Mechanical Engineering - Heat Transfer, Refrigeration and Air Conditioning - Discussion

The correct answer is SO2.

Ammonia - 77.7°c.
R12 - 157.7°c.
SO2 - 75.2°c.
CO2 - 78.5°c.

The freezing point at atmospheric pressure:

Ammonia=-77.8° C.
Carbon dioxide=-78.55° C.
Sulphur dioxide=-75.2° C.
R-12 =-157.5° C.

Nh3 = -77.8 in C.
Co2 = -78.
So2 = -75.2.
R12 = -157.

So, the correct answer is SO2.

So2 should be the right answer 75.2°c.

The correct answer is: Ammonia.

The freezing points of the mentioned refrigerants are:

- Ammonia (NH3): -77.7°C (-107.9°F)
- Carbon dioxide (CO2): -56.6°C (-69.9°F)
- Sulphur dioxide (SO2): -75.5°C (-103.9°F)
- R-12 (Dichlorodifluoromethane): -157.6°C (-251.7°F)

Among these, Ammonia has the highest freezing point, which is -77.7°C (-107.9°F).

Note that refrigerants with higher freezing points are more suitable for applications where the evaporator temperature is not extremely low.
However, other factors like boiling point, critical temperature, and environmental impact also influence the choice of refrigerant.