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The air blower's flow rate is variable. For a single VAV air handler that serves multiple thermal zones, the flow rate to each zone must be varied as well. Simple VAV terminal unit. A VAV terminal unit, [9] often called a VAV box, is the zone-level flow control device. It is basically a calibrated air damper with an automatic actuator. The VAV ...
An HVAC system that has a stable supply-air temperature, and varies the air flow rate to meet the temperature requirements. Compared to constant air volume systems, these systems conserve energy through lower fan speeds during times of lower temperature control demand. Most new commercial buildings have VAV systems.
DCV is primarily used in variable-air-volume (VAV) systems. In DCV VAV systems, airflow to a zone is modulated to control the temperature and outdoor airflow to the space. Using the pollutant levels measured in a zone, the system’s controller sets the zone’s minimum airflow requirement to dilute the pollutant concentration.
Constant air volume (CAV) is a type of heating, ventilating, and air-conditioning system. In a simple CAV system, the supply air flow rate is constant, but the supply air temperature is varied to meet the thermal loads of a space. [1] Most CAV systems are small, and serve a single thermal zone.
Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV), is an HVAC technology invented by Daikin Industries, Ltd. in 1982. [1] Similar to ductless mini-split systems, VRFs use refrigerant as the primary cooling and heating medium, and are usually less complex than conventional chiller -based systems.
A centrifugal fan produces more pressure for a given air volume, and is used where this is desirable such as in leaf blowers, blowdryers, air mattress inflators, inflatable structures, climate control in air handling units and various industrial purposes. They are typically noisier than comparable axial fans (although some types of centrifugal ...
The Tales of Known Space were first published primarily as short stories or serials in science fiction magazines. Generally the short fiction was subsequently released in one or more collections and the serial novels as books. Some of the shorter novels (novellas) published in magazines were expanded as, or incorporated in, book-length novels.
Centrifugal fans are, like axial fans, constant-volume devices, meaning that, at a constant fan speed, a centrifugal fan moves a relatively constant volume of air rather than a constant mass. This means that the air velocity in a system is fixed, but the actual mass of air flowing will vary based on the density of the air.