Types Of Cooling Systems

Centralized cooling systems offer several advantages, including easier maintenance, improved air quality, and better humidity control. With all the plant located in a single area, maintenance personnel can access and service equipment more efficiently. Additionally, centralized systems can provide better air quality by allowing for more effective filtration and humidification. Furthermore, centralized systems can maintain a consistent humidity level throughout the building, which is particularly important in applications such as data centers or laboratories where precise environmental control is critical.

Variable air volume (VAV) systems and constant volume (CV) systems are two types of centralized air systems. In a CV system, the airflow rate remains constant, while the temperature is controlled by adjusting the cooling or heating coil output. In contrast, VAV systems vary the airflow rate to match the changing cooling or heating demands of the building. VAV systems are more energy-efficient and can provide better zone control, but they require more complex controls and may be more expensive to install. CV systems, on the other hand, are simpler and less expensive, but may waste energy by constantly circulating air at a fixed rate.

An air handling unit (AHU) in a centralized cooling system typically consists of several components, including heating and cooling coils, a humidifier, filters, and fans. The heating coil is usually connected to a hot water supply, while the cooling coil is connected to a chilled water supply. The humidifier adds moisture to the air to maintain a desired humidity level, while the filters remove airborne contaminants. The fans, which can be axial or centrifugal, move the conditioned air through the ductwork to the building spaces.

Local cooling systems differ from centralized cooling systems in that they are decentralized and typically serve a single room or zone. Local systems can include window units, split systems, or packaged terminal air conditioners (PTACs). They are often less expensive to install and can provide more precise temperature control, but may be less efficient and more difficult to maintain than centralized systems. Local systems are often used in applications where a centralized system is not feasible or cost-effective, such as in small buildings or in areas with limited mechanical space.

Chillers are a crucial component of centralized cooling systems, providing chilled water for the cooling coils. The benefits of using chillers include high cooling capacities, precise temperature control, and energy efficiency. Chillers can also be designed to operate at part-load conditions, making them suitable for buildings with varying cooling demands. Additionally, chillers can be configured in multiple arrangements, such as in series or parallel, to provide redundancy and improve system reliability.

Heat raising systems, such as gas boilers or heat pumps, support centralized cooling systems by providing hot water for the heating coils in the air handling units. During the heating season, the hot water is circulated through the coils to warm the air, which is then distributed to the building spaces. The heat raising system can also provide hot water for other building services, such as domestic hot water or space heating. In some cases, the heat raising system can be designed to recover heat from the chiller condenser, improving overall system efficiency.