To maintain low temperatures in refrigerators and freezers without using ice packs, modern refrigerators and freezers utilize electricity, a refrigeration system, and various design features to regulate and control the temperature. Here's how they work:
Compression Refrigeration System: Most household refrigerators and freezers use a compression refrigeration system, which consists of four key components: a compressor, condenser, expansion valve, and evaporator. The refrigeration system contains a refrigerant, a chemical compound with a low boiling point, which undergoes phase changes to absorb and release heat, providing the cooling effect.
Compressor: The compressor is the heart of the refrigeration system. It compresses the refrigerant, raising its pressure and temperature.
Condenser: The high-pressure, high-temperature refrigerant then flows to the condenser, where it releases heat to the surrounding environment. The condenser coils are located on the back or bottom of the refrigerator and are designed to dissipate the heat efficiently.
Expansion Valve: After the refrigerant leaves the condenser, it passes through an expansion valve, where its pressure is reduced suddenly. This causes the refrigerant to evaporate rapidly, leading to a significant drop in temperature.
Evaporator: The cold, low-pressure refrigerant now enters the evaporator coils, which are usually located inside the freezer or refrigerator compartments. As the refrigerant evaporates and absorbs heat from the inside of the appliance, it cools the air and the stored food.
Fans: Many modern refrigerators and freezers have fans that circulate air within the compartments, ensuring even cooling and temperature distribution.
Thermostat: The refrigerator has a thermostat that senses the temperature inside the compartments. When the temperature rises above the desired level, the compressor kicks in, and the refrigeration cycle starts again to lower the temperature.
Insulation: Like the old iceboxes, modern refrigerators and freezers are also well-insulated to minimize heat exchange with the external environment. Quality insulation helps maintain the cold temperature inside the compartments more effectively.
Automatic Defrost: Some modern refrigerators and freezers have automatic defrost systems. These systems periodically melt any accumulated ice or frost on the evaporator coils to maintain efficiency and prevent excessive ice buildup.
By utilizing this advanced refrigeration technology and design, modern refrigerators and freezers can maintain low temperatures without the need for ice packs or ice blocks. The constant and controlled refrigeration cycle keeps the food fresh and safe for consumption.