What is a 'chiller' used for in HVAC systems?

A chiller is an essential component in HVAC (Heating, Ventilation, and Air Conditioning) systems, specifically designed to remove heat from a liquid through the use of a vapor-compression or absorption refrigeration cycle. This process effectively lowers the temperature of the liquid, typically water, which is then circulated through building systems to cool air or equipment.

The refrigeration cycle involves several steps, including evaporation, compression, condensation, and expansion, which together facilitate heat removal from the liquid. This chilled liquid can either be used directly to cool spaces or contribute to larger systems like cooling towers or air handling units.

Unlike heating systems or water circulation processes that focus on adding warmth, or air filtration systems that target air quality, the primary function of a chiller is thermal management—specifically, the extraction of heat, making it vital for maintaining comfortable indoor conditions in commercial and industrial settings. Thus, option C accurately represents the fundamental role of a chiller in HVAC systems.