Keeping your refrigerator's interior cold requires several related energy processes.
Refrigerators use several processes -- electrical, mechanical, thermal and chemical -- to keep food cold. Each process converts or transfers energy from one form into another. Each transformation allows the refrigerator to remove heat from the inside of the refrigerator and dissipate this heat outside the refrigerator.
Electrical Energy Transformed Into Mechanical Energy
Refrigerators produce a familiar hum. This hum is caused by the conversion of electrical energy into mechanical energy by means of an electrical motor. Electrical motors use electrical windings to convert electrical energy into transient electromagnetic fields. The rotor inside an electrical motor turns when these fields are used in conjunction with permanent magnets. The rotor is connected to the refrigerator's compressor, which moves the refrigerant through the refrigeration lines, allowing the refrigerant to carry heat from the inside of the refrigerator to the outside.
Chemical Processes Affecting Refrigeration
Refrigerators contain a chemical refrigerant (either chlorofluorocarbon or tetrafluoroethane) inside a sealed cooling system. When this refrigerant is compressed into a small space at high pressure, the refrigerant absorbs heat. As this heated refrigerant passes through the outside radiator -- or condenser -- at the back of the refrigerator, the refrigerant loses this heat. The cooled refrigerant is pushed into the coils in the refrigerator interior to cool the air in the refrigerator compartment. The cooler finally is routed back into the compressor to start the cooling cycle anew.
How the Second Law of Thermodynamics Applies to a Refrigerator
The Second Law of Thermodynamics explains the impossibility for heat to flow from a cold object to a hot object without any work being done. Simply stated, heat energy will spontaneously disperse from being localized to being spread out if there is nothing preventing that energy from dispersing. Using this principle, heat energy is removed from the refrigerator's inside compartment. This heat is carried from the compartment and is disposed of through the condenser coils. These coils radiate the waste heat to the air surrounding the coils while cooling the refrigerant, thus completing the work cycle of cooling the refrigerator interior.
Temperature Regulation
Refrigerators keep food cold by transferring thermal energy from the refrigerator interior to the exterior. Refrigerators are not vacuum sealed; therefore, all refrigerators allow some heat to creep into the interior compartment. Refrigerators use a bimetallic thermocouple to control the temperature. When two dissimilar metals are joined together, a voltage differential is created, which increases as the ambient temperature increases. This voltage can be used to turn on the compressor motor via an electric relay to cool the refrigerator compartment.
Tags: refrigerator interior, energy from, cool refrigerator, cool refrigerator compartment, electrical energy
