Compression cooling and absorption cooling are two different methods used to achieve cooling, and they work on different principles. Here's a brief explanation of each and their application in refrigerators and freezers:
Compression Cooling:
- Compression cooling is the most common method of cooling used in household refrigerators and freezers, as well as in many air conditioning systems.
- The key component in compression cooling is the compressor. The refrigerant gas is compressed, which causes it to heat up. This high-pressure, high-temperature gas then flows through a condenser coil located outside the appliance, where it releases heat to the surrounding air, causing the refrigerant to condense into a high-pressure liquid.
- The high-pressure liquid refrigerant then passes through an expansion valve, which reduces its pressure and temperature. This results in the refrigerant becoming a low-pressure liquid-gas mixture, which is then sent into the evaporator coil inside the refrigerator or freezer.
- In the evaporator coil, the refrigerant absorbs heat from the interior of the appliance, cooling the air and items inside. As the refrigerant absorbs heat, it evaporates into a low-pressure gas once again, and the cycle continues.
Absorption Cooling:
- Absorption cooling is a less common cooling method used in some specialized applications and older refrigeration systems.
- Absorption cooling relies on a heat source (such as a gas burner or electric heater) to generate the necessary heat to drive the cooling process.
- In an absorption cooling system, a mixture of water and ammonia (or other refrigerant-absorbent pairs) is used. The refrigerant-absorbent mixture is heated in a generator using the external heat source, causing the refrigerant (ammonia) to evaporate and separate from the absorbent (water).
- The refrigerant vapor then travels to a condenser, where it liquefies by releasing heat to the surroundings, similar to the compression cooling process.
- The liquid refrigerant then flows through an expansion valve and an evaporator, just like in compression cooling. As it absorbs heat in the evaporator, it evaporates into a vapor once more, and the cycle repeats.
Refrigerators and freezers typically use compression cooling due to its efficiency, compactness, and widespread availability. Absorption cooling systems are less commonly found in modern domestic refrigeration due to their lower efficiency and larger size.
In summary, compression cooling is the dominant technology used in household refrigerators and freezers, while absorption cooling is used in specific applications and older refrigeration systems.