In HVAC systems, air is typically cooled by passing it over a cooling coil. Most cooling coils are finned-tube heat exchangers in which cool water or refrigerant flows through tubes, and the tubes have external fins to increase heat transfer area. If the air is cooled below the dewpoint temperature, water will condense and must be drained from the bottom of the cooling coil. A schematic of a cooling coil is shown below.
