An air handling unit is a collection of elements mounted in big, accessible box-shaped units called modules that contain the necessary ventilation for purifying, conditioning, or rejuvenating the interior air in a building or premises.
FREMONT, CA: A central hydronic system's essential equipment is the air-handling unit (AHU), which processes and conditions the air before distributing it to various conditioned regions. The needed volume of outside air and recirculating air is frequently combined and conditioned in an AHU. The discharge air temperature is then kept within predetermined limits via a control mechanism. Following that, the motive force is added to the conditioned supply air, and it is disseminated to various conditioned regions via ductwork and space diffusion devices. Numerous air-handling equipment is modular, allowing for the addition of components as needed. AHUs are composed of the following components: an outdoor air intake and mixing box section, a fan section comprised of a supply fan and fan motor, a coil section comprised of a water-cooling coil, and, depending on the application, a humidifier. AHU supply volume flow rates range from 2000 to 63,000 cubic feet per minute (945 to 29. 730 liters per second). Whether a return fan or a relief fan should be installed to an air system is determined by the air system's structure and operating characteristics, as well as the return system's total pressure loss. A heating coil is mainly employed in the air conditioning unit that serves the perimeter zone or warms up the heating season in the morning. The usage of a pre-cooling coil to cool water from the cooling tower as a water economizer is explained. Humidifiers are used in air conditioning processing and health care facilities where space humidity must be managed.
The following are some of the components of an air handling unit that may be included in the equipment.
Housing: The housing for the AHU's various components is typically made of metal; however, some are coated to avoid corrosion.
1-2 inches of polyurethane foam or polyurethane urethane is used to insulate the parts with fans and coils to prevent condensation on the panel. Additionally, a drain pan is employed as a precaution in the event of water condensation.
Fan: A centrifugal fan is utilized to circulate air throughout the building's various components. Backward Inclined, Backward Curved, Forward Curved, and Airfoil are the most common types of fans.
The fan to use will be determined by the air volume and static pressure requirements of the system. Typically, the system's designer will perform this selection using specialist software.
The motor and fan are typically mounted on the vibration isolator unless the drive assembly is external to the fan casing to minimize vibration's influence on the panel.
Variable air volume (VAV) systems have grown in popularity in recent years due to their ability to vary the volume of air delivered based on the load condition. When the load is high, the fan speed is increased; when the load is low, the fan speed is decreased.
The fan's speed is controlled by employing a frequency inverter rather than a standard motor such as a PSC motor. The frequency inverter enables more precise fan speed control, as a wide range of fan speeds from extremely low to extremely high can now be used depending on the load conditions.
This technique has improved energy efficiency and is consistent with the trend toward greener energy.