Nitrous oxide (N2O) as low-stage refrigerant

[DaBit]

For us hobbyists it is hard to obtain refrigerants, and typical low stage refrigerants useable below the -60C / -75F mark, such as R23 or R508b, is really impossible.

Viable alternatives are R170 (ethane) and R1150 (ethylene).

Another possible alternative from thermodynamic point of view is nitrous oxide (N2O), which can possibly be obtained though automotive tuning shops by us hobbyists.

Some properties:

- Melting point : -91 °C / -132F
- Boiling point (1.013 bar) : -88.5 °C / -126F
- Critical temperature : 36.4 °C / 97F
- Latent heat of vaporization (1.013 bar at boiling point) : 376.14 kJ/kg
- DOT Hazard class : Non-flammable Gas
- Toxicity: None Established
- good compatibility with copper, fair compatibility with carbon steel

Gas decomposition under pressure might happen above 300C / 570F, but we don't get there.

At 15 bar (~225psi) condensing pressure, condesning temperature is ~ -33C / -27F, which is doable with R507 or R404a in the high stage.

I don't have much data on this gas, but would it be suitable as 'The Alternative When Everything Else Fails'? Would it be compatible with POE oil?

Wat would be the discharge temperature when evaporating at -85C and condensing at -35C, with heat exchange between suction and liquid lines?