Deep freezers, like other refrigeration appliances, work based on the principles of thermodynamics. The reason deep freezers are hot on the outside but chilly on the inside is due to how they transfer heat to maintain the low temperatures required for freezing.
Here's a simplified explanation of how deep freezers work:
Compression and Condensation: Deep freezers use a refrigerant, a special fluid with properties that allow it to change from a gas to a liquid and back easily. The first step involves compressing the refrigerant gas, which increases its pressure and temperature. As a result, the refrigerant becomes hot.
Heat Dissipation: The hot, high-pressure refrigerant gas then moves through a set of coils or tubes located on the back or bottom of the freezer, called the condenser. The condenser is designed to dissipate the heat from the refrigerant to the surrounding air.
Expansion and Evaporation: After the heat is removed from the refrigerant in the condenser, it becomes a high-pressure liquid. This high-pressure liquid is then passed through an expansion valve or capillary tube, where it undergoes a sudden pressure drop. As the pressure drops, the refrigerant expands and transforms into a cold, low-pressure gas.
Cooling the Interior: The cold refrigerant gas enters the interior of the freezer through another set of coils or tubes, known as the evaporator. This is where the cooling of the freezer's interior takes place. The evaporator absorbs heat from the freezer's contents, including the air and items stored inside. As the heat is absorbed, the refrigerant evaporates and turns back into a gas.
Returning to the Compressor: The refrigerant gas, now heated and low-pressure again, returns to the compressor to restart the cycle.
The process of transferring heat from the freezer's interior to the exterior through the condenser causes the outer surface of the freezer to feel warm or hot. Meanwhile, the evaporation of the refrigerant in the evaporator cools down the inside of the freezer, creating the chilly environment necessary for freezing and preserving food.
So, the temperature difference between the outside and inside of the deep freezer is a result of the heat transfer process essential for cooling the interior and maintaining the freezing temperatures.