A chill water coil is a type of heat exchanger that is used to cool down air or other fluids. It works by passing a coolant, such as water, through a series of coils or pipes. As the coolant passes through the coils, it absorbs heat from the air or fluid, thus cooling it down. Chill water coils are often used in air conditioning systems, refrigeration systems, and other cooling applications. They are also used in industrial processes, such as in power plants and chemical plants, to cool down process fluids. Chill water coils are a cost-effective and efficient way to cool down air or other fluids, making them a popular choice for many applications.