High Ambient 130ish deg F - 410a, 407c or 134a Question

[leeave96]

I am considering the following refrigerants for a high ambient application - replacing R-22. This is a new design and I can select what ever refrigerant I want, so long as it is a non-ozone depleting refrigerant.

I gather R-410a is a suitable replacement for R-22 and better in performance than that of R-22 at around 95 deg F ambients. However when the ambient starts to get-up to 130 deg F and higher, R-410a's lower critical temperature starts to lag behind R-22.

Question is - how does R-407c compare at such high temperatures and what about R-134a as it has a much higher critical temperature at 214 deg F vs R-410a at 162 deg F.

Any advice would be appreciated.

Thanks,
Bill

 

[MintJulep]

You might find this interesting.

http://www.fire.nist.gov/bfrlpubs/build02/PDF/b02186.pdf

 

[stanlsimon]

I don't know what type of equipment you are putting the refrigerant into. New, existing, large, small or whatever?

If existing equipment, there are concerns about seal materials and compatibility. Also each refrigerant needs to be miscible with whatever type of oil is in the system.

R134a is a good anesthesia. Other refrigerants will cause suffocation. If you are looking at a larger system piped inside a mechanical room you need to follow the ASHRAE standard 15 for refrigeration equipment rooms.

 

[HVAC68]

What kind of application ? DX ? Chilled water ?

Check with the manufacturers as well. You may end up specifing something which may be available with only manufacturer !

For example, Carrier (to my knowledge) doesn't have R134a DX air-cooled condensing units.

Check with them regarding the availability, specifically for the high ambient application. Some products may be available for normal ambient, but, probably not available for high ambient application.

HVAC68