Refrigerant gases are used as coolants in refrigerators for several reasons:
Efficient cooling: Refrigerant gases have excellent heat transfer properties, making them highly efficient for absorbing heat from the refrigerator's interior and releasing it outside through the condenser coils. They can efficiently change state between gas and liquid, facilitating the heat exchange process.
Low boiling point: Refrigerant gases have low boiling points, which means they can evaporate at relatively low temperatures. This property allows them to absorb heat from the refrigerator's interior, cooling it down.
Non-toxic and safe: Refrigerant gases used in modern refrigerators are designed to be non-toxic and safe for household use. Older refrigerants like chlorofluorocarbons (CFCs) were harmful to the environment and ozone layer, but newer refrigerants like hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) have been developed to be more environmentally friendly.
Regarding your question about refrigerant gas being just a gaseous form of oxygen with impurities: Refrigerant gases used in refrigerators are not simply oxygen or air. They are specific chemical compounds chosen for their cooling properties and safety. Common refrigerants used today include R-134a (tetrafluoroethane) and R-410A (a blend of difluoromethane and pentafluoroethane).
The reason refrigerant gas doesn't feel "ice cold" when you touch it is that the refrigerant is in a gaseous state at room temperature. In a gaseous state, the molecules are spread out and have more energy, so they do not produce the same sensation of coldness as you would feel when touching a solid (like ice) or a liquid (like water). However, when the refrigerant is in its liquid state inside the refrigerator's cooling system, it is extremely cold, and its ability to absorb heat allows it to cool down the refrigerator's interior.
It's crucial to handle refrigerants properly and avoid releasing them into the atmosphere, as they can contribute to greenhouse gas emissions and climate change. That's why refrigerant management and disposal are essential aspects of maintaining a refrigerator's environmental impact.