When you close the door of a refrigerator, everything inside doesn't freeze immediately because the cooling system of the refrigerator is designed to maintain a controlled and stable temperature. The refrigerator operates using a thermostat that senses the internal temperature and activates the cooling mechanism as needed to maintain the desired level of coldness.
Here's how the process works:
Cooling Mechanism: The refrigerator uses a refrigeration system that typically involves a compressor, condenser, evaporator, and refrigerant. The compressor compresses the refrigerant gas, raising its temperature. The high-temperature gas then flows through the condenser coils, where it releases heat to the surrounding air, causing the gas to condense into a high-pressure liquid.
Expansion and Evaporation: The high-pressure liquid refrigerant then passes through an expansion valve, where it undergoes a sudden drop in pressure. This causes the refrigerant to evaporate and turn into a low-pressure gas. The evaporation process absorbs heat from the interior of the refrigerator, cooling it down.
Temperature Regulation: The thermostat in the refrigerator continuously monitors the internal temperature. When the temperature rises above the desired level, the thermostat signals the compressor to start the cooling process again, and when the temperature reaches the desired level, the compressor is turned off. This cycle repeats to maintain a consistent and optimal temperature.
So, when you close the refrigerator door, the cooling system continues to regulate the temperature inside. The cooling process is not instantaneous, and it takes time for the interior to reach the desired level of coldness. Additionally, the items inside the refrigerator act as thermal mass, helping to stabilize the temperature and prevent rapid fluctuations.
If everything inside the refrigerator were to freeze immediately when the door is closed, it would lead to excessive cooling and could potentially damage some sensitive food items or cause containers to burst due to the expansion of freezing liquids. The refrigerator's design and temperature control are meant to prevent such extreme conditions and ensure proper preservation of the stored food while maintaining an optimal cooling environment.