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

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.

Ammonia:- 107.9.
Carbon Dioxide:- 70.
Sulpher Dioxide:- 104.
R-12:- 252.

These are the freezing points of the four refrigerants in deg. celsius, so we can say that carbon dioxide has highest freezing point.

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.

The freezing point of ammonia, co2, so2 & R12 are -77.73c, -78.5c, -72c and -157.7c respectively. So the correct answer id sulphur dioxide.

High freezing point means it freezes at a higher temperature. Meaning 0 degrees is a higher freezing point than -27 degrees.

The correct answer is SO2.

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

Co2 freezing point is -56.6.
And the boiling point is -78.5.
It's opposite characteristics than others.

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

So, the correct answer is SO2.

Ammonia = -77.
Carbon dioxide = -78.5.
Sulphur dioxide=-72.
R12= - 157.7.

Nh3-> 77.7.
Co2 -> 57.
So2-> 75.2.
R12-> 135.8.