What is a "cooling coil" used for in refrigeration?

A cooling coil is primarily utilized in refrigeration systems to cool air. This process occurs as air is passed over refrigerant-filled tubes within the coil. The refrigerant inside these tubes absorbs heat from the air, resulting in a drop in temperature as the air circulates around the coil. This fundamental principle of heat exchange establishes the cooling effect that makes refrigeration systems effective for maintaining lower indoor temperatures.

In contrast, the other options describe functions that are not characteristic of a cooling coil. Heating air would involve using a heating element or a different type of coil, rather than a cooling coil. Increasing humidity typically concerns processes like humidification or vaporization, which would not involve a cooling coil. Additionally, while removing heat from the environment is a broader concept applied to refrigeration systems overall, it does not specifically define the role of the cooling coil, which is focused on cooling the air rather than directly interacting with environmental heat.