A cooling coil is a device intended to allow the contents of the coil to cool as they move through it. Cooling coils can be used in materials processing to control the temperatures of various components, and they are also employed in heating and cooling systems where space is at a premium and other cooling arrangements are not feasible. This cooling mechanism is relatively simple and can usually be implemented at reasonably low cost.
As materials move through a cooling coil, heat exchange occurs. Heat is lost through the surface area of the coil, making the contents colder. The amount of heat lost depends on the length of the coil; just as people try to keep hot water pipes short to prevent heat loss between the water heater and the end source, people can make cooling coils extremely long to promote heat loss. The coiled design allows for a long of surface area for heat exchange in a relatively confined space, as the tubing does not have to be stretched out.
Depending on how a system is designed, materials may be actively pumped through a cooling coil or the system may take advantage of the coil design to pull materials through. In a pressurized system, the differences in density between cold and hot materials drive the circulation of materials through the cooling coil, keeping up a steady flow. The temperature never fully stabilizes, as new hot materials always enter one end while the cooled materials leave the other.
People can use an array of cooling coils to make a space get colder even faster. Coils can also be wrapped around components that must be kept chilled. These components are positioned in the area of the coil where the right temperature is reached, and the material inside the coil circulates freely to provide cooling.
Proper maintenance of cooling coils is critical. They can become fouled over time, reducing the total circulation and making it harder to reach the desired temperature. Corrosion can also become a problem, as it may eat through the coil and create a leak. Many substances used as refrigerants inside cooling coils are toxic and can pose a health hazard if they are inadvertently released. Other concerns can include wear around the sites of joints, creating a leak in a cooling coil, as well as a potential reduction in pressure inside the cooling system that may cause it to stop functioning correctly.