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View Full Version : When its not ok to add vapor... Refrgeration definition of azetorope?







pwned
03-11-2013, 04:14 PM
It is a generally accepted practice that to liquid charge blends with a large distillation range such as R-404A to avoid fractionation. The distillation point difference causes fractionation which the more volatile portion leaves first and leaving the left over richer in less volatile fractions.

Why is it ok to add 507 as vapor, but 410A is expected to be added as liquid only just like 404A?


R-410A is considered zeotropic and service standards in the US for A/C discourages vapor charging.

http://www.sciencedaily.com/releases/2013/08/130804081117.htm


Azeotrope blends are assigned 500 series numbers, such as HFC 507 and HCFC/CFC 502, CFC/HFC 500.

Azeotrope only holds true at the azeotrope temperature. DuPont says ~502 is around 0.3F glide.
http://www2.dupont.com/Refrigerants/en_US/assets/downloads/h45938_Suva_temp_glide.pdf

Tecumseh permits 507 charged as vapor:
http://www.tecumseh.com/en/canada/library/~/media/North%20America/Files/Guidelines%20and%20Manuals/Refrigerant%20Documentation_North%20America/Tecumseh%20Guidelines%20for%20Utilization%20of%20R404A%20and%20R507.ashx

507 does have ~0.3F of glide:
http://www.honeywell-refrigerants.com/americas/?document=hfc-retrofit-guidelines-hfc-404a-and-hfc-507-to-hfc-407f&download=1

410A <0.5F per DuPont, some others say <0.3F
http://www2.dupont.com/Refrigerants/en_US/assets/downloads/h45938_Suva_temp_glide.pdf



410A isn't perfectly azeotropic but neither are 500, 502 and 507.

Tayters
03-11-2013, 08:30 PM
The theory as I was taught it is that with a zeotrope liquid the molecules of the different refrigerants are bound to each other but when a gas they are seperate.
With an azeotrope they stay bound together in liquid or vapour so the composition remains the same. Why you get a glide then (although it is on the small side!) I can't answer for an azeotrope.

You might find more detailed info in the font of all knowledge (not you Install Monkey but I'm sure you've got a nugget or two stashed away:cool:) that is Wikipedia although I got lost in the first paragraph.

http://en.wikipedia.org/wiki/Azeotrope

Cheers,
Andy.