A simple answer to why refrigerator cooling coils are made of copper is that copper is an excellent conductor of electricity. A more detailed explanation deals with how the refrigerator functions and how various elements interact with each other and adapt to the changing temperatures.
What is behind your fridge?
Let us do a quick roundup of the components of the fridge and its working. The refrigerator consists of a thermally insulated compartment attached to a heat pump that transfers the heat from the case to the external environment, thereby decreasing the temperature inside below room temperature, usually around 3 to 5 degrees Celsius.
The coolant’s cooling effect absorbs internal heat and runs through the evaporator coils that are on the back of the fridge. The heat in the coolant gets dissipated from the back of the refrigerator to the surrounding environment. This is the basic working of any fridge and deep freezer in India and abroad.
Where does the copper come in?
The evaporator through which the coolant passes consists of many thin wires usually made of aluminum or copper. These wires run between the coolant pipes and absorb the heat to dissipate them.
Copper is preferred for the evaporator tubes because it is relatively inert and has excellent ductility (it can be stretched, molded, and drawn into thin wires quickly). This means it can be soldered easily at relatively lower temperatures and can make tight seals. This is true for any deep freezer in India. The entire copper setup can be used alongside compounds with low melting points and have good adhesive properties.
The significant advantage of using copper is that it is an excellent thermal conductor. It also exhibits less internal material fatigue from cyclical temperature and pressure changes when compared to other conductors such as aluminum.
Although the price of copper comes on the costlier side, copper is much easier to repair when compared to aluminum. Hence, coils that are made out of copper are stronger and more durable.
On the topic of maintenance, too, it has been seen that especially deep freezers in India, which have to adapt to the varying climate conditions, are better off with copper coils since they are easy to clean and maintain. Unlike aluminum coils that need to be placed inside a cabinet for protection from damage, copper coils can be managed with minimum coverage.