Refrigerant mixing

[ultralo1]

In trying to further my understanding of the cascade systems that I work on, I have a question regarding mixing the refrigerants. The old systems used R500 and R503. Sometimes R290 or pentane was added. Now we are using R508b and R23 in the 2nd/low stage with a variety of other refrigerants added in small quantities. A variety of "normal" refrigerants in the 1st/high stage mostly mixed as a "coktail". Every manufacturer has their own unique mix for both stages. So this gets to my questions.

How does an engineer calculate the final product of a mix? Is it a mathmatical formula that gives exacts or does it start as a formula and then gets "tweaked" in prototyping? How are the consituent(sp?) gases selected for the end product? When adding a small amount of refrigerant in the mix to aid in oil misability how does this effect the final temp? When bleeding gas from the high/discharge side of the compressor are the gases still mixed in the correct proportions or are you fractionating out the mix? What are the gas physics "laws" that I need to understand to work with these mixes?

For those that dont know me. I repair, rebuild, and maintain a variety of different scientific refrigeration systems on a university campus.

Thanks

[The MG Pony]

http://www.xtremesystems.org/forums/showthread.php?goto=newpost&t=144007

Read this thread, you get to watch one be designed, parted out, assembled and charged.

All open for all to see and explained in detail, amazing auto cascade -141c! made from a 5000btu/h AC

[ultralo1]

Holy Crap Batman!!!!!

I made it to page 6 before my brain fried.

Thank you very much. That man is amazing. I will have days of reading material.

PS. I have had alot of fun in Abbotsford.

[The MG Pony]

Oh ya? Cool, The air show is still held there!

Ya he is amazing, it so many ways, amazing skill, amazing kindenes, amazing generousity! Definetaly read through it a few times and it all makes sense after it soaks in lol.

[ultralo1]

I read the entire thread today. It was definately mindblowing. I will have to reread it and a few others on that site. I plan on getting in touch with him on monday. There seems to be alot of good people on that site with alot of knowledge.

It is great to find a place where the physics of what is happening are discussed. I understand the mechanical side, I am now trying to get to the "heart" of the systems.

I never made it to the air show.:( One of my customers facilities was about a mile south of the half way point of the east to west run way. I spent one week a month for 2 years out there. Beautiful place and great people out in BC.
Thanks again

[The MG Pony]

hehe no prob and glad you like the site, we often get into the "deep" physics there.

Guess the only solution is for ya to come back for the show! ;)