certainly get you to -100C (-148F). One of the systems I worked on was for atmospheric storage of ethylene at -155F (about -104C) so that should be OK.

One of the problems when working with these very low temperatures is the need to stainless steel or a lot of superheat to raise the gas temperature to within the limits of the equipment and material used.

The ethylene compressors were all stainless steel and so expensive we decided to not bid the project since the risk to reward ratio was not in our favor.

Your English is fine. In fact, it's better than my Dutch (which I'm trying to work on for one of our other moderators in Belgium).:o

[Rob S]

You're best bet is to use 1150 as the second stage. Not to say it can't be done with 508B.. but you'll end up running in a very low vaccum. Which will end up putting your discharge temperatures to an unexceptible level.

I've only built a R404a and 1150 system as an experiment. Used a split air cooled condensor for both stages.. (one side of the split for a desuperheater). A plate exchanger and for the cascade condensor flooded it. Ended up putting the TXV bulb on the inlet to a Acumulator. The acumulator was of the sub-cooling type. Inorder to get max effect from flooding, superheat, sub-cooling, and just above min compressor superheat. With this set up I was able to keep the Discharge pressure at around 250psig.
Ran the test chamber at -105C for 2months...

Oil was TD150 with 2 oil seporators. A collesent and helix.

[jan willem]

tks Rob

i've had some questions about your reply:
running in very low vaccum i think you mean with R508b or not.
at what condensor temp you work in the second stage -35C or -40C.
i'll think that your installation is much bigger than ours you work with txv we work with capulary our load by -100C is about the 50 watts.
can you tell me who is the suplyer of TD 150 i called to day some compangy's in the netherlands but the never heard of TD 150.
what do you mean with a collesent and helix?
maby we can change some information about low temp installations.
maby a idea for web ram to start a forum special for low temp

jan willem

[Rob S]

Yes. With 508B as your second stage refrigerant. You'd end up running in a very low vaccum.

Yes the condensing temp was around there. -35C to -40C. Never did calc out a load for the small 152mm x 152mm x 152mm chamber. I made the chamber some time ago for testing purposes only.
For the High stage I used a 1/2 ton X charge 404A low temp TXV.
Used two 1.5hp low temp compressors... what I had at the time.

TD 150... I'm refering to Zerol 150 made by Nu-Calgon.

Oil separators... Ya I can't spell worth a crap.
Talking about a Helical (Henry 5180) and Coalescent (Temprite 321) Put the Coalescent before the desuperheater and the Helical after the desuperheater.

Yes.. I forum for just Ultra-Low temp would be great. I've never seen one myself.

Something to think about. You could do the same amount of work with an Auto Cascade setup. High temp refrigerant of your choice, R410a, and R1150.
There is another refrigerant that might be better to use than 410A tho... MO89
http://www.refrigerants.dupont.com/Suva/en_US/products/isceon89.html
How about R423a, MO89, and 1150.

[jan willem]

Hi Rob S

I think about auto cascade for a view years of making it but i don't have much information about this.
About MO89 vs R-410a Before 1993 we where making 1 stage installations to -65C/-70C with R13b1.In 1993 it was forbitten by low to us it so we hade to look for another ref.
first we hade a good alternetive called mixflon made by Dehon in france. after 2 years the didn't make it any more so we hade to look for another ref. we tested propyleen/MO89 didn't work not lower than -50C.we tested FX-80 of dehon we came to -60C.last year tha called us to tel us that the production stopped of FX-80 :mad: so we hade to look again.In last December we testsd R410a and came to -58C. so to make a long story short with our results is R-410a better than MO89.
R-423a i never worked with it:confused:

[Rob S]

I haven't used any MO89 myself.. But I've hear that Virtis is using it in their new Freeze Driers.
Personaly I prefer 13b1 myself too.. Can almost set my calendar to the next compressor change :)

Back to 1150.. All I can say is be ready for some head-acks.

Maybe you should think about a 3stage unit..
R404a or 507, R508b, and R14.
I think a 3 stage would last longer than a 2 stage with 1150. Unless you had a chilled water loop you could tap into for condensing and desuperheating.

[jan willem]

Hi rob,

the first 2 alinia's i don't understand??????

A 3stage unit i buildt it for 5 years ago for the space industie in the usa.
By testing the unit it cost me 4 compressors in the 3stage every time when thr temp coms below -115C the compressor breakdown.
at that time i think about a auto change cascade.
I now one person who can make this kind of units but do'n't whant to give me information he worked with 5 diverend Ref. and for the last stage he used argon.
he use one compressor 3 pk scroll and the temp in the chamber was about -173C.

I hope that you have some information about auto change.If you whant you can send it to my email.

I hope that i get my R-1150 next week so i can test

question about you what kind of installation you make for work

[Rob S]

I really dont have any design info on an auto-cascade system. Seeing I'm not an engineer.. just a service Tech. Any experiment I do is just to see if I can do it.
Mostly all I get to do is solve and work out the problems after the 1yr warrenty is up. Basicly just redesign as needed.

Think JTSTEN designs them... not sure if he comes around on this forum anymore tho.